Hyperkalemic periodic paralysis is a disorder that involves occasional episodes of muscle weakness and, sometimes, higher-than-normal levels of potassium in the blood.

It is one of a group of genetic disorders that includes hypokalemic periodic paralysis and thyrotoxic periodic paralysis.

Hyperkalemic periodic paralysis is due to faulty genes. In most cases, it is passed down through families (inherited). Occasionally, it occurs randomly in families. It is believed that the disorder is related to problems with the way the body controls sodium and potassium levels in cells.

Unlike other forms of periodic paralysis, persons with hyperkalemic periodic paralysis do not have low blood potassium levels. In fact, there may be normal or high levels of potassium in the bloodstream during and between attacks.

Risk factors include a family history of periodic paralysis. The condition occurs in approximately 1 in every 100,000 people. It affects men more often then women.