Electrolyte Abnormalities Associated with Medications

The European Society of Cardiology recommends monitoring electrolytes in patients taking HCTZ, as it can cause all three electrolyte abnormalities—hyponatremia, hypochloremia, and hypokalemia—through increased renal excretion of sodium, chloride, and potassium 1, 2.
The American Heart Association suggests that Lipitor, Plavix, Flomax, and Dutasteride do not typically cause these electrolyte disturbances 1.
The European Society of Cardiology notes that Valsartan can cause hyperkalemia rather than hypokalemia when used alone, but when combined with HCTZ, the effects may balance out or HCTZ's potassium-wasting effect predominates 1, 2.

Target Electrolyte Ranges and Monitoring

The American College of Cardiology recommends target serum potassium ranges of 4.0-5.0 mEq/L to minimize cardiac risk 3.
The European Society of Cardiology suggests target serum sodium levels of >135 mEq/L, and discontinuing diuretics if <125 mmol/L 3.
The American Heart Association recommends checking electrolytes within 1-2 weeks after initiation or dose changes of HCTZ or Valsartan, and rechecking at 3 months, then every 6 months thereafter 1.

The American College of Cardiology recommends adding a potassium-sparing diuretic rather than chronic oral supplementation for persistent diuretic-induced hypokalemia 3, 4.
The European Society of Cardiology suggests avoiding rapid correction of hyponatremia >20 mEq/L in the first 24 hours due to the risk of osmotic demyelination syndrome 4.