A set of rare disorders in which chemicals called porphyrins accumulate in tissues
As the body makes haemoglobin, the red pigment in blood, it produces chemicals called porphyrins. Normally, porphyrins are turned into haemoglobin, but in porphyria this change is blocked and they build up in the body. There are several forms of porphyria. Most forms are due to abnormal genes. The most common is inherited in an autosomal dominant manner (see Gene disorders). Some forms are associated with sunlight exposure, liver disease, excessive alcohol use, or AIDS (see HIV infection and AIDS). In susceptible people, porphyria may be a side effect of some drugs.
Each type of porphyria causes different symptoms. In some, the symptoms are persistent; in others, they are intermittent and triggered by sunlight, alcohol, or drugs. Symptoms may include:
Dark, purplish urine.
Rashes or blisters in areas that are exposed to sunlight.
Pain or weakness in the arms or legs.
Severe intermittent porphyria can cause psychiatric problems such as delusions.
Porphyria is diagnosed by testing blood, faeces, or urine for porphyrins. There is no cure, but avoiding triggers may reduce the frequency of attacks. In some forms, intravenous glucose may help to prevent attacks or limit their severity.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.