The health care provider may suspect hypokalemic periodic paralysis based on a family history of the disorder. Other clues to the disorder are muscle weakness symptoms that come and go with normal or low results of a potassium test.
Between attacks, a physical examination shows nothing abnormal. Before an attack, there may be leg stiffness or heaviness in the legs.
During an attack of muscle weakness, blood potassium level is low. This confirms the diagnosis. There is no decrease in total body potassium. Blood potassium level is normal between attacks.
During an attack, muscle reflexes are decreased or absent. And muscles go limp rather than staying stiff. Muscle groups near the body, such as the shoulders and hips, are involved more often than the arms and legs.
Tests that may be done include:
- ECG, which may be abnormal during attacks
- EMG, which is usually normal between attacks and abnormal during attacks
- Muscle biopsy, which may show abnormalities
Other tests may be ordered to rule out other causes.