MDRD GFR Equation

Sex

Race (historical reference)

Serum Creatinine

mg/dL

Age

years

Estimates GFR in CKD patients using creatinine and patient characteristics.

Why Use

Noninvasively estimates the measured GFR to determine degree or presence of decreased kidney function. The MDRD equation performs equally to the newer CKD-EPI Equation in patients with GFR of <60 ml/min/1.73m2. Performs superiorly to the Cockcroft-Gault Equation .

When to Use

Patients with chronic kidney disease, to estimate kidney function.

Formula

GFR = 175 × Serum Cr -1.154 × age -0.203 × 1.212 (if patient is black*) × 0.742 (if female) Use serum Cr in mg/dL for this formula. From Levey 2006 . Note: the original MDRD study equation used a constant of 186, which the authors later revised to 175 to accommodate for standardization of creatinine assays over IDMS. The evidence doesn't seem to strongly suggest that the revised version is demonstrably better than the original (furthermore, the same authors of MDRD also developed the newer CKD-EPI equations , which are more accurate at a broader range of estimated GFR than the MDRD equations). *Race may/may not provide better estimates of GFR; optional. See here for more on our approach to addressing race and bias on MDCalc.

Pearls / Pitfalls

The MDRD equation cannot be used for acute renal failure. It is only useful in estimating glomerular filtration rate (GFR) in stable chronic kidney disease. Despite improvements to the MDRD equation, it tends to significantly underestimate measured GFR. Underestimation of GFR is particularly significant in patients with a GFR >60 ml/min/m2; 29% in healthy patients undergoing evaluation for kidney donation.

Management

Patients should be classified into CKD stage by both eGFR and albuminuria status. Patients with decreased GFR, increased urinary albumin excretion or both, are at high risk of progressive CKD and should be referred to nephrology for further management. From KDIGO 2012 Clinical Practice Guideline .

Advice

Patients with decreased GFR are at higher risk of progressive kidney disease. Management of contributing risk factors, such as diabetes and hypertension, is critical to slowing progression. Investigation of the underlying cause of decreased GFR is warranted if not clear from the history. Medications should be dose-adjusted for the most recent available eGFR. In this setting, eGFR and creatinine clearance may be used interchangeably, though they are physiologically different terms. Cutoffs for many medications are <60, <45 and <30 ml/min/m2, as well as adjustments for advanced kidney disease and dialysis patients.

More Information

From: KDIGO 2012 Clinical Practice Guideline.