What is the MDRD GFR equation?
The MDRD GFR equation estimates glomerular filtration rate from serum creatinine, age and sex. This calculator uses the 4-variable IDMS form (Levey 2006) and reports eGFR in mL/min/1.73 m² with a CKD stage band. It is for adults with chronic kidney disease context — not for AKI or children.
How filtration is estimated
Creatinine plus age and sex go into the MDRD formula to give indexed eGFR.
Typical adult teaching case
Female, 55 years, creatinine 1.0 mg/dL — the Example button loads this case.
IDMS 4-variable ≈ 57.6 mL/min/1.73 m² (G3a). CKD-EPI 2021 on the same labs is shown next to MDRD after you calculate.
How is GFR calculated?
- Confirm an adult patient — MDRD is not a paediatric formula.
- Enter sex, age, and serum creatinine (mg/dL or µmol/L).
- Press Calculate for eGFR in mL/min/1.73 m² and a CKD GFR category.
- Compare with CKD-EPI 2021 in the results panel when you need a modern estimate.
GFR calculation formula MDRD
The primary GFR creatinine equation here is the re-expressed MDRD equation eGFR for IDMS-traceable creatinine (Levey 2006):
4-variable IDMS (default)
eGFR = 175 × Scr−1.154 × Age−0.203 × 0.742 if female × 1.212 if Black
Conventional (non-IDMS) 4-variable
eGFR = 186 × Scr−1.154 × Age−0.203 × 0.742 if female × 1.212 if Black
Extended 6-variable (Levey 1999)
eGFR = 170 × Scr−0.999 × Age−0.176 × BUN−0.170 × Alb0.318 × 0.762 if female × 1.180 if Black
Scr and BUN are in mg/dL; albumin in g/dL. Convert µmol/L creatinine by dividing by 88.4. That is how to calculate eGFR from GFR inputs on this GFR by MDRD calculator.
MDRD equation variables
The 4-variable equation uses creatinine, age and sex (plus a published race coefficient in the original paper). An older 6-variable form also used BUN and albumin. Weight is not an MDRD input — Cockcroft-Gault uses weight and lives on the creatinine clearance calculator.
MDRD GFR vs eGFR
What is estimated GFR (MDRD)? It is one eGFR formula. GFR is the physiologic rate; eGFR is the estimate. MDRD GFR vs eGFR is mostly wording: this page’s MDRD result is an eGFR. Pair it with the eGFR calculator (CKD-EPI 2021) when you need current race-free reporting.
MDRD vs CKD-EPI
CKD-EPI vs MDRD GFR equation: CKD-EPI 2021 is preferred for new reports and is race-free. MDRD underestimates high-normal GFR and still appears on older labs and papers. This CKD-EPI MDRD GFR calculator comparison uses the same creatinine, age and sex.
MDRD vs Cockcroft-Gault
MDRD is BSA-indexed eGFR. Cockcroft-Gault is creatinine clearance in mL/min using weight. Drug labels often still cite CrCl — use the creatinine clearance calculator when dosing protocols name Cockcroft-Gault.
GFR stages chart (CKD staging)
| Stage | eGFR | Meaning |
|---|---|---|
| G1 | ≥ 90 | Normal or high |
| G2 | 60–89 | Mildly decreased |
| G3a | 45–59 | Mild to moderate |
| G3b | 30–44 | Moderate to severe |
| G4 | 15–29 | Severely decreased |
| G5 | < 15 | Kidney failure range |
CKD diagnosis also needs kidney damage markers (for example albuminuria), not eGFR alone.
SI units and historical MDRD forms
Creatinine can be entered in mg/dL or µmol/L (divide µmol/L by 88.4). Labs that still cite conventional (186) or 6-variable MDRD are using older assay or research forms — this calculator reports the IDMS 4-variable equation used on modern standardized creatinine.
Calculation example
Female, 55 years, Scr 1.0 mg/dL:
- MDRD IDMS = 175 × 1−1.154 × 55−0.203 × 0.742 ≈ 57.6 mL/min/1.73 m² (G3a).
- CKD-EPI 2021 on the same creatinine is shown next to MDRD after Calculate.
MDRD GFR FAQ
What is the MDRD GFR equation?
A creatinine-based eGFR from the Modification of Diet in Renal Disease study. Default here is the 4-variable IDMS form (175 × Scr^−1.154 × age^−0.203, with sex and optional race factors).
What is GFR and eGFR?
GFR is measured filtration. eGFR is estimated from labs. MDRD output is eGFR in mL/min/1.73 m².
How is GFR calculated with MDRD?
Use mg/dL creatinine (or µmol/L ÷ 88.4), adult age, sex factor, optional race factor, and 175 or 186 depending on assay standardization.
MDRD GFR vs eGFR — same thing?
MDRD is one eGFR equation. CKD-EPI is another. Neither is measured GFR.
What are the MDRD equation variables?
4-variable: creatinine, age, sex, race. 6-variable also uses BUN and albumin.
MDRD vs CKD-EPI — which should I use?
Prefer CKD-EPI 2021 for current clinical reporting. Use MDRD to interpret older labs or protocols that still name it.
How does MDRD differ from Cockcroft-Gault?
MDRD is indexed eGFR. Cockcroft-Gault is weight-based CrCl in mL/min. Use the creatinine clearance calculator when a protocol names CrCl.
Can I use SI units and the extended equation?
Yes — switch creatinine to µmol/L. The original 6-variable equation with BUN and albumin is described in the formula section; this calculator runs the IDMS 4-variable form.
Is MDRD for normal kidney function?
It is less accurate when true GFR is high. Not for AKI, pregnancy, or children.
How do I read the GFR stages chart?
G1–G5 follow KDIGO eGFR bands. Staging CKD also needs albuminuria and clinical context.
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User Reviews
4.8 / 5 from 3 recent users of this MDRD GFR calculator
Clear IDMS 4-variable result with CKD stage labels — easy to teach next to CKD-EPI 2021.
SI unit swap and CKD-EPI 2021 side-by-side help explain why labs moved off MDRD without hiding the original equation.
Example case and GFR stages chart are useful. Sex, age and creatinine are all you need to run MDRD.
Related kidney tools: eGFR calculator (CKD-EPI 2021), creatinine clearance calculator, BUN creatinine ratio calculator, and body surface area calculator.