Myxedema coma and cardiac ischemia in relation to thyroid hormone replacement therapy in a 38-year-old Japanese woman

Introduction: Although thyroid hormone deficiency, either clinical or subclinical, is an established risk factor for cardiovascular disease, coronary ischemia in a premenopausal woman in her 30s is relatively rare.Case summary: A 38-year-old woman was referred to our hospital with severe breathlessness and depressed consciousness. Physical examination found facial, abdominal, and pretibial edema; coarse hair, hoarse voice, and dry skin; engorged jugular veins; a distant heart sound; and reduced bilateral entry of air into the chest. Laboratory examinations revealed severe hypothyroidism, hyperlipidemia, and elevated serum levels of carcinoembryonic antigen (CEA) and carbohydrate antigen 125 (CA125). A computed tomography scan showed massive pleural and pericardial effusions. After 3 months of levothyroxine replacement therapy (initial dose: 12.5 μg/d; maintenance dose: 125 μg/d), all abnormal laboratory values associated with hypothyroidism returned to within normal ranges, with the exception of a transient and paradoxical rise in serum thyroid-stimulating hormone levels. However, 3 weeks after the initiation of therapy, the patient reported intermittent chest pains during the course of therapy, and a coronary artery angiogram revealed diffuse stenosis of all 3 branches. The patient underwent coronary artery bypass grafting, with subsequent improvement in coronary perfusion.Discussion: Careful cardiovascular evaluation is recommended before the start of thyroid hormone replacement therapy. In addition, care should be taken in the interpretation of serum biomarkers of malignancy (eg, CEA, CA125) in patients with myxedema, as values may be elevated in a hypothyroid state.Conclusions: Long-standing hypothyroidism may be associated with severe coronary atherosclerosis, even in a relatively young, premenopausal woman. The potential adverse cardiovascular effects of thyroid hormone must be considered during replacement therapy, even in relatively young patients.