2022 年 9 巻 1 号 p. 83-87
A 69-year-old asymptomatic male was found to have high brain natriuretic peptide (BNP) levels (284.8 pg/mL) at a health check-up. He was referred to the cardiology department, and no abnormal findings were found on the electrocardiogram and echocardiogram. Palpitation and shortness of breath appeared three days after consultation. He then developed atrial fibrillation, and laboratory testing revealed a free tri-iodothyronine, free thyroxine, thyroid stimulating hormone (TSH), and TSH receptor antibody level of 5.56 pg/mL, 1.64 ng/dL, <0.01 μIU/mL, and 5.7 IU/L, respectively. He was treated with thiamazole (10 mg/day), which alleviated his symptoms and decreased the BNP to 20.5 pg/mL. Since the patient was asymptomatic and presented with an elevated BNP only, it was difficult to diagnose Graves’ disease. Heart diseases and hyperthyroid states, including Graves’ disease, should be considered in patients with high BNP levels, even when they are asymptomatic.
