Porphyria is a group of rare disorders that usually have a genetic cause. The body uses the natural chemical porphyrin to produce heme, an essential part of red blood cells. Porphyria occurs when the body is unable to efficiently use porphyrin to make heme, leaving the chemical to accumulate. Eight disorders comprise the group, and diagnosis depends on which of the eight enzymes required to make heme is lacking.
Poryphyria is divided into two groups, which are further subdivided. Acute porphyria consists of four separate conditions: variegate porphyria (VP), hereditary coproporphyria (HCP), acute intermittent porphyria (AIP), and delta-aminolevulinic acid dehydratase (ALAD) porphyria (ADP). All types are very rare. Of people with genetic mutations that cause acute porphyrias, only ten to 20% have an acute attack. Most remain asymptomatic throughout their life.
Acute porphyrias come on quickly, last anywhere from a few days to weeks, and improve slowly. The attacks can be severe and typically affect the nervous system. Symptoms include seizures, high blood pressure, breathing problems, anxiety, muscle pain or tingling, nausea, vomiting, constipation, diarrhea, and severe abdominal pain.
Cutaneous porphyrias do not affect the nervous system. Instead, they cause skin symptoms, usually as a result of sun exposure. There are several types of cutaneous porphyrias: porphyria cutanea tarda (PCT), erythropoietic protoporphyria (EPP), and x-linked protoporphyria (XLP). Congenital erythropoietic porphyria (CEP) and hepatoerythropoietic porphyria (HEP) occur in childhood.
Symptoms of cutaneous porphyrias occur as a result of sun exposure, though they can also be triggered by sensitivity to artificial light. Their symptoms include redness, swelling, thin skin with changes in pigmentation, excessive hair growth in exposed areas, and blisters on the face, arms, and hands. People with this type of porphyria may also have itchy skin and dark brown urine.
Most porphyrias are genetic. Scientists identified the genes for each of the enzymes used to make heme and, through testing, can recognize which is abnormal. Some types of porphyrias only occur when the person inherits a mutated gene from each parent, while others require only a single inherited mutation. One type, porphyria cutanea tarda, is not genetic and stems from outside causes, including excess iron, smoking, alcohol use, HIV, hepatitis C, and estrogen use.
Although an individual cannot take measures to avoid genetic issues, other outside factors can trigger a porphyria attack in someone with the mutated gene. The factors increase the demand for heme production, causing porphyrins to build up quickly and include drug use, smoking, extreme dieting or fasting, stress, hormone supplements, and exposure to sunlight.
Doctors diagnose porphyria through a physical exam and discussion of symptoms. If the physician suspects porphyria, urine, stool, and blood tests can confirm because these samples will contain high levels of porphyrins. Once detected, the physician may order genetic testing to determine the specific type of porphyria.
Acute porphyrias are treated with heme or glucose loading. This procedure is done over a few days and requires either an infusion of heme or oral ingestion of a concentrated glucose solution. This approach decreases the production of porphyrin by the liver, warding off an attack before it occurs. If symptoms are severe, an individual could develop significant liver damage and the physician may recommend a liver transplant.
The best way to treat cutaneous porphyrias is to prevent them. People who know they are at risk can avoid sun exposure and receive regular blood draws to reduce the heme iron in the body. Some medications also reduce the production of porphyrins. People with erythropoietic protoporphyria may require a bone marrow transplant to successfully cure the disease, and any type of cutaneous porphyria can require a liver transplant if the condition becomes severe.
People with some types of acute porphyria can keep it under control by eating a diet containing a high percentage of carbohydrates; low-carb diets and fasting can lead to an attack. Anyone undergoing therapeutic blood draws should make sure they drink enough fluids before each procedure. Some people may also require vitamin supplements.
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