What it is (overview)

The Estimated Glomerular Filtration Rate (eGFR) is a calculated lab value that estimates how well your kidneys filter blood each minute. It is one of the most widely used measures of kidney function and overall renal health. The eGFR is typically reported automatically when a blood test shows your serum creatinine level. Creatinine is a waste product made by your muscles; healthy kidneys remove it from the blood and pass it into urine.

Because creatinine levels are influenced by factors such as age and sex (and sometimes body size and muscle mass), laboratories use a formula to convert creatinine into an estimated filtration rate. This estimated rate reflects the kidneys’ “filtering power,” also known as the glomerular filtration rate. Results are most often reported as mL/min/1.73 m².

In plain language, eGFR helps answer: “How well are my kidneys cleaning my blood?” In general, a higher eGFR suggests better kidney filtering, and a lower eGFR suggests reduced kidney function. Many labs flag an eGFR below about 60 that persists for 3 months or longer as a possible sign of chronic kidney disease (CKD). Very low eGFR values can indicate advanced kidney disease and may require urgent evaluation, especially if symptoms are present. Your clinician will interpret your eGFR alongside your medical history and other kidney tests (often including a urine albumin-to-creatinine ratio) to understand the full picture.

When & why it's usually done

An eGFR is commonly ordered as part of routine labs or a metabolic panel because kidney health affects many body systems. It may be used as a screening diagnostic test, to help diagnose suspected kidney disease, or to monitor known kidney problems over time.

Your clinician may recommend an eGFR blood test if you have symptoms or findings that could suggest kidney trouble, such as:

Possible symptoms/signs include swelling in the legs/ankles, foamy urine, changes in urination (frequency, amount, or nighttime urination), fatigue, nausea, poor appetite, trouble concentrating, shortness of breath, persistent itching, or high blood pressure that is new or difficult to control. Many people with early kidney disease have no symptoms, which is why testing is important for people at risk.

Common reasons and risk factors for checking eGFR include:

Diabetes, high blood pressure, a family history of kidney disease, older age, heart disease, obesity, smoking, recurrent urinary tract infections, kidney stones, or conditions that can affect the kidneys (such as autoimmune disease). eGFR is also used to monitor kidney function when taking medications that can affect the kidneys (for example, some pain relievers/NSAIDs, certain antibiotics, lithium, or chemotherapy), and before imaging studies that use iodinated contrast dye. It may also help guide safe dosing for many medications, since drug clearance often depends on kidney filtration.

Common diseases related to it

• Chronic kidney disease (CKD)
• Acute kidney injury (AKI)
• Diabetic kidney disease (diabetic nephropathy)
• Hypertensive kidney disease (kidney damage from high blood pressure)
• Glomerulonephritis (inflammation of the kidney’s filtering units)
• Polycystic kidney disease (PKD)
• Obstructive uropathy (blockage from enlarged prostate, stones, or tumors)
• Recurrent kidney stones and related kidney impairment
• Autoimmune diseases affecting kidneys (e.g., lupus nephritis)
• Chronic heart failure with cardiorenal syndrome

Health goals where it may help

• Tracking and protecting kidney function over time (renal health monitoring)
• Early detection and risk reduction for kidney disease, especially in diabetes or high blood pressure
• Safer medication use by supporting kidney-based dosing decisions
• Monitoring the effects of treatments aimed at slowing CKD progression (blood pressure, blood sugar, and kidney-protective therapies)
• Assessing overall cardiometabolic risk, since kidney function is closely linked to heart and vascular health
• Pre-procedure safety planning (e.g., before contrast imaging or certain surgeries)
• General wellness screening as part of periodic blood work, particularly with increasing age or other risk factors