Increase Your Levothyroxine Dose Immediately
Your TSH of 6.01 mIU/L while on Synthroid 100mcg indicates inadequate thyroid hormone replacement requiring a dose increase of 12.5-25mcg, with the goal of normalizing TSH to 0.5-4.5 mIU/L. 1
Why Your Current Dose Is Insufficient
- A TSH above 4.5 mIU/L in a patient already on levothyroxine therapy represents undertreatment, even though your free T4 remains in the normal range 1
- This pattern defines subclinical hypothyroidism in the context of ongoing treatment, indicating your current 100mcg dose is not providing adequate thyroid hormone replacement 1
- Persistent TSH elevation above 4.5 mIU/L carries approximately 3-4% annual risk of progression to overt hypothyroidism and may contribute to persistent hypothyroid symptoms, adverse cardiovascular effects, and unfavorable lipid profiles 1, 2
Recommended Dose Adjustment Strategy
Increase your levothyroxine by 12.5-25mcg based on your age and cardiac status: 1
- If you are under 70 years old without cardiac disease: Increase by 25mcg to 125mcg daily 1
- If you are over 70 years old or have any cardiac disease: Increase by 12.5mcg to 112.5mcg daily to minimize cardiac risk 1
The FDA-approved levothyroxine label supports titration in 12.5-25mcg increments every 4-6 weeks until euthyroid status is achieved 3
Monitoring Timeline After Dose Adjustment
- Recheck TSH and free T4 in exactly 6-8 weeks after increasing your dose, as this represents the time needed to reach steady-state levels 1
- Do not adjust your dose more frequently than every 6-8 weeks, as levothyroxine has a long half-life and premature adjustments risk overcorrection 1
- Your target TSH should be 0.5-4.5 mIU/L with normal free T4 levels 1
- Once your TSH stabilizes in the normal range, annual monitoring is sufficient unless symptoms change 1
Critical Medication Timing Instructions
Take levothyroxine on an empty stomach, 30-60 minutes before breakfast with a full glass of water 3
- Wait at least 4 hours before taking calcium supplements, iron, phosphate binders, bile acid sequestrants, or antacids, as these medications significantly impair levothyroxine absorption 3
- Proton pump inhibitors and H2 blockers may reduce levothyroxine absorption by decreasing gastric acidity 3
- Taking levothyroxine before dinner instead of before breakfast reduces its therapeutic efficacy and should be avoided 4
Common Pitfalls to Avoid
- Never accept a TSH above 4.5 mIU/L as adequate treatment - this represents undertreatment even with normal free T4 1
- Do not wait to increase your dose - persistent TSH elevation while on therapy warrants immediate adjustment 1
- Avoid excessive dose increases - jumping by more than 25mcg risks iatrogenic hyperthyroidism, which increases risk for atrial fibrillation, osteoporosis, and cardiac complications 1
- Do not recheck labs before 6 weeks - earlier testing will not reflect steady-state levels and may lead to inappropriate dose adjustments 1
What Happens If You Don't Increase Your Dose
Continuing at your current inadequate dose carries several risks: 1
- Persistent hypothyroid symptoms including fatigue, weight gain, cold intolerance, and cognitive dysfunction
- Adverse effects on cardiovascular function and cardiac output
- Unfavorable lipid metabolism with elevated LDL cholesterol
- Diminished quality of life
- Approximately 5% annual risk of progression to overt hypothyroidism
Special Considerations
If you have cardiac disease, atrial fibrillation, or are over 70 years old, use the smaller 12.5mcg increment and consider more frequent monitoring within 2 weeks rather than waiting the full 6-8 weeks 1
Approximately 30-60% of elevated TSH levels normalize spontaneously, but since you are already on treatment and your TSH has risen above the normal range, this represents true inadequate replacement rather than transient elevation 1, 2