Treatment of overt hypothyroidism

• Levothyroxine (1.5–1.7 µg/kg/d), re ✓ TSH q5–6wk, titrate q8-12 wks if TSH not in range
• Lower starting dose (0.3–0.5 µg/kg/d) if at risk for ischemic heart disease or elderly
• ↑ dose typically needed if: poor GI absorption: meds that ↓ absorption (iron, calcium, cholestyramine, sucralfate, PPI), celiac disease, IBD meds that accelerate T4 catabolism (eg, phenytoin, phenobarbital) initiation of estrogen replacement; pregnancy (~30% ↑ by wk 8): TSH goals change by trimester: 1st = 0.1–4.0 mIU/L, 2nd & 3rd = gradual return of TSH to nonpregnant nl range (Thyroid 2017;3:315)