Snapshot A 22-year-old man presents to the emergency department after a crush injury to his lower extremities. He reports muscular pain, weakness, and palpitations and noticed that his urine is "tea-colored." On physical exam, there is tenderness upon palpation of his lower extremities and 4-/5 power in the same area. Urinalysis is heme positive. Laboratory testing is significant for a potassium level of 6.5 mEq/L and creatinine kinase level of 1,500 units/L. An electrocardiogram is shown. Introduction The major intracellular cation is potassium and magnesium login to view 4 more bullets Normal potassium homeostasis login to view 5 more bullets Disruptions in potassium homeostasis can result in hyperkalemia or hypokalemia login to view 22 more bullets Factors that Influence Potassium Shifts Shifts out of Cells (Hyperkalemia) Shifts into Cells (Hypokalemia) Insulin deficiency β2-adrenergic antagonists Acidosis cells attempt to buffer excess hydrogen ions to shift these ions into the cells in exchange for this intracellular uptake of hydrogen, potassium is transferred out the cell this attempts to achieve electroneutrality Digitalis secondary to dose-dependent Na+/K+ -ATPase pump inhibition Cell lysis (e.g., rhabdomyolysis ) Exercise Hyperosmolarity Succinylcholine ↑ insulin Hyperglycemia this stimulates endogenous insulin secretion from the pancreas in normal conditions β2-adrenergic agonists Alkalosis Hyposmolality