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Tests for kidney disease

kidneys red blue drawing
Learn about kidney tests that can help doctors find kidney disease early, such as blood tests, urine tests, kidney ultrasound and kidney biopsy.
Medically reviewed by
AKF's Medical Advisory Committee
Last updated
November 22, 2021

The only way to know how well your kidneys are working is to get tested. Kidney disease often has no symptoms until your kidneys are badly damaged. Testing is especially important if you have diabetes, high blood pressure or a family history of kidney disease. 

Ask your doctor about these kidney tests. Finding and treating kidney disease early can help you slow or stop damage to your kidneys.

Blood test: eGFR

eGFR (estimated glomerular filtration rate) is a measure of how well your kidneys are working. Your eGFR is a number based on a blood test that measures the amount of creatinine, a waste product in your blood. It is also based on your age, sex, weight and race. 

The stages of kidney disease are based on the eGFR number. 

Stage 1

eGFR 90 or higher, normal range with some signs of kidney damage, such as protein in urine (pee) or physical damage to the kidneys

Stage 2

eGFR 60-89, normal range with mild loss of kidney function and signs of kidney damage, such as protein in urine or physical damage to the kidneys

Stage 3

eGFR 30-59, moderate kidney damage, sometimes with symptoms such as swelling in hands and feet or back pain

Stage 4

eGFR 15-29, severe kidney damage and other health problems such as high blood pressure or anemia

Stage 5

eGFR less than 15, the kidneys are close to failure or have already failed – this is life-threatening without treatment

Blood test: Serum creatinine test

A serum creatinine test measures the amount of creatinine, a waste product in your blood. When your kidneys are not working well, your serum creatinine level goes up.

Blood urea nitrogen (BUN) test

Your blood urea nitrogen (BUN) level is based on a blood test that measures the amount of urea nitrogen in your blood. Urea nitrogen is a waste product that your body makes after it breaks down protein.

Urine test

A urine test is when a doctor examines a small amount of your urine (pee) to check for signs of kidney disease and other health problems. When your kidneys are damaged, they may let protein leak into your urine. This can be one of the earliest signs of kidney disease.

Learn more about the two types of urine tests

Kidney ultrasound

icon doctor with kidney chart

One way your doctor can look at your kidneys is by doing a kidney ultrasound. A kidney ultrasound (also called a renal ultrasound) is a safe and painless imaging test that uses sound waves to make pictures of your kidneys.

Learn more about kidney ultrasound

Kidney biopsy

One way your doctor can see if your kidneys are damaged is to do a kidney biopsy. A kidney biopsy is a procedure where doctors take a small piece of tissue from your kidneys to look at it under a microscope. 

Learn more about kidney biopsy

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