European Biological Variation Study (EuBIVAS): within- and between-subject biological variation estimates for serum biointact parathyroid hormone based on weekly samplings from 91 healthy participants.

Background: The European Biological Variation Study (EuBIVAS) was created by the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Working Group on Biological Variation to establish high-quality biological variation (BV) estimates for clinically important measurands. In this study, the aim was to deliver reliable BV estimates for the biointact parathyroid hormone (PTH 1-84). Methods: Serum samples were obtained from a population of 91 healthy individuals (38 men, 43 premenopausal women, and 10 post-menopausal women; 21-69 years) from 5 European countries, with all samples stored at -80 degrees C prior to analysis. PTH 1-84 analysis was performed at the San Raffaele Hospital (Milan, Italy) on the Roche Cobas e801. All samples from each individual were analysed in duplicate within a single run. CV-ANOVA was applied, after analysis of variance homogeneity and outliers, to obtain BV estimates for PTH 1-84 with 95% CIs. Results: The within-subject BV [CVI (95% CI)] estimates were significantly different between men and women [13.0% (12.1- 14.2%) and 15.2% (14.3-16.3%), respectively], while the between-subject estimates [CVG (95% CI)] were similar (men: 26.8% (21.4-35.1%), pre-menopausal women: 27.8% (22.7-36.1%)], allowing for delivery of updated analytical performance specifications and reference change values. Conclusions: Updated BV estimates for serum PTH 1-84 based on the large-scale EuBIVAS may be beneficial for the diagnosis and management of parathyroid glands and bone turnover pathologies.