LAB TEST
Glomerular filtration rate
Glomerular filtration rate (GFR) is a test used to check how well the kidneys are working. Specifically, it estimates how much blood passes through the glomeruli each minute. Glomeruli are the tiny filters in the kidneys that filter waste from the blood.
How the Test is Performed
A blood sample is needed. The blood sample is sent to a lab. There, the creatinine level in the blood sample is tested. Creatinine is a chemical waste product of creatine. Creatine is a chemical the body makes to supply energy, mainly to muscles. The lab specialist combines your blood creatinine level with several…
How to Prepare for the Test
Your health care provider may ask you to temporarily stop any medicines that may affect the test results. These include antibiotics and stomach acid medicines. Be sure to tell your provider about all the medicines you take. Do not stop taking any medicine before talking to your provider. Tell your provider if you are…
How the Test will Feel
When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there might be some throbbing or a slight bruise. This soon goes away.
Why the Test is Performed
The GFR test measures how well your kidneys are filtering the blood. Your provider may order this test if there are signs that your kidneys are not working well. It may also be done to see how far kidney disease has progressed. The GFR test is recommended for people with chronic kidney disease. It is also recommended…
Normal Results
According to the National Kidney Foundation, normal results range from 90 to 120 mL/min/1.73 m 2 . Older people will have lower than normal GFR levels because GFR decreases with age. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk…
What Abnormal Results Mean
Levels below 60 mL/min/1.73 m2 for 3 or more months are a sign of chronic kidney disease. A GFR lower than 15 mL/min/1.73 m2 is a sign of kidney failure and requires immediate medical attention. Lower than normal GFR may indicate: Too little blood flow to the kidneys Loss of body fluids (dehydration) Heart or liver…
Risks
There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood from some people may be more difficult than from others. Other risks associated with having blood drawn are slight, but can include: Excessive…
References
Gharavi AG, Landry DW. Approach to the patient with renal disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine . 27th ed. Philadelphia, PA: Elsevier; 2024:chap 106. Krishnan A, Levin A. Laboratory assessment of kidney disease: glomerular filtration rate, urinalysis, and proteinuria. In: Yu ASL, Chertow GM,…
This is a summary. Read the full article at www.ucsfbenioffchildrens.org (reviewed 20/08/2023).
This page is general information and is not medical advice. It does not replace a registered doctor, and it is not a prescription or a recommendation to use any medicine or test. Prices are listed prices and may change. Always follow the advice of your doctor or pharmacist.