Increase Your Levothyroxine Dose
Your current levothyroxine dose is insufficient—increase it by 12.5-25 mcg and recheck TSH in 6-8 weeks. 1, 2
Why Your Dose Needs Adjustment
Your elevated TSH with normal T4 indicates subclinical hypothyroidism despite treatment, meaning your thyroid replacement is inadequate. 1, 2 This situation requires dose escalation because:
- Persistent TSH elevation above the reference range (0.5-4.5 mIU/L) increases your risk of progression to overt hypothyroidism by approximately 5% per year 1
- Inadequate replacement is associated with adverse cardiovascular effects, abnormal lipid metabolism, and reduced quality of life 1
- Recent evidence demonstrates increased mortality in hypothyroid patients with TSH values outside the reference range 2
Specific Dose Adjustment Protocol
Standard Approach (Age <70, No Cardiac Disease)
- Increase levothyroxine by 25 mcg daily 1, 2
- This larger increment is appropriate for younger patients without cardiac comorbidities 1
Conservative Approach (Age >70 OR Cardiac Disease)
- Increase by only 12.5 mcg daily 1, 2
- Smaller increments prevent cardiac complications including angina, arrhythmias, or cardiac decompensation 1, 3
Critical Monitoring Timeline
- Recheck TSH and free T4 in exactly 6-8 weeks—this represents the time needed to reach steady state after dose adjustment 1, 2
- Do not adjust doses more frequently, as levothyroxine has a long half-life requiring this interval 3
- Once TSH normalizes (0.5-4.5 mIU/L), monitor annually or sooner if symptoms change 1
Common Pitfalls to Avoid
Excessive dose increases: Jumping to full replacement doses risks iatrogenic hyperthyroidism, which occurs in 14-21% of treated patients and increases risk for atrial fibrillation, osteoporosis, and fractures—especially dangerous in elderly patients. 1, 2
Ignoring medication interactions: Iron, calcium supplements, proton pump inhibitors, and dietary fiber all reduce levothyroxine absorption—take levothyroxine on an empty stomach, separated from these substances by at least 4 hours. 4
Treating a single abnormal value: However, since you're already on levothyroxine, this represents inadequate dosing rather than a spurious lab result. 1
Missing malabsorption: If TSH remains elevated despite dose increases and confirmed adherence, consider gastrointestinal disorders (celiac disease, H. pylori infection, atrophic gastritis) that impair absorption. 4
Special Considerations
If You Have Cardiac Disease or Atrial Fibrillation
- Use the 12.5 mcg increment 1
- Consider repeating testing within 2 weeks rather than waiting 6-8 weeks 1
- Monitor for chest pain, palpitations, or worsening dyspnea 3
If You're Pregnant or Planning Pregnancy
- More aggressive TSH normalization is warranted, targeting the lower half of the reference range 1, 2
- Levothyroxine requirements typically increase 25-50% during pregnancy 1
If You Have Positive TPO Antibodies
- Your progression risk to overt hypothyroidism is higher (4.3% vs 2.6% per year) 1
- This further justifies prompt dose adjustment 1
What to Expect After Dose Increase
Your symptoms should gradually improve over 6-8 weeks as thyroid hormone levels stabilize. 1 If symptoms persist despite TSH normalization, consider whether they're truly thyroid-related or attributable to other conditions. 5, 6
The goal is TSH within 0.5-4.5 mIU/L with normal free T4, which prevents both the complications of undertreated hypothyroidism and the serious risks of overtreatment. 1, 2, 7