What Is Acute Intermittent Porphyria?

Acute intermittent porphyria (AIP) is a rare disease that is caused by a problem with how blood cells are made. It’s one type of a larger group of rare conditions called porphyrias.

Porphyrias can affect the skin and nervous system. The conditions develop when a gene mutation interrupts the chemical process that is responsible for creating blood cells. When the process is disrupted, a chemical that is meant to be used to create hemoglobin builds up in your blood and tissues.

This article will cover how acute intermittent porphyria develops, how it is different from other forms of porphyria, and what to expect if you have the condition.

Symptoms

The symptoms of AIP can vary, but the hallmark of this type of porphyria is neurological symptoms like:

• Abdominal pain or swelling
• Pain the arms, legs, and back
• Constipation
• Nausea
• Vomiting
• Anxiety
• Confusion
• Numbness or tingling
• Muscle weakness
• Breathing problems
• Low sodium
• Increased heart rate
• High blood pressure
• Irregular heart rhythms
• Hallucinations
• Seizures
• Urinary retention
• Urinary incontinence
• Changes in the color of your urine

The difference between AIP and other acute porphyrias is how often the symptoms appear and how long they last.

AIP occurs as a limited episode or attack that can last from hours to days. However, without proper diagnosis and treatment, the episodes can last a week or months.

Once you recover from an attack, you are typically free from symptoms. However, recovery from one attack does not mean that the condition is resolved. Some people with AIP—3% to 5%—have recurring attacks (often at least four each year) for several years.

Causes

While some forms of porphyria are acquired, most are the result of a genetic mutation that is passed through families. Each form of porphyria is associated with a different gene mutation. For AIP, the affected gene is one that makes an enzyme called hydroxymethylbilane synthase (HMBS).

Not everyone with AIP has symptoms. In most cases, the symptoms of the condition do not develop unless they are triggered by things like:

• Certain drugs or medications
• Alcohol consumption
• Fasting or dieting
• Stress
• Infections
• Hormonal changes

When AIP is triggered, not only are porphyrin precursors not converted into heme as they should be, but your body also starts overproducing the chemicals. The overproduction increases how much porphyrin builds up in your body.

Diagnosis

Getting a diagnosis of AIP can be difficult because of how quickly each attack subsides and how infrequently they can develop in the first place. Additionally, AIP symptoms can be caused by many other neurological conditions.

If you know you have a family history of porphyria, diagnosing the condition will probably be a quicker process. If no one else in your family has porphyria, your doctor will talk to you about your symptoms and do tests that can eliminate more common conditions that could explain your symptoms.

If your doctor decides to test you for porphyria, you will be asked to provide samples of blood, urine, or stool for testing. A lab will measure the porphyrin levels in your samples.

High concentrations of these chemicals can lead to a porphyria diagnosis. Genetic testing will come next to help your doctor figure out the specific type of porphyria that you have.

Treatment

Acute attacks of AIP are usually treated with an infusion of heme, which is created by separating heme cells from donated blood. For the best results, these infusions should be given as soon as possible after the start of a severe or moderate attack.

Other treatments can include glucose and fluid infusions. It’s also important to address the other symptoms of AIP, like a racing heart (tachycardia) and muscle weakness, because they can lead to complications.

Prognosis

There is no cure for any form of porphyria, but treatments can relieve your symptoms and help prevent complications. While treatments for AIP are usually very effective, a delay in diagnosis or treatment can be fatal.

When fatal, the primary cause of death in people with AIP is:

• Misdiagnosis that led to a delay in treatment or being treated with medications that made the condition worse
• Prolonged mechanical ventilation because of respiratory muscle weakness
• Cardiac arrest from abnormal heart rhythms

Coping

Identifying the things that trigger an AIP attack will be a big part of learning to cope with AIP. For example, you might need to make some lifestyle changes and have regular heme infusions.

While it can be overwhelming to hear that you have a rare disease, you don’t have to go through the process of learning to live with it alone. Several organizations offer resources and support that are specific to AIP, including:

• National Organization for Rare Disorders
• American Porphyria Foundation
• British Porphyria Association
• European Porphyria Network
• Porphyria Association Inc. (Australia)
  

Summary

Acute intermittent porphyria (AIP) is one of a group of rare conditions that can affect the nervous system and skin. While management of the condition has improved greatly over the last few decades, it can still be fatal if it’s not diagnosed and treated correctly and quickly.

A Word From Verywell

It can be hard to learn to live with a rare disorder like porphyria, and getting the right diagnosis and treatment for a rare condition can be even more difficult. However, you should rest assured that AIP is a manageable condition when it’s diagnosed and treated early.

If you have family members with some form of porphyria, you may want to talk to your doctor about genetic testing for AIP—especially if you have experienced symptoms.