# eGFR Calculator (MDRD Simplified)

Estimate glomerular filtration rate (eGFR) with the simplified 4-variable MDRD equation (2006 re-expressed, IDMS-traceable): eGFR (mL/min/1.73 m²) = 175 × SCr^−1.154 × Age^−0.203 × (0.742 if female) × (1.212 if Black). The 175 constant replaced the original 186 after IDMS-standardized creatinine calibration. The legacy race coefficient 1.212 is OFF by default (the 2021 CKD-EPI race-free equation removed it) and is provided only for historical comparison. Returns a BSA-INDEXED eGFR for CKD staging (G1–G5); for drug dosing use un-indexed CrCl (Cockcroft-Gault). Derived from Levey AS et al., Ann Intern Med 2006. Valid for stable adults, not AKI/pregnancy/extremes. Not medical advice.

> Canonical page: https://elysiatools.com/en/tools/egfr-mdrd

- **Category:** Health

- **Keywords:** egfr, MDRD, glomerular filtration rate, kidney function, CKD, chronic kidney disease, serum creatinine, nephrology, renal, IDMS

## Overview

Estimate glomerular filtration rate with the simplified 4-variable MDRD equation using age, sex, and IDMS-traceable serum creatinine. The calculator returns a BSA-indexed eGFR in mL/min/1.73 m² and assigns a CKD stage from G1 to G5 for stable adults.

## Inputs

- **Age (years)** (number): Patient age in years. Must be ≥18 and ≤120.
- **Sex** (select)
- **Serum Creatinine (mg/dL)** (number): Serum creatinine in mg/dL (IDMS-traceable). Must be positive.
- **Apply race coefficient 1.212 (legacy MDRD)** (checkbox): If checked, multiplies by 1.212 (legacy Black coefficient). OFF by default — modern NKF/ASN guidance uses race-free CKD-EPI 2021.
- **Decimal Places** (number)

## When to use

- Estimate eGFR for CKD staging in a stable adult.
- Review how age, sex, and serum creatinine affect an MDRD eGFR result.
- Compare a standard race-free MDRD estimate with the legacy 1.212 coefficient for historical reference.

## How it works

- Enter an age from 18 to 120 years and a positive serum creatinine value in mg/dL.
- Select the patient's sex; the female adjustment is applied when Female is selected.
- The calculator applies the simplified MDRD formula: 175 × SCr^−1.154 × age^−0.203, with the female factor when applicable.
- Review the eGFR, unit, CKD stage, and whether the legacy race coefficient was applied.

## Use cases

- Clinicians and students reviewing eGFR calculations and CKD stage thresholds.
- Patients organizing stable kidney-function results for discussion with a healthcare professional.
- Researchers or analysts comparing standard MDRD outputs with the legacy coefficient for historical data.

## Frequently asked questions

### What does this calculator estimate?

It estimates eGFR with the simplified 4-variable MDRD equation and reports a BSA-indexed result in mL/min/1.73 m².

### What inputs are required?

Age and serum creatinine are required. Sex is available as a male or female selection and defaults to Male.

### Is the race coefficient enabled by default?

No. The 1.212 coefficient is off by default and is provided only for historical comparison.

### Can I use this result for medication dosing?

No. This is a BSA-indexed eGFR for CKD staging; drug dosing generally requires an un-indexed creatinine clearance estimate such as Cockcroft-Gault.

### When should this MDRD calculator not be used?

It is not intended for acute kidney injury, pregnancy, or body-size extremes, and it is not a substitute for medical advice.

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