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Estimate your Glomerular Filtration Rate (GFR) using the CKD-EPI 2021 formula to assess kidney function and chronic kidney disease (CKD) stage.
CKD-EPI 2021 Formula (simplified):
eGFR = 142 × min(Cr/k, 1)^a × max(Cr/k, 1)^-1.2 × 0.9938^Age × [1.012 if female]
k = 0.7 (females) or 0.9 (males); a = -0.241 (females) or -0.302 (males)
Glomerular Filtration Rate (GFR) measures how well your kidneys filter waste from the blood, expressed in mL/min/1.73m2. A higher number means better kidney function. Normal GFR for young adults is about 100-120 mL/min/1.73m2.
eGFR (estimated GFR) is calculated from serum creatinine, age, and sex using a formula like CKD-EPI. True GFR requires special laboratory tests. eGFR is widely used clinically because it is easy to calculate from routine blood tests.
Normal creatinine is approximately 0.7-1.2 mg/dL for men and 0.5-1.0 mg/dL for women. However, creatinine alone is not enough - eGFR provides better context. High creatinine with low eGFR suggests reduced kidney function.
CKD has 5 stages based on eGFR: G1 (90+) normal, G2 (60-89) mildly decreased, G3a (45-59) mild-moderate, G3b (30-44) moderate-severe, G4 (15-29) severely decreased, G5 (<15) kidney failure.
Yes. GFR naturally declines about 1 mL/min/1.73m2 per year after age 40. An 80-year-old with a GFR of 60 may have age-related decline rather than disease. Age is factored into the CKD-EPI formula.
Creatinine levels are affected by muscle mass (higher in muscular individuals), diet (high meat intake raises creatinine), hydration status, certain medications, and kidney function. Athletes may have naturally higher creatinine.