A 16-year-old sprinter on the high school track team has recently complained of extreme weakness after completing his events. He specifically said that his legs felt "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.
Upon visiting the doctor, his plasma K+ was 4.5mEq/L. After having the patient perform a strenuous run on the treadmill, his serum K+ was 2.2 mEq/L. The patient was diagnosed with primary hypokalemic periodic paralysis and placed on a treatment regime.
1. How would low serum potassium cause muscle weakness and/or paralysis?
2. Why might eating carbohydrates exacerbate the low serum potassium in our patient?
1. Before we get to that question, it is important to know that primary hypokalemic periodic paralysis has been proposed to be caused by genetic defects of calcium or sodium channels (http://brain.oxfordjournals.org/content/129/1/8). Precipitating ...
This solution discusses the pathophysiology of primary hypokalemic periodic paralysis and precipitating factors affecting the symptoms.