Kidney function tests are urine or blood tests that evaluate how well your kidneys are working. Most of these tests measure glomerular filtration rate (GFR). GFR assesses how efficiently your kidneys clear waste from your system.

What do your kidneys do?

Your kidneys are part of your urinary system. The two kidneys sit in the back of your abdomen just below your ribcage. They help your body filter waste materials and expel them as urine. Your kidneys are also vital for producing:

• Hormones that maintain blood pressure.

• Red blood cells, which carry oxygen throughout your body.

• Vitamin D, which maintains bone and muscle health.

Why might I need a kidney function test?

Some conditions, such as diabetes or high blood pressure (hypertension), affect how well the kidneys work. If you have one of these conditions, your healthcare provider may use kidney function tests to help monitor these conditions.

You may also need a kidney function test if you have symptoms that indicate possible kidney problems. These symptoms might include:

• Blood in your urine (hematuria).

• Painful urination (dysuria).

• Frequent urge to urinate.

• Problems with starting to pee.