Patients become symptomatic around the age of 10. The weakness attacks in hyperPP are relatively short lasting, and range from minutes to hours. The attacks can happen upwards of ten times per month.Hypo-kalemic PP (hypoPP) is associated with low potassium levels. The onset of hypoPP occurs between the ages of 15 and 35. The prevalence of hypoPP is estimated to 1/100,000. HypoPP can be triggered by many external factors such as stress, high-sugar diet, and rest after exercise. During hypoPP attacks, the serum potassium concentrations can drop to less than 3 mM. Furthermore, hypoPP attacks are considerably longer lasting than hyperPP. As exercise is a trigger for periodic paralysis attacks, recently there is more research going into the physiological changes that accompany exercise including changes in blood pH. Diagnosis
This disease is unusually difficult to diagnose. Patients often report years of wrong diagnosis and treatments that made them worse instead of better. Part of this may be that migraines are present in up to 50% of patients and can cause a confusing array of symptoms including headaches, speech difficulties and visual, auditory or sensory auras. DNA testing is available for only a half dozen common gene mutations, while dozens of known mutations are possible but are not routinely tested. Electromyography (EMG) findings are not specific but the McManis Protocol, also called the Compound Muscle Amplitude Potential test (CMAP) can be used by a skilled neurologist capable of utilizing the EMG, which can give assistance in diagnosing several of these PP disorders.
That is, it is a selective mixed agonist–antagonist of the estrogen receptors (ERs), with estrogenic actions in some tissues and antiestrogenic actions in other tissues. The medication has estrogenic effects in bone, partial estrogenic effects in the uterus and liver, and antiestrogenic effects in the breasts. The affinity of toremifene for the ER is similar to that of tamoxifen. In studies using rat ER, toremifene had about 1.4% and tamoxifen had about 1.6% of the affinity of estradiol for the ER. The affinities (Ki) of toremifene at the human ERs have been reported as 20.3 ± 0.1 nM for the ERα and 15.4 ± 3.1 nM for the ERβ. In other rat ER studies, toremifene had 3–9% of the affinity of estradiol for the ER while its metabolites N-desmethyltoremifene and 4-hydroxytoremifene had 3–5% and 64–158% of the affinity of estradiol for the ER, respectively. The affinity of another metabolite, 4-hydroxy-N-desmethyltoremifene, was not assessed. 4-Hydroxytoremifene showed about 100-fold higher antiestrogenic potency than toremifene in vitro in one study, but not in another. 4-Hydroxy-N-desmethyltoremifene has also been found to be strongly antiestrogenic in vitro. The metabolites of toremifene, particularly 4-hydroxytoremifene, may contribute importantly to the clinical activity of the medication. On the other hand, some authorities consider toremifene not to be a prodrug.Toremifene is very similar to tamoxifen and shares most of its properties. There are some indications that toremifene may be safer than tamoxifen as it is not a hepatocarcinogen in animals and may have less potential for genotoxicity.