AUA Summit - Kidney Failure: Symptoms, Causes & Diagnosis


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What is Kidney (Renal) Failure?

Sometimes kidneys are no longer able to filter and clean blood. This can cause unsafe levels of waste products to build up. This is known as kidney (or renal) failure. Unless it is treated, this can cause death.

What are Kidneys?

The kidneys are 2 bean-shaped organs, each about the size of a fist. They are found in your back on either side of the spine. Healthy kidneys clean waste products from the blood by making urine. They also balance the amount of certain elements in your blood (such as sodium, potassium, and calcium), and make hormones that control blood pressure and red blood cells.

What is Kidney Failure?

Before kidney failure occurs, patients have "chronic kidney disease" (CKD). Kidney (renal) failure is when kidneys don't work as well as they should, to the point where kidney replacement is required. Kidney replacement can be accomplished by different kinds of dialysis or by kidney transplant. The term "kidney failure" covers a lot of problems. These problems can result in kidney failure:

  • Your kidney doesn't get enough blood to filter
  • Your kidney is hurt by a disease like
    • high blood sugar (diabetes)
    • high blood pressure
    • glomerulonephritis (damage to the kidney's tiny filters; one example: lupus)
    • polycystic kidney disease
    • and many others
  • Your kidney is blocked by a kidney stone or scar tissue (blockage of ONE kidney usually does not cause kidney failure because the other kidney is not affected; but blockage of two kidneys can lead to an emergency).


The symptoms of CKD are often quite mild; people may have significantly reduced kidney function and not be aware of it. The symptoms of kidney failure can differ based on how bad the kidney failure is, how quickly it is getting worse, and what is causing it.

There are 2 main types of kidney (renal) failure: acute (sudden) and chronic (over time).

Acute Renal Failure – more commonly known today as “acute kidney injury”(AKI)

AKI occurs when the kidneys suddenly stop filtering waste products from the blood.

The signs of AKI can be:

  • swelling of the hands, feet and face (edema)
  • internal bleeding
  • confusion
  • seizures
  • coma
  • abnormal blood and urine tests
  • high blood pressure

Chronic Kidney Disease (CKD; previously known as Chronic Renal Failure – CRF)

CKD builds slowly with very few symptoms in its early stages.

A patient with CKD may not have any symptoms until kidney function declines to 20% or less. At that stage, these signs may appear:

  • abnormal blood and urine tests
  • high blood pressure
  • weight loss for no reason
  • low red blood cell count (anemia)
  • nausea
  • vomiting
  • metal taste in your mouth
  • loss of appetite
  • shortness of breath
  • numbness and tingling
  • confusion
  • coma
  • seizures
  • easy bruising
  • itching
  • fatigue
  • muscle twitches and cramps
  • weak bones that break easily
  • itching
  • swelling of the hands, feet and face (edema)
  • trouble sleeping


AKI is most likely to happen with:

  • low blood flow (such as after complicated surgery or an accident)
  • swelling (inflammation) of the kidney (such as a reaction to a drug or infection)
  • sudden blockage (such as by a kidney stone)
  • very high blood pressure

With AKI, the kidney often returns to normal or near normal after the cause is treated.

CKD is permanent loss of kidney function. The most common causes are:

  • high blood pressure
  • chronic glomerulonephritis (kidney damage)
  • high blood sugar (diabetes)
  • polycystic kidney disease
  • blocked urinary tract


Overall kidney function is judged by the level of filtration that occurs. Filtration is accomplished by the tiny blood vessels in the kidney called “glomeruli”. So overall kidney function is called the “glomerular filtration rate” (GFR), measured as the volume of blood filtered per minute (milliters/minute). Normal values are about 100 ml/min, but varies with age and sex. GFR can be estimated (eGFR) using formulas that take into account your age, sex and a blood test called creatinine.

Kidney failure is most often found when the creatinine level is high, indicating that kidney function is reduced. Creatinine is a molecule made by your muscles. A normal kidney will remove creatinine from the blood stream and get rid of it in urine. More creatinine in the blood is a sign that the kidneys aren't cleaning the blood as well as they should. This test can spot something is wrong before a patient with kidney failure feels sick.


To treat AKI, you have to treat the cause (such as blood pressure that is too high or too low, a kidney stone or high blood sugar). Sometimes you need dialysis for a short time.

With CKD, treating the cause (such as high blood pressure and/or high blood sugar) can slow the disease. The goal is to prevent CKD from turning into advanced kidney disease, or end stage kidney disease (ESKD, formerly known as end stage renal disease, ESRD).

When kidney function falls below 10% of normal, dialysis or a kidney transplant is usually needed, especially if you have signs of uremia (a buildup of waste in the blood), like nausea, loss of appetite, weight loss and itching.


Dialysis is a way to remove extra salt, acid, potassium and waste products from the blood. The 2 types of dialysis are hemodialysis and peritoneal dialysis.

Hemodialysis:  For hemodialysis, a tube (catheter) is stuck into one of the veins in your neck or leg. Preferably, an access, or arteriovenous fistula, is constructed in the arm. Hemodialysis is most often done 3 times a week for 3 to 4 hours at a time.

Peritoneal dialysis: Peritoneal dialysis is done through a tube permanently set in your belly. Fluid is then run into the abdomen, takes out the extra salt and potassium and water, and then removed. Most exchanges of fluid can be done by an automated “exchanger” while you sleep.

Most adults have dialysis done in an outpatient hemodialysis center. Most children have peritoneal dialysis done at home. Peritoneal dialysis has a number of advantages and is becoming more frequently used in adults in the US.

Kidney Transplant

A kidney transplant is when a surgeon puts a healthier kidney from another person into your body. Kidney transplant is the best way to treat many patients with end stage kidney disease.

Kidneys for transplant come from people who have agreed to donate their kidneys when they die (deceased donors) or donated by healthy people (living donors). Living donors are most often family members of the patient. There is a shorter wait time to surgery for a transplant from a living donor. (This is because there is a waiting list for kidneys from deceased donors and not enough donors.) Also, patients with kidneys donated by living donors live longer (and the kidneys last longer) than those with kidneys from deceased donors or who just stay on dialysis.

With modern medical techniques, the living kidney donor doesn't need to be a blood family member to get a good result.

About 90,000 patients are on the wait list for deceased donor kidney transplants in the U.S. But only 10,000 deceased donor kidney transplants are done each year due to the lack of donated kidneys. Another 6,000 kidney transplants are done each year from living kidney donors.

More Information

To learn more about kidney health, check out the below resources:

National Kidney Foundation (NKF)

American Association of Kidney Patients (AAKP)

American Kidney Fund (AKF)

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