Hypothyroidism management

ATA2014

Levothyroxine is first-line (strong rec, preparation of choice). Full replacement roughly 1.6 mcg/kg/day; start low and titrate slowly in older adults, and at 12.5 to 25 mcg/day with known CAD. Take 60 min before breakfast or at bedtime 3+ hr after the evening meal. Steady state in about 6 weeks; recheck TSH 4 to 6 weeks after any dose change. Target TSH within the reference range, about 0.4 to 4.0 mIU/L; 4 to 6 mIU/L is reasonable over age 70 to 80.

USPSTF2015Grade I

Insufficient evidence to assess benefits vs harms of screening for thyroid dysfunction in nonpregnant, asymptomatic adults. No routine TSH screening recommended in this group; test based on signs, symptoms, or risk factors.

ATA2026

Pregnancy: women on levothyroxine should raise the dose about 20 to 30% (or double it 2 days a week) at a positive pregnancy test, aiming for TSH 0.5 to 2.5 mIU/L; resume the prepregnancy dose after delivery and recheck TSH at about 6 weeks. Test only women with risk factors, not all. For a new mild TSH rise (under about 6 mIU/L), repeat testing 1 to 3 weeks later before treating is an option. No levothyroxine for euthyroid TPO-positive women with infertility, planned fertility treatment, or recurrent miscarriage.

BMJ Rapid Recommendations2019Grade Strong recommendation against

Subclinical hypothyroidism (raised TSH, normal free T4) in nonpregnant adults: do not routinely start thyroid hormone, because it does not improve quality of life, fatigue, mood, or weight; monitor for progression or resolution instead. Does not apply to women trying to conceive or TSH above 20 mIU/L, and may not apply to young adults (about 30 or younger) or those with severe symptoms.