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Can subclinical hypothyroidism cause myxedema coma?
Elderly male with primary hypothyroidism, HTN, and progressive worsening cognition over several months. PCP has been increasing LT4 dose as outpatient from 50>75>112mcg 1 month ago (no outpatient TFTs available). One day, he had sudden onset lethargy and was found to have a new onset complete heart block (HR 20s), hypotension, hypoglycemia, and hyponatremia. Normothermic and somnolent on exam.
TSH: 19, FT4 0.9 [0.8-1.5] (took levothyroxine 112mcg this AM). Random cortisol 12 (albumin 3.3).
Would you treat it as a myxedema coma? Could the normal free T4 be from taking LT4 this morning?
Answer from: at Community Practice
While the patient's signs and symptoms mimic myxedema coma, he does not have, by definition, "myxedema" (severe hypothyroidism). The patient's normal FT4 can't be explained by his taking his levothyroxine that morning, given the 7-day half-life of levothyroxine. If he hadn't been taking his medicati...
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Answer from: at Community Practice
Agree with Dr. Cooper. Also, there are a few case reports describing complete AV block from uncontrolled hypothyroidism (Mire Waberi et al., PMID 36582852). It is possible that this is the alternative explanation for poor circulation and likely precipitation of heart failure in this elderly gentlema...