Title: Digoxin Toxicity With Normal Digoxin Levels?
題目：地高辛濃度正常的地高辛中毒
Author作者: Feng Xiao ?
Digoxin toxicity can occur in patients with normal digoxin levels. In patients taking digoxin in recommended doses, digoxin toxicity can occur in the setting of hypokalemia or hypomagnesemia, even though the serum digoxin level is within normal limits.
地高辛中毒可發生在地高辛水平正常的患者。服用推薦劑量的地高辛患者，即使血清地高辛濃度在正常范圍內，地高辛中毒也可在低鉀血癥或低鎂血癥情況下發生。
Digoxin directly inhibits the sodium-potassium ATPase pump in the membrane of the cardiac myocyte, causing an increase in intracellular sodium and calcium which increases myocardial contractility.
地高辛直接抑制心肌細胞膜的鈉 - 鉀ATP酶泵，導致細胞內的鈉和鈣的增加,進而增加心肌收縮力。
Hypokalemia increases digoxin cardiac sensitivity because potassium and digoxin compete for the same ATPase-binding site. Magnesium is a cofactor of the sodium-potassium ATPase pump. Hypomagnesemia increases myocardial digoxin uptake, further inhibiting sodium-potassium ATPase pump activity.
由于鉀和地高辛競爭同樣的ATP酶結合位點，低鉀血癥會增加心臟對地高辛的敏感度。鎂是鈉 - 鉀ATP酶泵的輔助因子。因此低鎂血癥會增加心肌地高辛的吸收，進一步抑制鈉 - 鉀ATP酶泵活性。
It is known that long-term digoxin users often have hypokalemia or hypomagnesemia, presumably due to diuretic usage in patients with congestive heart failure.
眾所周知，長期使用地高辛的患者往往有低鉀或低鎂血癥，因為充血性心臟衰竭患者多需要利尿劑。
In a suggestive clinical setting, do not exclude the possibility of digoxin toxicity simply because the digoxin level is in the therapeutic range, and be sure to check serum potassium and magnesium levels.
在臨床懷疑地高辛中毒情況下，不要僅僅是因為地高辛濃度在治療范圍內就排除這種可能性，一定要檢查血清鉀和鎂的水平。
References參考文獻:?
(1) Raja Rao MP, et al. J Emerg Med 2013; epub, May 20, 2013.?
(2) Dec GW. Med Clin North Am 2003;87:317-337.?
(3) Chan KE, et al. J Am SocNephrol 2010;21:1550-1559.