甲狀腺毒性週期性麻痺(TPP)好發於亞洲的成年男性’特徴為甲狀腺功能亢進的患者發生因鉀離子轉移入細胞内而引起的低血鉀與肌肉無力》TPP病患的甲狀腺功能亢進症狀通常不明顯，不容易第一時間診斷，不正確而過多的鉀離子補充容易造成危及生命的反彈性高血鉀，所以我們必須更了解TPP的病生理機轉來幫助我們診斷》TPP的發病機制一直被認為與Na+/K+-ATPase的活性增加有關，最近，一項研究發現高達33%的TPP患者有内向整流鉀離子通道(Kir2.6)的基因（KCNJ18)突變，Kir2.6鉀離子通道在調節骨骼肌休息膜電位中扮演了重要的角色，這個結果提供了進一步檢視TPP發病機制的重要方向》然而在台灣只有1.6% (2/120) TPP患者有Kir2.6突變，其他影響Kir2.6通道的因素如：胰島素與交感神經興奮，胰島素與交感神經興奮不只會增加Na+/K+-ATPase活性，也會抑制Kir2.6通道的功能。不管任何原因造成Kir2.6通道功能下降，減少外向鉀電流，會誘發低血鉀引起的逆理性去極化，進一步導致Na+通道失活和肌肉無法收縮。TPP的發病機制現在知道與Na+/K+-ATPase的活性增 加和Kir2.6通道功能下降有關，但是機制尚不完全清楚，仍有待進ー步的研究。

Thyrotoxic periodic paralysis (TPP), a hyperthyroidism-related hypokalemia and muscle-weakening condition resulting from a sudden shift of potassium into cells, was prevalent in young East Asian males. Failure to recognize TPP may lead to improper management and life-threatening rebound hyperkalemia. However, signs and symptoms of hyperthyroidism may not be obvious. The pathogenesis of thyrotoxic periodic paralysis has long been thought related to increased Na+- K+ ATPase activity stimulated by thyroid hormone, hyperadrenergic activity and hyperinsulinemia. Recently, KCNJ18 gene mutations which alter the function of an inwardly rectifying potassium channel named Kir2.6 have been detected in up to 33 % of cases. All disease Kir2.6 mutants exert dominant negative mutations on wild type Kir2.6 which play an important role in regulating resting membrane potentials of skeletal muscle. These results provide important insights into the mechanism of pathogenesis of TPP. However, only 1.6% (2/120) patient of TPP in Taiwan was found with Kir2.6 mutation. Insulin and catecholamines not only stimulate Na+/K+-ATPase activity but can also inhibit Kir channels. Decreased outward K+ current from hypofunction of Kir2.6 predisposes the sarcolemma to hypokalemia-induced paradoxical depolarization during attacks, which in turn leads to Na+ channel inactivation and inexcitability of muscles. The underlying mechanisms of TPP remain, however, incompletely understood awaiting further studies. (J Intern Med Taiwan 2013; 24: 388-398)