Kidney function tests

Kidney Function Tests

Kidney function tests evaluate the role and health of the kidneys. The tests check how well the kidneys are filtering the blood, how well the kidneys are making urine, and how well the kidneys are performing their other functions. They may show early signs of kidney damage, or help identify other kidney problems.


Generally, no special preparation is necessary for this test. There could be exceptions, so speak to your doctor to find out if any special preparation is needed. You may need to fast or limit certain activities if the doctor has asked you to do so.


The procedure of the test usually involves the doctor collecting a sample of your blood and urine. The sample is tested in the laboratory to check the concentration of various waste products, including creatinine and urea, in the fluids.

Types of Tests

  • Blood Urea Nitrogen (BUN)
  • Blood Creatinine Level
  • Glomerular Filtration Rate (GFR)
  • Urine Analysis
  • Osmolarity
  • Sodium Urine Test
  • Urine pH Test
  • Urinary Albumin


There are minimal risks associated with a kidney test. The test may cause slight discomfort or pain when the needle is inserted. The risk of infection is minimal. Ask your doctor any questions or concerns that you may have prior to the procedure.

Why Do Doctors Order Kidney Tests?

Doctors may order kidney tests when you have symptoms of a possible kidney problem, such as nausea, vomiting, and a general feeling of being unwell. Also, it may be used to monitor an existing or ongoing condition or to monitor the effectiveness of prescribed medication.

When Should You Have Kidney Tests?

Your doctor will recommend when you should have a kidney test based on your current health status and your risk factors for kidney disease. The National Kidney Foundation recommends that everyone over the age of 18 should have regular kidney tests, such as urine tests and creatinine tests, done every year. Your doctor may also recommend more frequent tests if you have a higher risk for kidney disease due to diabetes or another condition.