A Longitudinal, Real-World Study of the Relationship between Levothyroxine Dose and Suboptimal Hypothyroidism Treatment
Authors' conclusion
We identified a dose-dependent relationship between LT4 dose and suboptimal treatment over a 6-month study period.
Study context
- Population
- Levothyroxine (LT4)-treated adults with at least 2 thyroid stimulating hormone (TSH) collections at least 30 days apart over the study period
- Participants
- 4,449 adults
- Exposure
- LT4 dose classes
- Outcome
- Occurrence of TSH outside an age-adjusted normal range (suboptimal treatment) after a normal TSH value
- Follow-up
- Within 6 months
Methodological details6-month longitudinal, repeated measures (generalized estimating equations), time-to-event (Cox proportional hazards models)
- 6-month longitudinal
- Repeated measures (generalized estimating equations)
- Time-to-event (Cox proportional hazards models)
Main finding
As reported in the abstract
TSH outside the age-adjusted range (repeated measures analysis) · 6 months
Odds ratio
1.98
P < 0.001
51-100 µg
Odds ratio
3.39
P < 0.001
101-150 µg
Odds ratio
5.65
P < 0.001
>150 µg
Observational data: associations, not effects.
Further findings
TSH outside wide range (0.1-10.0 mIU/L), repeated measures analysis · 6 months
- Results were similar when the outcome was defined as TSH outside 0.1-10.0 mIU/L
TSH outside age-adjusted range, time-to-event analysis (Cox proportional hazards) · 6 months
- HRs for LT4 doses of 51-100, 101-150 and >150 µg, respectively (p-values <0.001)
- 1.58, 2.73, and 3.08
Original publication
A Longitudinal, Real-World Study of the Relationship between Levothyroxine Dose and Suboptimal Hypothyroidism Treatment. Thyroid. Published 17 June 2026. doi:10.
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