Renal failure can be acute, which is usually reversible, or chronic, which is a lifelong condition. Acute renal failure occurs quickly, while chronic renal failure may happen gradually.

A person can learn to recognize renal failure, also called kidney failure, by memorizing the early warning signs. These include urinary problems and feeling short of breath.

However, some people may not experience symptoms. In these cases, the only way to recognize renal failure is to contact a doctor and receive a diagnosis.

This looks at the first signs of renal failure, whether the condition can be asymptomatic, symptoms, diagnostic tests, at-home kidney tests, and more.

Renal failure can be asymptomatic, and a person may not know they have the condition until their kidneys fail.

In the early stages of renal failure, a person may not experience any noticeable symptoms.

According to the Centers for Disease Control and Prevention (CDC), around 90% of people who have chronic kidney disease are unaware of their illness.

To diagnose renal failure, a doctor may order several tests. These may include:

  • Urine test: A urine test can help doctors find any abnormalities in the urine. Doctors will look for albumin, a type of protein that is an early sign of kidney disease.
  • Blood tests: Doctors may order blood tests to check the levels of electrolytes in the blood. Additionally, elevated levels of substances such as creatine could indicate kidney dysfunction.
  • Abdominal X-ray: This can help doctors rule out other causes of symptoms.
  • Renal ultrasound: A renal ultrasound uses sound waves to create images of the kidneys, which doctors can use to check for blockages, abnormalities, tumors, or other problems. This may also involve a Doppler-flow kidney ultrasound, which doctors use to determine blood flow through an organ.
  • Renal biopsy: For a kidney biopsy, a doctor can extract a small piece of the kidney tissue, to check for cell damage.

A person can use an at-home kidney test to measure urine or blood. However, a person should always follow up with a doctor afterward — they may wish to perform additional tests.

Urine tests

Two types of urine tests measure kidney function — a dipstick test and a urine albumin-to-creatine ratio (UACR) test.

A dipstick test measures the levels of a protein called albumin in the urine. When kidneys are healthy, they filter albumin in the bloodstream, so the presence of the protein indicates the kidneys are not functioning correctly.

To perform a dipstick test, a person places a color-coded testing strip into a sample of urine, and if the strip’s color changes, the urine could contain albumin.

A UACR test measures the amount of albumin a person has in their urine compared to the waste product creatine. A level higher than 30mg per gram can indicate improper kidney functioning.

Blood tests

Individuals can order a finger-prick blood test, to collect a sample of their blood at home, and send it back to a laboratory to assess the data and provide results.

Experts will check the blood to determine how well the kidneys filter waste. Doctors refer to this test as a glomerular filtration rate (GFR) test.

The results of GFR levels are as follows:

GFR stageGFR resultIndication
260–89early-stage kidney disease
3a59–44mild kidney disease
3b44–30moderate kidney disease
415–29severe kidney disease
5<15kidney failure

For more information on at-home kidney tests, click here.

A person should consult a doctor if they have any signs of renal failure, as the condition can lead to severe complications if untreated.

A person should seek emergency medical care if they experience any severe symptoms, such as:

If a person’s kidneys fail, they will require either dialysis or a kidney transplant.

Dialysis removes waste and extra fluid from the body, which the failed kidneys cannot do. Peritoneal dialysis uses the lining of the abdomen to complete waste removal, while hemodialysis uses an artificial kidney machine.

In a kidney transplant, surgeons replace the old kidney with a healthy donor kidney.

This section answers some frequently asked questions on recognizing the signs of renal failure.

What are the five signs of kidney failure?

Five of the early signs of kidney failure include:

  • too little urine leaving the body
  • swelling in legs, ankles, and around the eyes
  • fatigue or tiredness
  • shortness of breath
  • chest pain or pressure

How can I check my kidneys at home?

A person can check their kidney function using an at-home urine test, such as a dipstick or UACR test, or a finger prick test to check their GFR levels.

What color is urine when your kidneys are failing?

Urine may be frothy or cloudy when a person’s kidneys are failing.

Some people may not have symptoms of renal failure, and may not know they have the condition until their kidneys fail.

If a person does have symptoms, early signs can include swollen legs and ankles, low output of urine, and feeling short of breath. As renal failure progresses, symptoms may include fatigue, nausea, chest pain, and muscle cramps.

Doctors can perform several diagnostic tests to diagnose the condition, including blood, urine, and imaging tests.

A person can perform an at-home test to check the levels of the protein albumin in the urine, and finger-prick blood tests to check levels of GFR.

If the kidneys fail, a person will require either dialysis or a kidney transplant.