甲狀腺機能低下症酷似多發性肌炎一病例報告

Hypothyroidism Masquerading as Polymyositis: A Case Report

罹患甲狀腺機能低下症的病人，常常出現肌肉及骨骼系統症狀，例如肌肉無力、虛弱、疼痛、抽筋、僵硬及動作遲緩等，通常症狀輕微且發病過程緩慢。大部份此類病人之血清肌肉酵素都會升高，但真正引起肌肉病變者卻不多，僅有少數出現典型近端肌肉無力及肌肉酵素升高而曾被誤認、並當成多發性肌炎來治療。我們報告一例罹患甲狀腺機能低下症、高脂血症及高血壓之48歲男性病人出現近端肌肉無力及肌肉酵素升高，初步被臆斷為多發性肌炎，但經甲狀腺素治療後，其症狀及血液檢查皆迅速改善，於3個月後完全康復，且除了持續甲狀腺素治療以外，無須其他藥物，即可維持正常血脂肪及血壓。因為甲狀腺機能低下性肌肉病變可能酷似多發性肌炎，但治療容易，且預後良好，對於所有罹患不明肌肉病變或肌肉酵素升高的病人皆應檢查甲狀腺機能。

Musculoskeletal symptoms are widely recognized manifestations among hypothyroid patients. They are usually mild and insidious, consisting of weakness, cramps, pain, slowness, or stiffness. Although the serum muscle enzymes are increased in most patients with hypothyroidism, true myopathy develops in very few patients. Rarely, a hypothyroid patient with typical proximal muscle weakness and elevated muscle enzymes may be thought to have polymyositis. We report a 48-year-old male with hypothyroidism presenting with hyperlipidemia, hypertension and proximal muscle weakness with elevated muscle enzymes. The initial diagnosis was polymyositis. However, his symptoms and laboratory data improved significantly after treatment with levothyroxine. He had totally recovered by 3 months later. This case illustrates the importance of testing thyroid function in patients with unexplained myopathy or elevated muscle enzymes. If the myopathy is secondary to hypothyroidism, it can be completely reversed with adequate thyroid replacement.