Changes in serum TSH across the adult lifespan: 22-year follow-up of the HUNT Study
Authors' conclusion
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.
Study context
- Population
- Adults without thyroid medication or overt thyroid dysfunction, HUNT Study, Norway; TSH measured 1995–1997, 2006–2008 and 2017–2019127,483 TSH measurements
- Participants
- 80,284 adults
- Exposure
- TSH change with age, men vs women
- Outcome
- Within-individual TSH change, expressed as geometric mean ratio (GMR; fold change in geometric mean TSH)
- Follow-up
- 22 years
Methodological detailslongitudinal, linear mixed models, linkage to Norwegian Prescribed Drug Registry
- Longitudinal
- Linear mixed models
- Linkage to Norwegian Prescribed Drug Registry
Main finding
As reported in the abstract
Within-individual change in mean TSH
| Group | Value | Geometric mean ratios (GMR) |
|---|---|---|
| Men | mean increase 0.13 mIU/L | 1.09 (95%CI 1.07, 1.10) |
| Women | 0.97 (95%CI 0.96, 0.98) |
Value
Menmean increase 0.13 mIU/L
Women— not stated in the abstract
Geometric mean ratios (GMR)
Men1.09 (95%CI 1.07, 1.10)
Women0.97 (95%CI 0.96, 0.98)
Observational data: associations, not effects.
Further findings
| Outcome | Values |
|---|---|
| Within-individual TSH change, men aged ≥70 years at baseline · 22 years | Men aged ≥70 years mean increase 0.5 mIU/L · GMR 1.32 (95%CI 1.15, 1.48) |
Mean TSH by age (cross-sectional and longitudinal measurements integrated)
- Mean TSH higher at older age in men; association with age weaker and less consistent in women
TSH distribution by age
- TSH distribution widened at older age in both sexes
Original publication
Changes in serum TSH across the adult lifespan: 22-year follow-up of the HUNT Study. Eur J Endocrinol. Published 11 June 2026. doi:10.
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