A Young Man with Hypokalemia

A 37-year-old Hispanic man presented to the emergency department with three days of progressive dyspnea and fatigue. He had history of kidney disease since he was very young, including hypokalemia, nephrolithiasis and osteomalacia. His medications included potassium citrate, which he neglected to take for the past week.

He has four siblings, one of whom has a similar condition. Physical examination reveals ...