Acute intermittent porphyria (AIP) is a rare condition that causes an enzyme deficiency. This can cause a person to experience abdominal pain, nausea, vomiting, and seizures.

Porphyrias are rare conditions that mainly affect a person’s skin or nervous system. A person typically inherits these disorders. AIP causes a deficiency of the enzyme hydroxymethylbilane synthase (HMBS).

AIP is a type of porphyria that affects approximately 1 in 2,000 people.

This article explains what AIP is and outlines its symptoms, causes, risk factors, and more.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Heme is a compound present in the body that binds to iron. It plays a role in a number of bodily functions, such as:

  • oxygen transport
  • oxygen storage
  • oxygen metabolism
  • antioxidation
  • electron transport

The body uses a multi-step process to create heme. Each step of the process uses a different enzyme.

Porphyrias are a group of rare conditions that occur due to a deficiency in the enzymes that the body needs to create heme.

AIP is a common, severe form of porphyria. It occurs due to a deficiency of the enzyme HMBS.

This enzyme deficiency can then cause porphyrin precursors to accumulate in the body. Porphyrin precursors are substances that the body converts into heme. When these precursors build up in the body, they cause AIP symptoms.

Common symptoms of AIP include:

Medical professionals often categorize porphyrias into acute and cutaneous porphyrias. Acute porphyrias affect the nervous system, and cutaneous porphyrias affect the skin. AIP is a type of acute porphyria.

Medical professionals refer to the times when symptoms occur as “attacks.” If a person experiences an attack and does not receive early treatment, the attack could become severe and may be life threatening. If a person experiences an acute AIP attack, they will likely require treatment in a hospital.

Symptoms of acute porphyria may be mild or severe. They can also last a few days or a few weeks.

Common symptoms of acute porphyrias include:

A person may develop mental changes, including:

People with AIP may experience nerve problems, such as:

They may also develop urinary symptoms, including:

Individuals with AIP have a mutation in the HMBS gene. Medical professionals associate this gene with the creation of the HMBS enzyme.

HMBS gene mutations can cause the body to develop an HMBS enzyme deficiency. Mutation of the HMBS gene causes approximately 50% of HMBC deficiencies.

However, in many cases, the gene mutation alone is not enough to cause a person to experience the symptoms of AIP. Often, the symptoms of AIP occur due to specific triggers. These triggers are additional factors that can cause the symptoms to develop.

Possible triggers of AIP in people with the HMBS gene mutation include:

AIP is more common in females than in males. It most commonly affects people ages 15–45 years old.

Certain factors can increase a person’s risk of acute AIP attacks. These include:

If a person is experiencing the symptoms of an AIP attack, they should contact a doctor. A doctor will often recommend they go to a hospital for treatment of their symptoms.

A doctor may also be able to recommend steps a person can take to help prevent a future AIP attack. These steps typically include:

  • avoiding medications that may be unsafe for people with AIP
  • eating a nutritious, balanced diet and avoiding fasting or extreme diets
  • avoiding smoking
  • avoiding heavy alcohol consumption
  • taking medications that can help reduce the number of future AIP attacks

A medical professional will treat an AIP attack with intravenous (IV) heme. This helps replenish the amount of heme in a person’s body, which reduces the accumulation of porphyrin precursors.

The reduced amount of these precursors in the body helps reduce a person’s symptoms. This treatment should begin as soon as possible and will typically last for around 4 days.

The only established cure for AIP is a liver transplant. This involves removing the liver and replacing it with a healthy liver from a donor. Many medical professionals only suggest a liver transplant as a treatment option for people experiencing severe and frequent AIP attacks and significantly reduced quality of life.

Complications of AIP include:

The following are some questions people frequently ask about AIP.

Is porphyria related to lupus?

Lupus is a chronic autoimmune disease that causes the immune system to attack healthy tissue. It can affect almost any organ in the body, and symptoms can differ from person to person.

Medical professionals believe there may be a link between porphyrias and lupus. However, it is rare for people to have both conditions at the same time.

What triggers AIP?

If a person has a specific gene mutation, certain things can trigger AIP. These triggers include:

  • hormonal changes associated with puberty
  • certain prescribed medications
  • certain recreational drugs
  • excess alcohol consumption
  • infection
  • dietary changes
  • fasting

AIP is a rare genetic condition that causes a deficiency of the HMBS enzyme. This deficiency causes a toxic precursor to accumulate in the body.

If a person has the genetic mutation that causes AIP, certain factors can trigger the condition’s symptoms. These triggers include hormonal changes, medications, and dietary changes.

Common symptoms of AIP include severe abdominal pain, constipation, a rapid heart rate, and increased blood pressure, among others.

A healthcare professional can treat an AIP attack with IV heme. The only possible cure for AIP is a liver transplant. However, this comes with risks of serious complications, so medical professionals only suggest this treatment if a person has severe AIP.