CASE

Primary Hypokalemic Periodic Paralysis

Jimmy Jaworski is a 16-year-old sprinter on the high school track team. Recently, after he completed his events, he felt extremely weak, and his legs became like rubber. Eating, especially carbohydrates, made him feel worse. After the most recent meet, he was unable to walk and had to be carried from the track on a stretcher. His parents were very alarmed and made an appointment for Jimmy to be evaluated by his pediatrician. As part of the workup, the pediatrician measured Jimmys serum K⁺ concentration, which was normal (4.5 mEq/L). However, because the pediatrician suspected a connection with K⁺, the measurement was repeated immediately after a strenuous exercise treadmill test. After the treadmill test, Jimmys serum K+ was alarmingly low (2.2 mEq/L). Jimmy was diagnosed as having an inherited disorder called primary hypokalemic periodic paralysis and subsequently was treated with K⁺ supplementation.