The health care provider may suspect hyperkalemic 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 high results of a potassium test.
Between attacks, a physical examination shows nothing abnormal. During and between attacks, potassium blood level can be normal or high.
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.