National Human Genome Research Institute
What is porphyria?
The porphyrias are a group of different diseases, each caused by a specific abnormality in the heme production process. Heme is a chemical compound that contains iron and gives blood its red color. The essential functions of heme depend on its ability to bind oxygen. Heme is incorporated into hemoglobin, a protein that enables red blood cells to carry oxygen from the lungs to all parts of the body. Heme also plays a role in the liver where it assists in breaking down chemicals (including some drugs and hormones) so that they are easily removed from the body.
Heme is produced in the bone marrow and liver through a complex process controlled by eight different enzymes. As this production process of heme progresses, several different intermediate compounds (heme precursors) are created and modified. If one of the essential enzymes in heme production is deficient, certain precursors may accumulate in tissues (especially in the bone marrow or liver), appear in excess in the blood, and get excreted in the urine or stool. The specific precursors that accumulate depend on which enzyme is deficient. Porphyria results in a deficiency or inactivity of a specific enzyme in the heme production process, with resulting accumulation of heme precursors.
What are the signs and symptoms of porphyria?
The signs and symptoms of porphyria vary among types. Some types of porphyria (called cutaneous porphyria) cause the skin to become overly sensitive to sunlight. Areas of the skin exposed to the sun develop redness, blistering and often scarring.
The symptoms of other types of porphyria (called acute porphyrias) affect the nervous system. These symptoms include chest an abdominal pain, emotional and mental disorders, seizures and muscle weakness. These symptoms often appear quickly and last from days to weeks. Some porphyrias have a combination of acute symptoms and symptoms that affect the skin.
Environmental factors can trigger the signs and symptoms of porphyria. These include:
Alcohol Smoking Certain drugs, hormones Exposure to sunlight Stress Dieting and fasting How is porphyria diagnosed?
Porphyria is diagnosed through blood, urine, and stool tests, especially at or near the time of symptoms. Diagnosis may be difficult because the range of symptoms is common to many disorders and interpretation of the tests may be complex. A large number of tests are available, however, but results among laboratories are not always reliable.
How is porphyria treated?
Each form of porphyria is treated differently. Treatment may involve treating with heme, giving medicines to relieve the symptoms, or drawing blood. People who have severe attacks may need to be hospitalized