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Lookup NU author(s): Dr Salman RazviORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
Objective: Some evidence suggests that higher serum TSH may be part of normal aging, but studies are limited to 13-year follow-up. We examined TSH changes over 22-year follow-up across the adult lifespan.Design: Longitudinal analyses of the population-based HUNT Study, Norway, with TSH measurements from 1995-97, 2006-08 and 2017-19.Methods: In individuals without thyroid medication or overt thyroid dysfunction, we estimated i) geometric mean serum TSH by age, integrating cross-sectional and longitudinal measurements using linear mixed models, ii) percentiles of the TSH distribution by age, and iii) within-individual TSH change during follow-up, expressed by geometric mean ratios (GMR) reflecting the fold change in geometric mean TSH. Results: We included 127,483 TSH measurements among 80,284 participants, of whom 36,886 had ≥2 measurements and 11,749 had ~22-year follow-up. When integrating all cross-sectional and longitudinal measurements, mean TSH was higher at older age in men, while the association with age was weaker and less consistently observed in women. When examining within-individual change, mean TSH increased modestly by 0.13 mIU/L (GMR 1.09; 95%CI 1.07,1.10) over 22 years in men, but not in women (GMR 0.97; 95%CI 0.96,0.98). This increase was stronger at 0.5 mIU/L in men aged ≥70 years at baseline (GMR 1.32; 95%CI 1.15,1.48). The TSH distribution widened at older age in both sexes.Conclusions: Mean serum TSH increased with age in older men, but showed only modest or no age-related change in younger men and in women. The wider TSH distribution at older age supports the need for age-specific TSH reference ranges.
Author(s): Asvold BO, Denos M, Taylor PN, Razvi S, Bjoro T, Brumpton BM, Haug EB
Publication type: Article
Publication status: Published
Journal: Europen Journal of Endocrinology
Year: 2026
Volume: 194
Issue: 6
Pages: 819-826
Print publication date: 01/06/2026
Online publication date: 11/06/2026
Acceptance date: 01/05/2026
Date deposited: 28/05/2026
ISSN (print): 0804-4643
ISSN (electronic): 1479-683X
Publisher: Oxford University Press
URL: https://doi.org/10.1093/ejendo/lvag097
DOI: 10.1093/ejendo/lvag097
Data Access Statement: Due to privacy protection for participants, individual-level data from the HUNT Study are not publicly available. For information on how to apply for data from the HUNT Study, please see: https://www.ntnu.edu/hunt/data.
PubMed id: 42274232
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