Myxedema Coma Secondary to Central Hypothyroidism: A Rare but Real Cause of Altered Mental Status in Pediatrics

Background: Myxedema coma (MC), a medical emergency defined as severe hypothyroidism leading to altered mental status, is more common in older women with hypothyroidism. Methods/Results: A 7-year-old Caucasian male with chromosome 1q deletion presented with altered mental status preceded by milestone regression. His presenting labs results were: Thyroid-stimulating hormone (TSH) 0.501 μIU/ml and free thyroxine (T₄) <0.5 ng/dl. His morning cortisol level was 8.1 μg/dl with repeat testing, while TSH was 1.119 μIU/ml and free T₄ was 0.5 ng/dl. Low-dose cosyntropin test showed baseline and peak cortisol levels of 1.9 and 16 μg/dl, respectively. Aside from altered mental status, heart block was present in addition to hypothermia and hypercarbia. Diffuse cerebral cortical and corpus callosum atrophy were seen on MRI. An intravenous (i.v.) stress dose of hydrocortisone was administered for 24 h prior to an i.v. loading dose of levothyroxine. His activity level subsequently returned to baseline within 48 h after treatment had been initiated. Conclusion: Though MC is rare, occurring mainly with noncompliance in primary hypothyroidism, it may occur at the diagnosis of secondary hypothyroidism. Based on features like hypothermia, hypoventilation, and cardiovascular instability occurring in the setting of central hypothyroidism, it should be suspected and managed urgently in order to avert the associated high mortality resulting from treatment delays.