Understanding kidney failure
Why kidneys fail, and what happens next
If someone you know is looking for a kidney, this page answers the question you probably have first: why does a person end up needing one? Here is what kidneys do, what can go wrong, and what the path forward looks like.
Seven short chapters, about a ten-minute read.
What kidneys do
Most people have two kidneys, each about the size of a fist, sitting toward the back just below the rib cage. Their main job is to filter the blood, removing waste and extra fluid and turning it into urine.
- Filter the blood
- Control blood pressure
- Signal for red blood cells
- Keep bones healthy
- Balance minerals
Kidneys do more than that, though. They help control blood pressure. They make a hormone that tells the body to produce red blood cells. They help keep bones healthy. And they keep minerals like potassium in a safe range. When kidneys are not working well, all of these jobs can be affected, not just filtering.
What kidney disease means
Chronic kidney disease means the kidneys are doing their jobs at less than full strength. Doctors follow it with two tests. A blood test estimates how well the kidneys filter. A urine test looks for a protein that healthy kidneys keep out of the urine. Together they place the disease in a stage: early, where filtering is close to normal; middle, where it has dropped in a noticeable way; late, where very little filtering power is left.
Here is the sentence worth remembering: kidney disease is not kidney failure. Only the last stage is kidney failure. Many people live for years in an early or middle stage without ever reaching it, especially with the right care.
Kidney disease is also often silent at first. A person can lose a real amount of function before feeling anything at all, because the parts of the kidney still working take over for the parts that are not. That is why it is usually found on a routine blood or urine test, not because someone feels sick.
Share of people with kidney disease at each stage, 2017–2020
Kidney disease includes every stage
What causes kidney failure
For most people, the path to kidney failure traces back to one of a few conditions. Two are the most common causes by far. Two others are less common but worth knowing, because they can affect younger people who have neither of the common conditions.
Of every ten people on the kidney waiting list
Years of high blood sugar wear out the kidney's tiny filters, so protein starts slipping through.
- What it is
- High blood sugar, kept up over many years, that slowly damages the tiny filters inside the kidneys.
- Who it tends to affect
- People living with diabetes, more often the longer they have had it.
- How it leads to kidney failure
- The tiny filters gradually work less well, letting protein leak into the urine and losing filtering power over time.
- What is different about it
- Keeping blood sugar and blood pressure in a healthy range can slow this down a great deal, and most people with diabetes never reach kidney failure at all.
- What this means for finding a donor
- Kidney failure from diabetes is not passed down the way some rarer kidney conditions are, so a relative can usually be screened like anyone else. The team still asks about family history and checks each donor's own blood sugar. That check is part of how they keep a donor healthy.
Blood pressure that stays high pushes hard on the small blood vessels that feed the filters, until they stiffen and the filters are damaged.
- What it is
- Blood pressure that stays high for years, which slowly narrows and stiffens the small blood vessels that feed the kidneys.
- Who it tends to affect
- People living with high blood pressure, especially when it has stayed high for a long time without being brought under control.
- How it leads to kidney failure
- Stiffened blood vessels bring less blood to the kidneys' tiny filters, which lose strength and, eventually, filtering power.
- What is different about it
- This cause is highly treatable — medicine and everyday habits can both bring blood pressure down and protect the kidneys along the way.
- What this means for finding a donor
- Like diabetes, this does not usually change who can be screened as a donor. Blood pressure does tend to run in families, so the team checks every donor's own blood pressure carefully — that check is there to protect the donor.
Damage to the tiny filters, often from the body's own defences, scars them so protein leaks out.
- What it is
- A group of conditions in which the kidney's tiny filters become inflamed or damaged, often because the body's own immune system is involved.
- Who it tends to affect
- People of any age, including children and younger adults who do not have diabetes or high blood pressure.
- How it leads to kidney failure
- Inflammation lets protein, and sometimes blood, leak into the urine, and over time it can scar the filters so they stop working.
- What is different about it
- Some of these conditions can come back in the new kidney after a transplant. Transplant teams know which ones do, so they plan for it from the start, with regular checks and medicine ready if it happens. Knowing the exact condition ahead of time is what makes that planning possible.
- What this means for finding a donor
- Because some of these conditions can run in families, a close relative who considers donating is usually screened for the same condition first.
Fluid-filled sacs grow inside the kidney, making it bigger and crowding out the parts that still work.
- What it is
- An inherited condition in which fluid-filled sacs slowly grow inside the kidneys and crowd out the tissue that still works.
- Who it tends to affect
- Most often, people who inherited the condition from a parent — it runs in families and tends to be found earlier in life than the two most common causes. In a small number of people it appears with no family history at all.
- How it leads to kidney failure
- As the sacs grow larger and more numerous, they leave less and less working tissue behind to filter blood.
- What is different about it
- The kidneys grow larger as the cysts fill them, so doctors follow their size as well as how well they filter. For some people there is medicine that slows that growth.
- What this means for finding a donor
- A brother, sister, or grown child who considers donating is tested for the condition before being cleared to give a kidney. In a younger adult the cysts can be too small to see on a scan, so that test is sometimes a genetic one.
Some conditions are far less common than the ones above, but they matter. Several affect children or younger adults, several run in families, and several are glomerular diseases — the group described in the tab before this one.
Proteins from the body's defences drift into the tiny filters and pile up there.
IgA nephropathy
A condition where a natural immune protein settles inside the kidney's tiny filters and causes inflammation there. It often first shows up in teenagers or young adults, sometimes noticed just after a common cold.
Scars form in patches on some of the kidney's tiny filters.
FSGS (focal segmental glomerulosclerosis)
A condition where scarring develops in patches across the kidney's tiny filters. It can happen on its own or run in families, and it is one of the conditions that can come back in a transplanted kidney, which the transplant team watches for closely.
In lupus, the body's defences turn on its own tissue, and the kidney's filters become inflamed.
Lupus nephritis
Kidney inflammation caused by lupus, a condition where the immune system attacks the body's own tissue. It affects far more women than men and is usually managed with ongoing medicine that keeps the immune system in check.
A protein the filter wall is built from doesn't fit as it should, so the wall can't hold together and starts to leak.
Alport syndrome
An inherited condition that affects a protein the kidney's filters depend on, often along with changes in hearing and sometimes vision. It runs in families and tends to affect men more severely than women.
Part of the body's defences attacks the small blood vessels inside the kidney and damages their walls.
Atypical hemolytic uremic syndrome
A rare condition, often inherited, where part of the immune system damages small blood vessels inside the kidneys. It can appear suddenly at any age and is treated with medicine that calms that immune response.
Part of the body's defences coats the tiny filters and slowly clogs them.
C3 glomerulopathy
A rare condition where part of the immune system builds up inside the kidney's tiny filters and damages them over time. It can run in families or happen on its own, and it can be treated with medicine that targets that part of the immune system.
A natural substance gets stuck inside the kidney's cells and builds up as crystals.
Cystinosis
A rare inherited condition where a natural substance builds up inside cells throughout the body, including the kidneys, and slowly damages them. It is usually found in early childhood and is treated with medicine that lowers that buildup and slows the damage. It does not come back in a transplanted kidney.
The body can't break down a certain fat, so it collects inside the kidney's cells.
Fabry disease
A rare inherited condition where the body cannot break down a certain type of fat, which then builds up in the kidneys and other organs over time. It runs in families and can affect the heart and nerves as well as the kidneys. Medicine can replace the enzyme the body is missing, and the condition does not come back in a transplanted kidney.
The cells lining the kidney's tubes can't take small proteins back in, so they wash out in the urine and calcium builds up as stones.
Dent disease
A rare inherited condition, found almost only in boys and men, where the kidney's tubes can't take back small proteins and calcium as they should. Calcium can build up and form kidney stones, and kidney function can fall slowly over many years.
What this means for finding a donor
The transplant team looks closely at which condition caused the kidney failure. For some of these, a relative can carry the same condition without knowing it, so relatives are tested first. If a relative is not the right donor, a friend, a coworker, or someone outside the family still can be. Knowing the condition early is what lets the team plan the whole transplant around it.
- What it is
- Sometimes the cause is a blockage, an infection, or another condition entirely. And sometimes no cause is ever found, even after every test.
- Who it tends to affect
- Anyone. It is a common enough group that the waiting list counts it as one of its main categories.
- How it leads to kidney failure
- The path varies by cause, but the result is the same: the kidneys gradually lose enough filtering power to need a treatment path.
- What is different about it
- Not knowing the cause does not change what a working kidney can do, and it does not usually change who can be screened as a donor.
- What this means for finding a donor
- Because there is no known inherited condition to test for, relatives can usually be screened the same way anyone else would be.
A simplified drawing. Details differ from person to person.
The numbers behind the causes
- 40.1 million
- Americans had diabetes in 2023, diagnosed and undiagnosed
- About 1 in 8 people. Diabetes is the single most common cause of kidney failure, which is why keeping blood sugar in a healthy range is one of the most protective things a person with diabetes can do for their kidneys.
- CDC — National Diabetes Statistics Report, 2023 data, read 2026
- 47.7%
- of US adults had high blood pressure, 2021 to 2023
- Close to half the adult population, counted as a reading at or above 130 over 80, or taking medicine for it. High blood pressure is the second most common cause of kidney failure, and it is also one of the most treatable — medicine and lifestyle changes both bring it down.
- CDC/NCHS Data Brief 511, Aug 2021–Aug 2023
- 1 in 5
- US adults with high blood pressure have it under control
- More than half of people with high blood pressure are taking medicine for it, and about 1 in 5 have brought it into a healthy range. Getting it under control is one of the most useful things a person can do to protect their kidneys.
- CDC/NCHS Data Brief 511, Aug 2021–Aug 2023
- 10 to 20-plus years
- typical time from the start of diabetes to kidney failure, when it happens
- Kidney damage from diabetes builds slowly. When it does lead to kidney failure, that usually takes one to two decades. Most people with diabetes never reach kidney failure, and good blood sugar and blood pressure control across those years is a large part of why.
- Diabetic nephropathy natural-history review (PMC), published 2004
What kidney failure means
Kidney failure is the last stage of kidney disease, the point where the kidneys are no longer doing enough of their job to keep a person healthy on their own. Waste and fluid build up, and the hormone jobs the kidneys normally handle slow down too.
Reaching this stage does not happen overnight, and it does not mean there is nothing left to do. It means it is time to choose among several real treatment paths, each one described below.
The treatment paths
There are several real paths once kidneys fail. None of them is wrong. The right one depends on a person's body, their life, and what matters most to them.
Here is what a week actually looks like on each path, and what people say about living it, in plain terms.
- Clinic visit
- Day off
- Clinic visit
- Day off
- Clinic visit
- Day off
- Day off
- Time and place
- Most people go to a dialysis center a few days a week, spending a few hours there each visit while a machine filters the blood.
- Food and fluids
- A dietitian helps plan meals around how much fluid and which minerals the body can safely handle between visits.
- Medicines
- Medicine manages the jobs the kidneys used to do, like blood pressure and red blood cell counts, alongside the dialysis sessions themselves. Dialysis takes over the filtering, not the kidney's other jobs, which is why those medicines matter.
- Work, travel and family life
- Many people build work and family life around fixed clinic days, and centers exist in most cities, which can make travel easier to plan for.
- What people report
- Many people live full, active lives on this schedule, and having care staff close by for every session is a comfort some people value.
- Who it tends to suit
- People who prefer having a care team present for every session, or whose home is not set up for dialysis equipment.
- Home session
- Day off
- Home session
- Home session
- Day off
- Home session
- Home session
- Time and place
- After training, sessions happen at home, often more often than in-center visits, though each one can be shorter, on a schedule the person sets up themselves.
- Food and fluids
- More frequent, gentler sessions often mean fewer limits on fluids and food than the in-center schedule.
- Medicines
- The same kidney-support medicines are still needed, and a home care team stays in close contact to review results.
- Work, travel and family life
- Doing sessions at home can make it easier to keep a regular job or care for family, once the training and setup are in place.
- What people report
- People who choose this path often report feeling better day to day, alongside more control over when treatment happens.
- Who it tends to suit
- People willing to learn the equipment, who have a helper at home or feel confident managing it on their own.
- Home exchange
- Home exchange
- Home exchange
- Home exchange
- Home exchange
- Home exchange
- Home exchange
- Time and place
- A soft tube placed in the belly lets a cleansing fluid flow in and out, done at home each day, often overnight while a person sleeps.
- Food and fluids
- This method often allows a more flexible diet and more fluid than hemodialysis, since it works more gently and more often.
- Medicines
- The same kidney-support medicines are used alongside it, and supplies are delivered to the home on a regular schedule.
- Work, travel and family life
- Without fixed clinic days, this path tends to suit people who travel for work or want a schedule that fits around daily life.
- What people report
- People often value the independence of this path, though it does ask a household to keep a clean, organized space for supplies.
- Who it tends to suit
- People who want to avoid needle sticks, still have some kidney function of their own, and can keep a clean space at home.
- Lab visit (early on)
- Regular life
- Regular life
- Regular life
- Regular life
- Regular life
- Regular life
- Time and place
- Once recovered, there is no weekly treatment schedule at all, just regular life, with lab visits on a calendar that spreads out further over time.
- Food and fluids
- Most people can eat and drink close to normally, with a few food-safety habits to protect against infection while on medicine that manages the immune system.
- Medicines
- Daily medicine keeps the body from reacting against the new kidney, taken for as long as the kidney works.
- Work, travel and family life
- This path tends to give back the most freedom for work, travel, and family life once recovery is complete.
- What people report
- Across many studies put together, people with a working transplant report better physical health, better mental health, and more satisfaction with life than people on dialysis. Those studies could only watch who chose or qualified for each path — none of them assigned people at random. So part of the difference is likely that people healthy enough for a transplant started out healthier.
- Who it tends to suit
- People whose health allows for the surgery and who have found a kidney, whether from a living or a deceased donor.
- Regular life
- Regular life
- Regular life
- Regular life
- Regular life
- Regular life
- Regular life
- Time and place
- There is no dialysis schedule and no surgery. Care happens through regular visits with a full team, focused on comfort and symptoms. This is a real, chosen medical path, not giving up on care.
- Food and fluids
- Diet is guided by comfort and symptoms rather than the stricter limits dialysis requires.
- Medicines
- Medicine manages symptoms like tiredness, itching, and fluid buildup, chosen around what matters most to the person.
- Work, travel and family life
- Without a dialysis schedule, day-to-day life can stay closer to what it already was, shaped around comfort and priorities.
- What people report
- People who choose this path are often focused on comfort and time with family, and a full care team stays involved throughout.
- Who it tends to suit
- People for whom this path fits their goals better than dialysis or a transplant — often people who are also managing other serious health conditions.
Why transplant, specifically
For most people, a working transplant offers more years of life and more freedom day to day than staying on dialysis. The operation carries real risk of its own: for the first few months the risk is higher than it would have been on dialysis. That risk falls away. At around eight months the two even out, and from there the transplant keeps pulling ahead.
Getting a transplant before dialysis starts
The best long-term results for a new kidney come when the transplant happens early — before dialysis, or soon after it starts. A living donor is the route a person can actually plan around: the surgery is scheduled in advance with a healthy, willing donor, instead of waiting for a call that could come at any time.
What the research says about transplant
- 3 times a week
- typical in-center hemodialysis schedule, about four hours a visit
- Most people who choose in-center hemodialysis go three days a week, for about four hours each visit. Home hemodialysis usually runs more often, in shorter sessions, on a schedule the person sets up around their own life.
- NIDDK, read 2026
- 110 studies
- compared life after a kidney transplant with life on dialysis
- Covering nearly two million people in total, this review found that transplant recipients lived longer and reported better physical health, better mental health, and more life satisfaction than people on dialysis. The studies were all observational, not trials — people healthy enough for a transplant tend to start out healthier, so some of the difference is very likely that rather than the transplant alone.
- American Journal of Transplantation — Tonelli et al., 2011, 2011 systematic review
- 89.9%
- five-year survival of a living-donor kidney transplant, recipients aged 18 to 34
- Against 82.5% for a deceased-donor kidney at the same ages. Living-donor kidneys tend to keep working longer. The kidney spends far less time outside a body before it is placed, and the surgery is planned well ahead of time, with a healthy, carefully screened donor.
- OPTN/SRTR Annual Data Report, transplants 2017–2019, 2024 report
- 63%
- ten-year kidney survival, transplant within six months of starting dialysis versus after two years on it
- Against 29% for people who had been on dialysis more than two years. A transplant that happens early — before dialysis, or soon after it starts — is linked with the best long-term results for the new kidney, and a living donor is what makes that timing something a person can plan.
- Transplantation — Meier-Kriesche & Kaplan, 2002 paired-donor-kidney analysis
The numbers behind this
Every figure here is sourced and dated. They describe the scale of kidney disease and kidney failure in the United States, and where a transplant fits among the treatment paths.
Expected remaining years of life, 2023
- 37 million
- US adults were estimated to have chronic kidney disease in 2023
- About 1 in 7 adults (14%). Most of them do not know it, because the early stages have no symptoms. Kidney disease is common; kidney failure is the last stage of it, and most people with kidney disease never reach it.
- CDC, 2023 estimate, read 2026
- 131,564
- people started treatment for kidney failure in 2023
- Each of them began dialysis or received a transplant that year. The count has grown as the population has grown and aged, while the rate per person fell over the last two decades and has levelled off recently.
- USRDS Annual Data Report, 2023 data, published 2025
- 39.1%
- of people on the kidney waiting list have diabetes as the primary cause, 2024
- The largest single cause among people waiting for a kidney, and the leading cause of kidney failure nationally. Over many years, high blood sugar can damage the tiny filters inside the kidneys.
- OPTN/SRTR Annual Data Report, 2024 data, published 2026
- 20.1%
- of people on the kidney waiting list have high blood pressure as the primary cause, 2024
- The second-largest cause among people waiting. Blood pressure that stays high for years can narrow and stiffen the small blood vessels that feed the kidneys. Together, diabetes and high blood pressure account for most of the list.
- OPTN/SRTR Annual Data Report, 2024 data, published 2026
- 17.3 years
- expected remaining lifetime with a working kidney transplant, 2023
- Compared with 6.4 years for people on dialysis, across all ages. Some of that gap is the transplant itself, and some is that people well enough to receive one tend to be healthier to begin with — the two have never been compared in a trial. Even so, it is one of the main reasons transplant is the treatment doctors recommend for most people whose kidneys have failed.
- USRDS Annual Data Report, 2023 data, published 2025 (Table H.13)
- 31.8%
- of living-donor kidney transplants in 2024 happened before dialysis ever started
- Against 15.0% of deceased-donor transplants. A transplant before dialysis is linked to the best long-term results, and a living donor is the one route whose timing can be planned rather than waited for.
- OPTN/SRTR Annual Data Report, 2024 data, published 2026
- 92,000+
- people are waiting for a kidney
- The wait for a deceased donor kidney is typically three to five years. A living donor is the one route that does not depend on waiting for a phone call.
- American Kidney Fund, reviewed March 2026
- 831,192
- people were living with kidney failure in the US at the end of 2023
- An all-time high. The count keeps climbing mainly because people are living longer on treatment. Everyone in this count is on dialysis or living with a transplant.
- USRDS Annual Data Report, 2023 data, published 2025
- 49,249
- new adults joined the kidney waiting list in 2024, a record
- The number of transplants performed each year is growing too. A living donor is the one route off this list whose timing a person can actually plan around.
- OPTN/SRTR Annual Data Report, 2024 data, published 2026
Where to go from here
If reading this raised a question about what you could do, here is where to go next.
My Kidney Story does not collect, store, or evaluate medical information, and nothing on this page is medical advice. Donor eligibility is determined solely by a transplant center after its own independent evaluation.