Abstract
Hypothermia is usually caused by exposure to cold ambient temperatures. Some patients, however, have no obvious historyof cold exposure. Hypothyroidism should be recognized as a cause of hypothermia in certain situations. We report a case of transient central hypothyroidism presenting as hypothermia. A 74-year-old woman presenting with a disturbance in consciousness for the second time was transferred to our department because of deep hypothermia without exposure to cold ambient temperatures. Active rewarming normalized her body temperature, but her consciousness disturbance persisted. We performed an endocrinological examination to reveal the cause of the consciousness disturbance and subsequently diagnosed her as having hypothyroidism, based on a low serum-free T4 level. An additional thyrotropin-releasing hormone (TRH) test showed a decrease in thyroid-stimulating hormone (TSH) in response to TRH, suggesting that the hypothermia was caused by central hypothyroidism. Hormone supplementation was performed, and her consciousness disturbance rapidly improved. Since her serum-free T4 level gradually increased over the course of several weeks, we speculated that her hypothyroidism was transient. An endocrinological examination should be considered in patients who present with hypotermia accompanied by a consciousness disturbance to reveal the underlying disorder.
