porphyria

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porphyria

 [por-fēr´e-ah]
a genetic disorder characterized by a disturbance in porphyrin metabolism with resultant increase in the formation and excretion of porphyrins (uroporphyrin and coproporphyrin) or their precursors; called also hematoporphyria. Porphyrins, in combination with iron, form hemes, which in turn combine with specific proteins to form hemoproteins. hemoglobin is a hemoprotein, as are many other substances essential to normal functioning of the cells and tissues of the body.

Two general types are known: the erythropoietic porphyrias, which are concerned with the formation of erythrocytes in the bone marrow; and the hepatic porphyrias, which are responsible for liver dysfunction. Manifestations of porphyria include gastrointestinal, neurologic, and psychologic symptoms, cutaneous photosensitivity, pigmentation of the face (and later of the bones), and anemia with enlargement of the spleen. Large amounts of porphyrins are excreted in the urine and feces.

Treatment of this condition has been primarily symptomatic and varies in its effectiveness. Emphasis is on prevention of attacks by avoiding fasting and drugs that precipitate the symptoms. Photosensitivity may be controlled by avoiding exposure to light. Removal of the spleen is useful in some cases of the erythropoietic type of porphyria. Drug therapy includes the use of phenothiazines, chlorpromazine and promazine in particular. These drugs allay pain and nervousness and apparently allow a period of remission from symptoms. Meperidine hydrochloride (Demerol) may be given for pain and hydroxypheme (Hemetin) is given intravenously to compensate for genetic impairment of heme synthesis.

Patients with porphyria must not be given barbiturates, sulfonamides, alcohol, or chloroquine as these chemicals may precipitate or intensify attacks. It is recommended that persons with this disease carry with them at all times identification saying that they have porphyria so that in an emergency they will not be given medication that could precipitate an attack or even death.
acute intermittent porphyria (AIP) a hereditary, autosomal dominant, form of hepatic porphyria manifested by recurrent attacks of abdominal pain, gastrointestinal dysfunction, and neurologic disturbances, and by excessive amounts of δ-aminolevulinic acid and porphobilinogen in the urine; it is due to an abnormality of pyrrole metabolism. Called also intermittent acute porphyria.
congenital erythropoietic porphyria (CEP) a form of erythropoietic porphyria, with cutaneous photosensitivity leading to mutilating lesions, hemolytic anemia, splenomegaly, excessive urinary excretion of uroporphyrin and coproporphyrin, and invariably erythrodontia and hypertrichosis. Called also Günther disease.
porphyria cuta´nea tar´da (PCT) the most common form of porphyria, characterized by cutaneous photosensitivity that causes scarring bullae, discoloration, growth of facial hair, and sometimes sclerodermatous thickenings and alopecia; it is frequently associated with alcohol abuse, liver disease, or hepatic siderosis. Urinary levels of uroporphyrin and coproporphyrin are increased. There are two main types: an autosomal dominant (or familial ) form in which activity of the affected enzyme is reduced to half normal in liver, erythrocytes, and fibroblasts; and a sporadic (but probably also familial) form in which the reduction is confined to the liver. Both types are believed to be heterozygous and clinical expression occurs in adulthood, precipitated by disease or environmental factors. A more severe homozygous form begins in childhood and is called hepatoerythropoietic porphyria.
erythropoietic porphyria porphyria in which excessive formation of porphyrin or its precursors occurs in bone marrow erythroblasts; the group includes congenital erythropoietic porphyria and erythropoietic protoporphyria.
hepatic porphyria porphyria in which the excess formation of porphyrin or its precursors is found in the liver; it includes acute intermittent porphyria, variegate porphyria, and hereditary coproporphyria.
hepatoerythropoietic porphyria (HEP) a severe homozygous form of porphyria cutanea tarda believed to result from an autosomal dominant defect in the same enzyme as is affected in porphyria cutanea tarda; it is clinically identical to that disease but onset is in early childhood and enzyme activity in liver, erythrocytes, and fibroblasts is virtually absent.
intermittent acute porphyria acute intermittent porphyria.
porphyria variega´ta (variegate porphyria (VP)) a hereditary, autosomal dominant, type of hepatic porphyria characterized by chronic cutaneous manifestations, notably extreme mechanical fragility of the skin, particularly areas exposed to the sunlight, and by episodes of abdominal pain and neuropathy. There is typically an excess of coproporphyrin and protoporphyrin in the bile and feces.

por·phyr·i·a

(pōr-fir'ē-ă),
A group of disorders involving heme biosynthesis, characterized by excessive excretion of porphyrins or their precursors; may be inherited or acquired, as from the effects of certain chemical agents (for example, hexachlorobenzene).

porphyria

(pôr-fîr′ē-ə)
n.
Any of several disorders of porphyrin metabolism, usually hereditary, characterized by the presence of large amounts of porphyrins in the blood and urine.

por·phyr′ic adj.

porphyria

Metabolic disease Any of a family of inborn errors of porphyrin metabolism–most commonly acute intermittent porphyria Clinical Confusion, nausea, acute abdominal pain, extreme sensitivity to sunlight resulting in skin lesions; it is acutely exacerbated by alcohol and medications Lab ↑ urinary excretion and circulating levels of porphyrins or precursors–eg, porphobilinogen, δ-aminolevulinic acid. See Acute intermittent porphyria, Congenital erythropoietic porphyria, Erythropoietic porphyria, Porphyria cutanea tarda, Variegate porphyria.

por·phyr·i·a

(pōr-fir'ē-ă)
A group of disorders involving heme biosynthesis, characterized by excessive excretion of porphyrins or their precursors; may be acquired, as from the effects of certain chemical agents (e.g., hexachlorobenzene), or inherited.

porphyria

Any of several inherited disorders in which substances called porphyrins accumulate in the body because of a deficiency of certain ENZYMES. Porphyrins are components formed in the course of the synthesis of HAEMOGLOBIN. The effects are numerous. There may be extreme sensitivity to sunlight, sweating, rapid heart rate, abdominal pain, vomiting, constipation, paralysis and other nervous system disturbances including psychotic disorders. In some cases the effects are mainly on the skin and include blistering, scarring and baldness, especially on exposure to light. Treatment is difficult and varies with the different types. Avoidance of sunlight is often important.

Porphyria

Any of a group of disturbances of porphyrin metabolism characterized by excess pophyrins (various biologically active compounds with a distinct structure) in the urine and by extreme sensitivity to light.

Patient discussion about porphyria

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