hormonal and metabolic disorders
Acute Intermittent Porphyria
Introduction
Acute intermittent porphyria, which causes abdominal pain and neurologic symptoms, is the most common acute porphyria. Many people never experience symptoms. Symptoms may include vomiting, abdominal or back pain, weakness in arms or legs, and mental health symptoms. The most common symptom is generalized abdominal pain that lasts for several hours to days. Laboratory tests are best done on urine samples taken during the attack. Maintaining good nutrition and avoiding alcohol and medications that trigger attacks are important. Attacks are treated by giving glucose and sometimes heme. Givosirandecreases the number and severity of acute attacks. Porphyrias are a group of disorders caused by deficiencies of enzymes involved in the production of heme. Heme is a chemical compound that contains iron and gives blood its red color. Heme is a key component of several important proteins in the body. (See also Overview of Porphyrias .) Acute intermittent porphyria occurs in people of all ethnic groups. In most countries, it is the most common of the acute porphyrias. Other acute porphyrias include Variegate porphyria Hereditary coproporphyria Delta-aminolevulinic aciddehydratase-deficiency porphyria, which is extremely rare Variegate porphyria and hereditary coproporphyria may also cause skin (cutaneous) symptoms. Acute intermittent porphyria is due to a deficiency of the enzyme porphobilinogen deaminase (also known as hydroxymethylbilane synthase) that leads to accumulation of the porphyrin precursors delta-aminolevulinic acidand porphobilinogen initially in the liver. Acute intermittent porphyria is inherited due to a single abnormal gene from one parent. The normal gene from the other parent keeps the deficient enzyme at half-normal levels, which is sufficient to produce normal amounts of heme. Most people with a deficiency of porphobilinogen deaminase never develop symptoms. In some people, however, certain factors can precipitate symptoms, causing an attack. Factors that can cause an acute porphyria attack include Many medications (including sex hormones, barbiturates, antiseizure medications, and sulfonamide antibiotics) Hormonal changes in women (increasedprogesterone, which occurs monthly in the days following ovulation) Low-calorie, low-carbohydrate diet Ingestion of alcohol Exposure to organic solvents (for example, in dry cleaning fluids or paints) Emotional stress Infection and other illnesses Surgery Smoking Usually a combination of factors is involved in causing an attack. Sometimes the factors that cause an attack cannot be identified. Attacks are more common in women than in men and occur only very rarely before puberty. Very rarely, the disorder is inherited from both parents (and therefore two abnormal genes are present). Symptoms may then appear in childhood and include developmental abnormalities. Many medications can cause an acute porphyria attack. The following websitePorphyria Drugscan be used to learn the risk of a medication. 