Hypokalemic periodic paralysis | Thyrotoxic periodic paralysis | Hyperkalemic periodic paralysis | Andersen syndrome | |
Age at onset | First or second decade | >20 years | First decade | First or second decade |
Attack frequency | Infrequent (a few times a year) | Infrequent | Frequent (up to several a day) | Monthly |
Attack duration | Hours to days | Hours to days | Minutes to hours | Days |
Precipitants | Exercise Carbohydrate load Stress Others* | Exercise Carbohydrate load Stress Others* | Exercise Fasting Stress K-rich food | Rest after exercise |
Potassium level during attack | Low | Low | Normal or elevated | Low, normal, or elevated |
Associated features | Later-onset myopathy | Symptoms of thyrotoxicosis Low TSH with high T4 or high T3 | Myotonia on examination and/or EMG Later-onset myopathy | Dysmorphic features Ventricular arrhythmias Long QT interval |
Etiology | Autosomal dominant inherited defect in calcium or sodium ion channel on muscle membrane | Thyrotoxicosis Possible inherited predisposition | Autosomal dominant inherited defect of sodium ion channel on muscle membrane | Autosomal dominant inherited defect of inward rectifying potassium channel |
Penetrance | Nonpenetrance common, especially in females | High | Nonpenetrance and incomplete penetrance common | |
Epidemiology | Clinical expression in males more frequent than females | Highest incidence in individuals from East Asia (eg, China, Japan) and in males more than females | Sexes equally affected | Marked intrafamilial phenotypic variation |
Preventive treatment | Carbonic anhydrase inhibitors K-sparing diuretics | Euthyroid state Propranolol | Carbonic anhydrase inhibitors Thiazide diuretics Inhaled beta-agonists as needed | Carbonic anhydrase inhibitors |
K: potassium; TSH: thyroid-stimulating hormone; T4: thyroid hormone (thyroxine); T3: thyroid hormone (triiodothyronine); EMG: electromyography.
* Refer to UpToDate topics on periodic paralysis.Do you want to add Medilib to your home screen?