BES2020 BES 2020 Biological variation and analytical goals of four thyroid function biomarkers in healthy European volunteers (1 abstracts)
1Clinical Biology Department, CliniquesUniversitaires Street Luc, Université catholique de Louvain, Brussels, Belgium; 2Pôle de recherche en Endocrinologie, Diabète et Nutrition, Institut de Recherche Expérimentale et Clinique, Cliniques Universitaires Street -Luc and Université Catholique de Louvain, Brussels, Belgium; 3Department of Laboratory Medicine, Clinique Street -Luc Bouge, Namur, Belgium; 4Department of Pharmacy, Namur Research Institute for Life Sciences, University of Namur, Belgium; 5Department of Endocrinology and Nutrition, Cliniques Universitaires Street -Luc, Universite Catholique de Louvain, Brussels, Belgium
*Contributed equally to this work
Background: Interpretation of thyroid function tests by means of biological variation (BV) data is essential to identify significant changes between serial measurements at an individual level. Latest BV data on thyroid parameters in adults included in the EFLM Biological Variation Database have been published in 2008.
Objectives: We aimed at determining the BV of four thyroid function test (thyroid-stimulating hormone (TSH), free thyroxin (FT4), free triiodothyronine (FT3) and thyroglobulin (Tg)) by applying recent recommendations to acquire BV data on a latest generation of immunoassay.
Methods: Nineteen healthy volunteers (8 males and 11 females) were drawn every week during 5 consecutive weeks. Samples were analyzed in duplicate on the Cobas 602 analyzer (Roche Diagnostics). After normality assessment, outlier exclusion, and homogeneity of variance analysis, analytical variation (CVA), within-subject biological variation (CVI) and between-subject biological variation (CVG) were determined using nested ANOVA.
Results: CVA, CVI and CVG were 0.9%, 19.7% and 37.6% for TSH; 3.6%, 4.6% and 10.8% for FT4; 2.2%, 6.0% and 8.6% for FT3; and 0.9%, 15.4% and 84.9% for Tg. Index of individuality (II) for all parameters was between 0.2 and 0.7. The reference change value was 54.7% for TSH, 16.2% for FT4, 17.7% for FT3 and 42.8% for Tg.
Conclusion: The integration of our updated and reliable BV characteristics for thyroid hormones can facilitate the interpretation of thyroid function tests by a better identification of significant change between serial measurements.