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.
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.
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.
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.
Diabetes
The single most common reason a person comes to need a kidney. Over many years, high blood sugar can damage the tiny filters inside the kidneys.
High blood pressure
The second most common cause. Blood pressure that stays high for years can narrow and stiffen the small blood vessels that feed the kidneys.
Glomerular disease
A real cause at any age, including in younger adults. The kidney's tiny filters are damaged, often inflamed, and often because the body's own immune system is attacking them.
Polycystic kidney disease
An inherited condition in which fluid-filled sacs slowly grow in the kidneys and crowd out working tissue. It usually runs in families, and it tends to be found earlier in life than the other common causes.
Other or unknown causes
Sometimes the cause is a blockage, an infection, or another condition entirely. And sometimes, even after every test, the cause is never found. That is not the person's fault, and it does not change what a working kidney can do for them.
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.
Dialysis
A machine or a fluid exchange takes over some of the kidney's filtering work. It does not take over the kidney's other jobs, which are managed with medicine instead. Hemodialysis uses a machine, usually at a center a few days a week, though it can also be done at home. Peritoneal dialysis uses the lining of the belly as a filter, done at home, often overnight. Many people live full, active lives on either kind.
Kidney transplant
A working kidney, from a living donor or a deceased donor, is placed in the body to take over filtering. For most people whose kidneys have failed, it is the treatment doctors recommend, because of how much it gives back in years and in daily life.
Conservative kidney care
Treating the symptoms of kidney failure without dialysis or a transplant. This is a real, chosen medical path, not giving up on care. It suits some people, often those managing other serious health conditions, and a full care team stays involved throughout.
Why transplant, specifically
For most people, a working transplant offers more years of life and more freedom day to day than staying on dialysis. Part of that is the transplant, and part is that people well enough for one tend to start out healthier. 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
A transplant that happens before dialysis ever starts is linked with the best long-term results for the new kidney. A living donor is the route a person can actually plan around. The surgery can be scheduled in advance with a healthy, willing donor, instead of waiting for a call that could come at any time. That is why living donation matters so much to the people waiting.
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.
- 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
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.