Levothyroxine Dose Adjustment for Rising TSH
Increase the levothyroxine dose from 112 mcg to 125 mcg daily. 1
Rationale for Dose Increase
- Your patient's TSH has risen from 8 to 13.7 mIU/L, indicating worsening hypothyroidism despite current therapy. 2, 1
- TSH >10 mIU/L warrants dose adjustment regardless of symptoms, as this level carries approximately 5% annual risk of progression to overt hypothyroidism and is associated with increased cardiovascular risk. 2, 1
- The persistent elevation despite levothyroxine therapy clearly indicates the current 112 mcg dose is insufficient to meet thyroid hormone requirements. 1
Specific Dose Adjustment Protocol
For patients under 70 years without cardiac disease:
- Increase by 25 mcg increments (from 112 mcg to 137 mcg would be the standard increase). 2, 1
- However, since levothyroxine comes in 125 mcg tablets, the practical next dose up from 112 mcg is 125 mcg daily (a 13 mcg increase). 2
For patients over 70 years or with cardiac disease:
- Use smaller 12.5 mcg increments to avoid cardiac complications. 2, 1
- This would mean increasing from 112 mcg to 125 mcg (13 mcg increase), which falls within the safer range for this population. 1
Critical Considerations Before Increasing Dose
- Rule out adrenal insufficiency before increasing levothyroxine, particularly if the patient has any history of pituitary disease, autoimmune conditions, or is on immunotherapy. 1
- If central hypothyroidism is suspected, always start corticosteroids several days before increasing thyroid hormone to avoid precipitating adrenal crisis. 2, 1
Monitoring After Dose Adjustment
- Recheck TSH and free T4 in 6-8 weeks after the dose adjustment to evaluate response. 2, 1
- Target TSH should be within the reference range of 0.5-4.5 mIU/L. 1, 3
- Free T4 helps interpret ongoing abnormal TSH levels during therapy, as TSH may take longer to normalize. 2, 1
- Once adequately treated with stable TSH, repeat testing every 6-12 months or if symptoms change. 2, 1
Common Pitfalls to Avoid
- Do not delay treatment waiting for symptoms to develop—TSH >10 mIU/L requires dose adjustment regardless of symptom status. 1
- Do not adjust doses more frequently than every 6-8 weeks, as levothyroxine requires this time to reach steady state. 2, 1
- Avoid excessive dose increases that could lead to iatrogenic hyperthyroidism, which increases risk for atrial fibrillation, osteoporosis, and cardiac complications. 2, 1
- Approximately 25% of patients on levothyroxine are unintentionally maintained on doses sufficient to fully suppress TSH, highlighting the importance of careful monitoring. 2