What you should know about acute intermittent porphyria
Acute intermittent porphyria, also known as AIP is a disorder that affects the production of heme. This hereditary condition develops due to low levels of an enzyme, porphobilinogen deaminase (PBGD) which is also referred to as hydroxymethylbilane synthase. While low levels of the enzyme do not necessarily trigger AIP symptoms, other factors such as drugs, hormones and dietary changes may set off symptoms. Ordinarily, most people with the condition never experience full-blown AIP, however, symptomatic individuals usually present with nausea and abdominal pain.
AIP belongs to conditions known as porphyrias. These disorders are characterized by high levels of porphyrins and porphyrin precursors due to lack of certain enzymes that are essential for the making of heme, a component of hemoglobin and other hemoproteins found in cells. Normally, there are 8 enzymes involved in the production of making heme and not less than 7 major forms of poryphyria. People with AIP experience slightly different symptoms depending on the form of porphyria. It is important to note that people with one type of the condition do not develop any other type of poryphyria.
Primarily, porphyrias are classified into two broad categories: erythropoietic and hepatic. Erythropoietic types of the condition originate from bone marrow while hepatic types originate from the liver. Porphyrias presenting via the skin are known as cutaneous porphrias while acute porphyiras describe types of the condition accompanied by neurological complications as well as pain. Most forms of the disorder occur due to inherited problems of metabolism, this includes AIP, a hepatic form of poryphyria.
Symptoms of Acute intermittent porphyria:
Acute intermittent porphyria can present with a wide range of symptoms that may involve various organs in the body. The severity of attack usually varies from one person to another. In some instances when the condition is not properly diagnosed and treated, AIP can cause life-threatening problems. To complicate the situation further, the wide range of symptoms which vary from person to person may make diagnosing the condition even more difficult.
Brief symptoms of Acute intermittent porphyria:
- Rapid Heart Rate
- Severe Abdominal Pain
- Nausea & Vomiting
- Emotional Changes
- Muscle Weakness
- Many Inaccurate Diagnoses
Symptoms associated with the disorder usually develop over several hours or days. Most individuals recover from attacks within days, however, if an acute attack is not properly diagnosed and treated, recovery can take longer. Once the person has recovery, the affected individual does not present with symptoms in between attacks.
People who develop AIP symptoms usually experience these symptoms after puberty. Attacks mostly start in the 20s or 30s but can occur at puberty. This is linked to hormonal upheavals that occur at age. However, other factors such as low caloric intake, use of recreational drugs, travel and stress are also known to trigger AIP symptoms.
Normally, nausea and abdominal pain are the first signs of trouble in people developing acute intermittent porphyria . The pain is usually severe and often described as cramping, steady and widespread. Pain may also occur in the low back, neck and buttocks. Other symptoms include:
- Urinary tract problems such as incontinence and urinary retention.
- Psychiatric problems such as hysteria, insomnia delirium and anxiety.
Neurological complications such as paralysis and muscle weakness. Peripheral neuropathy is characterized by burning sensation or tingling which begin in the feet or arms. With time, the affected person develop muscle weakness in the leg which may affect the trunk of the body and arms. Eventually, the weakness may cause partial paralysis. In rare circumstances, respiratory failure may occur due to paralysis of muscles in the respiratory system.
Gastrointestinal problems are quite common during an acute attack. They include vomiting, ileus or blocking of the small intestine, nausea and diarrhea and abdominal distention or swelling.
Causes of Acute intermittent porphyria
Acute intermittent porphyria is caused by several factors including environmental and genetic issues. Researchers have found that people with AIP have a mutation in the HMBS gene. Since genes give instructions for creating proteins, when a mutation occurs, the protein produced is likely to be inefficient, absent or faulty.
Majority of the people who have a mutation of the gene do not develop AIP symptoms. To develop full-blown AIP, triggers are required. These factors or triggers vary from person to person and may even change during the patient’s lifetime.
The HMBS mutation that makes people vulnerable to developing AIP is inherited as an autosomal dominant trait. Primarily, genetic disorders are determined by a combination of genes for a specific trait that is on chromosomes passed on to offspring by both parents.
Acute intermittent porphyria Diagnosis
Diagnosis of AIP is suspected in people who experience several abdominal pain and nausea without any physical explanation for these symptoms. To confirm the condition, molecular genetic testing of HMBS gene is conducted. Most of the time, the test is 98 percent accurate in diagnosing the disorder.
Acute intermittent porphyria Treatment
The goal of treating acute intermittent porphyria is to reduce heme synthesis and decrease the production of porphyrin precursors. Treatment usually requires the coordinated efforts of a team of specialists including neurologists, pediatricians, and hematologists to comprehensively and systematically develop patient’s treatment plan. Normally, if the attack is mild, high levels of glucose can treat and prevent heme synthesis.
During AIP attacks, pain can be quite severe and relieve is often achieved using narcotics. In addition, stool softeners and laxatives should be administered to manage constipation.
Treatment can also include beta-blockers to mitigate tachycardia and prevent arrhythmia. Vomiting and nausea, which are common symptoms of the condition can be treated using lorazepam or olanzapine. Additional treatment for patients experiencing attacks may include monitoring electrolyte and fluid balance as well as dietary counseling.
Ultimately, prognosis of acute intermittent porphyria is usually good as long as the condition is recognized early and treated before it causes severe nerve damage. Though most people who suffer from AIP recover after an attack, they may develop chronic pain and muscle problems from a severe attack may take months to resolve.