Myxedema Coma as the Initial Presentation of Undiagnosed Hypothyroidism: A Rare but Reversible Emergency

Myxedema coma is a rare, life-threatening endocrine emergency representing the extreme manifestation of untreated hypothyroidism. It usually presents with nonspecific symptoms such as confusion, hypothermia, and bradycardia, which can lead to delayed recognition, particularly in elderly patients with multiple comorbidities. We report the case of a 77-year-old man with hypertension, stage 4 chronic kidney disease, anemia of chronic disease, myeloma, and prostate cancer who presented with reduced consciousness following a period of increasing lethargy and confusion. On arrival, he was hypotensive and hypothermic with a Glasgow Coma Scale (GCS) score of 8/15 and extensive lower limb edema, extending up to the abdomen. Laboratory investigations revealed severe hypothyroidism (thyroid-stimulating hormone (TSH) >99.9 mU/L; free thyroxine (T4) 8 pmol/L) and mild infection. A diagnosis of myxedema coma was made, and he was treated with intravenous hydrocortisone, nasogastric levothyroxine (later addition of intravenous liothyronine after discussion with the endocrinology team), antibiotics, and supportive measures, including cautious rewarming and fluid resuscitation. His level of consciousness improved within 48 hours, and thyroid function gradually normalized. The case illustrates how myxedema coma may be the first manifestation of previously undiagnosed hypothyroidism and highlights the diagnostic challenge posed by overlapping comorbidities.