Hypokalemic Periodic Paralysis

Diagnosis & Tests

The health care provider may suspect hypokalemic periodic paralysis if the symptoms come and go, potassium levels are low during attacks, and other disorders known to cause low potassium are not suspected. Hypokalemic periodic paralysis is also likely if other family members have the disorder.

Between attacks, a physical examination shows nothing abnormal. Before an attack there may be leg stiffness or heaviness in the legs. Performing mild exercise when these symptoms start may help prevent a full blown attack.

During an attack, muscle reflexes may be decreased or absent and muscles go limp rather than staying stiff. The muscle groups near the body, such as shoulders and hips are involved more often than the arms and legs. The health care provider may attempt to trigger an attack to aid in diagnosis by reducing potassium levels through administration of insulin and glucose.

• Serum potassium is low during attacks but normal between attacks (confirming the diagnosis of hypokalemic periodic paralysis).
• An ECG or heart tracing may be abnormal during attacks.
• An EMG or muscle tracing is normal.
• A muscle biopsy may show abnormalities.