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eGFR (MDRD) Calculator

Estimate kidney filtration rate using the 4-variable MDRD equation.

How it is calculated

The tool applies the 4-variable MDRD equation: eGFR = 175 × SCr−1.154 × Age−0.203, where SCr is serum creatinine in mg/dL and Age is in years. The result is multiplied by 0.742 when sex is set to female and by 1.212 when race is set to Black. The answer is rounded to a whole number and shown in mL/min/1.73m2. It is then placed in a stage band: G1 at 90 or above, G2 60–89, G3a 45–59, G3b 30–44, G4 15–29 and G5 below 15. Creatinine must be above zero and age above zero and at most 130, otherwise no result is shown. The equation was built for adults, and the tool does not otherwise restrict age.

Worked example

Take a 55-year-old woman with serum creatinine 1.2 mg/dL. Creatinine part: 1.2−1.154 ≈ 0.810. Age part: 55−0.203 ≈ 0.443. Base value: 175 × 0.810 × 0.443 ≈ 62.8. Female factor: 62.8 × 0.742 ≈ 46.6. The tool shows 47 mL/min/1.73m2 and the stage Stage G3a (mild–moderate, 45–59). The same values for a man with no race factor give 63, which falls in G2.

Try this example →

Common mistakes

  • Typing creatinine in µmol/L, as many labs report it, instead of mg/dL. A value such as 100 is treated as 100 mg/dL and the eGFR drops to 0, shown as Stage G5.
  • Expecting the sex and race fields to be cosmetic. Female lowers the result by about 26 % and Black raises it by about 21 %, so a wrong selection can move the stage band.
  • Entering a very low creatinine such as 0.1. The formula has no ceiling for creatinine, so a 55-year-old man gets an eGFR of 1,106, which is not a physiological value.
  • Reading one number as a diagnosis. This is an estimate from one blood value, and the stage label is only a band of that estimate.
  • Using the tool for children. The equation was built for adults, yet any age above 0 up to 130 gives a number, so a 10-year-old still gets a result that should not be trusted.

Sources

About this calculator

The 4-variable MDRD equation estimates glomerular filtration rate (eGFR) — the standard measure of how well the kidneys filter blood — from serum creatinine, age, sex, and race, without requiring a urine collection. It was derived from data collected in the Modification of Diet in Renal Disease (MDRD) study, a National Institutes of Health-funded trial published by Levey and colleagues in the late 1990s and refined in 2006 to work with standardized (IDMS-traceable) creatinine assays used by modern labs.

Nephrologists and primary care physicians use MDRD-derived eGFR to stage chronic kidney disease (CKD) into categories from G1 through G5, decide when to refer a patient to a nephrologist, and adjust dosing for kidney-cleared medications. It has largely been supplemented or replaced in many labs by the CKD-EPI equation, which is more accurate at higher, near-normal GFR values, but MDRD remains widely reported and referenced, especially for patients already diagnosed with reduced kidney function.

Enter a creatinine value along with age, sex, and race to see the estimated GFR this equation produces, expressed in mL/min/1.73m². Current NKF-ASN guidance (2021) recommends the race-free CKD-EPI 2021 equation instead; MDRD and its 1.212 race coefficient are kept here as the legacy formula.

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