eGFR (MDRD)

MDRD: estimating glomerular filtration rate

The MDRD equation (Modification of Diet in Renal Disease, 4-variable IDMS-traceable) estimates GFR normalized to 1.73 m²: eGFR = 175 · Scr^(−1.154) · age^(−0.203) · (0.742 if female) · (1.212 if Black) in mL/min/1.73 m². Take a man of 60 with Scr 1.0 mg/dL who is non-Black, and you get eGFR ≈ 175 · 1.0^(−1.154) · 60^(−0.203) ≈ 77 mL/min/1.73 m². Above 60 mL/min/1.73 m² it loses accuracy and reads low against the true GFR.

Clinical context

For years MDRD was the standard for CKD screening and staging under KDIGO criteria. CKD-EPI 2021 has since taken its place, since it's more accurate (especially for eGFR > 60) and carries no race coefficient. That race adjustment in MDRD drew criticism for having no biological basis and for feeding healthcare inequity. Reach for MDRD only when there's a historical reason, like legacy reports or a comparison against old measurements. When you're staging fresh, go with CKD-EPI 2021.

FAQ

MDRD or CKD-EPI? CKD-EPI 2021. MDRD is dated, and the race coefficient is no longer recommended.

Does it work for dose adjustment? No. For drug dosing you want Cockcroft-Gault, which gives absolute ClCr rather than a value normalized to 1.73 m².

Does it work in AKI? No. The formula assumes creatinine is at steady state, so it falls apart while renal function is still changing.