Estimated glomerular filtration rate (eGFR) reflects how well the kidneys filter waste from blood. Two widely-used formulas — Cockcroft-Gault and MDRD — give different estimates suited to different clinical contexts.
Estimates creatinine clearance (CrCl). Requires body weight — commonly used for drug dosing.
CrCl mL/min
Modification of Diet in Renal Disease. Normalised to body surface area (1.73 m²). Used for CKD staging.
eGFR mL/min/1.73m²
| Stage | eGFR (mL/min/1.73m²) | Description |
|---|---|---|
| G1 | ≥ 90 | Normal or high |
| G2 | 60–89 | Mildly decreased |
| G3a | 45–59 | Mildly to moderately decreased |
| G3b | 30–44 | Moderately to severely decreased |
| G4 | 15–29 | Severely decreased |
| G5 | < 15 | Kidney failure |
Cockcroft-Gault:
\[ \text{CrCl} = \frac{(140 - \text{age}) \times \text{weight} \times F}{72 \times \text{Scr}} \]
F = 1.0 (male), 0.85 (female) · Scr in mg/dL
MDRD (4-variable, IDMS-traceable):
\[ \text{eGFR} = 175 \times \text{Scr}^{-1.154} \times \text{age}^{-0.203} \times F \]
F = 1.0 (male), 0.742 (female) · Scr in mg/dL
For clinical use, verify results with laboratory reference ranges. MDRD may underestimate GFR in patients with normal or near-normal kidney function. For precise drug dosing, Cockcroft-Gault with actual body weight is generally preferred.