What are some common causes of hypokalemia?
Hypokalemia can occur from one of four mechanisms:
1. Pseudo-hypokalemia: Artifactual decrease in potassium level after phlebotomy, most commonly due acute leukemia where white blood cells take up the potassium from blood sample.
2. Redistribution: Shifts from ECF to ICF due to insulin, aldosterone and β2 adrenergic agonists, hypokalemic period paralysis.
3. Increased GI losses: chronic diarrhea, vomiting, nasogastric suction, laxative abuse.
4. Kidney potassium loss: Drugs (diuretics and others), primary and secondary hyperaldosteronism, hypomagnesemia, Bartter, Gitelman, and Liddle syndrome, bicarbonaturia from metabolic alkalosis, and renal tubular acidosis. Reduced effective arterial blood volume due to GI fluid losses or diuretics stimulates aldosterone secretion increasing potassium secretion.