All causes of hypokalemia can be divided into 3 big groups:
- Decreased intake (unlikely to be a sole cause)
- Intracellular shift
- External loss (GI or renal)
A step-by-step approach to diagnosis of hypokalemia
Step 1: Review current medication history. Drugs that can promote hypokalemia (via intracellular shifting or increased losses/decreased intake):
- K-deficient fluids
- loop/thiazide diuretics
- insulin, dextrose
- albuterol, terbutaline and other beta agonists
- catecholamines