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Primary hypothyroidism — USMLE Step 3 MCQ

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HardAmbulatory Medicine / Primary CarePrimary hypothyroidismUSMLE Step 3

An older patient is hypothermic, bradycardic and obtunded with sodium 121 mEq/L, low free T4 and markedly elevated TSH. Which initial endocrine treatment is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: E — Give IV hydrocortisone before an IV levothyroxine loading dose

The best answer is “Give IV hydrocortisone before an IV levothyroxine loading dose”. This is myxedema coma. Because concomitant adrenal insufficiency cannot initially be excluded, stress-dose glucocorticoid precedes thyroid hormone; IV levothyroxine loading and intensive supportive care follow without waiting for confirmatory adrenal testing. Myxedema coma is treated with IV levothyroxine loading, empiric stress-dose glucocorticoid before thyroid hormone, supportive care and consideration of IV liothyronine.

Reference: American Thyroid Association Task Force Guideline: Treatment of Hypothyroidism: https://pubmed.ncbi.nlm.nih.gov/25266247/