Calculate eGFR with the MDRD equation from serum creatinine in mg/dL or µmol/L, age and sex, or reverse-solve the creatinine for a target eGFR.

Legacy adult MDRD equation; labs now prefer 2021 CKD-EPI. Not for children, pregnancy, acute kidney injury or drug dosing.

The former racial term is for reproducing historical results, not recommended current care.

Optional settings

MDRD Formula

The MDRD calculator estimates glomerular filtration rate (eGFR), which is a standardized measure of kidney filtration expressed in mL/min/1.73 m2. It uses standardized serum creatinine, age and sex coefficients in the IDMS MDRD equation. This is a legacy comparison tool: current U.S. recommendations favor the 2021 CKD-EPI equation. Simply omitting the historical racial multiplier from MDRD does not produce that newer equation.

MDRD = 175 × Crmg / dL - 1.154 × Age - 0.203 × S × R
Crmg / dL = (Crμ mol / L) / (88.4)
S = 0.742 for female, 1.000 for male
R = 1.000 by default; optional historical comparison uses 1.212

If you enter creatinine in µmol/L, the calculator first converts it to mg/dL and then applies the equation. The result is normalized to a body surface area of 1.73 m2, which is why the output is reported as mL/min/1.73 m2.

Variable Definitions

Input Meaning Why It Matters
Serum Creatinine The concentration of creatinine in blood, entered in mg/dL or µmol/L. Higher creatinine generally lowers the estimated GFR.
Age The patient’s age in years. The equation adjusts downward with increasing age.
Sex Used to apply the sex coefficient in the classic MDRD equation. Changes the estimate to account for average differences in creatinine generation.
Race Coefficient The original MDRD model contained a racial multiplier; it is retained here only as an explicitly selected historical comparison. This reproduces a legacy calculation; it is not recommended for current clinical reporting.

How to Use the MDRD Calculator

  1. Select the creatinine unit that matches the lab value you have.
  2. Enter the serum creatinine result.
  3. Enter age in years.
  4. Select sex.
  5. Leave the historical multiplier at No multiplier unless explicitly reproducing an older MDRD report. This is not the 2021 CKD-EPI equation.
  6. Click calculate to return the estimated GFR.

Because the formula is very sensitive to creatinine, even a small change in the lab value can materially change the eGFR result. Double-check the unit before calculating.

Example Calculation

Using standardized creatinine of 100 µmol/L, age 60 years, the female coefficient, and no historical multiplier:

MDRD = 175 × ((100) / (88.4)) - 1.154 × 60 - 0.203 × 0.742 × 1.000 ≈ 49.05

That gives an estimated GFR of approximately 49.05 mL/min/1.73 m2.

How to Interpret the Result

The MDRD result is an estimate of filtration, not a diagnosis by itself. Kidney disease staging depends on the eGFR value, whether the finding persists for at least 3 months, and whether other signs of kidney damage are present.

eGFR Range General Interpretation
90 or higher Normal or high filtration. This alone does not confirm kidney disease.
60 to 89 Mildly reduced filtration; significance depends on persistence and other kidney findings.
45 to 59 Mild to moderate reduction in kidney filtration.
30 to 44 Moderate to severe reduction in kidney filtration.
15 to 29 Severely reduced kidney filtration.
Below 15 Very severe reduction in kidney function that usually requires urgent medical evaluation.

When the MDRD Estimate Can Be Less Reliable

  • Rapidly changing kidney function or suspected acute kidney injury
  • Pregnancy
  • Children and adolescents
  • Very low muscle mass or very high muscle mass
  • Amputation, paralysis, severe malnutrition, or other situations where creatinine production is atypical
  • Cases where lab methods or reporting standards differ from the classic MDRD structure

Practical Notes

  • MDRD estimates kidney filtration from a blood test; it is not the same as a measured creatinine clearance study.
  • The primary output is indexed to 1.73 m2. The optional Mosteller BSA estimate uses √[height(cm) × weight(kg) / 3600], and de-indexed GFR = indexed eGFR × BSA / 1.73. This is not measured GFR or creatinine clearance and does not establish a drug dose.
  • Different labs may report eGFR using a different equation, which can lead to slightly different results from the same creatinine value.
  • This calculator is for educational legacy comparison. Use a current laboratory equation for clinical assessment; MDRD is less reliable at higher GFR and in the situations listed above. The inverse solve is algebraic only, not a prediction or treatment target.

Frequently Asked Questions

What does a higher MDRD value mean?
A higher eGFR usually indicates better kidney filtration, while a lower eGFR suggests reduced kidney function.

Why can two calculators give different answers?
Differences in unit conversion, rounding, creatinine calibration, and the exact equation used can all change the final estimate.

Is one low result enough to diagnose chronic kidney disease?
No. A single estimate should be interpreted with the full clinical picture, repeat testing, and other kidney markers.

Does this calculator replace medical advice?
No. It is a screening and educational tool. Clinical decisions should be made using a full medical assessment and the reporting standard used by the treating clinician or laboratory.