One-step quantitative thyrotropin assay for the detection of hypothyroidism in point-of-care conditions

Objectives Different screening strategies for early diagnosis of hypothyroidism have been discussed increasingly. We demonstrate the applicability of a miniaturized microparticle assay format for rapid and quantitative determination of increased thyrotropin (TSH) concentrations in serum. Design and methods Porous microparticles were used as solid phase for a noncompetitive, one-step, kinetic immunoassay with varying incubation times and time-resolved fluorescence detection. Results The analytical (mean of zero + 3 SD) and functional (CV <15%) detection limits were 1.5 and 6.0 mIU/L for 2-min, 0.5 and 1.5 mIU/L for 7-min, and 0.2 and 0.5 mIU/L for 15-min assays, respectively. A good correlation was found with the Chiron Diagnostics ACS:180 assay (slopes 0.885–1.051, y-intercepts < ± 0.20 mIU/L, Sy x ≤ 0.10 mIU/L, r > 0.98, n = 20). Conclusions The kinetic TSH assay provides reproducible and quantitative information on thyroid status within minutes and is applicable for the detection of hypothyroidism in point-of-care (POC) conditions.