MDRD GFR Equation

Q: Is MDRD still used clinically?

Most laboratories have transitioned to CKD-EPI, but MDRD may still appear on older reports. CKD-EPI is now preferred.

Q: Why is MDRD less accurate at higher GFR?

The MDRD equation was developed in patients with known CKD and was not validated in healthy individuals, leading to underestimation at higher GFR values.

Estimates glomerular filtration rate using the 4-variable MDRD equation.

Nephrology Internal MedicineEvidence-BasedUpdated 2026-08-06

Clinical decision-support tool for qualified healthcare professionals. Results are not a diagnosis and should not replace professional clinical judgment.

Clinical Notes

The Modification of Diet in Renal Disease (MDRD) equation estimates glomerular filtration rate (eGFR) from serum creatinine, age, and sex. It was the reference equation for estimating GFR for many years before being updated and progressively superseded by the CKD-EPI equation in laboratory reporting and clinical staging. The validity of the estimate depends on creatinine measurement being standardized and traceable to the isotope dilution mass spectrometry (IDMS) reference method. When only non-IDMS-traceable creatinine values are available, the MDRD equation performs differently, which is why the laboratory's creatinine standardization must match the equation version used. The equation reports eGFR normalized to a standard body surface area (mL/min/1.73m2), not an absolute clearance. Compared with CKD-EPI, the MDRD equation is generally less accurate at higher GFR values (where CKD-EPI shows less systematic bias) and was derived from a predominantly CKD population. It is intended for adults and is not validated in children, pregnant women, or patients with rapidly changing kidney function (such as acute kidney injury), severe malnutrition, amputations, or unusual muscle mass, where steady-state assumptions do not hold. An estimated GFR is an approximation of kidney function, not a measured value and not a diagnosis by itself; MDRD-based eGFR alone is not appropriate as a standalone diagnosis of chronic kidney disease. The result should be interpreted together with the clinical context, and where accuracy matters most, a measured GFR test may be preferred.

Calculator Information

Specialty

Internal Medicine

📋 Reference Ranges

Normal Range

≥90 mL/min/1.73 m²

Reference ranges for this calculator
Classification	Range
G1: Normal or high	≥90
G2: Mildly decreased	60–89
G3a: Mild to moderate	45–59
G3b: Moderate to severe	30–44
G4: Severely decreased	15–29
G5: Kidney failure	<15

What This Calculator Measures

Estimates glomerular filtration rate (eGFR) using the 4-variable MDRD equation, primarily encountered in older laboratory reports and historical comparisons.

How to Use

Enter the patient's age, sex, and serum creatinine (mg/dL).
Review the estimated eGFR and the corresponding CKD G stage.
For new clinical decisions, prefer the CKD-EPI 2021 equation when available.

How the Calculation Works

The MDRD equation estimates eGFR = 175 x (serum creatinine)^-1.154 x (age)^-0.203 x 0.742 (if female), with creatinine in mg/dL and age in years.

Variables Explained

Age

Age in years, raised to the -0.203 power.

Sex

Biological sex; females receive a 0.742 multiplier.

Serum Creatinine

Serum creatinine in mg/dL, raised to the -1.154 power.

Interpretation Guide

MDRD eGFR is interpreted using the same KDIGO G stages as CKD-EPI: G1 ≥ 90, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29, and G5 < 15 mL/min/1.73 m². The equation applies a female adjustment factor (× 0.742).

Sex-specific interpretation

Clinical Significance

The MDRD equation made eGFR reporting practical and remains important for interpreting older laboratory results and understanding why CKD-EPI has replaced it.

When It Is Useful

Comparing with older laboratory reports that still report MDRD eGFR
Historical interpretation of eGFR trends
Where CKD-EPI is unavailable

When It Is Not Useful

For new clinical decisions when CKD-EPI is available
For medication dosing without drug-specific guidance (Cockcroft-Gault is commonly referenced)
In acute kidney injury with unstable creatinine
At extremes of body size or muscle mass without clinical correlation

Common Mistakes

Using MDRD for a new clinical decision when CKD-EPI is available.
Comparing MDRD results with CKD-EPI values when tracking a trend, since the equations give different numbers.
Applying MDRD in children or pregnancy, where the equation has not been validated.

Limitations

Tends to underestimate GFR when the true GFR is above 60 mL/min/1.73 m².
Was developed in patients with known CKD and is less accurate in healthy individuals.
Values may differ from CKD-EPI; trends should be compared within the same equation.
Less accurate at extremes of muscle mass and body habitus.

Worked Example

A 65-year-old woman has a serum creatinine of 1.1 mg/dL.

Inputs:

age: 65

sex: 2

creatinine: 1.1

Expected Result: eGFR ≈ 175 × 1.1^-1.154 × 65^-0.203 × 0.742 ≈ 50 mL/min/1.73 m², corresponding to CKD stage G3a (45–59).

Evidence & References

Source:: Nephrology
Content updated:: 2026-08

Levey AS, et al. Ann Intern Med. 1999;130(6):461-470.

References

Levey AS, Bosch JP, Lewis JB, et al. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Ann Intern Med. 1999;130(6):461-470. (Original Description)
KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. (Guideline)

Frequently Asked Questions

Is MDRD still used clinically?

Most laboratories have transitioned to CKD-EPI, but MDRD may still appear on older reports. CKD-EPI is now preferred.

Why is MDRD less accurate at higher GFR?

The MDRD equation was developed in patients with known CKD and was not validated in healthy individuals, leading to underestimation at higher GFR values.

Disclaimer: This calculator is intended for educational and clinical decision support purposes only. eGFR is an estimate and MDRD has been largely superseded by CKD-EPI for current clinical decisions.