Who Is a Candidate for a Kidney Transplant? What the Evaluation Team Looks For

The nephrology appointment is winding down when the doctor sets the lab printout aside and says the sentence that changes the shape of the afternoon: “I think it is time we talked about transplant.” The patient hears the word and reaches, almost reflexively, for the questions everyone reaches for. Am I too old? Too heavy? Do my blood sugars rule me out? Would anyone even want to give me a kidney?

Those questions are the right ones, and they have more hopeful answers than most people expect. Working out who is a candidate for kidney transplant is not a pass-or-fail exam with a secret rubric. It is a structured medical evaluation with one job: to find out whether a new kidney is likely to help you more than it could harm you.

This explainer walks through what that evaluation actually involves, which findings tend to move people forward, which ones usually lead to a pause rather than a no, and what to ask when you sit down with the team.

Who is a candidate for kidney transplant? The eligibility criteria in plain language

Strip away the jargon and the eligibility criteria rest on three questions. Do your kidneys have so little function left that a transplant is the better long-term treatment? Can your body withstand a three-to-four-hour operation under general anesthesia? And can you take, and keep taking, medicines that deliberately dampen your immune system for as long as the kidney works?

The first question is about kidney function. Clinicians estimate it with eGFR, the estimated glomerular filtration rate, a blood-test-based number that approximates how many milliliters of blood your kidneys filter each minute. In the United States, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) notes that you can be placed on the waiting list once your eGFR is 20 or lower, or once you have started dialysis, the treatment that filters waste from the blood when kidneys cannot.

The second question is about surgical fitness, which is why the heart, lungs and blood vessels get so much attention during the workup. The third is about life after surgery: immunosuppression, the medicine-driven suppression of the immune response that stops your body attacking the donor organ, works only if it is taken every single day.

Notice what is not on this list. There is no fixed age ceiling, no absolute weight cutoff, no requirement that you already be on dialysis, and no expectation that you have a donor lined up. Those factors are weighed, certainly, but they are weighed alongside everything else. The team is asking whether a transplant is a safe and sensible bet for you specifically, not whether you fit a stereotype of the ideal recipient.

Who needs a kidney transplant in the first place?

Healthy kidneys do more than make urine. They clear waste products, balance fluid and electrolytes, help regulate blood pressure, activate vitamin D for bone health and signal the bone marrow to make red blood cells. When chronic kidney disease progresses to kidney failure, every one of those jobs falters at once.

Kidney failure has many starting points. According to the NIDDK and MedlinePlus, the most common causes in adults are diabetes and high blood pressure, which damage the tiny filtering vessels over years. Other routes include glomerulonephritis (inflammation of the kidney’s filtering units), polycystic kidney disease (an inherited condition in which fluid-filled cysts crowd out working tissue), long-standing urinary tract obstruction and some autoimmune diseases such as lupus.

Once kidneys fail, there are three broad paths: dialysis, transplant, or conservative management, which means treating symptoms without replacing kidney function. Transplant is not simply “the next step after dialysis.” Mayo Clinic describes it as a treatment option for end-stage kidney disease that many people choose because a working transplanted kidney can do what dialysis only partly does, around the clock, without sessions. The NIDDK also points out that a transplant can take place before dialysis ever begins; this is called a preemptive transplant.

So who needs one? Anyone whose kidney function has fallen to the point where failure is here or clearly coming, and for whom the team believes transplant offers a better balance of benefit and risk than the alternatives. That judgment, not the diagnosis on the chart, is what sends you to the evaluation clinic.

How the transplant evaluation actually works, step by step

A referral starts the process, usually from your kidney specialist, though in many systems you can also ask for one yourself. From there, the pattern is broadly similar across programs, with local variations in order and pace.

First comes an education session. Someone on the team, often a transplant coordinator, explains what a transplant involves, what living and deceased donation mean, what the medicines do and what the waiting list is. This is where you are expected to ask awkward questions, and the team is expected to answer them.

Next is the clinical workup. You meet a transplant nephrologist, a transplant surgeon, a social worker and often a dietitian and a pharmacist. Mayo Clinic lists the core components: a thorough physical examination, blood and urine tests, imaging such as X-rays, ultrasound or CT, cancer screening appropriate to your age and sex, and a psychological and social evaluation. Many programs add a dental review, because hidden mouth infections become a problem once the immune system is suppressed.

Then the pieces come together at a selection meeting. Everyone who assessed you compares notes and lands on one of three outcomes: list now, list after specific issues are addressed, or do not list at this time. If something needs sorting first, a heart test, a vaccination, a follow-up scan, you are told what it is and why.

Finally, if you are listed, you are registered with the national organ allocation system and begin accruing waiting time. The NIDDK notes that in the United States waiting time can count from the date dialysis began, even if you were listed later. Throughout, the decision rests with the transplant team, but you remain the person steering: you can pause, ask for a second opinion within the program, or decline.

Kidney transplant tests: what each one tells the team

The sheer number of tests can feel like an obstacle course. It helps to know that each one answers a specific question rather than hunting for reasons to say no.

Blood typing establishes ABO compatibility, the same blood group rules used for transfusion. Tissue typing identifies your HLA antigens, the protein markers on cell surfaces that the immune system uses to tell self from non-self. The closer the HLA match with a donor, the fewer targets for rejection. Antibody screening measures how many pre-formed antibodies you carry against common HLA types, often reported as a percentage of the donor pool you would react against. Prior pregnancies, transfusions or earlier transplants raise this number. A crossmatch, run once a specific donor is identified, mixes your serum with donor cells to confirm no immediate reaction. MedlinePlus describes this sequence as the standard matching pathway.

Cardiac testing ranges from an electrocardiogram and echocardiogram to a stress test or coronary angiography, depending on your risk. Chest imaging and lung function tests check whether you can safely be ventilated during anesthesia. Abdominal and pelvic imaging maps the blood vessels where the new kidney will be connected and looks at the bladder, which must be able to receive urine.

Infection screening covers hepatitis B and C, HIV, tuberculosis and viruses such as cytomegalovirus, because immunosuppression can reactivate dormant infections. Age-appropriate cancer screening is included for the same reason.

Lastly, the psychosocial assessment is not a character test. It asks practical things: who drives you to appointments, how you manage medicines now, whether finances or housing are stable enough to support follow-up. Problems identified here are usually solvable, and identifying them is the point.

Who is usually accepted, and who is usually asked to wait

Transplant teams rarely think in terms of a single yes-or-no switch. Most findings sort into three groups: those that support listing, those that call for a pause while something is fixed, and the smaller set that genuinely make transplant unsafe. The table below summarizes patterns described by Mayo Clinic and MedlinePlus; your own program’s criteria may differ in detail.

Factor	What the team looks for	Typical effect on listing
Kidney function	eGFR about 20 or lower, or on dialysis	Meets threshold for listing
Heart and lung health	Able to tolerate general anesthesia and surgery	Supports listing; untreated severe disease may pause or prevent
Active infection	Untreated bacterial, viral or fungal infection	Usually a pause until treated
Cancer history	Active disease, or recent treatment	Pause for a disease-free interval set by the team
Body weight	Surgical and healing risk at higher BMI	Often addressed with support rather than refusal
Substance use	Current alcohol, tobacco or drug misuse	Pause, with help to stop
Adherence and support	Reliable medicine-taking, follow-up attendance	Strength when present; plan built when absent
Severe cognitive decline	Inability to manage medicines even with help	May prevent listing

Two things stand out. The “pause” column is the longest, and that is deliberate: most reasons for delay are reasons the team can work on with you. The second is that conditions on the list interact. Diabetes, for example, is the most common cause of kidney failure and is not a barrier in itself, but it raises the stakes on the heart assessment. The evaluation is less a checklist than a conversation between findings.

Is there an age limit for kidney transplant?

No fixed one. Mayo Clinic states plainly that a kidney transplant can be performed at any age, and the NHS likewise says that transplant is considered for most people with kidney failure regardless of age, with the deciding factor being whether the person is well enough for surgery and the medicines afterward.

What changes with age is not eligibility but the weight of the surrounding questions. Older adults are more likely to carry coronary artery disease, peripheral vascular disease, or frailty, the clinical term for reduced physiological reserve that makes recovery slower and complications more likely. Those are the things the team is actually evaluating when an eighty-year-old is referred, not the number on the birth certificate.

Two practical points often surprise people. First, age cuts both ways in allocation. Many systems try to pair kidneys expected to function for a long time with recipients expected to live a long time, and vice versa. Older candidates may therefore be offered kidneys from older donors, which can shorten the wait. Second, time matters more as you age. Every year on dialysis is a year of cardiovascular strain, so a candidate who is borderline at 72 is unlikely to be a stronger candidate at 76. That is one reason specialists encourage early referral rather than waiting to see how things go.

Children are assessed in dedicated pediatric programs with their own criteria, where growth, development and family support feature heavily. The principle is the same across the lifespan: the question is physiological age and overall health, not chronological age.

Heart, lungs and the question of surviving surgery safely

If one part of the evaluation deserves to be called the hinge, it is the cardiovascular assessment. People with kidney failure carry a heavy burden of heart disease, partly because the two conditions share causes, and partly because kidney failure itself accelerates calcification of arteries and strains the heart with fluid overload and anemia.

The operation is significant. Cleveland Clinic describes a procedure lasting roughly three to four hours, during which the donor kidney is placed low in the abdomen and its vessels are joined to the iliac artery and vein, the main blood vessels supplying the leg. Clamping and reopening those vessels, together with anesthesia and fluid shifts, demands a heart that can cope.

So the team looks. A resting electrocardiogram and echocardiogram are near-universal. For candidates with diabetes, long dialysis histories or symptoms, a stress test or coronary angiography follows. The purpose is twofold: to find disease that needs treating before surgery, and to estimate the risk of a heart attack or stroke around the time of the operation. Mayo Clinic lists heart attack and stroke among the recognized risks of the procedure itself.

Finding coronary disease is not the end of the road. Blockages can often be treated, after which the candidate is reassessed. What tends to close the door is severe disease that cannot be improved: advanced heart failure with very poor pumping function, or lung disease that would make ventilation unsafe. In those cases the honest conclusion is that surgery would carry more risk than the kidney could repay.

Smoking belongs in this section too. Beyond lung effects, it damages the blood vessels the surgeon relies on. Most programs ask candidates to stop and offer help to do so.

Cancer, infection and immunosuppression: why timing matters

The medicines that protect a transplanted kidney work by turning down the immune system. That same system is what finds and destroys early cancer cells and holds dormant infections in check. Give those processes less supervision, and problems that were controlled can resurface. This is the single mechanism behind two of the most common reasons for delay.

With cancer, teams generally want a disease-free interval before listing. The length varies by cancer type and stage; some low-risk skin cancers need little or no waiting, while others require years. Mayo Clinic lists active or recently treated cancer among the conditions that may make someone not a candidate at a given time. The key phrase is “at a given time.” A history of cancer is a reason to plan carefully, not a permanent exclusion, and the transplant team will usually coordinate with your oncologist on the interval.

Infection follows similar logic. An untreated infection, whether a diabetic foot ulcer, a dental abscess or an infected dialysis access site, can become dangerous once immunosuppression begins. MedlinePlus notes that an active infection is a standard reason to defer transplant. Chronic viral infections such as hepatitis B, hepatitis C and HIV are not automatic barriers in modern practice; they are assessed and, where appropriate, treated before or around transplant.

Vaccination is the preventive side of the same coin. Because some vaccines cannot be given safely once the immune system is suppressed, programs typically review and update immunizations during evaluation. A reasonable question to ask the team is which vaccines they want completed before listing, and how long before surgery they need to be given.

Weight, diabetes and blood pressure: modifiable, not disqualifying

Few topics cause more anxiety in the evaluation clinic than body weight, and few are more often misunderstood. Body mass index, or BMI, a ratio of weight to height squared, is one of the factors teams consider, because higher BMI is associated with wound complications, longer surgery and a technically harder operation. Some programs set a threshold above which they ask candidates to lose weight before listing. Others take a more individualized view that considers fat distribution and overall fitness.

What matters for you is that this is framed as a pause with support, not a rejection. Dietitians are part of the team for exactly this reason, and the conversation should be about a realistic plan, not a verdict. Respectful care means being told the clinical reasoning, not being made to feel judged.

Diabetes sits in a similar category. It is the leading cause of kidney failure, so excluding people with diabetes would exclude a large share of those who need transplant most. The condition does not rule you out; it does mean the team pays close attention to blood sugar control, to the heart, to circulation in the feet and to the eyes. For some people with type 1 diabetes, a combined kidney and pancreas transplant is discussed, a decision that belongs entirely to the specialist team.

High blood pressure is nearly universal in kidney failure and is simply managed as part of preparation. The point across all three is the same: they are variables the team expects to see and knows how to work with. Where medicines are involved, their adjustment belongs to your prescribing clinicians, and the evaluation is a reason to talk with them, never a reason to change anything on your own.

Living donor or deceased donor: how matching works and what it means for candidacy

Kidneys come from two sources. A deceased donor kidney is allocated through a national system when a suitable organ becomes available. A living donor kidney comes from a healthy person, often a relative, partner or friend, sometimes a stranger, who chooses to give one of their two kidneys. The NHS notes that most living-donor kidneys begin working immediately and that the procedure can be scheduled, which avoids an unpredictable wait.

Having a willing donor does not change whether you are a candidate; you still complete the full evaluation. It does change the timeline, often dramatically. The NHS reports that the average wait for a deceased donor kidney in the UK is around two to three years, while a living donor transplant can proceed once both of you are cleared.

Matching follows the sequence described earlier. Blood group compatibility comes first, then HLA tissue typing, then a crossmatch to rule out pre-formed antibodies against that specific donor. A potential donor also undergoes their own extensive medical and psychological assessment, because the program’s duty to protect the donor is as strong as its duty to the recipient.

Two developments widen the pool. Paired exchange programs allow an incompatible donor-recipient pair to swap with another pair so that both recipients receive a compatible kidney. Blood-group-incompatible transplants are also possible in selected cases using additional treatment before surgery, a decision made case by case by the team.

If you have a potential donor, the right first step is to ask the transplant coordinator how your program handles donor inquiries. Donors are typically assessed by a separate team to avoid any pressure, and either party can step back at any point without explanation.

What the following weeks and months usually look like, from listing to recovery

Being accepted is a beginning, not an end. For deceased-donor candidates, the stretch after listing is a waiting period measured in months to years, with periodic re-evaluation so the team knows you remain fit for surgery when the call comes. Blood samples are drawn regularly to keep antibody screening current, and you are expected to report new illnesses, hospital stays or changes in weight.

The call itself can come at any hour. You are asked to arrive quickly, a final crossmatch is run, and surgery follows if all is clear. Occasionally a candidate is called in and sent home because the final tests or the organ’s condition rule it out; this is frustrating but not a mark against you.

After surgery, Mayo Clinic describes a hospital stay of up to about a week while the team monitors kidney function, fluid balance and early signs of rejection or infection. Some kidneys work immediately; others take days or weeks to “wake up,” and short-term dialysis may bridge that gap. Neither pattern predicts the long-term result on its own.

Follow-up is intensive at first, often several visits a week, with blood tests to fine-tune anti-rejection medicine levels. The frequency tapers over months as things stabilize. Mayo Clinic suggests most people can return to work and normal activity within roughly eight weeks, with lifting restrictions during healing. Timelines vary with your starting health, and your own team’s guidance overrides any general range.

Life afterward is built around daily medicines, regular monitoring and attention to infection risk. People commonly describe it as trading the rigid schedule of dialysis for a more flexible, but still disciplined, routine.

What are the potential side effects of a kidney transplant, and how does candidacy affect them?

Understanding the risks is part of understanding candidacy, because the evaluation is essentially an attempt to estimate how these risks apply to you. Mayo Clinic and the NHS group them into two categories: complications of the operation and effects of the medicines.

Surgical risks include bleeding, blood clots, infection at the wound, leakage or blockage of the ureter (the tube carrying urine from kidney to bladder), narrowing of the connected artery, and in a small number of cases failure of the kidney to function. Rejection, in which the immune system attacks the new organ, can occur early or years later; it is often treatable when caught early, which is why follow-up blood tests matter so much. Rarely, an infection or cancer can be transmitted from the donor, a risk donor screening is designed to minimize.

Medicine-related effects are broader. Anti-rejection regimens typically combine drug classes such as calcineurin inhibitors, antimetabolites and corticosteroids, each working on a different step of immune activation. Mayo Clinic lists potential side effects including increased infection risk, higher rates of certain cancers (particularly skin cancer), new-onset diabetes, raised blood pressure and cholesterol, weight gain, bone thinning, tremor and changes in hair growth. Which of these you are most exposed to depends partly on findings from your evaluation, which is why, for example, a strong family history of diabetes or existing osteoporosis is noted rather than ignored.

None of this is meant to alarm. Every one of these risks is weighed against the known burdens of staying on dialysis, which carries its own cardiovascular, infectious and quality-of-life costs. The evaluation exists so that comparison is made for you as an individual, by people who know your full picture.

What people often get wrong about who is a candidate for kidney transplant

Myths about eligibility stop people from asking for a referral, which is the quietest way a transplant gets missed. A few deserve direct correction.

“You have to be on dialysis first.” Not so. The NIDDK describes preemptive transplant, performed before dialysis starts, as an established option once eGFR falls to about 20 or below. Many specialists actively prefer it when a living donor is available.

“Over 65 means automatic refusal.” Mayo Clinic and the NHS are explicit that there is no upper age limit. Fitness for surgery and for the medicines is what counts.

“Diabetes disqualifies you.” Diabetes is the most common reason people need a transplant. It changes the assessment, not the answer.

“A past cancer is a permanent no.” Most cancers call for a disease-free interval, set in discussion with your oncologist, after which listing is reconsidered.

“You need a family donor to qualify.” Candidacy and donor availability are separate questions. Plenty of people are listed with no donor in sight and receive a deceased-donor kidney.

“If one program says no, that is final.” Criteria differ between programs, and a decision can be revisited when circumstances change. Asking what would need to be different, and whether re-evaluation is possible, is entirely reasonable.

“A transplant fixes everything.” A functioning kidney is a treatment, not a reset. It brings its own medicines, monitoring and risks, and the underlying disease that damaged your kidneys may still need managing. Candidates who understand this tend to find the evaluation less bewildering, because the team’s questions suddenly make sense: they are preparing you for a long relationship with a new organ, not a single event.

Questions to ask your care team during evaluation

The evaluation is a two-way exchange, and the most useful appointments are the ones where you arrive with questions written down. These are the ones experienced patients and coordinators most often wish people had asked earlier.

• Based on what you know so far, which parts of my health are you most focused on, and why?
• Is there anything in my results that would lead you to pause listing, and what would need to change?
• Would a preemptive transplant make sense in my case, or should I prepare for dialysis in the meantime?
• How does my antibody level affect my likely wait, and are there options such as paired exchange if I have an incompatible donor?
• Which vaccinations do you want completed before listing?
• How will my diabetes, blood pressure or weight be managed during the waiting period, and who coordinates that with my existing doctors?
• What does the follow-up schedule look like in the first three months, and how far will I need to travel for it?
• Which of the anti-rejection side effects am I personally at higher risk of, given my history?
• Who do I call if I get sick while on the list, and will that affect my status?
• If I were declined, could I be re-evaluated later, and what would you want to see?

A few habits make the answers more useful. Bring someone with you; two sets of ears catch more. Ask the team to write down anything you are expected to do before the next visit. And if a decision feels rushed or unclear, say so. Good programs would rather spend another appointment than have a candidate leave confused. Every clinical decision in this process stays with the treating team, but the quality of that decision improves when you are an informed participant in it.

When to call your doctor: red flags during evaluation, on the waiting list, and after transplant

Kidney failure does not pause while you are being evaluated, and the waiting period can last years. Knowing which symptoms need a same-day call, and which need emergency care, is part of being a well-prepared candidate.

Seek emergency care immediately for chest pain or pressure, sudden shortness of breath, inability to breathe lying flat, sudden weakness or numbness on one side of the body, difficulty speaking, confusion, or a seizure. In kidney failure these can signal fluid overload, dangerously high potassium, heart attack or stroke, all of which the Mayo Clinic and MedlinePlus list among the serious complications of advanced kidney disease and its treatment.

Call your kidney team the same day for a fever, a new or worsening infection anywhere (including the mouth, feet or a dialysis access site), vomiting that prevents you keeping down medicines, a rapid unexplained weight gain with swelling, markedly reduced urine output if you still pass urine, or new bleeding. Any hospital admission, new cancer diagnosis, or change in your medicines should also be reported to the transplant coordinator, because it may affect your readiness if an organ becomes available.

After transplant, the list shifts. The NHS and Mayo Clinic advise urgent contact for fever, pain or tenderness over the new kidney, a sharp drop in urine output, blood in the urine, sudden swelling, flu-like symptoms, or redness and discharge from the wound. These can be early signs of rejection or infection, both of which are far more manageable when caught within hours rather than days.

One short rule covers most situations: if a symptom is new, rapid, or frightening, do not wait for the next scheduled visit. Transplant programs expect these calls and build their on-call systems around them.

Frequently asked questions

Who needs a kidney transplant?

People whose kidneys have failed or are close to failing, most often from diabetes, high blood pressure, glomerulonephritis or polycystic kidney disease. Transplant is one of three paths at that stage, alongside dialysis and conservative management. Specialists generally raise it once eGFR falls to about 20 or below, and the final judgment about whether it suits a particular person rests with the transplant evaluation team.

Is there an age limit for kidney transplant?

No. Mayo Clinic and the NHS both state that transplant can be considered at any age. What the team assesses is whether your heart, lungs and overall health can cope with surgery and lifelong immunosuppressive medicines. Older candidates may be matched with kidneys from older donors, which can shorten the wait, and early referral matters because time on dialysis adds cardiovascular strain.

What are the kidney transplant eligibility criteria most programs use?

Core criteria are advanced kidney failure (eGFR about 20 or lower, or on dialysis), fitness to undergo a major operation, absence of untreated active infection or active cancer, and the ability to take daily medicines and attend follow-up. Weight, substance use and psychosocial support are considered as modifiable factors. Programs vary in detail, so the specific list belongs to your team.

What are the potential side effects of a kidney transplant?

Surgical risks include bleeding, blood clots, infection, ureter leakage or blockage and, uncommonly, kidney failure or rejection. Medicine-related effects listed by Mayo Clinic include higher infection risk, increased rates of some cancers, new diabetes, raised blood pressure and cholesterol, weight gain, bone thinning and hair changes. Your team weighs these against the known burdens of remaining on dialysis.

How much does a kidney match test cost?

This article does not provide cost figures, because charges and coverage vary widely by country, insurer and program. In many systems the recipient’s health plan or national service covers donor testing, but that is not universal. The transplant coordinator or financial counselor at your program is the right person to explain exactly what is covered for you and for any potential donor.

How do you find out if you are a kidney donor match?

Contact the transplant program evaluating the person you wish to help. A separate donor team arranges blood group testing, HLA tissue typing and a crossmatch, followed by a full medical and psychological assessment of your own health. If you are not directly compatible, paired exchange may still make donation possible. Either party can withdraw at any stage without giving a reason.

Can you get a kidney transplant before starting dialysis?

Yes. The NIDDK describes preemptive transplant, performed before dialysis begins, as an established option once eGFR is about 20 or lower. It is most practical when a living donor is available, because deceased-donor waits often exceed the time before dialysis becomes necessary. Whether it fits your situation is a decision for your nephrologist and the transplant team.

Does diabetes stop you being a candidate for kidney transplant?

No. Diabetes is the most common cause of kidney failure, so people with diabetes make up a large share of transplant recipients. It does mean the team looks closely at the heart, circulation and blood sugar control during evaluation. For some people with type 1 diabetes, a combined kidney and pancreas transplant may be discussed by the specialist team.

What disqualifies you from a kidney transplant?

Few things are absolute. Severe heart or lung disease that cannot be improved, active cancer that is not controlled, and an inability to manage medicines even with support are the main barriers. Most other issues, such as infection, recent cancer treatment, weight or substance use, lead to a pause while they are addressed, after which listing is reconsidered.

How long does the kidney transplant evaluation take?

It varies with how many tests you need and how quickly results and specialist appointments can be arranged, typically a matter of weeks to a few months rather than days. Candidates with complex heart histories or recent cancer usually take longer. Ask your coordinator for an expected timeline and what you can do, such as completing vaccinations or dental checks, to avoid delays.

References

• Kidney Transplant (NIDDK, National Institutes of Health)
• Kidney transplant (MedlinePlus Medical Encyclopedia)
• Kidney transplant (NHS)
• Kidney transplant: Risks (NHS)

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.