Symptomatic Hyponatremia after Using Low-dose Combination Diuretics in Elderly Woman:

Hyponatremia, defined as a serum sodium concentration below 135 mEq/L (or 135 mMol/L), is the most common electrolyte imbalance in adults. Diuretics are one of common causes of hyponatremia, and thiazide diuretic is associated with virtually all cases of diuretic-induced hyponatremia. Typically, thiazide-induced hyponatremia occurs in high-dose, more than 25 mg per day. But in high risk group, such as elderly female with low body weight, low-dose thiazide can cause hyponatremia. Furthermore, risk of hyponatremia can be increased when using more than two different diuretics simultaneously. Also, mild hyponatremia, around 125 mEq/L, is usually asymptomatic, but it can cause significant symptoms in elderly. The authors report a case of symptomatic hyponatremia after using low-dose combination diuretic, hydrochlorothiazide 12.5 mg with spironolactone 12.5 mg, in an elderly woman, with review of several literatures.