MSK Individual Readiness Assurance Test (iRAT) Practice Test 2026 - Free iRAT Practice Questions and Study Guide

HYPP is Hyperkalemic Periodic Paralysis, a genetic disorder of skeletal muscle where attacks of weakness are linked to elevated potassium in the blood. The faulty sodium channel in muscle cells causes abnormal depolarization, and during an attack potassium shifts into the bloodstream, producing hyperkalemia. This excess potassium depolarizes the muscle membrane enough to inactivate sodium channels, so muscles can’t generate new action potentials and paralysis results. So the electrolyte abnormality you’d expect is high potassium. Low potassium, high sodium, or low calcium would not characteristically cause HYPP episodes.