Increase Your Levothyroxine Dose to 137.5 mcg or 150 mcg Daily
Your TSH of 3.49 mIU/L indicates inadequate thyroid hormone replacement on your current 125 mcg dose, and you should increase your levothyroxine by 12.5-25 mcg to normalize your TSH into the optimal range of 0.5-2.5 mIU/L. 1, 2
Why Your Current Dose Is Insufficient
Your TSH level demonstrates subclinical hypothyroidism despite treatment, meaning your current levothyroxine dose is not providing adequate thyroid hormone replacement 1. The American Medical Association recommends adjusting levothyroxine dosage when TSH remains elevated above the reference range in patients already on therapy 2, 1.
The therapeutic goal for levothyroxine-treated patients is to achieve a TSH level between 0.5-2.5 mIU/L, with most patients having thyroxine values in the upper third of the reference range 3. Your current TSH of 3.49 is well above this optimal target and places you at increased risk for persistent hypothyroid symptoms and cardiovascular complications 2.
Recent evidence demonstrates that mortality increases in hypothyroid patients when TSH remains outside the normal reference range, making normalization of your TSH critical for long-term health outcomes 4.
Recommended Dose Adjustment
- Increase your levothyroxine to either 137.5 mcg daily (adding a 12.5 mcg increment) or 150 mcg daily (adding a 25 mcg increment) 1, 2, 5
- The 12.5-25 mcg increment range is the standard recommendation for dose adjustments in patients already on replacement therapy 1, 2
- Given your TSH is moderately elevated (not severely elevated), a 12.5 mcg increase to 137.5 mcg daily would be the more conservative and appropriate initial adjustment 2
Monitoring After Dose Adjustment
- Recheck your TSH and free T4 in 6-8 weeks after increasing your dose, as this represents the time needed to reach a new steady state 1, 2, 5
- Do not adjust your dose more frequently than every 6-8 weeks, as premature adjustments before reaching steady state is a common pitfall that can lead to overtreatment 2
- Once your TSH stabilizes in the target range (0.5-2.5 mIU/L), monitor thyroid function tests every 6-12 months 1, 2
Your FSH Level Is Not Relevant to This Decision
Your FSH of 10.2 mIU/L is a marker of ovarian function and has no bearing on levothyroxine dosing decisions 2. The management of your hypothyroidism should be based solely on your TSH and free T4 levels, not FSH 2, 1.
Critical Considerations
- Ensure you are taking your levothyroxine consistently on an empty stomach, 30-60 minutes before breakfast, as absorption issues are a common cause of elevated TSH despite apparent adequate dosing 1
- Avoid taking levothyroxine with calcium supplements, iron, proton pump inhibitors, or other medications that can impair absorption 2
- If your TSH remains elevated after dose adjustment despite confirmed medication adherence, consider switching to liquid levothyroxine formulation, which has more reliable absorption 6
Risks of Remaining Undertreated
Persistent elevation of TSH on therapy is associated with:
- Ongoing hypothyroid symptoms including fatigue, weight gain, and cold intolerance 2
- Adverse effects on cardiovascular function and lipid metabolism 2
- Increased risk of progression to more severe hypothyroidism 2
- Reduced quality of life 2
Approximately 25% of patients on levothyroxine are maintained on inadequate doses, highlighting the importance of regular monitoring and appropriate dose adjustments 2.