Objectives: In children, thyroid hormones are essential for correct physical and neurological development. The recommended process for defining reference intervals (RIs) is the direct approach; however, indirect methods are an effective alternative. This study aimed to explore age- and sex-dependent relationships between serum concentrations of thyroid hormones in a large population-based cohort of healthy Spanish Caucasian children and calculate RIs.
Material and methods: Results of serum thyroid-stimulating hormone (TSH) and free thyroxine (fT4) were collected from laboratory data of N (TSH = 23201; fT4 = 20728) patients aged 1 month - 15 years. These results were validated with a prospective study. Analyses of serum concentrations of TSH and fT4 were performed on ARCHITECT i2000 (Abbott Diagnostics, US). Percentiles (2.5th to 97.5th) were determined for each variable and taken as the RI.
Results: No difference was found between serum TSH concentrations in male and female children of all age groups. A difference between serum fT4 concentrations in males and females and an age-dependent correlation for both sexes were found.
Conclusion: There is very little consensus on RIs in children. Our data confirm it is possible to use data mining techniques to calculate reliable and clinically useful RIs.
Keywords: Pediatrics; Reference values; Thyroid hormones.
Copyright © 2021. Published by Elsevier Inc.