Patients with hypokalemic periodic paralysis have periods of muscle weakness. In some cases, a patient can have severe paralysis. A genetic disorder, hypokalemic periodic paralysis is autosomal dominant, meaning that for a child to have the disorder, she only needs one of her parents to pass on the gene.
While the exact number of patients with hypokalemic periodic paralysis is not known, Genetics Home Reference from the U.S. National Library of Medicine estimated that it affects 1 in 100,000 people.
The disorder results from mutations of two genes: CACNA1S and SCN4A. These genes provide the body with the instruction to produce proteins involved in controlling the flow of ions that help skeletal muscles contract and relax. The mutations affect the skeletal muscles’ ability to contract, leading to the episodes of muscle weakness or paralysis.
Genetics Home Reference pointed out that in a small group of patients with hypokalemic periodic paralysis, they do not have mutations of these two genes. The cause is unknown in these cases.
Many patients start to have symptoms during their adolescence, though symptoms before age 10 may occur. MedlinePlus noted that an onset in adulthood is rare and may be the result of other disorders.
The muscle weakness or paralysis often occurs in the hips and shoulders, though some patients have symptoms in the muscles of their eyes, arms, legs, and muscles involved in swallowing and breathing. Patients can have symptoms when they are waking up or after rest. This is rare during exercise.
Other triggers of symptoms include alcohol consumption or meals that are high in carbohydrates and salt. The duration of the weakness or paralysis ranges from three to 24 hours.
Some patients may have an episode once a year, while others can have them more frequently, as many as every day.
Treatment for hypokalemic periodic paralysis involves relieving the patient’s symptoms and preventing future episodes. During an episode, a patient may take potassium to ease symptoms.