β-Trace Protein Is Not Better than Cystatin C as an Indicator of Reduced Glomerular Filtration Rate

Abstract
Recent studies suggest that serum cystatin C [reviewed in Refs. (1)(2)] and β-trace protein (3)(4) identify reductions in glomerular filtration rate (GFR) better than creatinine does. Woitas et al. (5) compared for the first time the diagnostic performance of cystatin C, β-trace protein, β2-microglobulin, and creatinine in relation to inulin clearance. They noted that we reported a higher diagnostic accuracy of β-trace protein in a study with 115 diabetic patients (4). As explanation, Woitas et al. (5) offered different patient characteristics.