Hypokalaemia can be caused by
excess fluid loss decreased levels of potassium intake
renal impairment,
overuse of laxatives,
GI losses and some diuretics (Tortora and Derrickson 2009b,Thibodeau and Patton 2012).
The most serious effects of hypokalaemia are electrocardiogram (ECG) changes that can lead to ventricular arrhythmias in severe cases.