ToolsCalculators
Weight-based levothyroxine dose for adult hypothyroidism
Estimates a full or reduced starting levothyroxine replacement dose from body weight.
Weight-based levothyroxine dose for adult hypothyroidism
Body weight
Patient category
Complete the fields above to see the result.
When to use
- Selecting an initial levothyroxine dose in adults with overt hypothyroidism who do not already have an established maintenance dose.
Formula
Full replacement dose = 1.6 mcg/kg/day; reduced starting dose (older adults or cardiac disease) = ~1.0 mcg/kg/day. Rounded to the nearest 12.5 mcg.
Pearls and pitfalls
- Use ideal/lean body weight rather than actual weight in patients with obesity.
- Frail elderly patients or those with coronary disease are often started at a fixed low dose (25-50 mcg/day) rather than full weight-based dosing.
- Recheck TSH no sooner than 6 weeks after any dose change.