An eGFR (estimated glomerular filtration rate) is a blood test that checks how well your kidneys are working by estimating how much blood your kidneys filter each minute. It is calculated from your blood creatinine level — a normal waste product made when you use your muscles — together with your age, sex, and often your weight and height, entered into a standard formula. In some cases it is estimated using a blood protein called cystatin C instead, because cystatin C levels are not affected by muscle size, age, or diet. According to MedlinePlus, an eGFR is a more accurate way to measure kidney health than a creatinine level alone, and it can help show how serious kidney disease is. It is an estimate: MedlinePlus notes an eGFR "isn't a perfect test and may not always reflect kidney damage."
Early kidney disease often causes no symptoms, so an eGFR is commonly done as part of a routine check-up or to screen people at higher risk of kidney disease. Per MedlinePlus, higher-risk groups include people with diabetes, high blood pressure, heart disease, a family history of kidney disease, and those who are older, smoke, or have obesity. It may also be ordered when someone has possible symptoms (such as swelling in the legs, feet, ankles, hands, or face; urinating more or less often than usual; fatigue; muscle cramps; itchy or dry skin; or nausea and loss of appetite), and it is used to monitor kidney function over time in people already diagnosed with kidney disease.
Reference ranges are general and vary by the laboratory, the equation used, and by your age, sex, and body factors — your own lab report and your clinician's interpretation are what apply to you, not any single number listed here. MedlinePlus does not frame results as one fixed cutoff: in general a normal eGFR means you probably don't have kidney disease; an eGFR below normal or low may mean you have kidney disease; and a very low eGFR may mean kidney failure. For general orientation only, MedlinePlus's Medical Encyclopedia describes eGFR in units of mL/min/1.73 m2, with normal results roughly in the 90–120 range, and NIH's NIDDK states that a GFR of 60 or more is in the normal range, a GFR below 60 may mean kidney disease (chronic kidney disease is generally considered when the value stays below 60 for three or more months), and a GFR of 15 or less is called kidney failure. A single result can also be abnormal without kidney damage, so a low value is usually confirmed and interpreted over time rather than from one test.
A higher or normal eGFR is generally the reassuring direction and usually suggests the kidneys are filtering well. A high eGFR is not typically treated as a problem on its own. This is general information and not a diagnosis.
A below-normal or low eGFR may suggest reduced kidney function and can be seen with kidney disease; a very low eGFR may suggest kidney failure. These are general possible associations, not a diagnosis or a complete list — MedlinePlus notes it is also possible to have an abnormal result even if you don't have kidney damage. A low result is interpreted in the context of your overall health, other test results, and whether it stays low over time. Your eGFR should be interpreted by your health care provider, who considers your full medical picture and how your numbers change over time to decide what your result means for you. This is general information, not medical advice.
Reference ranges vary by laboratory, age, sex, and method — the range on your own report is what applies to you. A single value out of range doesn’t confirm any condition; your clinician interprets it alongside your symptoms, history, and other results. This page is general information, not medical advice.
General reference, not medical advice, and not a substitute for your clinician. Lab reference ranges and interpretation depend on the laboratory and on your individual situation — discuss your results with a licensed healthcare professional.