Evaluation of the BRAHMS KRYPTOR Thyroglobulin “Mini-recovery” Test in Thyroid Healthy Subjects

Abstract

The aim of the work was to compare the automated thyroglobulin (Tg) assay on the automated BRAHMS KRYPTOR platform (hTG KRYPTOR) to the established BRAHMS Tg Plus immunoradiometric assay for the measurement of Tg levels and regular Tg recovery rates and to assess a recovery test using a low Tg concentration of 10 μg/l ("mini-recovery") in samples with a native Tg level of <10 μg/l. Tg levels and recovery rates, as well as the mini-recovery, were determined in 208 serum samples from thyroid-healthy patients using both assays. The reference ranges for the Tg-Plus assay are 2.0-51.0 μg/l for Tg levels and 81.5-108% for recovery rates at 100 μg/l. The reference ranges for hTG KRYPTOR are 2.4-47.8 μg/l for Tg, 83.3-110.4% for a conventional recovery with 80 μg/l in Tg levels ≥ 10.0 μg/l (n=121) and 94.4-122.9% for the mini-recovery with Tg <10.0 μg/l (n=87). The correlation between the Tg-Plus and hTG KRYPTOR is excellent for Tg (r2=0.95; p<0.001), but not significant for recovery rates. Tg levels determined using the KRYPTOR Tg assay are clinically comparable to the conventional Tg-Plus assay. New features of the KRYPTOR assay such as the ability to perform a "mini-recovery" still require further study before clinical use.