Kidney Function

Estimating glomerular filtration rate (GFR) using the Cockcroft-Gault (CG) or Modification of Diet in Renal Disease (MDRD) Study equation is recommended for assessing kidney function. These equations include serum creatinine (Cr) together with variables such as age, sex, ethnicity, and body weight. The CG formula overestimates kidney function because it was designed for Cr clearance estimation on the basis of ideal weight. The MDRD Study equation has low accuracy in healthy persons because it was developed in patients with kidney disease. The quadratic and CKD Epidemiology Collaboration (CKD-EPI) equations were proposed to improve the accuracy of estimated GFR (eGFR) calculation. Here, we evaluate their performance over a wide range of GFRs, assessed using inulin clearance in adults with and without kidney disease. Because Cr generation is a major confounder of all Cr-based estimating equations, the equations’ performance also was evaluated according to observed Cr excretion rate.