Long-term stability of thyroid peroxidase antibody (anti-TPO) in serum in the Danish General Suburban Population Study

作者：Christian Zinck Jensen, Birte Nygaard, Jens Faber, Palle Pedersen, Morten Kranker Larsen, Jørgen K. Kanters, Henrik E. Poulsen, Mark D. Kellogg, Christina Ellervik · 发表于：Clinical Chemistry and Laboratory Medicine (CCLM) · 年份：2023 · DOI：10.1515/cclm-2022-0845 · 被引用次数：9 · 研究领域：Thyroid Disorders and Treatments、Immunotoxicology and immune responses、Thyroid Cancer Diagnosis and Treatment

Abstract Objectives We evaluated the long-term stability of thyroid peroxidase antibody (anti-TPO). Methods In the Danish General Suburban Population Study (GESUS), serum samples were biobanked at −80 °C during 2010–2013. In a paired design with 70 subjects, we compared anti-TPO (30–198 U/mL) measured on fresh serum on Kryptor Classic in 2010–2011 (anti-TPO fresh ) with anti-TPO remeasured on frozen serum (anti-TPO frozen ) on Kryptor Compact Plus in 2022. Both instruments used the same reagents and the anti-TPO n automated immunofluorescent assay, which was calibrated against the international standard NIBSC 66/387, based on the Time Resolved Amplified Cryptate Emission (TRACE) technology from BRAHMS. Values greater than 60 U/mL are regarded as positive in Denmark with this assay. Statistical comparisons included Bland-Altman, Passing-Bablok regression, and Kappa statistic. Results The mean follow-up time was 11.9 years (SD: 0.43). For anti-TPO frozen vs. anti-TPO fresh , the line of equality was within the confidence interval of the absolute mean difference [5.71 (−0.32; 11.7) U/mL] and the average percentage deviation [+2.22% (−3.89%; +8.34%)]. The average percentage deviation of 2.22% did not exceed analytical variability. Passing-Bablok regression revealed both a statistically significant systematic and proportional difference: Anti-TPO frozen =−22.6 + 1.22*(anti-TPO fresh ). Frozen samples were correctly classified as positive in 64/70 (91.4%; Kappa=71.8%). Conclusions ...