Levothyroxine Dose Adjustment for Elevated TSH
Increase levothyroxine by 12.5-25 mcg daily when TSH is elevated, with the specific increment determined by patient age, cardiac status, and degree of TSH elevation. 1, 2, 3
Dose Adjustment Algorithm
For patients under 70 years without cardiac disease:
- Increase by 25 mcg increments every 4-6 weeks until TSH normalizes to the reference range (0.5-4.5 mIU/L) 1, 2, 3
- More aggressive titration is appropriate in this population to achieve euthyroidism efficiently 1
For patients over 70 years or with cardiac disease/atrial fibrillation:
- Increase by smaller 12.5 mcg increments every 6-8 weeks to avoid cardiac complications 1, 2, 3
- Elderly patients with coronary disease face increased risk of cardiac decompensation, angina, or arrhythmias even with therapeutic levothyroxine doses 1
For patients with TSH >10 mIU/L:
- More urgent treatment is warranted with 25 mcg daily increases regardless of age, as this threshold carries approximately 5% annual risk of progression to overt hypothyroidism 1, 2
- Treatment should be initiated even in asymptomatic patients at this TSH level 1
Monitoring Protocol After Dose Adjustment
Recheck TSH and free T4 in 6-8 weeks after any dose change to evaluate response, as the peak therapeutic effect may not be attained for 4-6 weeks 1, 2, 3
For high-risk patients (atrial fibrillation, serious cardiac disease, or multiple comorbidities), consider repeating testing within 2 weeks rather than waiting the full 6-8 weeks 1
Once TSH is stabilized within the reference range, monitor every 6-12 months or whenever symptoms change 1, 2
Special Population Considerations
Pregnant patients with pre-existing hypothyroidism:
- Increase levothyroxine by 12.5-25 mcg per day when TSH exceeds trimester-specific reference ranges 2, 3
- Monitor TSH every 4 weeks until stable, then each trimester 2, 3
- Levothyroxine requirements typically increase 25-50% during pregnancy 1
Patients on immunotherapy:
- Consider treatment even for mild TSH elevation if fatigue or hypothyroid symptoms are present, as thyroid dysfunction occurs in 6-9% with anti-PD-1/PD-L1 therapy 1
Critical Pitfalls to Avoid
Never start or increase thyroid hormone before ruling out adrenal insufficiency in patients with suspected central hypothyroidism or hypophysitis, as this can precipitate adrenal crisis 1
Avoid excessive dose increases that could lead to iatrogenic hyperthyroidism, which increases risk for osteoporosis, fractures, atrial fibrillation, and ventricular hypertrophy 1, 4
Do not adjust doses too frequently—wait the full 6-8 weeks between adjustments to allow steady state to be reached 1
Approximately 25% of patients on levothyroxine are unintentionally maintained on doses sufficient to fully suppress TSH, increasing risks for cardiac and bone complications, highlighting the importance of regular monitoring 1