β-Trace protein — A marker of kidney function in children: “Original research communication–clinical investigation”

Objectives:To determine the pediatric reference interval for serum β-trace protein (β-TP) and to compare β-TP with established LMW markers of GFR, i.e., cystatin C (CysC) and β2-microglobulin (β2-M).Design and methods:All three LMW markers were measured immunonephelometrically. In 106 children above the age of 2 years without evidence of kidney disease, non-parametric reference intervals were calculated. The relative rise of the GFR marker concentrations above the upper reference was studied in 107 samples from 96 patients covering the entire GFR range.Results:Above 2 years, the reference range of β-TP was constant at 0.43–1.04 mg/L. With decreasing Schwartz-GFR, there was a comparable rise in β-TP and β2-M, while CysC rose less in the group with GFR below 30 mL/min/1.73 m2 (278 ± 49% [CysC] versus 336 ± 65% [β-TP] and 342 ± 76% [β2-M]; p = 0.043 and 0.027, respectively).Conclusions:These data confirm the potential of ß-TP as an endogenous GFR marker in children.