Acute intermittent porphyria is an INHERITED condition. It is passed on from generation to generation. This means that it may be passed on from parents to their children; there is a 50% chance that an affected parent will pass the affected gene to each of their children. Both boys and girls stand an equal chance of being affected.
The condition cannot be cured, however, most people with AIP will never have any problems. Attacks occur in about one in five patients, more often in females than males. The most common age for an attack is from the late teens to the early forties and attacks are extremely rare in children before puberty.
Symptoms and their severity will vary from patient to patient, and some people will be totally asymptomatic (without any symptoms) throughout their lives. Most people have only one or a few acute attacks; only a minority suffer repeated attacks, sometimes over several years. Although acute attacks can be very severe, nowadays they are rarely fatal and most people make a full recovery. However, everyone with AIP is at risk of acute attacks, therefore it is vital to take a few simple precautions to reduce the risk of attacks.
In AIP, only acute attacks occur – the skin is never affected.
For more information on acute intermittent porphyria, please see the acute porphyria FAQs.
Variegate Porphyria (VP)
Like AIP, variegate porphyria is an inherited condition. People with VP are prone to skin problems and to acute attacks. In variegate porphyria, the skin changes and attacks of acute porphyria do not always occur at the same time.
For more information on the acute symptoms, please see the acute porphyria FAQs, while for more detail on the skin aspects, please see our cutaneous pages.
Hereditary Coproporphyria (HCP)
Hereditary coproporphyria is also an inherited condition. People with HCP are prone to acute attacks, and can have skin problems during an acute attack.
For more detail on the acute symptoms, please see the acute porphyria FAQs, while for more detail on the skin aspects, please see our cutaneous pages.
Aminolevulinate dehydratase (ALAD) deficiency porphyria (ADP)
ALAD deficiency porphyria, also called plumboporphyria, is an extremely rare condition and in the few cases described is similar to AIP. Please see the above notes on AIP and the acute porphyria FAQs.
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Acute porphyria is a term that includes four similar inherited diseases: acute intermittent porphyria, variegate porphyria, hereditary coproporphyria, and ALAD deficiency porphyria. They are grouped together because acute attacks of porphyria occur in each one. These attacks are uncommon and are often difficult to diagnose. About 1 in 75,000 people suffer from them.
Acute intermittent porphyria is the commonest type. In this disease, only acute attacks occur and the skin is never affected. If you have variegate porphyria or hereditary coproporphyria, your skin may also be affected. In variegate porphyria, the skin changes and attacks of acute porphyria may not occur at the same time.
Acute attacks almost always start with severe pain which is usually in the abdomen but may also be felt in the back or thighs. Nausea, vomiting and constipation are common. Some people may become very confused during an acute attack and behave in ways that are unusual for them. They may later find it difficult to remember details of their illness. Convulsions and muscular weakness, which may lead to paralysis, are less common symptoms. Their pulse rate and blood pressure may increase but rarely to dangerous levels. An acute attack usually lasts for no longer than one or two weeks. If paralysis occurs, recovery is gradual but slow.
Acute attacks are often provoked by drugs, alcohol or hormonal changes, for example, those associated with the menstrual cycle. The most common age for an acute attack is from the late teens to the mid-thirties. They are extremely rare in children before puberty. Most people have only one or a few acute attacks; only a minority suffer repeated attacks, sometimes over several years. Although acute attacks can be very severe, particularly if precipitated by drugs or alcohol, nowadays they are rarely fatal.
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.
Each type of acute porphyria is the end result of an alteration in a hereditary particle of DNA known as a gene. This alteration is inherited so that each person with porphyria will often have a number of relatives who will also have inherited the altered gene. A different gene is altered in each type of acute porphyria. This means that when two or more people are affected in the same family they will have the same disease. A person newly diagnosed with porphyria will often have a number of relatives, both close and distant, 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 and in variegate porphyria and hereditary coproporphyria, skin disease.
The gene alteration responsible for each type of acute porphyria is passed down through families in what is called an autosomal dominant pattern. Genes, which contain the blueprint for all the components required by the body, usually occur in pairs. Sometimes a small error can occur in the copying of one of these genes resulting in a permanent gene alteration which is called a mutation. When a mutation in only one of the pair of genes causes a disease, as is the case in the acute porphyrias, it is called an autosomal dominant mutation. This altered gene (mutation) may then be inherited from parent to child and the risk of an affected person passing this gene onto any of his or her offspring is one chance in two. This risk is the same even if the affected person has never had any symptoms of porphyria. Thus the disease often appears to have skipped a generation.
Altogether there are eight main types of porphyria, including the four acute porphyrias described on this page. Most of the others affect only the skin. They are called porphyrias because they cause accumulation of chemicals called porphyrins (purple-red pigments named from the Greek for purple) or the simpler chemicals that are used up by the body to make porphyrins. When porphyrins accumulate in the skin, it becomes very sensitive to sunlight and this causes the skin symptoms of porphyria. Accumulation of the simpler chemicals in the liver leads to acute attacks of porphyria. Porphyrins are important in the body because they combine with iron to form haem, a red pigment which has the vital function of enabling the body’s cells to use oxygen. The acute porphyrias are metabolic disorders that affect biochemical processes. They do not cause blood disease or liver disease.
It is important for you to find out which type of porphyria you have because the inherited abnormality and symptoms are different in each one.
Not all people who inherit a gene mutation for one of the acute porphyrias will develop an acute attack. It is estimated that at least three-quarters of people who inherit an acute porphyria gene will never experience an acute attack of porphyria. In those who do become ill, it appears that additional factors are usually required for an attack to occur. Our knowledge of these factors is incomplete, but among the most important are a number of drugs, some of which are widely used, and alcohol. However acute attacks do occasionally occur in the absence of any identifiable provoking factor. Experience over many years has shown that if people who have inherited one of the acute porphyrias are careful to avoid certain drugs, alcohol and other known factors that may provoke an acute attack, their chance of becoming ill is much reduced.
For diagnosis of an attack of acute porphyria and identification of the type of porphyria, samples of urine, blood and stools (faeces) need to be carefully tested in a laboratory that has an expertise in porphyria. The tests measure the concentration of porphyrins and related chemicals which will be 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.
In a patient who is known to have inherited an acute porphyria, it may be difficult to decide whether an illness is an attack of acute porphyria or caused by something else. In this situation, urine and, sometimes, other tests can often help your doctor to decide whether you are suffering from an acute attack of porphyria or some other illness. It is important that people with porphyria do not attribute all their illnesses to porphyria. If they do, common but potentially serious conditions like appendicitis may be overlooked.
The best time to be tested for porphyria is at the earliest opportunity, provided a reliable test is available for use at that age. In practice, this means that families should be offered screening for acute porphyria as soon as possible after a relative has been found to have the condition, starting with the patient’s parents, brothers and sisters, and children. When one or other parent is already known to have an acute porphyria, their children should be tested as soon as practicable after birth. It is worth enquiring about this during pregnancy as your doctor will then be able to find out when your baby should be tested. In some cases, it is now possible to test baby at birth but it may be necessary to wait until your child is one year old or, occasionally, even older.
There are two man advantages of early diagnosis. First, 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. Second, if an acute attack does develop, your doctor will be able to make the diagnosis and start special treatment early. The symptoms of an attack of acute porphyria are not always easy to recognise and, if the condition is not already diagnosed, there is a risk that your doctor will use drugs that may make the attack worse or may even think that an operation is necessary.
For relatives who have not had an acute attack, and especially for children, urine testing is often unhelpful. For these people, a special test on blood, and sometimes urine or faeces as well, need to be carried out in a specialist reference laboratory. For some families, it is now becoming possible to use DNA tests to detect the gene mutation that causes porphyria. DNA tests are more accurate than other methods but are complicated and are not yet available for all families. Your doctor should be able to arrange specialist testing for you. If you live a long way from a specialist porphyria laboratory, the samples can easily be sent by post.
Many acute attacks are precipitated by controllable or avoidable factors such as drugs, alcohol, fasting (including dieting) or hormones.
Drugs: People with acute intermittent porphyria must take great care with medication, as many chemical agents are capable of inducing an acute attack. It is important ALWAYS to check the safety of any medicine or remedy. This includes prescription medicines as well as over-the-counter treatments, tonics and herbal remedies, some of which have been known to cause attacks. While many drugs are considered suspect, there are many other drugs available and good alternatives can almost always be found. For a list of safe drugs click here.
Some people with porphyria may occasionally need a drug, perhaps for a serious illness, that carries some risk of provoking an acute attack or which has been introduced so recently that there is little information about its effect on porphyria. In this situation, your doctor, after fully discussing and explaining the risks, may decide to prescribe the drug for you.
Even though acute attacks are very rare before puberty, it is safest for children if they also avoid all drugs that are not known to be safe in porphyria.
The response of people with porphyria to drugs that have been reported to produce acute attacks in others is unpredictable in that a reaction does not invariably follow in every case. When there is a reaction, it always takes the form of an acute attack, which develops within days of taking the provoking drug. Reactions such as dizziness, feeling faint, allergies or short-lived skin rashes, which may occur immediately or very soon after taking the drug are common after drugs and rarely have anything to do with porphyria.
Alcohol: While many doctors experienced in the care of those with acute porphyria strongly recommend absolute avoidance of alcohol, some people may find this recommendation difficult to follow. Experience has shown that people who have experienced an acute attack greatly reduce the risk of further attacks if they become teetotal for life. For those shown by testing to have inherited the gene responsible for one of the acute porphyrias but who have not experienced an acute attack, it is best that they avoid alcohol. However, it this proves impossible a reasonable compromise is to keep intake as low as practicable and, in particular, to avoid heavy red wines, brandy and other liqueurs.
Diet: Low calorie diets, such as those used to reduce weight, and prolonged periods with little food may provoke an acute attack. It is therefore important to keep to a normal diet with regular meals, eating enough to maintain a desirable body weight. People who have had an acute attack should obtain advice from a dietician about how this is best achieved for their particular circumstances. Enough should be eaten to maintain a normal body weight with 55- 60% of the total food energy intake coming from carbohydrate. At least three regular meals should be eaten each day; some people, particularly women with pre-menstrual problems, may find it easier to eat small meals every three hours rather than three normal sized meals.
Patients with severe porphyria, particularly those who have repeated attacks, may need special dietary advice from their doctor and a dietician. If you are overweight, you should consult your doctor about the sort of diet that will allow you to lose weight gradually but safely.
Warning jewellery: It is important to wear a wrist bracelet or neck pendant at all times to warn that you have porphyria. Such warning is particularly helpful in emergencies when you may not have an opportunity to explain that you have porphyria. Details can be obtained from the Medic Alert Foundation, 12 Bridge Wharf, 156 Caledonian Road, London, N1 9UU or at www.medicalert.co.uk.
Anaesthetics and surgical operations: You must tell your surgeon and anaesthetist in advance that you have porphyria. A special anaesthetic that is safe in porphyria will be needed.
The dentist: You should tell your dentist that you have an acute porphyria. Dentists often use local anaesthetic agents and the safety of at least one of these has been questioned in the past.
Immunisations: All vaccines licensed for human uses are safe to administer to people who have an acute porphyria.
Women are at least three times more likely than men to experience an acute attack, due mostly to female hormones, particularly progesterone. This hormone is found in the combined oral contraceptive (the pill), as well as in hormone replacement therapy (HRT) which is frequently prescribed for post- menopausal women. Oral contraceptive and HRT preparations containing progesterone or related compounds (progesterones) should be avoided, if at all possible, by women with acute porphyria. Injectable and implantable long-term hormone preparations are very dangerous and must always be avoided.
In special circumstances, where the risk is low and the benefits high, your doctor may consider, after discussion with you, that the use of progesterone-containing preparations, particularly in replacement doses given through the skin from patches, is justified.
Pre-menstrual symptoms: In some women, attacks are clearly related to the pre-menstrual phase of the menstrual cycle and your doctor may need to consider a number of treatment options such as using special hormones to suppress your periods for 1-2 years. If you do need this sort of treatment, it needs to be done under close supervision by a doctor and will need regular monitoring.
Pregnancy: Though nearly all pregnancies are uneventful, there is a small increased risk of having an acute attack during or after pregnancy. However, the chances and dangers of such an acute attack are much diminished if porphyria has been previously diagnosed. It is therefore very important for the doctors providing care during pregnancy to know that you have acute porphyria. For those who have experienced an acute attack severe enough to require hospital care, pregnancy is best delayed until at least 12 months after recovery from the acute episode.
Early recognition of an acute attack allows early treatment. The early symptoms which herald an acute attack are often easily recognised by those who have previously experienced an attack. When these symptoms are recognised, immediate increase in carbohydrate intake (sweet or starchy food and drinks) may help to reduce the severity and duration of the acute episode.
If symptoms are severe, or don’t settle within 24 hours, you should contact your doctor, as you may need to be admitted to hospital. This will allow for:
- Confirmation of the acute attack by measuring PBG in urine.
- Early start of specific treatment: for example, with haem arginate (Normosang).
- Treatment for the various symptoms accompanying the attack, such as drugs to relieve pain and nausea, or actions to maintain an adequate intake of calories.
Your doctor should contact the National Acute Porphyria Service (NAPS: 029 2074 7747) who will give advice about treatment and provide haem arginate if needed.
NAPS provides clinical advice and haem arginate where appropriate for patients having either one-off acute attacks or recurrent attacks of porphyria. There are three full NAPS centres and two associate centres: Kings College Hospital, London; Addenbrooke’s Hospital, Cambridge; University Hospital of Wales, Cardiff; Salford Royal Hospital, Salford; and St James University Hospital, Leeds.
Initially, your doctor would need to contact the emergency number at the University Hospital of Wales: 029 2074 7747. This 24/7 number should be used at all times for new patients, and out of working hours for existing NAPS patients.
Early recognition is more difficult for those people who have inherited an acute porphyria but who have never experienced an acute attack. As a consequence, there is often considerable apprehension about pains that usually turn out to be due to causes other than acute porphyria. It must be noted that people with porphyria commonly experience abdominal discomfort, just like those who do not have the condition, and a doctor will need to consider other medical conditions which may cause abdominal pain. These conditions include a range of bowel disturbances, urinary infections and sometimes other urgent medical problems such as appendicitis. In this situation, the diagnosis of acute porphyria can usually be established or excluded by testing the urine for porphobilinogen (PBG), one of the precursors of porphyrins.
For people who require hospital admission, intravenous haem arginate, which helps to overcome the relative deficiency of haem in the liver and which takes away the body’s desire to increase the supply of the chemicals needed for haem production, may need to be given.
Other treatments are likely to include the use of drugs to relieve pain and nausea and to provide sedation. It is also important to maintain an adequate intake of calories and this may require feeding intravenously or through a naso-gastric tube.
The skin is never affected in acute intermittent porphyria. Skin problems occur in 10-20% of adults who have inherited the gene for variegate porphyria and are often their only symptom. Areas of skin exposed to sunlight, particularly the backs of the hands, face and legs, become fragile, break easily and form blisters. Broken areas may become infected, be slow to heal and leave small scars.
If you have skin problems, you should look after your skin carefully. Avoid direct sunlight as much as possible, even sunlight that passes through window glass in your home or car. Protect your skin from sunlight by wearing light cotton gloves, long sleeves and a hat when you go out. Not everyone will find this necessary or acceptable; adjust your clothing as it suits you. Ordinary sunscreen ointments are not effective. The only ones that may help are the thick, opaque preparations with high protection factors (often containing titanium oxide) that block both UVA and UVB light. Use silicone barrier cream and rubber gloves when working in the kitchen or elsewhere. Keep any broken or blistered skin clean by washing with water and a mild soap; avoid strong antiseptics.
Identical skin problems may occur in hereditary coproporphyria, but usually only during an acute attack of porphyria and are rarely persistent.
It should never be forgotten that most people found to have an acute porphyria are able to lead a normal healthy life. All that is needed is to take a few simple measures to decrease the risk of illness that are described on this site. Even the few who do become ill usually make a complete recovery and have no more than one or two acute attacks in early adult life. As one grows older, the risk of an acute attack decreases, particularly after the age of forty, but it never completely disappears.
Information provided on this site was written by Professor G.H. Elder (Department of Medical Biochemistry) and Dr D. Ravine (Department of Medical Genetics), University Hospital of Wales, Cardiff CF14 4XN. The authors thank patients with porphyria and their relatives, colleagues with an interest in the porphyrias and Dr R.J. Hift, The Lenon Porphyria Information Centre, University of Cape Town, for helpful comments.