Acute Porphyria

What is acute porphyria? The porphyrias are a group of inherited disorders of haem biosynthesis. Deficiencies occur in specific enzymes leading to the accumulation of different porphyrins and porphyrin precursors. Acute hepatic porphyria is a term that includes three similar inherited diseases: acute intermittent porphyria, variegate pophyria and hereditary coproporphyria where acute attacks of porphyria can occur in all. These attacks are uncommon, associated with a non specific clinical presentation, which make the diagnosis difficult. In most European countries, about 1 in 75 000 people suffer from them. The enzyme defect is not complete and only becomes apparent when demand for hepatic haem is increased by drugs, hormones, stress, infection or strict diet. Attacks are exceptional before puberty and the majority of carriers will never show signs of the condition (>90 % of cases remain latent). In 80% of cases, attacks of acute porphyria concern women aged between 15 and 45 years. What are the symptoms? The presenting symptom is most commonly intense and durable abdominal pain which may also be felt in the back or thighs. Other frequent symptoms include nausea, vomiting, constipation and to a lesser degree hypertension, tachycardia, sweating, pallor and pyrexia. An acute attack usually lasts for no longer than one or two weeks, but may be life threatening because of severe neurological complications like motor paralysis. If paralysis occurs, recovery is gradual but slow. Most people who have one or a few attacks of acute porphyria make a full recovery. They are then able to lead a normal life except that they need to take a few simple precautions to reduce the risk of having another attack. How to reduce the risk of having an acute attack? Acute attacks are often provoked by avoidable factors such as certain drugs, alcohol, hormonal changes, infections or fasting (dieting). It is essential for all carriers to ALWAYS check the safety of any medicine or remedy. This includes prescription medicines as well as over-the-counter treatments. Information on drugs considered safe or unsafe can be obtained on the European Porphyria Initiative website or by contacting Orphan Europe. People found to have an acute porphyria can also decrease the risk of illness by keeping to a normal diet with regular meals and avoiding alcohol and tobacco. How is it diagnosed? A good clue to a positive diagnosis is discoloration of the urine. During an attack the urine becomes a dark reddish brown after about 10-30 minutes. However, the absence of urine discoloration does not eliminate a possible diagnosis. Confirmation of diagnosis is done by measuring the urine concentration of porphyrins and their precursors ALA and PBG which will be very high in a patient with an attack of acute porphyria. It is important that these tests are carried out as soon as possible after the start of the illness as an accurate diagnosis may be difficult to establish after recovery from an acute attack, especially after several months or years. Should the rest of the family be screened for acute porphyria? A person diagnosed with porphyria will often have a number of relatives who will also have inherited the altered gene responsible for the type of acute porphyria in their family. Many of these relatives may not know that they have inherited an acute porphyria gene and that they are therefore at risk of developing an acute attack. An early diagnosis is important as those who are found to have inherited one of the acute porphyrias can be advised about how to reduce the risk of an acute attack. Also if an acute attack does develop, the physician will be able to make the diagnosis and start specific treatment early. Orphan Europe is able to provide every patient who has an established diagnosis of porphyria with a medical alert card. These personalized cards should be carried at all times. In the event of an emergency, clinicians will know to avoid potentially dangerous drugs. Treatment of an acute attack Withdraw any drugs or other potential provoking agents. Start appropriate supportive treatment using drugs that are safe in acute porphyria. Specific treatment should be started as soon as the diagnosis is established unless the attack is mild and clearly resolving. Two treatments are available: intravenous human hemin (Normosang®) and carbohydrate loading.