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Recognizing Acute
Intermittent Porphyria (AIP)
Acute intermittent porphyria (AIP) is a rare inherited disease caused by a partial deficiency of the enzyme porphobilinogen (PBG) deaminase in the heme biosynthetic pathway. PBG deficiency disrupts normal heme production, leading to overproduction of porphyrin precursors that cause diverse pathologic changes.1 The most common symptom is severe abdominal pain.2
Symptoms
Recognize the signs and symptoms of AIP
There is wide variability in the clinical features of an acute AIP attack.3 Gastrointestinal, urinary, neurologic, and cardiovascular symptoms commonly occur.2
ABDOMINAL PAIN, which is neuropathic in origin, is the most common AIP symptom.2
An accurate, timely diagnosis of AIP is critical
Delayed treatment can result in serious consequences, including neurologic damage or even death. AIP should be considered in any patient with symptoms that are prominent for AIP, particularly abdominal pain, when initial clinical evaluation does not support another cause.2
Incidence of Common AIP Symptoms*2

*Based on several series of patients with symptomatic AIP.
Dark or reddish urine is also a common symptom of AIP.2
Precipitating Factors
Patient characteristics and precipitating factors
In differentiating AIP from other conditions with these common symptoms, certain patient characteristics and possible precipitating factors should heighten the suspicion of AIP.
Acute AIP attacks are most common in women of reproductive age (most commonly in their 30s) during the luteal phase of their menstrual cycles.2-4
Exacerbating factors in AIP attacks
The enzyme deficiency of AIP predisposes patients to certain triggering factors that may lead to abnormally high accumulations of neurotoxic porphyrin precursors, which can precipitate an acute neurovisceral attack.7 Attacks are usually due to the additive effects of several precipitating factors,2 including:
- Endogenous steroid hormones, particularly estrogen and progesterone4
- Use of certain prescription drugs, especially barbiturates, hydantoins, rifampin, and sulfonamides,4 and often newly prescribed drugs5
- Use of alcohol or illicit drugs such as amphetamines, cocaine, and derivatives3
- Fasting4 or crash dieting2
- Cigarette smoking2,3
- Metabolic stress induced by infections or surgery2
- Psychological stress2
Family History
Family history of AIP
An acute attack of AIP should be suspected in individuals experiencing symptoms consistent with AIP who also have a family history of the disorder. However, one third of patients have no family history of AIP.1,8
AIP is inherited in an autosomal dominant manner. The estimated prevalence of acute attacks and the estimated frequency of clinical pathogenic variants are low; as a result, AIP penetrance is approximately 1% of all heterozygotes.9
Review genetic testing information
Some individuals may have only one or a few attacks in their lifetimes. Others may have recurrent attacks throughout their lives.2,7,8
Potential Consequences
Possible serious consequences of not recognizing AIP
Individuals with undiagnosed or inappropriately treated AIP attacks may suffer serious, potentially fatal, consequences, including:2
- Peripheral neuropathy
- Paresis
- Respiratory and bulbar paralysis
- Hepatocellular carcinoma
- Chronic neuropathic pain
- Renal impairment
- Death resulting from cardiac arrhythmia or paralysis during an attack
AIP should be considered in any patient with symptoms that are prominent for AIP, particularly abdominal pain, when initial clinical evaluation does not support another cause.2


