About one in 100,000 people have hyperkalemic periodic paralysis, a genetic disorder, according to MedlinePlus. Hyperkalemic periodic paralysis is part of a group of disorders, which also includes thyrotoxic periodic paralysis and hypokalemic periodic paralysis.
This disorder results from mutations on the SCN4A gene. This gene gives the body the blueprints to make a protein involved in skeletal muscle contraction. Normally, the protein produced by SCN4A makes the channels involved in the flow of sodium ions.
With the mutation, the sodium ion flow cannot be normally regulated, leading to problems with skeletal muscle contraction. This results in extreme muscle weakness. To have hyperkalemic periodic paralysis, the patient only needs one copy of the mutated gene. This pattern of inheritance is called an autosomal dominant pattern.
Patients with hyperkalemic periodic paralysis have intermittent episodes of either muscle weakness or paralysis. In between these episodes, patients have normal muscle strength. MedlinePlus noted that episodes of muscle weakness tend to last between one and two hours, but some patients have episodes that last the whole day.
Symptoms of hyperkalemic periodic paralysis commonly affect the hips and shoulders, though some patients have muscle weakness in their legs and arms. They can experience muscle weakness when resting after an activity or when they wake up in the morning.
Certain factors may trigger an episode of muscle weakness. For example, MedlinePlus noted that a patient may have an episode after eating a small amount of food that are rich in potassium or taking a medicine that contains potassium.
Fasting and exposure to the cold may also trigger an episode of muscle weakness. Either in between or during an episode of muscle weakness, the patient may have either normal or high levels of potassium in her blood. This differs from other types of periodic paralysis, in which patients have low levels of potassium in their blood.
To reduce the severity of an episode of hyperkalemic periodic paralysis, the patient may be given glucose, or another type of sugar.