Myxedema coma secondary to levothyroxine malabsorption in a patient previously submitted to bariatric surgery

Abstract

Treating hypothyroidism can be challenging in patients with malabsorption, as they require a higher daily dose of oral levothyroxine (L-T4). Oral L-T4 absorption occurs mainly in the jejunum and the ileum and is affected by gastric acidity. As a result, absorption can be impaired by bariatric surgery. This paper presents a case of myxedema in a young man who had previously undergone biliopancreatic diversion. He was referred to the Emergency Department with deteriorated mental state, hypotension, bradycardia and hypothermia. Laboratory tests revealed severe hypothyroidism and hypokalaemia. The clinical and biochemical profile of the patient suggested myxedema coma. The tablet-based L-T4 therapy was replaced with intravenous (iv) L-T4, oral liquid L-T4 and oral liothyronine (L-T3) and inotropic agents and supportive care were also administered, resulting in a gradual improvement in clinical condition. The patient reported taking L-T4 tablets as prescribed before hospitalization. In patients with malabsorption, impaired L-T4 absorption may lead to severe forms of hypothyroidism. This case outlines the need for more frequent monitoring of serum Thyroid Stimulating Hormone in patients submitted to bariatric surgery and suggests the benefit of using liquid L-T4 in the place of tablets in cases of malabsorption.

Figure 1. ECG at presentation showing marked bradycardia (37 beats per minute) and prolonged QTc (520 msec).