Estimating Glomerular Filtration Rate from Serum Creatinine and Cystatin C

This study presents an equation for estimating the glomerular filtration rate that uses both creatinine and cystatin C. It performs better than equations with either marker alone and is potentially useful for confirming chronic kidney disease. Clinical assessment of kidney function is part of routine medical care for adults. 1 More than 80% of clinical laboratories now report an estimated glomerular filtration rate (GFR) when serum creatinine is measured. 2 Despite standardization of serum creatinine assays, GFR estimates remain relatively imprecise 3 owing to variation in non-GFR determinants of serum creatinine, which may be affected in both acute and chronic illness. 1 Such imprecision can potentially result in the misclassification of patients whose estimated GFR is less than 60 ml per minute per 1.73 m 2 of body-surface area as having chronic kidney disease, leading to unnecessary diagnostic and therapeutic interventions. . . .