MDRD GFR Calculator

MDRD GFR Calculator for Nephrology. The result is a single eGFR in mL/min/1.73 m² that maps onto KDIGO CKD stages: G1 ≥90, G2 60-89, G3a 45-59, G3b 30-44, G4 15-29, G5 <15. The equation's accuracy is best in the CKD range it was built on; the derivation cohort had a mean measured GFR near 40 mL/min/1.73 m². Values ≥60 should be reported by laboratories simply as ">60," not as a precise number, because MDRD loses accuracy and underestimates true GFR in that band. A falling eGFR across serial measurements, more than any single value, drives referral and intervention decisions.

How this calculator works

The MDRD Study equation estimates GFR (normalized to 1.73 m² body surface area) from serum creatinine, age, sex, and Black vs non-Black race, without needing height or weight. The current IDMS-traceable 4-variable form is eGFR = 175 × (SCr)^-1.154 × (age)^-0.203 × 0.742 (if female) × 1.212 (if Black), with creatinine in mg/dL. The original 1999 version used a coefficient of 186 and was calibrated to the older (non-standardized) Cleveland Clinic creatinine assay; the coefficient dropped to 175 when the equation was re-expressed for standardized, isotope-dilution mass spectrometry (IDMS)-aligned creatinine. It is a log-linear regression model derived to predict measured iothalamate GFR.

When to use this calculator

Use it to stage chronic kidney disease and guide drug dosing in adults with stable, reduced kidney function, particularly when measured GFR below about 60 mL/min/1.73 m² is expected. It should not be used in acute kidney injury (creatinine is not in steady state), in children, in pregnancy, or in people at extremes of muscle mass (amputees, bodybuilders, cachexia, paraplegia). For general population screening and for eGFR values in or near the normal range, most guidelines now prefer the CKD-EPI 2021 creatinine equation, which MDRD systematically underestimates at higher GFR.

Inputs used

  • Serum creatinine
  • Age
  • Sex
  • Race coefficient when using the original MDRD equation

Clinical interpretation

The result is a single eGFR in mL/min/1.73 m² that maps onto KDIGO CKD stages: G1 ≥90, G2 60-89, G3a 45-59, G3b 30-44, G4 15-29, G5 <15. The equation's accuracy is best in the CKD range it was built on; the derivation cohort had a mean measured GFR near 40 mL/min/1.73 m². Values ≥60 should be reported by laboratories simply as ">60," not as a precise number, because MDRD loses accuracy and underestimates true GFR in that band. A falling eGFR across serial measurements, more than any single value, drives referral and intervention decisions.

Worked example

A 60-year-old non-Black woman with a standardized serum creatinine of 1.4 mg/dL: eGFR = 175 × (1.4)^-1.154 × (60)^-0.203 × 0.742. This works out to roughly 40 mL/min/1.73 m², placing her in CKD stage G3b (30-44), a level that warrants nephrology-informed monitoring and dose review of renally cleared drugs. The same creatinine in a 60-year-old man (no 0.742 factor) gives about 54 mL/min/1.73 m² (stage G3a).

Limitations and safety notes

MDRD assumes creatinine is at steady state, so it is invalid during acute kidney injury or rapidly changing function. Because creatinine reflects muscle mass, it overestimates GFR in low-muscle states (elderly, malnourished, amputees) and underestimates it in high-muscle individuals. It was validated almost entirely in patients with measured GFR under 60, so it is unreliable and biased low above that threshold, and it was derived in a predominantly non-diabetic, non-transplant CKD population that underrepresented older adults and non-Black, non-White groups.

Frequently asked questions

How does MDRD differ from CKD-EPI?

Both use creatinine, age, sex, and race, but CKD-EPI (2009, and the race-free 2021 update) is more accurate at eGFR above 60 mL/min/1.73 m², where MDRD reads systematically low. Guidelines now favor CKD-EPI for general reporting; MDRD remains widely embedded in older records and some dosing tools.

Why is the coefficient 175 in some versions and 186 in others?

186 belongs to the original 1999 equation calibrated to a non-standardized creatinine assay. When creatinine measurement was standardized to IDMS-traceable methods, the equation was re-expressed with a coefficient of 175. Use 175 with modern standardized creatinine results.

Do I need the patient's weight?

No. Unlike Cockcroft-Gault, MDRD needs only creatinine, age, sex, and race. It reports GFR already indexed to 1.73 m² body surface area, so weight and height are not inputs.

Should I apply the Black race coefficient?

The 1.212 factor was part of the original and 2006 equations, but major bodies (NKF-ASN 2021) recommend moving to race-free estimation. If your laboratory or protocol has adopted a race-free approach, prefer the 2021 CKD-EPI equation rather than adjusting MDRD.

Is MDRD valid for drug dosing?

It can guide dosing of renally cleared drugs, but many older drug labels and pharmacokinetic studies use Cockcroft-Gault creatinine clearance (not indexed to BSA). For narrow-therapeutic-index drugs, check which estimate the label specifies and de-index eGFR to the patient's actual BSA if needed.

References

  • Levey AS, Bosch JP, Lewis JB, Greene T, Rogers N, Roth D. A more accurate method to estimate glomerular filtration rate from serum creatinine: a new prediction equation. Modification of Diet in Renal Disease Study Group. Ann Intern Med. 1999. PMID: 10075613.
  • Levey AS, Coresh J, Greene T, Stevens LA, Zhang YL, Hendriksen S, Kusek JW, Van Lente F. Using standardized serum creatinine values in the modification of diet in renal disease study equation for estimating glomerular filtration rate. Ann Intern Med. 2006. PMID: 16908915.
  • Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. 2013.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: April 21, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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