potassium chloride are therefore recommended while other treatment is commenced. The effects of excess thyroid hormone typically respond to the administration of a non-selective beta blocker, such as propranolol (as most of the symptoms are driven by increased levels of adrenaline and its effect on the β-adrenergic receptors). Subsequent attacks may be prevented by avoiding known precipitants, such as high salt or carbohydrate intake, until the thyroid disease has been adequately treated. Treatment of the thyroid disease usually leads to resolution of the paralytic attacks. Depending on the nature of the disease, the treatment may consist of thyrostatics (drugs that reduce production of thyroid hormone), radioiodine, or occasionally thyroid surgery. Epidemiology TPP occurs predominantly in males of Chinese, Japanese, Vietnamese, Filipino, and Korean descent, as well as Thais, with much lower rates in people of other ethnicities. In Chinese and Japanese people with hyperthyroidism, 1.8–1.9% experience TPP. This is in contrast to North America, where studies report a rate of 0.1–0.2%. Native Americans, who share a genetic background with East Asians, are at an increased risk. The typical age of onset is 20–40. It is unknown why males are predominantly affected, with rates in males being 17- to 70-fold those in females, despite thyroid overactivity being much more common in women. History After several case reports in the 18th and 19th centuries, periodic paralysis was first described in full by the German neurologist Karl Friedrich Otto Westphal (1833–1890) in 1885. In 1926 the Japanese physician Tetsushiro Shinosaki, from Fukuoka, observed the high rate of thyroid disease in Japanese people with periodic paralysis. The first English-language report, in 1931, originated from Dunlap and Kepler, physicians at the Mayo Clinic; they described the condition in a patient with features of Graves' disease. In 1937 periodic paralysis was linked with hypokalemia, as well as precipitation of attacks with glucose and insulin. This phenomenon has been used as a diagnostic test. In 1974 it was discovered that propranolol could prevent attacks. The concept of channelopathies and the link with specific ion channel mutations emerged at the end of the 20th century. References External links Muscular disorders Thyroid disease