甲狀腺荷爾蒙分泌失調會影響我們的新陳代謝速率。甲狀腺功能低下的病人會有心跳 慢、便秘、怕冷、體重增加等症狀；甲狀腺功能亢進的病人則常以心悸、焦慮、手抖、怕 熱、體重減輕等症狀表現。我們可以在病史及理學檢查後，佐以甲狀腺功能檢驗TSH、free T4 或T4、T3、和自體免疫抗體以確定診斷。原發性甲狀腺功能低下的原因包括慢性自體免 疫性甲狀腺炎、醫源性( 甲狀腺手術切除、放射性碘治療、藥物)、先天性甲狀腺發育不全或 功能不足等。治療的原則是補充甲狀腺素至功能正常。對於年紀大的病人，須以小劑量開始 調整。甲狀腺功能低下若未適當治療，可能造成黏液水腫性昏迷(myxedema coma)。甲狀腺功 能亢進的原因包括葛瑞夫茲氏病、毒性甲狀腺結節腫、毒性多發性甲狀腺結節腫(Plummer’s disease) 等。其治療方式包括抗甲狀腺藥物( 如carbimazole、methimazole、propylthiouracil)、 手術、放射性碘。甲狀腺功能亢進若未適當治療，可能造成甲狀腺風暴(thyroid storm)，此 時除治療誘發因素( 如感染) 外，需以Lugol’s solution、β-blockers、thionamide、類固醇等治 療。

Dysfunction of thyroid hormone may affect our metabolism. Patients who have hypothyroidism may have symptoms like slow heart rate, constipation, cold intolerance, and increase of body weight, etc. However, palpitation, anxiety, restlessness, heat intolerance, and body weight loss may be seen in patients with hyperthyroidism. We could make the diagnosis according to the thyroid function test, such as thyroid stimulating hormone (TSH), free T4, T4, or T3, and autoantibodies after we reviewed the patient’s history and performed the physical examination. The causes of primary hypothyroidism included autoimmune thyroiditis, iatrogenic (thyroidectomy, I-131 ablation, or medication for treatment of hyperthyroidism), or congenital disease, etc. The treatment of hypothyroidism was daily use of the synthetic thyroid hormone levothyroxine, with low dose in the elder patients. Myxedema coma, a life-threatening condition is the result of long-term, undiagnosed hypothyroidism. Graves’ disease, toxic adenoma, or toxic multinodular goiter (Plummer’s disease) can cause hyperthyroidism. Treatment of hyperthyroidism included anti-thyroid drugs (thionamides, such as carbimazole, methimazole, or propylthiouracil), surgery, or radioactive iodine. Thyroid storm may be seen in the patients without adequate treatment of hyperthyroidism and we should look for the precipitating factors and provide aggressive management.