The effects of freeze–thaw on β-trace protein and β2-microglobulin assays after long-term sample storage

Abstract

To evaluate the effect of a freeze-thaw cycle on β-trace protein (βTP) and β2-microglobulin (β2M). We compared βTP and β2M concentrations before and after a single freeze-thaw cycle in long-term stored samples from 172 participants of the Third National Health and Nutrition Examination Survey (NHANES III). Measurements of βTP and β2M before and after freeze-thaw were highly correlated with Spearman's coefficients of 0.90 and 0.99, respectively. Serum concentrations of βTP were slightly lower after freeze-thaw (-0.05 mg/L, P=0.006). Measurements of β2M did not differ before and after freeze-thaw (P=0.35). βTP and β2M measurements were robust to a single freeze-thaw cycle, although β2M appeared more stable than βTP. These results have implications for future studies of these biomarkers.