Glomerular Filtration Rate (eGFR

Clinical Nephrology: CKD-EPI 2021 Standard & KDIGO Staging

The National Kidney Foundation (NKF) and the American Society of Nephrology (ASN) updated clinical guidelines to universally adopt the CKD-EPI 2021 race-free equation:

• Elimination of Race Multiplier: The 2021 equation removed the historical Black race adjustment coefficient, improving equity and standardizing diagnosis across diverse patient populations.

• KDIGO CKD Staging System:

• Stage G1: Normal kidney function with known kidney structural disease or albuminuria.

• Stage G2: Mild reduction, common in older adults.

• Stage G3a: Mild-to-moderate impairment; requires medication titration.

• Stage G3b: Moderate-to-severe impairment; nephrology co-management recommended.

• Stage G4: Severe renal insufficiency; dialysis/transplant planning.

• Stage G5: Kidney failure / End-stage renal disease (ESRD).

• Cockcroft-Gault vs. eGFR: While eGFR is used for chronic disease staging, many FDA drug package inserts still reference Cockcroft-Gault CrCl for pharmacokinetic dose adjustments (such as direct oral anticoagulants, vancomycin, and chemotherapy).

How to Use This Calculator

Enter your Biological Sex — select from Female, Male, Age (Years) (e.g. 62), Serum Creatinine (e.g. 1.2 mg/dL (or 106 µmol/L)), Creatinine Units — select from mg / dL (Standard US units), µmol / L (Standard SI units), and Body Weight (kg) [for Cockcroft-Gault CrCl] (e.g. 68 kg (or enter weight in kg)). Results update instantly — no submit button needed. Use metric or imperial units as labeled. For the most accurate result, measure height and weight in the morning without shoes.

The Formula

Estimated Glomerular Filtration Rate (eGFR) & Creatinine Clearance equations:

CKD-EPI 2021 Refit (Race-Free Standard):

eGFR = 142 × (S_cr, 1)^α × (S_cr, 1)^-1.200 × 0.9938^Age × (1.012 if female)

where = 0.7 (females), 0.9 (males); α = -0.241 (females), -0.302 (males); S_cr in mg/dL.

Cockcroft-Gault Creatinine Clearance (CrCl):

CrCl (mL/min) = ((140 - Age) × Weight (kg)) / (72 × S_cr) × (0.85 if female)

MDRD Study Equation:

eGFR = 175 × (S_cr)^-1.154 × (Age)^-0.203 × (0.742 if female)

Worked Example

For example, evaluating a 62-year-old female with serum creatinine and weight 68 kg: With \ and . The CKD-EPI 2021 eGFR is 142 × (1.714)^-1.200 × 0.9938^62 × 1.012 = 50 mL/min/1.73m^

• Cockcroft-Gault CrCl is ((140 - 62) × 68) / (72 × 1.2) × 0.85 = 52 mL/min.

Understanding Your Result

KDIGO (Kidney Disease: Improving Global Outcomes) eGFR staging: G1 Normal ≥90 mL/min/1.73m². G2 Mildly decreased 60–

• G3a Mild-moderately decreased 45–

• G3b Moderately-severely decreased 30–

• G4 Severely decreased 15–

• G5 Kidney failure below

• eGFR naturally declines approximately 1 mL/min/1.73m² per year after age 40 — a single reading must be interpreted in context of age, hydration status, and trend over time. Two readings more than 3 months apart are needed to confirm CKD staging.