Severe hypokalemia in a patient with subarachnoid hemorrhage

Hypokalemia is a common electrolyte disorder in the intensive care unit. Its cause often is complex, involving both potassium losses from the body and shifts of potassium into cells. We present a case of severe hypokalemia of sudden onset in a patient being treated for subarachnoid hemorrhage in the surgical intensive care unit in order to illustrate the diagnosis and management of severe hypokalemia of unclear cause. Our patient received agents that promote renal potassium losses and treatments associated with a shift of potassium into cells. We outline the steps in diagnosis and management, focusing on the factors regulating the transcellular distribution of potassium in the body.