Abstract

Hyperthyroidism has been recognised as the cause of secondary pulmonary hypertension (PH). However, several studies have reported that most PH cases due to hyperthyroidism are asymptomatic and not severe. Here, we report the case of a woman in her 30s with symptomatic and severe PH due to hyperthyroidism. She presented with a 2-month history of dyspnoea on exertion, palpitation and lower-extremity oedema. Echocardiography showed severe PH with estimated pulmonary arterial systolic pressure (ePASP) of 62 mm Hg. The diagnostic work-up showed severe PH due to hyperthyroidism. After treatment for hyperthyroidism, improvement of thyroid function contributed to a decrease in ePASP to 30 mm Hg. Similar to the present case, PH due to hyperthyroidism generally improves with the treatment of hyperthyroidism. Therefore, we must not overlook hyperthyroidism as a cause of PH and diagnose and start treatment for PH-causing hyperthyroidism at an early stage.