Hypokalemia
Low potassium is the finding. The clinical question is why it is low — and whether it is dangerous.
Start with severity + trajectory
Confirm the value, compare with baseline, and ask whether the decline is acute or chronic. Weakness, palpitations, syncope, significant neuromuscular symptoms, or ECG abnormalities change urgency.
Loss vs shift matters
Diuretics, GI losses, and renal potassium wasting can create true depletion. Insulin and beta-agonists can lower serum potassium through intracellular shift, which is a different mechanism.
Check magnesium + kidneys
Hypomagnesemia can promote renal potassium wasting and make hypokalemia difficult to correct. Kidney function also changes both the differential and the safety of replacement.
Persistent hypokalemia needs a cause
When the explanation is not obvious or the abnormality recurs, medication review, GI history, magnesium, acid-base context, and selected urine potassium assessment can help distinguish renal from extrarenal loss.
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