Porphyria: symptoms, types, triggers and diagnosis

Symptoms depend on the type. The British Porphyria Association explains that when porphyrins accumulate in the skin, it becomes very sensitive to sunlight, which causes the skin symptoms. Accumulation of the simpler chemicals (ALA and PBG) in the liver leads to acute attacks that damage nerves.

Severity varies dramatically in all types, and it says the more knowledgeable a person is about their condition, the more likely they are to stay well.

The British Porphyria Association says acute attacks almost always start with severe pain, usually in the abdomen but also felt in the back or thighs. Nausea, vomiting and constipation are common. Some people become very confused and behave in ways that are unusual for them. Convulsions and muscular weakness, which may lead to paralysis, are less common.

An acute attack usually lasts no longer than one or two weeks. If paralysis occurs, recovery is gradual but slow. It points out that people with porphyria commonly have abdominal discomfort like anyone else, and that other conditions such as appendicitis must not be overlooked, so not every illness is porphyria.

The porphyrias are caused by a build-up of porphyrins, purple-red pigments named from the Greek for purple, or the simpler chemicals the body uses to make them. Most are inherited and result from a faulty gene that leads to difficulty making haem, a constituent of many important proteins in the body and a component of haemoglobin.

To make haem, the body converts ALA and PBG into porphyrins through a pathway of steps carried out by enzymes. If one of those enzymes has a fault, the chemicals before the faulty step accumulate. The type of porphyria varies according to which enzyme is affected.

Most porphyrias are inherited. PCT is the exception: the British Association of Dermatologists says type 1 (sporadic) PCT, which is not inherited, accounts for 80% of cases, and type 2 (familial) PCT for 20%. Factors that make PCT worse include excessive alcohol, oestrogen therapy such as oral contraception or HRT, viral infections of the liver such as hepatitis C, and iron accumulation in the liver, sometimes due to haemochromatosis.

In acute porphyria, the British Porphyria Association lists triggers: numerous drugs (prescribed, over-the-counter or herbal), alcohol, fasting including dieting and gastric infections, hormones, infections and stressful situations. It says many drugs can induce an attack, so the safety of any medicine or remedy should always be checked.

It adds that women are at least three times more likely than men to have an acute attack, mostly due to female hormones, particularly progesterone. Attacks are very rare before puberty.

The British Porphyria Association says the first urgent test for an acute attack is urine porphobilinogen (PBG), which can usually be done in a local hospital. To identify the presence and type of porphyria, samples of urine, blood and stools need to be tested in a laboratory that specialises in porphyria. It stresses that tests should be done as soon as possible after the illness starts, as an accurate diagnosis may be difficult after recovery from an attack.

For PCT, the British Association of Dermatologists says it is diagnosed by measuring porphyrins in samples of blood, urine and faeces, each collected into a darkened container that excludes light. Other blood tests for liver function, glucose and iron may be done to look for associated conditions.

For an acute attack, the British Porphyria Association says early recognition allows early treatment. An immediate increase in carbohydrate intake (sweet or starchy food and drinks) may help reduce the severity of symptoms. If symptoms are severe, or do not settle within 24 hours, you should contact your doctor, as you may need to be admitted to hospital.

In hospital, treatment can include confirming the attack with urine PBG, early specific treatment with intravenous haem arginate, and treatment for symptoms such as pain and nausea, with attention to calorie intake. The National Acute Porphyria Service gives clinical advice and provides haem arginate where appropriate, and a doctor should contact it for advice.

For PCT, the British Association of Dermatologists says that although the underlying cause cannot be cured, the symptoms can be controlled. Treatment can include removing a unit of blood at regular intervals to lower iron levels, or low-dose hydroxychloroquine, alongside avoiding sunlight, alcohol and the combined contraceptive pill. For EPP, the British Porphyria Association says there is no easy treatment and it is mostly a matter of avoiding bright light.

Medicines: people with acute porphyria must take great care. The UK Porphyria Medicines Information Service compiles a list of safe drugs, and the British Porphyria Association advises that drugs not on the list should only be taken after expert advice. It says to tell your surgeon, anaesthetist and dentist that you have porphyria, so that safe anaesthetics and other medicines are used.

Alcohol and diet: it says alcohol is a common trigger, especially binge drinking, and that people who have had an attack greatly reduce the risk of further attacks if they stop drinking. Low calorie diets or long periods with little food may provoke an attack, so a normal diet with regular meals is recommended.

Pregnancy: it says nearly all pregnancies are uneventful, but there is a small increased risk of an acute attack during or after pregnancy, so doctors providing pregnancy care need to know you have acute porphyria. Women with acute porphyria should avoid oral contraceptives and HRT containing progesterone or progestogens if possible, and the copper or Mirena coils are considered safe.

Skin porphyrias: people with skin porphyrias do not need to follow the safe drugs list used by those with acute porphyrias, but should avoid sunlight as much as possible. It notes that light reflected off water, sand or snow, or passing through window glass, can cause symptoms in EPP.

A suspected acute attack needs prompt medical assessment. The British Porphyria Association says severe symptoms, or symptoms that do not settle within 24 hours, should be reported to a doctor because hospital admission may be needed. Very severe pain, repeated vomiting, confusion, convulsions or new muscle weakness should be treated as an emergency: call 999 or go to A&E, and tell staff that you have porphyria or may have it.

For skin symptoms, see a GP if you notice blistering or painful reactions after light exposure. If you already have a diagnosis, carry your medical information and a list of safe medicines, and tell any clinician treating you.

Porphyria is rare, so specialist support is concentrated in a few centres. The British Porphyria Association says the National Acute Porphyria Service has full and associate centres around the UK, and that clinicians treating a person in hospital can contact it for advice on treatment, haem arginate and safe prescribing. Routine care and referrals start with your GP.

Some people choose to see a private physician or dermatologist for symptoms or tests. Porphyria tests must be handled in specialist laboratories with the sample protected from light, so it is worth asking how the sample will be handled and sharing results with your NHS GP.