Porphyria
Porphyria is the name given to a number of different disorders which are usually inherited, and involve defective metabolism of the porphyrin ring, which is involved with the haem in the binding of Iron in haemoglobin - the red pigment in our blood cells which is responsible for the transport of oxygen and carbon dioxide in the bloodstream. Its defective breakdown means that the porphyrin gets deposited in skin or in other tissues such as nerves, and excreted in excessive amounts in the urine. There are a number of different forms of this disorder, the commonest being acute intermittent porphyria, where attacks of abdominal pain and neurological disturbance together with fast heart rate and high blood pressure can be precipitated by the ingestion of certain medicines or alcohol. In cutaneous porphyrias the porphyrin gets deposited in the skin where it becomes photosensitising, causing blistering lesions when exposed to sunlight. There is no treatment of porphyrias apart from avoiding precipitating agents and treating the complications. During acute attacks increased carbohydrate together with agents that reduce porphyrin synthesis such as haematin given intravenously may help.
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