Severe hypokalemia

The Electrical Bank Account Gone Negative

Think of potassium as the currency that cells use to stay electrically charged. Every cell holds most of its potassium inside (like money in savings), and the outside is mostly sodium (like an empty checking account). The difference between inside and outside creates electrical pressure—the resting membrane potential—that lets cells fire signals. When you lose potassium through vomit or diarrhea, it is like withdrawing money without depositing any back; when diuretics make you pee it out, it is like a leak in the vault; when insulin pushes potassium from blood into cells, it is like moving money from the register (blood) into the vault (intracellular) so the register looks empty even though total money exists. Once the register (blood potassium) drops below 2.5 mEq/L, the cells cannot generate enough electrical pressure to fire—muscles go limp, the gut stops moving, and the heart loses its rhythm. The body tries to close the leak by peeing less potassium, but that takes days and cannot catch a big, sudden drop. Without rapid refilling of that electrical register, the system collapses.