Hypokalemic periodic paralysis is a condition that causes episodes of extreme muscle weakness typically beginning in childhood or adolescence. Most often, these episodes involve a temporary inability to move muscles in the arms and legs. Attacks cause severe weakness or paralysis that usually lasts from hours to days. Some people may have episodes almost every day, while others experience them weekly, monthly, or only rarely. Attacks can occur without warning or can be triggered by factors such as rest after exercise, a viral illness, or certain medications. Often, a large, carbohydrate-rich meal or vigorous exercise in the evening can trigger an attack upon waking the following morning.
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Hypokalemic Periodic Paralysis HypoKPP is a rare inherited muscle disorder which is estimated to occur in only one of , individuals. Because it is inherited there may be several members in a family who have the disorder, which makes it obvious that the one in , figure is a statistical estimate, and does not represent real patients.
During severe attacks the patient may be unable to move and even appear unconscious. Even during paralysis the patient is awake and completely aware of their surroundings. A very few patients with HypoKPP begin having having attacks in infancy but most have their first attack between the age of years. Patients who develop symptoms at a young age may only have an attack once in while to begin with, but attacks tend to come more often later, and may eventually occur daily. Attacks may last an hour or two or sometimes a day or two.
Attacks vary from mild weakness in a hand, foot or limbs one time to complete paralysis the next. Some attacks cause muscle tenderness and aching and some are painless.
Patients may also have abortive attacks - daily weakness which varies hour to hour or day to day. These attacks can last for months and may be mistaken for permanent weakness. Some patients quit having paralysis when they are in their 40s but have abortive attacks instead.
Abortive attacks can be more trouble than paralytic attacks, because young patients usually feel strong between attacks of paralysis and patients with abortive attacks rarely feel strong.
A few patients have trouble breathing and swallowing. The low potassium level during attacks may cause irregular or weak heartbeat. Most patients have good muscle strength between attacks, but in most patients muscle tissue is damaged over time. Most patients have some reduction of muscle strength by the time they are years old. There is also a myopathic form of HypoKPP. By the time they are in their 60s they develop a permanent weakness of the legs which prevents them from climbing stairs, walking over rough ground, or walking distances.
This weakness may make it necessary to use a wheelchair. During attacks of muscle weakness, potassium moves from the blood into muscle cells. This makes the cell unable to contract properly. What tests are used to diagnose periodic paralysis? There are a variety of tests used. If the patient is brought to the hospital in the early stages of an attack it is easier for the doctor to do tests, but this rarely happens.
If the paralyzed patient has a low level of potassium in the blood 3. The patient with HypoKPP does not lose potassium in the urine during attacks. There is more information on this website about diagnostic tests and techniques.
See Diagnosis in Hypokalemic Periodic Paralysis. Hypokalemic Periodic Paralysis is caused by a genetic mutation which causes a malfunction in certain ion channels in the muscle membrane.
Ion channels are tiny pores openings that allow ions molecules of sodium and potassium to move through the cell membrane. For the muscles to work properly sodium and potassium ions must be kept in the correct ratio inside and outside the cell.
When the level of potassium in the blood falls these ion channels fail to regulate the flow of ions properly. The ratio of sodium and potassium inside and outside the cell become unbalanced.
The muscle responds less when asked to move, which is felt as weakness. If the imbalance becomes pronounced the muscle quits responding at all, i. This person with HypoKPP is very sensitive to drops in serum potassium. Some patients with HypoKPP may become paralyzed while their potassium levels remain within "normal" limits. So a parent may be affected without it being obvious.
About one in three cases happen as a result of a mutation which takes place at conception, like any birth defect. In the same family one child may have mild symptoms, the next may have worse symptoms and others may be unaffected. Even identical twins may be affected to different degrees. Those with HypoKPP have attacks when the potassium falls. In many patients the potassium level drops well below normal, but some patients never have very low potassium.
However the level of potassium always falls. Sweets or starchy foods trigger attacks because these foods cause potassium to move into the muscle cell, and lower the level of potassium in the blood. Potassium by mouth or by an IV line makes the attack go away. Patients with NormoKPP usually have an attack of weakness when they eat potassium-rich foods or are given potassium. Many HypoKPP attacks are triggered by food. Food triggers include sweet or starchy foods like candy, cakes, pie and other desserts, soft drinks which are sweetened with sugar, fruit juices, bread, cereal products, rice, potatoes, and pasta.
Foods like these are digested very quickly and raise blood sugar rapidly. The pancreas responds to this rapid rise in blood sugar by producing a lot of insulin. Insulin drives potassium from the blood into the muscle cell, which triggers weakness. Salty foods, like potato chips or pickles, are also a trigger for many HypoKPP patients. Getting too hungry, or eating a large meal especially if you are very hungry triggers episodes in many patients.
Other common triggers include unusual activity or exercise - usually the day before the attack, but sitting still for too long may also trigger attacks. Patients learn that pacing their activities is absolutely vital.
The activity level should be kept close to the same each day. Sleep is a strong trigger. Many patients wake up paralyzed in the morning or after a nap. Getting too cold or too hot makes some patients weak. Humid weather or a rapid change in the weather like a storm can trigger attacks in some patients. Some medications may cause attacks. These include muscle relaxants and beta-blockers, some tranquilizers, pain killers, antihistamines, the puffers used to treat asthma attacks, some antibiotics and cough syrups.
The eye drops used to dilate the pupil during eye exams have been reported to cause paralysis. Epinephrine or adrenaline , a drug routinely added to local anesthetics, should be absolutely avoided by patients with HypoKPP. Many patients report paralysis attacks occurring in the dentist's chair or following dental work, or after having a wound stitched or a mole removed.
Over the counter drugs can be dangerous and should be avoided if at all possible. Learn what your triggers are and learn to avoid them. For some people this is enough. For others it is necessary to take daily medication. The best place for treatment is almost always the patient's own family physician, if that physician is willing to read about HypoKPP and learn how to manage it.
Every patient responds a bit differently to treatment. Patients are often best cared for by the doctor who cares for their overall health. There are a number of research teams working on the PPs. Research is concentrating on the genetics and mechanics of the channelopathies, rather than on therapy and management. There's been nothing new in the way of therapy for many years, although we have learned how to apply therapies much more effectively, and we've made great strides in management.
Genetic testing is available, but it is not yet reliable enough to diagnose all HypoKPP patients. While a genetic test may be able to say you have HypoKPP, if the results of the test are negative that does NOT mean you do not have the disorder, as there are a number of variants which have yet to be identified.
If you plan to be tested it is wise to talk about this issue with your physician ahead of time, just in case your test comes back negative as many are still doing at this point. Make certain you will not be denied therapy by your physician or HMO should the test be negative! HypoKPP is caused by a mistake in the genetic 'blueprint' which was determined at the moment of conception.
At present there is no cure. A person who has HypoKPP will have the disorder all their life, but there is treatment available. This medication helps keep the potassium from getting out of balance in the first place, by affecting the mechanism that moves potassium from the blood into the cell.
Other carbonic anhydrase inhibitors called dichlorphenamide and methazolamide are more potent, and often work on patients who have been on Diamox many years and have become resistant to its effects.
Patients who take carbonic anhydrase inhibitors must be alert to potentially dangerous drug interactions as they slow the excretion of other drugs from the system. Avoid large doses of aspirin when taking carbonic anhydrase inhibitors. Diuretics which cause the kidneys to 'spare' or conserve potassium are also used to treat HypoKPP. Dyrenium and Aldactone spironolactone are in this family. Dyrenium is particularly useful as it causes the patient to excrete sodium as well as retain potassium.
Dyrenium sometimes comes mixed with an agent which makes patients excrete potassium, so it's important to make certain the medication the HypoKPP patient is receiving contains no potassium-wasting diuretic. Patients who are taking diuretics which cause the kidneys to conserve potassium should consult with their doctors before taking potassium supplements. Most people with HypoKPP still require potassium, even on diuretic therapy, but it should be carefully monitored. Those on carbonic anhydrase inhibitors generally need to take some potassium to replace what is lost due to therapy itself.
Most patients with HypoKPP use potassium to abort developing episodes. Patients differ in their reactions to different forms of potassium but, as a rule, most people find that the effervescent potassium citrate or bicarbonate tablets which dissolve in water are the most effective and easiest on the stomach.
Potassium chloride tablets are slow to dissolve and are hard on most people's stomachs, though some forms of potassium chloride capsules have coated granules of potassium which dissolve in the intestine and are much easier on the digestive system.
If potassium chloride tablets are required these are preferred by many patients.
Hypokalemic periodic paralysis
Hypokalemic periodic paralysis hypoPP or hypoKPP is a rare disorder in which a person experiences episodes of painless muscle weakness and often paralysis. This form of paralysis is associated with low potassium levels. People usually experience their first attack between the ages of 10 and Attacks occur randomly, but are often triggered by factors like foods or exercise.
Hypokalemic Periodic Paralysis FAQ
Hypokalemic periodic paralysis hypoPP is a disorder that causes occasional episodes of muscle weakness and sometimes a lower than normal level of potassium in the blood. The medical name for low potassium level is hypokalemia. HypoPP is one of a group of genetic disorders that includes hyperkalemic periodic paralysis and thyrotoxic periodic paralysis. HypoPP is congenital. This means it is present at birth. In most cases, it is passed down through families inherited as an autosomal dominant disorder.
Hypokalemic Periodic Paralysis: a case report and review of the literature
Metrics details. Hypokalemic Periodic Paralysis is one form of Periodic Paralysis, a rare group of disorders that can cause of sudden onset weakness. A case of a 29 year old male is presented here. The patient presented with sudden onset paralysis of his extremities. Laboratory evaluation revealed a markedly low potassium level. The patient's paralysis resolved upon repletion of his low potassium and he was discharged with no neurologic deficits.