If taking 100mcg (micrograms) of levothyroxine per day, should the dose be increased to 125mcg per day?

Levothyroxine Dose Adjustment for Hypothyroidism

For a patient currently taking 100mcg of levothyroxine per day with elevated TSH, the appropriate dose adjustment would be to increase to 125mcg per day. 1, 2

Rationale for Dose Adjustment

• The recommended increment for levothyroxine dose adjustment is 12.5-25 μg based on the patient's current dose, to normalize thyroid function 1
• For patients with persistent TSH elevation despite current therapy, increasing from 100mcg to 125mcg represents an appropriate 25% increase that follows standard dosing guidelines 2
• This incremental approach helps avoid overtreatment while effectively addressing the elevated TSH 1

Monitoring After Dose Adjustment

• After increasing the dose, recheck TSH and free T4 in 6-8 weeks to evaluate the response to the adjusted dose 1, 2
• Once the appropriate maintenance dose is established, monitor TSH annually or sooner if symptoms change 1
• Free T4 measurements can help interpret ongoing abnormal TSH levels during therapy, as TSH may take longer to normalize 1

Special Considerations

• For patients <70 years without cardiac disease, this 25 μg increment is appropriate and follows standard dosing protocols 1
• For patients >70 years or with cardiac disease, smaller increments (12.5 μg) would be preferred to avoid potential cardiac complications 1, 2
• Avoid excessive dose increases that could lead to iatrogenic hyperthyroidism, which increases risk for osteoporosis, fractures, and cardiac complications 1

Common Pitfalls to Avoid

• Undertreatment risks include persistent hypothyroid symptoms, adverse effects on cardiovascular function, lipid metabolism, and quality of life 1
• Adjusting doses too frequently before reaching steady state (should wait 6-8 weeks between adjustments) can lead to inappropriate dosing 1
• About 25% of patients on levothyroxine are unintentionally maintained on doses sufficient to fully suppress TSH, highlighting the importance of regular monitoring 1

Algorithm for Dose Adjustment

1. For TSH above reference range on current dose of 100 mcg: increase to 125 mcg daily 1, 2
2. Recheck TSH and free T4 after 6-8 weeks 1
3. If TSH remains elevated: consider further 12.5-25 mcg increase 1
4. If TSH becomes suppressed: reduce dose by 12.5-25 mcg 1
5. Once stable, monitor annually or with symptom changes 1, 2