What is the MDRD equation?

The 4-variable MDRD (Modification of Diet in Renal Disease) equation estimates eGFR using serum creatinine, age, sex, and race. The formula is: eGFR = 175 × Scr^−1.154 × Age^−0.203 × 0.742 (if female) × 1.212 (if Black). It was widely used before the CKD-EPI equation became the new standard.

How does MDRD differ from CKD-EPI?

MDRD tends to underestimate GFR in patients with normal or near-normal kidney function (eGFR > 60). CKD-EPI is more accurate across the full eGFR range and is now preferred by KDIGO guidelines. The 2021 CKD-EPI version also removes the race variable.

Why is the race correction controversial?

The 1.212 multiplier for Black patients in MDRD (and the original CKD-EPI 2009) was based on observed creatinine differences in study populations but can introduce bias, delay CKD diagnosis in Black patients, and perpetuate race-based clinical disparities. The 2021 CKD-EPI equation removed race entirely.

What creatinine units should I use?

US laboratories report creatinine in mg/dL; international labs often use µmol/L. Toggle the unit selector — the calculator divides µmol/L by 88.4 to convert to mg/dL before applying the formulas.

Can I use this for patients under 18?

No. Both MDRD and CKD-EPI are validated only for adults aged 18 and older. For pediatric GFR estimation, use the Bedside Schwartz or CKiD equations.

Is this a substitute for medical advice?

No. This tool is for educational and informational purposes only. Always consult a qualified healthcare provider for clinical interpretation of lab results and treatment decisions.

MDRD GFR Calculator

Enter serum creatinine, age, sex, and race to calculate eGFR using the MDRD and CKD-EPI 2021 equations, then see your KDIGO CKD stage.

Patient Parameters

Serum Creatinine

Normal: 0.74–1.35 mg/dL (men), 0.59–1.04 mg/dL (women)

Age (years)

Biological Sex

Race (MDRD only — see FAQ)

4-Variable MDRD Formula

175 × Scr^−1.154 × Age^−0.203
× 0.742 (female) × 1.212 (Black)

Fill in the parameters on the left and click Calculate GFR

MDRD eGFR

-- mL/min/1.73 m²

CKD Stage

015306090120+

CKD-EPI 2021 eGFR (preferred)

-- mL/min/1.73 m²

CKD Stage

015306090120+

Input Summary

Creatinine: --
Age: --
Sex: --
Race: --

KDIGO CKD Staging Reference

Based on eGFR; full staging also incorporates albuminuria (A1–A3).

Stage	eGFR	Description	Typical Action

Medical disclaimer: This tool is for educational and informational purposes only. eGFR is a screening estimate — CKD diagnosis requires at least two readings separated by 90 days plus assessment of albuminuria and clinical context. The MDRD race multiplier is controversial; the 2021 CKD-EPI equation (race-free) is the current guideline-recommended standard. Results do not replace professional clinical judgment or laboratory-reported values.

Summary

The MDRD (Modification of Diet in Renal Disease) study equation estimates eGFR from serum creatinine, age, sex, and race. This tool computes the 4-variable MDRD result alongside the 2021 race-free CKD-EPI equation — now the preferred standard — and maps both values to KDIGO CKD stages G1 through G5. The race multiplier in MDRD (1.212 for Black/African American patients) is noted as controversial and being phased out in favour of race-free formulas.

How it works

Enter serum creatinine in mg/dL or µmol/L — the unit toggle converts automatically.
Enter patient age in years (18 or older).
Select biological sex; female patients receive a 0.742 correction factor in the MDRD equation.
Select race for MDRD only — choose Black/African American if applicable (adds 1.212 multiplier).
Click Calculate GFR to compute both MDRD and CKD-EPI 2021 eGFR values.
Results show eGFR in mL/min/1.73 m², the corresponding KDIGO CKD stage, and a stage description.

Use cases

Estimate kidney function from a routine serum creatinine result.
Stage CKD according to KDIGO G1–G5 guidelines.
Compare MDRD and CKD-EPI 2021 results side by side.
Determine whether drug dose adjustments are needed based on renal function.
Monitor eGFR trends in patients with diabetes or hypertension.
Educate patients on what their creatinine value means clinically.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu