Donor Kidney Criteria: What Makes a Kidney Suitable?

Donor kidney criteria are the medical, anatomical, immunological and safety factors transplant teams use to determine whether a kidney can be donated and transplanted responsibly. A suitable donor kidney is not simply a kidney that “works.” Doctors must determine whether removing it is acceptably safe for the living donor, whether the kidney itself has sufficient function and suitable anatomy, whether the donor and recipient are compatible, and whether transplantation is expected to provide meaningful benefit to the recipient.

This creates two related but different questions.

The first is:

Can this person safely donate a kidney?

The second is:

Is this kidney suitable for this particular recipient?

A potential living donor can have excellent kidney function yet be incompatible with the intended recipient. Another person may be a strong blood-type and HLA match but have medical findings that make nephrectomy unsafe. A deceased donor kidney may have characteristics associated with shorter expected graft longevity yet still offer substantial benefit to the right recipient.

That is why responsible [Kidney Transplant] internal content should never describe one creatinine result, one donor age or one blood type as sufficient proof that a kidney is “good.”

Suitability is a multidisciplinary decision.

Donor kidney criteria: the direct answer

Donor kidney criteria include adequate kidney function, acceptable urine findings, suitable kidney anatomy, manageable stone and disease risk, safe donor health, appropriate infection and malignancy assessment, and an acceptable donor-recipient compatibility profile. For a living donor, the transplant team must also determine that removing one kidney leaves the donor with an acceptably low long-term health risk. KDIGO considers GFR of at least 90 mL/min/1.73 m² generally acceptable, values from 60–89 subject to individualized assessment, and values below 60 unsuitable for donation. Blood type, HLA antibodies and crossmatching then help determine whether the kidney can be transplanted safely into the intended recipient.

What does “a suitable donor kidney” actually mean?

Patients often use the word suitable as though it describes one property of the organ.

In reality, a kidney can be suitable in one sense and unsuitable in another.

It may be healthy enough to function well after transplantation but come from a living donor who should not undergo surgery.

It may come from an exceptionally healthy living donor but have an arterial configuration that requires careful surgical planning.

It may have ideal anatomy but be immunologically incompatible with the recipient.

It may be compatible and medically sound but involved in a proposed living-donor relationship that does not yet satisfy the destination country’s legal requirements.

For deceased donor transplantation, another layer is added: the transplant team evaluates the condition of an organ recovered after death, the circumstances of the donor’s illness, expected graft longevity and the recipient’s individual need.

A useful model is therefore to think of suitability as several gates.

A transplant team must consider all relevant gates before proceeding.

Living donor kidney criteria begin with donor safety

Living kidney donation is fundamentally different from recovering a kidney from a deceased donor.

A living donor is usually healthy and does not require nephrectomy for personal medical treatment.

Doctors are therefore intentionally exposing a healthy person to surgery in order to benefit somebody else.

That creates a high safety threshold.

The potential donor undergoes both medical and psychosocial evaluation. HRSA guidance explains that living donor evaluation is intended to identify occult kidney disease, infectious disease and medical conditions that could increase post-donation risk. Psychosocial assessment also evaluates decision-making capacity, psychiatric illness and possible coercion.

Current U.S. OPTN policy additionally requires living kidney donors to be excluded for specific circumstances such as uncontrollable hypertension or hypertension with end-organ damage, type 1 diabetes, and selected type 2 diabetes situations where individualized assessment indicates end-organ damage or unacceptable lifetime risk. General living-donor exclusions also include certain active malignancies, acute symptomatic infection until resolved, coercion and uncontrolled psychiatric conditions requiring treatment.

A kidney therefore cannot be called suitable merely because its laboratory values look good.

The person carrying it must also be suitable to donate.

Kidney function: one of the central donor kidney criteria

The most obvious requirement is that the potential donor’s kidneys function adequately.

But doctors do not evaluate this using serum creatinine alone.

Creatinine can be influenced by age, muscle mass and other factors. Transplant programs therefore estimate glomerular filtration rate and may confirm kidney function using measured GFR, creatinine clearance, cystatin C or repeat testing depending on the situation.

KDIGO recommends confirming donor kidney function when appropriate and provides three widely used decision ranges.

These values should not be interpreted as a do-it-yourself donor approval tool.

A GFR of 95 does not cancel other risk factors.

A GFR of 82 does not automatically mean rejection.

Age, blood pressure, urinary albumin, diabetes risk, family history and the expected function of the remaining kidney all affect the final decision.

The underlying principle is renal reserve.

After donation, the donor will have less total kidney tissue. The remaining kidney adapts, but the transplant team wants confidence that enough functional reserve remains for the donor’s future.

Why both kidneys may need to be evaluated separately

Most people have two kidneys that perform similarly.

Not everyone does.

One kidney may be smaller.

One may have a cyst, stone, vascular variation or scar.

One may contribute less to total kidney function.

When imaging shows kidney-size asymmetry, parenchymal abnormalities, vascular abnormalities or urinary-tract differences, KDIGO recommends assessing single-kidney function when needed. If the abnormality does not prevent living donation, KDIGO generally recommends donating the more affected kidney so that the donor keeps the better kidney.

That principle illustrates the ethical priority of living-donor surgery.

The goal is not:

“Give the recipient the absolute best kidney and leave the donor whatever remains.”

The goal is:

“Proceed only if donation is safe, and protect the donor’s future health when selecting which kidney to remove.”

Urine albumin: kidney function can look normal while damage is present

A donor can have an apparently reassuring GFR and still show evidence of kidney damage in the urine.

Albuminuria is particularly important.

KDIGO recommends measuring urinary albumin rather than relying only on total urinary protein during donor assessment.

Persistent albumin loss can indicate glomerular kidney injury or another process that may increase future chronic kidney disease risk.

This is one reason a potential donor who sends only creatinine and eGFR to a transplant coordinator has not completed kidney screening.

Donor kidney suitability requires evidence that the kidney is functioning adequately and is not showing markers of clinically important damage.

Transient albuminuria can occur, so abnormal results may require confirmation.

The transplant nephrologist needs to determine whether the abnormality is persistent, what caused it and how it changes the donor’s projected lifetime risk.

Blood in the urine can change donor kidney suitability

Microscopic blood in the urine can be caused by several conditions.

Some are temporary.

Others can indicate stones, urologic disease or glomerular kidney disease.

A single trace result should not automatically be interpreted as donor exclusion.

Persistent unexplained hematuria, however, requires investigation.

A person preparing to donate should therefore avoid the mindset:

“My kidney function is normal, so everything else in the urine report is irrelevant.”

Urine findings can expose a condition that is not yet affecting creatinine.

The purpose of donor evaluation is to discover those conditions before renal reserve is reduced by nephrectomy.

Kidney anatomy: what surgeons need to see

A living donor kidney must also be technically removable and transplantable.

CT angiography or another suitable imaging protocol allows the surgical team to evaluate:

kidney size and shape;

renal arteries;

renal veins;

ureter and collecting system;

stones;

cysts;

masses;

scarring; and

other structural abnormalities.

Current U.S. living-donor evaluation standards specifically include anatomical assessment of kidney size, masses, cysts, stones and vascular anatomy. OPTN medical-evaluation requirements also address kidney-specific history such as previous kidney injury, proteinuria, hematuria, nephrolithiasis and recurrent urinary infections.

An anatomical variation is not automatically a contraindication.

Humans vary.

Some people naturally have more than one renal artery or other vascular variations.

The relevant question is whether experienced donor and transplant surgeons believe the anatomy allows safe procurement and implantation without exposing donor or recipient to unacceptable risk.

Multiple renal arteries: does a kidney have to have one artery?

No.

A living donor kidney does not have to possess one perfectly simple renal artery to be transplantable.

Multiple renal arteries are encountered in clinical transplantation.

They can make the operation technically more complex because each important vessel must provide adequate blood supply after implantation.

The surgical team therefore studies vascular imaging before selecting the kidney.

The patient-level message is important:

complex anatomy is not the same thing as unsuitable anatomy.

A transplant surgeon decides whether the vascular configuration can be reconstructed and implanted safely.

The donor should not interpret a radiology comment such as “two renal arteries” as either automatic rejection or automatic acceptance.

Kidney size and asymmetry

Kidney size is another structural clue.

A substantial difference between the two kidneys may indicate unequal function or previous disease.

That is why KDIGO recommends further functional assessment when kidney size or anatomy differs.

Size also matters in relation to the recipient.

The concept of nephron mass reflects the amount of functioning kidney tissue available to meet the recipient’s metabolic needs.

A very small donor kidney transplanted into a much larger recipient has historically raised concern about whether the graft provides enough nephron mass.

However, a 2025 systematic review found that the evidence on donor-recipient size mismatch and major graft outcomes is complex rather than supporting one simple cutoff.

A transplant team therefore considers size as part of the total profile rather than using height or body weight as a stand-alone matching rule.

Can a kidney with a cyst be donated?

Sometimes.

Not every renal cyst indicates dangerous kidney disease.

Simple kidney cysts become more common with age and may have little clinical significance.

Other cystic findings can suggest hereditary disease, complex lesions or malignancy risk.

The transplant team therefore evaluates:

the number of cysts;

their appearance;

their location;

whether both kidneys are involved;

family history; and

whether imaging suggests a simple benign lesion or something requiring further investigation.

The same term—“kidney cyst”—can therefore describe very different situations.

This becomes particularly important when a biologically related donor is being evaluated for a recipient with polycystic kidney disease.

In that setting, isolated reassurance from one ultrasound report may not be enough. The transplant team needs confidence that the donor does not carry clinically relevant inherited disease.

Internal link: Polycystic Kidney Disease → /en/conditions/polycystic-kidney-disease

Kidney stones and donor kidneys

A history of kidney stones does not automatically make every kidney unsuitable.

The team wants to know:

Was there one isolated stone or recurrent disease?

Is a stone still present?

Does the donor have stones in one kidney or both?

What caused them?

Does metabolic testing suggest a high recurrence risk?

Current U.S. kidney-donor evaluation requirements include detailed assessment for candidates with relevant nephrolithiasis history, including metabolic urine testing in specified situations.

The logic is straightforward.

A donor who develops recurrent obstructing stones after nephrectomy has only one kidney remaining.

The consequences of future stone disease can therefore be more important than in someone who retains two kidneys.

Donor evaluation focuses not merely on whether a stone exists today but on the expected long-term recurrence risk.

Blood pressure and donor kidney criteria

Hypertension matters because it affects both cardiovascular and renal health.

A kidney can appear structurally normal while long-standing blood pressure has already increased future chronic kidney disease risk.

Current OPTN policy excludes living kidney donors with uncontrollable hypertension or hypertension accompanied by end-organ damage.

Some carefully selected people with controlled hypertension may still be considered under clinical guidelines and center-specific risk thresholds.

This is another example of why donor kidney criteria are not a simple checklist.

The transplant team needs to understand:

the donor’s age;

how high the blood pressure is;

how many medications are needed;

whether urinary albumin is present;

whether the heart or vasculature shows target-organ damage; and

what other metabolic risks exist.

A healthy older donor with stable blood pressure on one medication may not have the same risk profile as a much younger donor with difficult-to-control hypertension and albuminuria.

Diabetes and metabolic health

Diabetes is a central concern because it is a major cause of chronic kidney disease.

A potential donor who already has substantial diabetes-related kidney or vascular risk may not be a safe candidate for nephrectomy.

Current U.S. OPTN policy excludes living kidney donors with type 1 diabetes and requires exclusion of selected type 2 diabetes candidates when individualized assessment shows end-organ damage or unacceptable lifetime complication risk.

Prediabetes also matters.

It does not automatically mean the donor can never donate.

But age, BMI, family history, blood pressure, fasting glucose and HbA1c can collectively predict a future metabolic trajectory.

A young donor with several diabetes risk factors may live another 50 or 60 years with reduced renal reserve.

That long horizon changes the risk calculation.

Patients whose kidney failure resulted from diabetes can review your dedicated Diabetic Kidney Disease page for recipient-side context.

Internal link: Diabetic Kidney Disease → /en/conditions/diabetic-kidney-disease

Donor age: is a younger kidney always better?

Age influences kidney biology, but donor age does not work as one universal exclusion.

Older kidneys generally have less renal reserve than younger kidneys.

Older living donors also have a greater probability of hypertension, cardiovascular disease and other comorbidities.

Yet carefully selected older adults can donate kidneys.

The previous article in this cluster covers the age limit for donating kidney in detail.

For kidney suitability, the important principle is:

age modifies risk and expected graft longevity; it does not automatically determine suitability.

For deceased donor kidneys, age is explicitly incorporated into the U.S. Kidney Donor Profile Index.

For living donation, the medical team has the advantage of a full elective evaluation before surgery.

Kidney donor match: what actually has to match?

The secondary keyword kidney donor match is frequently misunderstood.

A donor kidney does not need to match every characteristic of the recipient.

The donor and recipient do not need to be the same age.

They do not need to be the same sex.

They do not need identical body size.

They do not need to be genetically related.

They do not necessarily need identical ABO blood types, although the blood-group combination must be appropriate for the planned pathway.

The core immunological matching process examines ABO compatibility, HLA characteristics, recipient antibodies and crossmatch results.

A strong donor candidate therefore needs both:

medical suitability to donate, and

acceptable compatibility with the intended recipient.

These concepts must remain separate.

Blood type is only one part of a kidney donor match

The previous Day 5 article explains blood type and tissue matching in detail.

At a high level, conventional ABO-compatible kidney transplantation generally follows this pattern:

But a compatible blood group does not make a kidney suitable by itself.

The donor may have unsafe kidney function.

The recipient may carry donor-specific HLA antibodies.

The crossmatch may be positive.

An anatomical problem may change surgical feasibility.

Matching is therefore a sequence of assessments rather than a single blood-type comparison.

HLA and donor-specific antibodies

Human leukocyte antigens are immune-system markers present on cells.

The recipient may develop antibodies against HLA antigens that are not their own.

Pregnancy, prior transplantation and blood transfusion can contribute to sensitization.

If a recipient already has strong antibodies directed against a potential donor’s HLA antigens, transplantation can carry increased rejection risk.

The transplant laboratory therefore characterizes both donor HLA and recipient antibody profile.

This is where a healthy kidney can become unsuitable for one recipient while remaining potentially suitable for another.

A kidney’s suitability is partly recipient-specific.

Crossmatch: the donor-specific compatibility test

Crossmatching asks whether the recipient has antibodies that react with this specific donor.

A negative crossmatch is generally reassuring for conventional transplantation.

A positive crossmatch can indicate major immunologic risk.

That does not mean the kidney itself is defective.

It means the proposed donor-recipient combination may be unsafe without another strategy.

Possible alternatives can include a different donor, paired kidney donation or selected specialist incompatibility-management pathways.

The exact options depend on the country and transplant program.

This distinction matters because patients often hear:

“Your donor kidney is not suitable.”

The more accurate explanation may be:

“The donor is healthy, but this kidney is not immunologically suitable for you through a standard direct pathway.”

Can a female donate a kidney to a male?

Yes. A female can donate a kidney to a male.

Being female does not prevent someone from donating a kidney to a male recipient, and sex mismatch is not a standard medical contraindication to living kidney donation.

Older studies produced mixed results about whether a female-donor-to-male-recipient combination could have somewhat different graft function, potentially because average kidney size and nephron mass differ between sexes.

More recent evidence is reassuring.

A 2025 dual-center study of more than 2,000 living donor kidney transplants compared male-to-male, female-to-male, male-to-female and female-to-female combinations. Ten-year death-censored graft survival was similar across the groups, with no statistically significant overall difference.

Another contemporary living-donor study found no significant difference in immediate graft function or survival according to donor sex.

Therefore, asking “can a female donate a kidney to a male?” should not be answered with a blanket concern about sex.

The correct answer is yes, provided the donor is medically suitable and the donor-recipient pair passes the full transplant evaluation.

Why some older studies raised concerns about female-to-male donation

The concern historically came partly from kidney size.

On average, men tend to have larger body size and potentially greater nephron demand.

A smaller kidney transplanted into a large recipient theoretically faces a greater functional workload.

Older meta-analyses found worse outcomes in some female-donor-to-male-recipient groups.

However, contemporary studies have not consistently reproduced a clinically meaningful survival disadvantage. A 2024 deceased-donor paired-kidney analysis found no significant association between donor-recipient sex discordance and rejection or graft failure after adjustment.

This is why modern counseling should avoid the simplistic statement:

“A woman’s kidney is too small for a man.”

The transplant team considers actual donor kidney function, donor and recipient body size, anatomy and immunologic factors rather than sex labels alone.

Donor-recipient size matching

Body size can be considered because the transplanted kidney needs enough functional capacity for the recipient.

But size matching is not an organ-allocation rule comparable with ABO compatibility.

A 2025 systematic review of donor-recipient size mismatch concluded that associations between size mismatch and graft outcomes are inconsistent and complex.

A smaller female donor can therefore donate successfully to a larger male recipient.

A tall male donor does not automatically provide a better kidney for every recipient.

The kidney’s measured function and the overall clinical picture are more informative than sex or height by themselves.

Can a mother donate a kidney to her son?

Yes.

A medically suitable mother can potentially donate a kidney to an adult or pediatric son.

The same principles apply:

the mother must be safe to donate;

kidney function must be adequate;

the recipient and donor must undergo compatibility assessment;

the anatomy must be suitable; and

the donation must meet the legal requirements of the country.

Pregnancy history can affect HLA sensitization in the recipient only if the recipient is the person who has been pregnant; it is not by itself a barrier to a mother donating.

Where biological family kidney disease is suspected, inherited risk can be relevant.

The Day 4 article on family-member donation explores this issue in greater detail.

Can a wife donate a kidney to her husband?

Yes.

Spouse-to-spouse kidney donation is widely performed.

Because the donor is not biologically related, HLA similarity may be lower than in some sibling pairs, but perfect HLA matching is not required.

A negative crossmatch and acceptable antibody profile can make a spouse a very suitable donor.

In Türkiye, spouse donation also intersects with specific legal relationship rules, so international patients need both clinical and regulatory review.

A healthy spouse is still not automatically approved.

The full living donor assessment applies.

Can the donor be a different race or ethnicity?

Yes.

Race and ethnicity are not themselves kidney-matching requirements.

ABO frequencies and HLA distributions can vary among populations, which can affect the statistical likelihood of finding certain matches in deceased-donor pools.

But an individual living donor is evaluated directly.

A donor and recipient from different ethnic backgrounds can be perfectly suitable for transplantation.

Modern transplant medicine increasingly emphasizes individual biological measurements rather than broad demographic assumptions.

Does a kidney donor have to be related?

Not in every healthcare system.

The United States and United Kingdom allow regulated living donation from people such as spouses, friends and selected nondirected donors.

Türkiye uses a more specific relationship and ethics framework for living donation.

Your previous Day 4 article addresses family-member rules in depth.

The key point for donor kidney criteria is that relationship does not determine kidney quality.

It determines part of the legal and psychosocial pathway.

A spouse’s kidney can be an excellent graft.

A sibling’s kidney can be medically unsuitable.

Paired donor kidney transplant: what happens when the donor is healthy but incompatible?

A paired donor kidney transplant—more commonly called kidney paired donation—can help when a person has a willing living donor who is medically suitable but incompatible with them.

Imagine two pairs.

Recipient A cannot receive Donor A’s kidney.

Recipient B cannot receive Donor B’s kidney.

But Donor A is compatible with Recipient B, and Donor B is compatible with Recipient A.

Through a regulated paired exchange, both transplants may become possible.

The U.S. OPTN operates a national Kidney Paired Donation Pilot Program for patients with willing living donors. HRSA notes that participating candidates may receive a living donor transplant sooner and potentially spend less time on dialysis.

NHS Blood and Transplant likewise operates a national living donor kidney-sharing scheme for incompatible pairs.

The important point is that the donor remains an identified, fully evaluated living donor.

Paired donation is not donor sourcing.

Paired donor kidney transplant is not organ trading

This distinction is especially important for Organ Transplant Abroad.

A regulated paired exchange does not involve buying or selling kidneys.

No kidney receives a commercial price.

Instead, legitimate donor-recipient pairs enter a supervised matching system designed to solve incompatibility.

Your platform’s Ethical Sourcing Policy should therefore be internally linked from this section.

Internal link: Ethical Sourcing Policy → /en/ethical-sourcing-policy

The website should continue to make the distinction explicit:

Organ Transplant Abroad coordinates lawful medical pathways for patients who already have potential donors; it does not find, broker or sell human organs.

Paired donor kidney transplant in Türkiye

Türkiye’s current Organ Transplant Services Regulation defines çapraz nakil, or cross transplantation, as transplantation in which donors are exchanged among patients who have unsuitable living donors.

The regulation establishes a Ministry-supervised framework and includes a national software system containing donor-recipient matching information.

Türkiye’s Ministry of Health also continues to maintain an official Living Kidney Donor Selection and Lifelong Follow-Up Clinical Protocol, most recently listed by the Ministry on December 31, 2025.

For an international patient, this has a practical consequence:

Do not assume that a paired exchange can be privately arranged outside the authorized national transplant process.

The transplant center must determine whether the pair qualifies and which regulated pathway applies.

Donor kidneys: living versus deceased donor suitability

The secondary keyword donor kidneys can refer to two very different sources.

Living donor kidneys come from medically evaluated people undergoing elective nephrectomy.

Deceased donor kidneys are recovered after death through an authorized organ-donation system.

Both can provide successful transplantation, but the evaluation process is different.

The phrase “donor kidney criteria” can therefore mean different things depending on whether the organ comes from a living or deceased donor.

How deceased donor kidneys are evaluated

A deceased donor kidney cannot be evaluated exactly like a living donor kidney.

The transplant team has limited time.

The donor may have experienced critical illness, circulatory instability or acute kidney injury before death.

Clinicians therefore review a combination of factors such as:

donor age;

kidney-function laboratory results;

urine output;

medical history;

hypertension and diabetes history;

cause and circumstances of death;

infectious-disease testing;

kidney anatomy;

procurement findings;

biopsy results when performed;

and machine perfusion information when available.

The decision is not simply:

“Is this kidney perfect?”

It is:

“Is the expected benefit of transplanting this kidney into this recipient greater than the alternative of declining it and continuing to wait?”

That distinction is fundamental to deceased-donor transplantation.

What is KDPI?

In the United States, deceased donor kidneys receive a Kidney Donor Profile Index, or KDPI.

KDPI ranges from 0 to 100 and describes the expected longevity of the kidney relative to other recovered deceased donor kidneys.

A lower number is associated with longer expected graft longevity.

A higher number is associated with shorter expected longevity.

HRSA explains that the current KDPI calculation uses donor factors including age, height, weight, mode of death, stroke as cause of death, hypertension history, diabetes history and serum creatinine.

KDPI is not a living-donor score.

It should not be applied to a parent or spouse being evaluated for living donation.

Does a high KDPI mean a kidney is bad?

No.

This is one of the most important points for patient education.

A high KDPI kidney is expected, on average, to function for a shorter period than a lower-KDPI kidney.

That does not mean it is worthless or unsafe.

HRSA’s clinician guidance notes that kidneys with KDPI above 85% have historically provided more than five and a half years of average graft function in the data used for the guide, while restricting acceptance to only low-KDPI kidneys may increase waiting time.

A patient who may otherwise wait several additional years on dialysis could potentially benefit substantially from accepting an organ with shorter expected longevity.

The decision depends on age, health, waiting time, availability of a living donor and individual preferences.

Therefore:

KDPI describes expected longevity—not moral or absolute organ quality.

Lower KDPI does not guarantee a perfect outcome

A kidney with a low KDPI can still fail.

A kidney with a high KDPI can function well for years.

The score summarizes population-level expectations.

It cannot predict exactly what will happen to one patient.

Recipient factors also affect graft survival.

Medication adherence, rejection, infection, recurrent kidney disease, cardiovascular events and other conditions can influence the outcome.

The transplant physician uses KDPI as one input—not as an oracle.

HRSA specifically states that KDPI is not intended to be the only metric used to determine organ suitability.

Deceased donor kidney biopsy

A biopsy can sometimes provide additional information about a deceased donor kidney.

Microscopic examination may assess chronic damage, vascular disease, glomerular changes or other structural features.

But biopsy interpretation has limitations.

Sampling represents only a small part of the kidney.

Quality can differ depending on how the tissue is obtained and processed.

The biopsy therefore sits alongside the donor’s history, creatinine pattern, age, anatomy and other information.

It should not automatically override every other factor.

Current U.S. policy and monitoring have increasingly standardized circumstances in which donor kidney biopsy information is collected and reported. HRSA continues to monitor minimum donor criteria associated with biopsy requirements.

Acute kidney injury in a deceased donor

A donor who develops acute kidney injury before death does not automatically provide unusable kidneys.

Some kidneys can recover function after transplantation.

Transplant teams therefore distinguish potentially reversible acute injury from substantial chronic kidney damage.

This is a specialized decision involving the donor’s clinical trajectory, urine output, creatinine pattern, biopsy information when available and recipient circumstances.

Patients should avoid equating one high terminal creatinine with an inevitably poor organ.

The same creatinine value can have different meaning depending on the clinical context.

Infection and donor kidney suitability

Infection screening protects the recipient because transplant recipients require immunosuppression.

Both living and deceased donors undergo transmissible-disease testing.

Current U.S. OPTN policies were updated in 2026, including shortened testing windows for HIV and West Nile virus and seasonal West Nile virus testing requirements affecting living donor evaluation.

An infection-related result does not always produce one automatic outcome.

Some infections prohibit donation.

Others can be treated or managed.

In selected cases, organs from donors with particular infections may be transplanted into appropriately selected recipients under specific protocols.

These decisions require specialist infectious-disease and transplant expertise.

The patient-level lesson is that “infection screening passed” is part of organ suitability—not an optional extra.

Cancer and donor kidney suitability

Malignancy creates concern because cancer can potentially be transmitted through transplantation.

For living donors, current OPTN policy excludes active or incompletely treated malignancy when it requires treatment beyond surveillance or carries more than minimal known transmission risk.

For deceased donation, malignancy risk is assessed differently depending on tumor type, stage and transmission potential.

A history of cancer does not mean every organ from every donor is automatically unusable.

But donor malignancy requires careful risk classification because immunosuppression can make transmitted cancer particularly dangerous.

Again, kidney suitability is a clinical risk assessment rather than a simplistic yes/no label based only on medical history.

Which living donor kidney is removed?

A healthy donor has two kidneys.

The transplant team needs to decide which one stays and which one is donated.

Donor protection is central.

Surgeons consider:

relative function;

kidney anatomy;

arteries and veins;

stones;

cysts or other abnormalities;

and technical surgical factors.

KDIGO recommends that when one kidney is more affected by an abnormality but donation can still safely proceed, the more affected kidney should generally be donated so that the donor retains the better kidney.

That can sound counterintuitive to recipients.

Why not give them the “best” kidney?

Because living donation must protect the healthy donor first.

The transplant proceeds only if the selected kidney remains appropriate for the recipient.

What does “left kidney preferred” mean?

Donor surgeons may sometimes prefer one side for technical reasons related to vascular anatomy.

Historically, the left kidney has often been attractive because of venous length.

But anatomy varies.

Modern laparoscopic donor surgery allows experienced teams to use either kidney when appropriate.

Side selection should not be reduced to “left is always better.”

The surgeon balances donor anatomy, kidney function and recipient technical needs.

The fundamental principle remains that the donor should retain the kidney expected to serve them best over the long term whenever medically feasible.

How kidney anatomy is matched to the recipient

Recipient anatomy can influence the transplant plan too.

A kidney transplant is usually placed in the lower abdomen rather than in the original kidney position.

The donor renal artery and vein need suitable recipient vessels.

The donor ureter must be connected to the recipient’s urinary tract.

Previous surgery, vascular disease or anatomical variation can affect how the operation is planned.

This means organ suitability is partly relational.

A kidney may be surgically straightforward for one recipient and technically more difficult for another.

Your later article on where a transplanted kidney is placed will cover this surgical anatomy more fully.

What if the donor has one slightly weaker kidney?

This depends on why the kidney is weaker and how much difference exists.

If the lower function reflects a benign anatomical difference and overall donor function is adequate, donation may still be possible.

In fact, leaving the donor with the stronger kidney can be desirable.

But if asymmetric function indicates underlying disease that affects both kidneys or signals a progressive condition, donation may not be safe.

That is why transplant teams may perform split renal-function testing when imaging or total GFR suggests meaningful asymmetry.

The cause matters as much as the number.

Can a kidney with a small stone be donated?

Sometimes.

A transplant center may accept selected donors with low stone recurrence risk.

The surgical team may consider which kidney contains the stone and whether the stone can be managed.

But repeated stone disease, metabolic abnormalities or bilateral stone burden can create greater concern.

This is a good example of how kidney suitability is not defined by one radiology word.

A stone must be interpreted in the context of:

size;

number;

location;

stone composition where known;

metabolic risk;

and likelihood of recurrence.

What if the donor has two kidneys of different sizes?

Size asymmetry triggers further investigation rather than an automatic answer.

Possible explanations range from normal variation to scarring, vascular problems or developmental differences.

The team may assess function from each kidney separately.

If the smaller or less-functional kidney is still adequate for transplantation and donation remains safe, that may be the kidney selected for removal.

If the asymmetry suggests important renal disease, donation may be declined.

Again, the purpose is to protect the donor.

Does a donor kidney have to be “100% healthy”?

“100% healthy” is not a useful medical term.

Some donor kidneys have minor anatomical variations, small benign cysts, multiple arteries or other findings that do not prevent successful transplantation.

A deceased donor kidney may have a higher KDPI and still offer meaningful benefit.

The transplant question is therefore not perfection.

It is acceptable risk and expected benefit.

Medicine rarely provides perfect organs.

It provides carefully evaluated options.

Donor kidney criteria for transplant abroad

When a patient is considering transplantation outside their home country, donor kidney criteria should not become less strict.

International travel adds logistics; it does not remove clinical standards.

A patient arriving with a potential living donor should expect the destination transplant center to evaluate donor safety, kidney function, anatomy, compatibility and legal eligibility.

External medical records can help with preliminary review, but the destination hospital may need to repeat or confirm critical tests.

This is especially relevant for:

measured kidney function;

blood and urine testing;

HLA and crossmatch testing;

kidney imaging;

infection screening;

and legal relationship documentation.

A patient should be cautious if an intermediary says:

“Your donor is approved because creatinine is normal.”

That is not a complete transplant evaluation.

Before travelling, families should organize donor and recipient records using your Documents to Prepare guide.

Internal link: Documents to Prepare → /en/blog/documents-to-prepare

Patients considering Türkiye should also read the dedicated Kidney Transplant in Turkey destination page because the destination’s legal framework matters alongside the medical assessment.

Internal link: Kidney Transplant in Turkey → /en/destinations/kidney-transplant-in-turkey

What Türkiye’s official living donor protocol means for international patients

Türkiye’s Ministry of Health currently lists the Böbrek Nakli Canlı Donör Seçimi ve Yaşam Boyu Takip Klinik Protokolü, or Living Kidney Donor Selection and Lifelong Follow-Up Clinical Protocol, among its official transplant guidance resources.

This is important because it reinforces that living kidney donation in Türkiye is not based solely on whether the family presents a willing donor.

The pathway includes formal medical assessment and long-term donor-care principles.

Türkiye’s current Ministry pages also state that organ transplantation can only be performed in centers authorized by the Ministry of Health and by multidisciplinary teams.

For medical tourism, that should be a non-negotiable standard.

A platform should coordinate patients toward authorized transplant centers rather than promising donor approval independently.

Legal suitability is separate from kidney suitability in Türkiye

A medically suitable kidney is not automatically a legally approved living-donor transplant.

Türkiye’s transplant regulation governs who may donate through the standard living-donor pathway and provides ethics-review mechanisms for other circumstances. It also defines cross transplantation and the Ministry’s donor-recipient matching system.

This creates three separate questions for an international family:

Is the donor medically safe?

Is the kidney suitable for this recipient?

Is the proposed living-donor pathway legally permitted?

A correct answer requires all three.

How to prepare a donor kidney case before international travel

The preliminary file should be organized honestly.

Useful donor information includes:

recent kidney-function testing;

urine results;

blood-pressure history;

fasting glucose or HbA1c where available;

medication list;

previous kidney stones;

important operations;

cancer history;

infection history;

kidney imaging;

and family history of renal disease.

The recipient file should include:

diagnosis;

current kidney function;

dialysis information if applicable;

blood group;

previous transplant history;

transfusion history;

HLA or antibody reports if available;

and relevant comorbidities.

Relationship documentation should be collected according to destination rules.

The goal is not to approve the donor remotely.

The goal is to identify obvious barriers before unnecessary travel and allow the transplant program to plan the formal evaluation efficiently.

What makes a kidney especially attractive for living donation?

There is no universal “perfect living donor kidney,” but a straightforward case generally combines several reassuring characteristics.

The potential donor has strong overall renal function.

Urine testing does not suggest significant renal damage.

Blood pressure and metabolic health are acceptable.

Imaging shows anatomy that can be managed safely.

There is no major recurrent stone risk.

Infection and cancer screening are appropriate.

The donor is medically and psychologically suitable for surgery.

Compatibility with the recipient is acceptable.

And the donor retains a kidney expected to provide strong long-term function.

These characteristics simplify the pathway.

They do not guarantee a complication-free transplant.

What can make a donor kidney more complicated but still usable?

Examples include:

multiple renal arteries;

minor anatomical variants;

a small simple cyst;

an isolated past kidney stone with low recurrence risk;

older donor age;

some donor-recipient size difference;

less-than-perfect HLA matching;

or ABO incompatibility where an appropriate regulated alternative pathway exists.

The existence of one complexity should not automatically be interpreted as a dangerous kidney.

A specialized transplant center assesses whether the risk remains acceptable.

What can make a living donor kidney unsuitable?

Reasons can come from the donor, the kidney itself or the pairing.

Examples include inadequate renal function, substantial kidney disease, major albuminuria, unsafe stone recurrence risk, significant anatomical disease, unacceptable surgical risk, active high-risk malignancy, unresolved infection or a compatibility profile carrying unacceptable rejection risk.

Coercion or unlawful payment can also prevent living donation even when every medical test is normal.

This distinction is crucial:

an organ can be medically excellent but ethically unusable through an unlawful donation pathway.

Does the donor kidney determine transplant success by itself?

No.

The donor organ matters greatly, but recipient care continues to determine outcomes after surgery.

A technically excellent kidney can fail because of severe rejection, medication nonadherence, infection or recurrent disease.

A kidney with less-than-ideal donor characteristics can function successfully for years.

Transplant success therefore depends on:

donor organ characteristics;

recipient health;

immune compatibility;

surgery;

immunosuppression;

follow-up;

infection prevention;

blood-pressure control;

and adherence to treatment.

A kidney transplant is not simply an organ purchase-and-replacement event.

It is a long-term treatment pathway.

Does donor kidney quality affect how long the transplant lasts?

Yes.

Donor kidney characteristics contribute to expected graft longevity.

Living donor kidneys often have strong outcomes partly because donors are carefully screened and surgery is scheduled.

Among deceased-donor kidneys, KDPI provides a population-level estimate of expected relative longevity in the U.S. system.

But donor quality does not fully determine the result.

Recipient age, HLA mismatch, recurrent kidney disease and post-transplant care also affect graft lifespan.

That topic is covered more fully later in your calendar in the article How Long Does a Kidney Transplant Last?

Is a living donor kidney always better than a deceased donor kidney?

Living donor transplantation has important advantages.

The transplant can be planned.

The donor has undergone extensive health screening.

Cold ischemia time is generally shorter.

The operation may occur before prolonged dialysis.

But the phrase “always better” is too absolute.

Some patients do not have a medically or legally suitable living donor.

Some living donors may have characteristics that require careful assessment.

A high-quality deceased-donor kidney can provide excellent outcomes.

The correct comparison is individualized rather than ideological.

The transplant team should evaluate the realistic options available to the patient.

Should a recipient reject an older donor kidney and wait for a younger one?

Not automatically.

Waiting itself has consequences.

A patient may remain on dialysis while hoping for another offer.

Age, health, local waiting times and likelihood of another kidney offer all matter.

For deceased donation, HRSA specifically notes that limiting acceptance to only lower-KDPI kidneys can increase waiting time.

For living donation, the decision to use an older donor requires a different donor-safety assessment.

The most useful question is not:

“Could I someday receive a better kidney?”

It is:

“What is the expected benefit and risk of this kidney compared with the realistic alternatives available to me?”

Donor kidneys and recipient age

An older kidney may sometimes be entirely appropriate for an older recipient whose expected graft needs differ from those of a 20-year-old recipient.

Conversely, a young recipient may benefit more from a kidney expected to provide longer graft longevity.

Allocation systems attempt to account for these considerations at the population level.

But every patient’s situation is different.

A living donor may offer the ability to transplant earlier, and earlier transplantation itself can have important benefits.

The decision therefore involves both organ longevity and timing.

Donor kidneys and children

Pediatric recipients present another special situation because they may need kidney function for many decades.

Organ longevity, size and future retransplant considerations become particularly important.

The U.S. kidney allocation system gives pediatric candidates additional priority for kidneys expected to function longer; HRSA states that candidates younger than 18 receive priority for a portion of lower-KDPI kidneys.

Living donation can also be highly valuable in pediatric transplantation when a suitable adult donor is available.

A child should not be treated as an ordinary living kidney donor.

Recipient age and donor age are completely different ethical questions.

Does a donor kidney need a biopsy before living donation?

Usually not as a routine requirement for every healthy living donor.

Living donor kidneys are evaluated extensively through laboratory testing, imaging and clinical assessment before surgery.

A kidney biopsy may be considered when a specific unexplained renal concern requires tissue diagnosis, but it is not an ordinary universal step for all potential living donors.

Deceased donor kidney biopsy is used differently and can help assess selected organs where donor factors create concern.

Patients should therefore not assume that a donor is insufficiently evaluated merely because no biopsy was performed.

Can a donor kidney be rejected after surgery has already started?

Occasionally unexpected anatomical or organ findings can be discovered during procurement.

Transplant teams have contingency procedures for such events.

This is uncommon in thoroughly evaluated living donors because imaging is performed beforehand.

For deceased donation, the procurement team directly inspects the organ and can identify trauma, masses or other unexpected abnormalities.

The safety principle is simple:

if a kidney is discovered to be unsuitable, transplantation should not proceed merely because plans have already been made.

Why transplant centers can disagree about a kidney

Transplant medicine contains risk thresholds.

One center may accept an older donor with carefully controlled hypertension.

Another may not.

One recipient may reasonably accept a higher-KDPI kidney because the alternative is a long wait.

Another patient with access to a living donor may decline it.

These differences do not always mean one center is unsafe and the other is correct.

Programs consider:

recipient risk;

local waiting time;

surgical expertise;

immunologic expertise;

program policies;

and acceptable donor-risk thresholds.

Second opinions can therefore be reasonable for borderline cases.

They should not be used to conceal medically important information or search for a center willing to ignore a clear safety problem.

Choosing a hospital for donor kidney evaluation

A living donor program should have more than a transplant surgeon.

Patients should expect access to transplant nephrology, experienced donor surgery, histocompatibility testing, imaging, psychosocial evaluation and regulated donor-protection processes.

International patients should also ask whether the hospital is authorized for the specific transplant type and how donor legal documents are reviewed.

Your current sitemap contains a dedicated Hospitals hub.

Internal link: Transplant Hospitals → /en/hospitals

The platform also has a Partner Disclosure page, which should remain available so users understand the nature of hospital relationships.

Internal link: Partner Disclosure → /en/partner-disclosure

Donor kidney criteria and cost should remain separate

Kidney suitability is a medical decision.

Price cannot improve kidney function.

A more expensive package cannot make an unsafe donor appropriate.

A cheaper package should not reduce compatibility testing or donor evaluation.

Patients seeking financial information should therefore be routed separately to the site’s Kidney Transplant Surgery Cost page.

Internal link: Kidney Transplant Surgery Cost → /en/costs/kidney-transplant-surgery-cost

This separation is important for YMYL integrity.

Eligibility content should explain clinical criteria.

Cost content should explain verified medical-service pricing.

The kidney itself should never be described as a purchased product.

A practical donor kidney suitability checklist

Families can think about donor kidney suitability in this order:

1. Is the potential donor legally and voluntarily able to donate?
2. Is donation medically safe for that person?
3. Are total and individual kidney functions adequate?
4. Do urine tests suggest kidney damage?
5. Is kidney anatomy surgically suitable?
6. Are stone, infection and cancer risks acceptable?
7. Is the donor-recipient blood-group pathway appropriate?
8. Are HLA antibodies and crossmatch results acceptable?
9. If incompatible, is a regulated paired-donation or specialist pathway available?
10. Does the recipient have a reasonable expected benefit from this kidney?
11. Does the destination’s legal framework permit the proposed living-donor pathway?
12. Is there a plan for both donor and recipient follow-up?

A “yes” to the first two questions does not guarantee a yes to the others.

The evaluation is deliberately layered.

Common myths about donor kidney criteria

“A normal creatinine means the kidney is suitable.”

False.

Donor assessment also considers confirmed kidney function, urine albumin, blood pressure, metabolic risk, anatomy and long-term donor health.

“The younger donor always has the better kidney.”

Not necessarily.

Age matters, but disease, kidney function, inherited risk and anatomy matter too.

“A woman cannot donate a kidney to a man.”

False.

Female-to-male living kidney donation is routinely possible. Contemporary research does not support treating sex mismatch as an automatic contraindication.

“A kidney with two arteries cannot be transplanted.”

Not automatically.

Vascular complexity requires surgical assessment but does not necessarily make the kidney unsuitable.

“A kidney with a cyst is unusable.”

Not necessarily.

The cyst must be characterized. A benign simple cyst is very different from complex cystic disease.

“A kidney stone automatically disqualifies a donor.”

No.

Stone history and recurrence risk are evaluated individually.

“A perfect blood-type match means the kidney is approved.”

False.

HLA antibodies, crossmatch, anatomy and donor medical safety still matter.

“High KDPI means a deceased donor kidney should never be accepted.”

False.

Higher KDPI predicts shorter average graft longevity relative to other deceased donor kidneys, but the organ can still provide meaningful benefit.

“Paired kidney donation is the same as trading organs.”

False.

Regulated paired donation is a medically supervised exchange of compatible donations between legitimate donor-recipient pairs, without purchasing organs.

Questions to ask when a transplant center says a kidney is unsuitable

Instead of accepting the word “unsuitable” without explanation, ask what the problem is.

Is the donor medically unsafe?

Is kidney function inadequate?

Is the anatomy difficult?

Is there a kidney disease concern?

Is the problem infection or malignancy risk?

Is the donor healthy but incompatible?

Is the crossmatch positive?

Is the barrier legal or ethical?

Is this a temporary finding that can be reassessed?

Would paired kidney donation be relevant?

These questions can prevent families from confusing donor rejection with incompatibility.

The difference between “donor unsuitable” and “kidney unsuitable”

Language matters.

Donor unsuitable means the person should not undergo living donation.

Kidney unsuitable can mean the organ itself has a functional, structural or transmission-risk problem.

Pair incompatible means donor and recipient may not transplant directly even though the donor and kidney are otherwise acceptable.

Legal pathway unresolved means medical compatibility is not the issue at all.

A good transplant team should explain which category applies.

Final answer: what are donor kidney criteria?

Donor kidney criteria determine whether donation is safe for the donor and whether the kidney is expected to function appropriately in the recipient.

For a living donor, this includes adequate renal function, acceptable urine findings, safe blood pressure and metabolic risk, suitable anatomy, manageable kidney-stone risk, appropriate infection and malignancy screening, surgical fitness and voluntary informed consent.

KDIGO considers GFR of at least 90 mL/min/1.73 m² generally acceptable, values from 60–89 subject to individualized assessment, and values below 60 unsuitable for living donation.

The donor kidney must then be evaluated against the intended recipient through blood-group assessment, HLA testing, antibody evaluation and crossmatching.

A female can donate a kidney to a male; donor-recipient sex mismatch is not an automatic barrier.

If a medically suitable living donor does not match the recipient, a regulated paired donor kidney transplant may provide another route in healthcare systems that operate paired-donation programs.

For deceased donor kidneys, organ assessment uses a different framework. In the United States, KDPI summarizes expected relative graft longevity using multiple donor characteristics, but HRSA emphasizes that KDPI should not be the only measure used to decide whether an organ is suitable.

For patients considering transplantation abroad, one more layer applies: the donor and transplant must satisfy the destination country’s legal and ethical rules. Türkiye maintains both a national living kidney donor clinical protocol and a Ministry-regulated organ-transplant framework.

The best definition of a suitable donor kidney is therefore not:

“a young kidney with normal creatinine.”

It is:

a kidney that has been evaluated in the context of donor safety, organ function, anatomy, compatibility, recipient benefit and the applicable legal transplant pathway.

This guide explains donor kidney criteria and what transplant teams mean when they say a kidney is suitable for transplantation. It covers living-donor kidney function, urine findings, anatomy, kidney stones, blood pressure, diabetes, age, infection and cancer screening, as well as blood type, HLA antibodies and crossmatching. It also explains whether a female can donate a kidney to a male, how donor and recipient size may affect assessment, what happens when a willing donor does not match, and how paired donor kidney transplant programs work. A separate section explains how deceased donor kidneys are evaluated, including KDPI, and how Türkiye regulates living-donor and cross-transplant pathways.