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porphyria

porphyria (por-fi-riă) n. one of a group of rare inborn errors of metabolism in which there are deficiencies in the enzymes involved in the biosynthesis of haem. The accumulation of the enzyme's substrate gives rise to the features of the disorder, which include the excretion of porphyrins and their derivatives in the urine, which may change colour on standing. acute intermittent p. a hereditary hepatic porphyria marked by recurrent attacks of acute abdominal pain, constipation, and psychotic behaviour. erythropoietic p. any porphyria in which the defect is primarily in the bone marrow. hepatic p. any porphyria in which the defect is primarily in the liver. p. cutanea tarda a hereditary or acquired hepatic porphyria in which light-exposed areas of the skin become blistered and fragile (see photodermatosis).

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Porphyria

Porphyria

What Is Porphyria?

How Is Porphyria Diagnosed and Treated?

Resource

Porphyria (por-FEER-ee-a) refers to a group of disorders that are genetic (hereditary). Common problems in porphyria include sensitivity to light, skin rashes, abdominal (ab-DOM-i-nal) pain, and discoloration of the urine.

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Genetic disorders

Porphyrins

What Is Porphyria?

When a person inherits a defective gene* from one or both parents, he or she may develop a form of porphyria. There are six classifications of this group of disorders. Some of them are rare. While exact numbers are not available, it is estimated that one person in 10,000 to 50,000 may be affected.

* genes
are chemicals in the body that help determine a persons characteristics, such as hair or eye color. They are inherited from a persons parents and are contained in the chromosomes found in the cells of the body.

All six types of porphyria are a result of a problem in the chemical process by which the body makes heme, a compound that carries oxygen and makes blood red. Making heme requires eight different enzymes*. If any one of these enzymes fails, compounds that should be turned into heme instead build up in the body, especially in the liver* and in the bone marrow*, and cause problems. Some of these compounds are called porphyrins (POR-fi-rinz), which is where the disease gets its name. The different forms of porphyria occur from the failure of different enzymes.

* enzymes
(EN-zymz) are natural substances that speed up specific chemical reactions in the body.
* liver
is a large organ located in the upper abdomen (AB-do-men) that has many functions, including storage and filtration of blood, secretion of bile, and participation in various metabolic (met-a-BOLL-ik) processes.
* marrow
(MAR-o) is the soft tissue that fills the cavities of the bones.

Acute intermittent porphyria

This form of porphyria does not appear unless it is triggered by certain drugs, starvation or crash dieting, infection, and some hormones* in women. This form of porphyria is more common in women than in men. It usually occurs first during the young adult years. Symptoms include stomach pain, leg cramps, and muscle weakness. As its name indicates, it tends to occur from time to time (intermittently). In its most acute* forms, it can cause seizures*, paralysis*, depression*, and even hallucinations* or coma*. It is thought that King George III of England suffered from some form of porphyria.

* hormones
are chemicals that are produced by different glands in the body. Hormones are like the bodys ambassadors: they are created in one place but are sent through the body to have specific regulatory effects in different places.
* acute
means sudden.
* seizures
(SEE-zhurz) are sudden attacks of disease, often referring to some type of violent spasms.
* paralysis
(pa-RAL-i-sis) is the inability to move some part of the body.
* depression
(de-PRESH-un) is a mental state marked by sadness and despair.
* hallucinations
(ha-loo-si-NAY-shunz) are sensory perceptions not based in reality.
* coma
(KO-ma) is an unconscious state, like a very deep sleep. A person in a coma cannot be awakened, and cannot move, see, speak, or hear.

Porphyria cutanea tarda (ku-TAY-ne-a TAR-da)

This is the most common form of porphyria and causes blisters* on the parts of the body that are exposed to sunlight. Some people with this form also develop liver disease. Substances that can cause an attack of this type of porphyria include alcohol, heavy intake of iron (iron overload), or the use of birth control pills. Porphyria cutanea tarda usually does not affect younger women. However, the increased use of substances that can trigger an attack, such as alcohol or birth control pills, has resulted in more younger women developing the disease. This type of porphyria is not inherited. Only about 20 percent of cases have a family history of the disease.

Protoporphyria

Protoporphyria (pro-to-por-FEER-ee-a) usually starts in childhood. The skin is extremely sensitive to sunlight, and painful rashes, redness, and itching may develop.

How Is Porphyria Diagnosed and Treated?

Diagnosis

Porphyria is diagnosed when an excess of porphyrins (compounds involved in making heme) is found in the urine. More laboratory tests help pinpoint specific forms of porphyria.

Treatment

Heme is given to treat acute intermittent porphyria. For porphyria cutanea tarda, in which there is an excess of iron in the body, the patient may be bled. A pint of blood is removed once or twice a week for several weeks, until iron levels drop to normal. Drug treatment for some forms of porphyria is available. Avoiding light and other substances that can trigger an attack is important for people who are susceptible to any form of porphyria. Sunscreens are not helpful for preventing skin eruptions. Sometimes, betacarotene (bay-ta-KAR-o-teen) is given to help with light sensitivity. Doctors recommend prevention of attacks by avoiding substances that trigger symptoms.

See also

Genetic Diseases

Metabolic Disease

Skin Conditions

Resource

American Porphyria Foundation (APF), P.O. Box 22712, Houston, TX 77227. Telephone 713-266-9617 http://www.enterprise.net/apf

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porphyria

porphyria Group of rare genetic disorders in which there is defective metabolism of one or more porphyrins, the breakdown products of haemoglobin. It can produce a wide range of effects, including intestinal upset, hypertension, weakness, abnormal skin reactions to sunlight, and mental disturbance. A key diagnostic indicator is that the patient's urine turns reddish-brown if it is left to stand.

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"porphyria." World Encyclopedia. . Encyclopedia.com. 19 Aug. 2017 <http://www.encyclopedia.com>.

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"porphyria." World Encyclopedia. . Retrieved August 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/porphyria

porphyria

porphyria a rare hereditary disease in which there is abnormal metabolism of the blood pigment haemoglobin. Porphyrins are excreted in the urine, which becomes dark; other symptoms include mental disturbances and extreme sensitivity of the skin to light. It has been suggested that George III suffered from porphyria.

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"porphyria." The Oxford Dictionary of Phrase and Fable. . Encyclopedia.com. 19 Aug. 2017 <http://www.encyclopedia.com>.

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"porphyria." The Oxford Dictionary of Phrase and Fable. . Retrieved August 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/porphyria