Lifestyle and dietary measures in Periodic Paralyses.: Dietary measures in PPs

Periodic paralyses (PPs) are rare skeletal muscle ion channelopathies caused by mutations in skeletal muscle sodium, calcium, and potassium channel genes. PPs can be divided into primary periodic paralyses (PPPs) and secondary PPs by the aetiology. Secondary PPs are common in hyperthyroidism, primary aldosteronism, renal tubular acidosis, or be related to other causes such as medication intake or potassium loss from the digestive or renal systems. Both conditions are characterized by episodic flaccid muscle weakness

Primary PPs are classified as Hypokalemic Periodic Paralyse, (HypoPP), normokalemic periodic paralysis (NormoPP), Hyperkalemic Periodic Paralyses (HyperPP), and Andersen-Tawil Syndrome (ATS). Common features are autosomal dominant inheritance, typical onset in the first or second decades, and episodic attacks of flaccid weakness often triggered by diet or rest after exercise.

The article focuses on the key role of potassium in promoting and/or preventing paralytic attacks and in avoiding them through appropriate dietary measures.

Introduction

Periodic paralyses (PPs) are rare skeletal muscle ion channelopathies caused by mutations in skeletal muscle sodium, calcium, and potassium channel genes^1-3. PPs can be divided into primary periodic paralyses (PPPs) and secondary PPs by the aetiology. Secondary PPs are common in hyperthyroidism, primary aldosteronism, renal tubular acidosis, or be related to other causes such as medication intake or potassium loss from the digestive or renal systems^4-5. Both conditions are characterized by episodic flaccid muscle weakness. The attacks of hypotonia and muscle weakness may be of variable duration, extent and intensity usually associated with altered blood potassium (K+) levels, hence the term “dyskalemic syndromes”. Primary PPs are classified as hypokalemic periodic paralysis (HypoPP), normokalemic periodic paralysis (NormoPP), or hyperkalemic periodic paralysis (HyperPP) based on serum K+ levels during paralytic attacks. Total prevalence of PPs is estimated between 1-9 cases per 100,000 people. Hypokalemia Type 1 (HypoPP1) is the most common form, accounting for approximately 70% of cases. Hypokalemia Type 2 (HypoPP2) is less common. Common features are autosomal dominant inheritance, onset typically in the first or second decades, episodic attacks of flaccid weakness often triggered by diet or rest after exercise^2-4. Andersen-Tawil syndrome (ATS) is a rare PP characterized by a triad of periodic paralysis, cardiac arrhythmias and skeletal and craniofacial anomalies, associated to high, low or normal serum K+ levels^6-7.

Hypokalemic Periodic Paralyses may be caused by variations in the CACNA1S gene (Hypo-PP1) which encodes the calcium channel in skeletal muscles³, located on long arm of the chromosome 1 (1q32,1) or by variations in the SCN4A gene (Hypo-PP2) which encodes the α-subunit of the voltage-gated sodium channel located on long arm of chromosome 17 (17q23.3). The condition causes recurrent episodes of muscle weakness lasting from hours to days often triggered by high-carbohydrate diet, cold, viral infection, insomnia, stress factors, corticosteroid administration⁸, and rest after heavy physical exercise. Resolution is spontaneous, often preceded by excessive sweating or profuse diuresis. Electrocardiographic changes can be observed during the attacks while cardiac rhythm and conduction disturbances are rarer. Patients usually complete recovery between the attacks, although some develop permanent fixed weakness later in life⁴. After age 50-60, the attacks tend to disappear.

Genetic forms of hypokalemic periodic paralysis also include those caused by mutations in the KCNJ18 gene, which encodes the kir2.6 potassium channel⁹, and those caused by mutations in the CACNA1S gene^10-12. Mutations in the KCNJ18 gene are responsible for thyrotoxic periodic paralysis (TPP)^13,14, a rare but potentially lethal cause of acute flaccid paralysis characterized by hypokalemia in the presence of thyrotoxicosis and often misdiagnosed in emergency rooms.

Mutations in the CACNA1S gene have been associated with hypokalemic periodic paralysis (HypoPP) ^10,11, susceptibility to malignant hyperthermia¹², and both recessive and dominant forms of congenital myopathy^15-16.

Normokalemic Periodic Paralysis (normo-PPs) is characterized by normal blood K+ levels during the attacks. It is caused by mutations in the SCN4A gene^17,18.

Hyperkalemic Periodic Paralyses (Hyper-PPs) constitute a heterogeneous group of conditions whose extreme clinical forms are the Garmstorp’s hereditary episodic adynamia^19,20 and the von Eulenburg’s congenital paramyotonia²¹, both inherited in an autosomal dominant pattern.

The first disease is characterized by brief attacks of diffuse paralysis lasting from a few minutes to an hour. These attacks can involve muscles innervated by cranial nerves and are triggered by rest after exercise, fasting, or exposure to cold. The more frequent prodromal symptoms are paresthesia, weakness and nausea that may resolve with moderate exercise. Myotonic phenomenon is commonly observed especially affecting the upper eyelid. In von Eulenburg’s congenital paramyotonia, paramyotonic episodes occur characterized by sudden and spontaneous contracture of muscle groups located in the facio-lingual region, triggered by exposure to cold which usually resolves with warming and mobilization. Sometimes, the episodes can be followed by widespread muscle weakness. Onset occurs in childhood. The Garmstorp form, unlike the von Eulenburg form improves after age 40. Both forms are caused by mutations in the SCN4A gene^3-4. Paradoxical myotonia (or paramyotonia), characterized by muscle stiffness that worsens with repeated exercise and movement, rather than improving (which is the opposite of classic myotonia), is typically linked to paramyotonia congenita caused by mutations in the SCN4A sodium channel.

Hyper-PPs also include Andersen-Tawil syndrome (ATS) characterized by the triad of a) hyperkalemic periodic paralysis, b) ventricular ectopias, and c) dysmorphic features^6-7. Cardiac involvement can range from inconsistent QT interval prolongation to brief bursts of bidirectional ventricular tachycardia, sometimes fatal, detectable on standard or 24-hour ECG. Ventricular ectopic beats tend to worsen with decreasing blood potassium levels. The syndrome is caused by mutations in the KCNJ2 gene that encodes the potassium channel, located on the long arm of chromosome 17, at position 17q24.3²². The management of these patients is complex due to the opposite responses of skeletal muscle and heart to changes in blood potassium concentration.

Diagnosis

The diagnosis of PPs is based on clinical symptoms such as spontaneous remission of attacks and a tendency to recur, and the detection of abnormal potassium levels during attacks (which are not always constant). In the past, to facilitate the diagnosis, provocative tests with glucose, insulin or epinephrine load were used when hypokalemic forms were suspected and with potassium chloride load in case of suspected hyperkalemic forms^23-25..

EMG demonstrates complete muscle inexcitability and absence of spontaneous activity during the paralysis phase. Between critical periods, the examination is mostly normal in hypokalemic forms, while it may reveal myotonic discharges in hyperkalemic forms even in the absence of clinical paramyotonia. Using standardized protocols comprising short and long exercise tests in patients with known ion channel gene defects causing myotonia or periodic paralysis, Fournier et al.²⁶ found by electromyography significant changes of compound muscle action potential, which generally matched the clinical symptoms. Combining the responses to the different tests, they were able to define five electromyographic patterns (I–V) correlated with subgroups of mutations that may be used in clinical practice as guides for molecular diagnosis²⁶.

Muscle biopsy, often normal, may reveal features of vacuolar myopathy in advanced stages, with sub-sarcolemmal tubular aggregates affecting type II fibers.

Laboratory tests measuring blood potassium levels performed during attacks, can guide the diagnosis.

ECG. Electrocardiographic manifestations including ST-segment depression, T-wave inversion, and prominent U waves may indicate severe underlying hypokalemia. These findings, associated with low potassium levels may suggest a possible diagnosis of hypo-PP. The presence of ventricular arrhythmias in the ECG trace should instead lead to the diagnosis of ATS.

Genetic diagnosis is based on the identification of variations in the CACNA1S (hypoPP1), SCN4A (hypoPP2) or KCN18 (TPP) genes for the hypokalemic forms, in SCN4A for the hyperkalemic form, or in KCNJ2 gene for the Andersen-Tawill Syndrome^4,5. Genetic analysis is the gold standard test to confirm the clinical diagnosis.

Management

The management of HypoPP include potassium dosage for acute attacks, choice of diuretic for prophylaxis, identification of triggers and creating a safe physical environment^27-28. Patients with HypoPP respond well to oral potassium supplementation, acetazolamide²⁹, and spironolactone³⁰ therapy during acute attacks^31,32. Potassium chloride is the favoured potassium salt given at 0.5-1.0 mEq/kg. The oral route is favoured, but if necessary, a mannitol solvent can be used for intravenous administration.

In hyperPP, attacks can be successfully treated by intravenous infusion of glucose solution with calcium gluconate and insulin^27,28. In some studies, dichlorphenamide (DCP) was effective in the prevention of episodic weakness in both hypokalemic and hyperkalemic periodic paralyses^33-35.

Chronically, acetazolamide²⁹, dichlorphenamide^-33-35, or potassium-sparing diuretics decrease attack frequency and severity but are of little value acutely. Spironolactone³⁰ have been proposed for HypoPP, acetazolamide²⁹ and salbutamol^36,37 for HyperPP, and tocainamide³⁸ in cases of paramyotonia congenita taking into account cardiac contraindications.

However, avoiding common triggers, such as resting after strenuous exercise and above all adopting appropriate dietary measures play a fundamental role in preventing attacks.

Lifestyle and dietary measures

Triggers

High carbohydrate (pasta, pizza) and salt intake (chinese food)^39,40, over-eating, alcohol, dehydration, cold, viral infection, corticosteroid administration⁸, insomnia, emotions, stress factors and rest after heavy physical exercise³² are the most frequently reported triggers in HypoPP. Fasting, intake of potassium, alcohol, cold foods or beverages, physical activity and rest after exercise are the most frequently reported triggers in HyperPP^37,39, that should be carefully investigated when collecting the patient’s immediate medical history. On the contrary, no nutrition related triggers are reported for ATS but exercise can induce ventricular arrhythmias.

Role of Potassium in PPs

K+ is the main mineral present in cells. The highest concentrations are in muscle and cardiac cells and in extracellular fluids; in combination with sodium (Na⁺), it participates in muscle and cardiac contraction. It is also crucial in regulating blood pressure and fluid balance in cells; it activates several enzymes involved in energy metabolism and participates in protein synthesis and in the conversion of sugars into glycogen. It plays a key role in the transmission of nerve impulses.

In healthy individuals, potassium deficiency is very unlikely. In general, significant deficiencies can result from severe gastrointestinal problems (prolonged vomiting or chronic diarrhea), kidney problems, or uncontrolled use of diuretics or laxatives. Diabetic acidosis can also be a cause, as can severely low-calorie and prolonged diets. The main disorders caused by potassium deficiency are muscle fatigue, nausea, attention deficit or poor concentration, drowsiness, behavioural changes, and cardiac arrhythmias in the most severe cases.

For a normal-weight adult without any specific health conditions, a daily potassium intake of 3,900 mg is considered adequate. These values remain unchanged during pregnancy and breastfeeding, but are lower in children under 10 years of age. Dietary potassium intake rarely exceeds 4,000–5,000 mg/day. However, to date, there is no scientific evidence documenting adverse effects from dietary intakes above this level in healthy adults, with normal kidney function.

Potassium is present more or less in all foods, but minimally processed fresh vegetables, dried fruit, and dried legumes are particularly rich in it. Table I lists the potassium content of the most commonly foods and beverages.

Because food preparation and cooking methods can also affect potassium content, it’s important to follow some recommendations, such as: avoiding soaking vegetables for long periods; preferring short-term cooking methods (e.g., pressure cooking, steaming); avoiding highly processed foods; choosing brown rice (250 mg K+/100 g) over white rice (92 mg/100 g); and prioritizing and/or excluding foods and beverages based on the specific periodic paralysis and potassium levels; finally, kept in mind that although many foods contain sufficient amounts of potassium to meet the daily needs, not all of it is absorbed effectively.

Welland et al.³⁹ explored self-management of diet and physical activity in a group of 14 participants aged 21 to 58 years with CACNA1S–related HypoPP. Participants highlighted the cumulative effect of triggers, reporting being more susceptible to attacks when exposed to multiple triggers at once. They also emphasized how regular meals with controlled portions of complex carbohydrates, limited intake of simple carbohydrates were able to reduce the number and intensity of attacks of muscle weakness and paralysis. On the other hand, regular mild to moderate exercise combined with warm-up and cool-down, and avoidance of physical inactivity contributed to prevent attacks of muscle weakness and paralysis.

Recent studies suggest that HypoPP significantly impairs quality of life, with progressive permanent muscle weakness and fatigue, especially with age, being more burdensome than attacks of muscle weakness and paralysis^40,41.

Sansone et al.⁴¹ reported that fatigue has a similar detrimental effect on both patients with musculoskeletal channelopathies (in particular HypoPP) and in patients with myotonic dystrophies, with the exception of patients with hyperkalemic periodic paralysis in whom muscle weakness and myotonia affected the perception of quality of life more than fatigue.

Holm-Yildiz et al.⁴² reported that muscle weakness and fatigue were the symptoms that most impacted patients’ lives, and that the “life activities” domain of INQoL questionnaire were most affected in HypoPP. Poor quality of life in their study was primarily related to cases of progressive, permanent muscle weakness rather than acute paralysis attacks, although approximately 50% of patients reported that the latter still had a significant impact on their daily life.

Conclusions

Dietary modifications and adjustments in physical activity may reduce symptoms in patients with HypoPP suggesting that in these patients special attention should be given to muscle weakness and fatigue. However, these measures should be tailored to individual needs by a dietitian experienced in these conditions and not self-managed by patients. Finding a balance between dietary restrictions and the enjoyment of food remains a challenge which underscores the importance of an integrated, multidisciplinary approach that takes into account both the episodes of weakness and muscle paralysis and overall quality of life.

Conflict of interest statement

None.

Funding

None.

History

Received: March 2, 2026

Accepted: March 27, 2026

Figures and tables

Table I. Potassium content of commonly used foods and drinks (in decreasing order)

FOODS	mg/100g
Dried Legumes
Soy beans	1740
Beans	1445
Lentils	980
Chickpease	881
Dried Fruits
Apricots	1150
Pistachios	780
Almonds	705
Roasted Peanuts	680
Walnuts	632
Roasted Hagelnuts	446
Whole Grains
Quinoa	926
Buckwheat	450
Fresh Vegetables
Spinach	570
Potatoes	570
Brussels Sprouts	450
Fennel	394
Essentials	380
Artichokes	376
Fresh Fruit
Dates	656
Avocado	485
Red Currants	370
Bananas	350
Melon	333
Apricot	320
Kiwi	312
Grapes	192
Fish
Dried/soaked cod	1500
Dried/soaked stockfich	1500
Anchovies in oil	700
Fresh cod	495
Salmon	420
Meat
Beaf, veal	350
Rabbit	330-360
Chicken	307
Pork	250-400
DRINKS	mg/L
Fruit Juices	200
Coffee (one cup)	68
Tea (one cup)	27
Coca-cola	0