AIP
Acute Intermittent Porphyria
Acute Intermittent Porphyria (AIP)
Acute Intermittent Porphyria (AIP) is characterized by potentially life-threatening acute attacks.
Acute attacks usually include severe abdominal pain as the main symptom, and can also include weakness, nausea, vomiting, constipation, confusion, restlessness, hallucination, and seizures. There can be other symptoms as well. These attacks can be triggered by certain factors like medications (e.g. barbiturates, sulfonamide antibiotics, anti-seizure drugs, and oral contraceptives), alcohol, dieting, infections, and others. Some people with AIP have few attacks in their life-time, and others can have many attacks. Some women can develop acute attacks around their menstrual cycle.
Acute attacks are more common in women compared to men, and are rare in children. Most people present with symptoms after puberty, in their 20s-30s.
AIP is the most common of the Acute Hepatic Porphyrias (AHP) which all have similar symptoms and require biochemical or genetic testing to distinguish.
AIP is caused by changes in the HMBS gene, which controls the HMBS enzyme in the heme pathway. Without enough of this enzyme, there is a buildup of compounds called ALA and PBG. These compounds can lead to episodes called acute attacks. Most people (>90%) with changes in the HMBS gene never develop acute attacks.
Acute attacks can be triggered or worsened by a number of factors including:
Some medications
Alcohol and drugs
Dieting or fasting
Infections
Hormone fluctuations related to the menstrual cycle
Acute Attack Symptoms
Acute attacks can include a wide array of symptoms. Most AIP patients do not experience all symptoms.
Severe abdominal pain
Severe pain in the chest, back, arms and legs
Headaches
Nausea
Vomiting
Constipation and urinary retention
Muscle weakness, numbness or paralysis- often beginning in the shoulders and hips
Tachycardia (fast heart rate) and hypertension (high blood pressure)
Insomnia (difficulty sleeping)
Anxiety, depression
Confusion, hallucinations (affecting any of the five senses), paranoia, psychosis
Seizures
Hyponatremia (low salt) and hypomagnesemia (low magnesium)
Urine may darken or redden when exposed to light
Some AIP patients also experience chronic symptoms. These symptoms may be related to ongoing recovery, nerve damage from attacks or chronically high porphyrin precursors. Common chronic symptoms include: fatigue, muscle weakness, pain and trouble sleeping.
Chronic Symptoms
Acute Intermittent Porphyria (AIP) is diagnosed using biochemical testing, specifically testing for levels of PBG in urine. Genetic testing can confirm the type of porphyria and identify the specific gene variant, but is not enough to confirm an AIP diagnosis.
For more information on testing visit the Seeking a Diagnosis page.
Acute attacks often require hospitalization. Hospitalization allows administration of medication to manage pain, and ensures adequate fluids and nutrition if vomiting or too nauseated to eat.
Approved treatments for AIP include:
Panhematin is an FDA approved medication which can help decrease the severity and length of the attack, and is more effective the earlier it is received. Panhematin is administered as an infusion once a day for several days to treat an acute attack.
Givlaari is a new treatment for people who have frequent attacks to try and prevent them
In very severe cases liver transplant may be considered.
Pain Management
Acute attacks can be very severe requiring strong pain medications to help relieve the pain. These are generally given during hospitalization. Some people may develop chronic symptoms including chronic pain and should consult with a pain specialist.
Medications
Avoiding known triggers of acute attacks is important. There is an online drug database to check which medications may be unsafe for people with AIP.
Nutrition
People with AIP should avoid dieting or fasting, and maintain a healthy, balanced diet.
People with AIP, even those who do not have acute attacks, should see a porphyria specialist at least once a year for regular follow-up to monitor for the long-term complications. People who have frequent attacks may need to see a specialist more regularly.
Long-term, patients with AIP may have an increased risk of developing high blood pressure, chronic kidney disease and kidney failure, and also have an increased risk of developing liver cancer, called hepatocellular carcinoma.
AIP is an autosomal dominant condition. Autosomal means that the defect is not on the chromosomes that determine sex, and dominant means that you only need to inherit one changed gene to have the disease.
All AIP patients have one changed copy of the HMBS gene inherited from one parent and one normal copy from the other parent. Each child of a parent with AIP will have a 50% chance of inheriting the changed copy and 50% chance of inheriting the normal copy from that parent.
There is an extremely rare form of AIP that can happen when someone has two changed copies of the HMBS gene. This form is called “Homozygous AIP” and usually presents in early childhood with serious neurological symptoms like seizures.
More AIP Resources
Check out our Spotlight Porphyria blog for answers to common (and uncommon) AIP questions, updates on the latest research and more!
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