Acute Intermittent Porphyria Clinical Presentation

Updated: Jan 13, 2023
  • Author: Thomas G DeLoughery, MD; Chief Editor: Emmanuel C Besa, MD  more...
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The onset of attacks in individuals with acute intermittent porphyria (AIP) typically occurs at age 18-40 years. Attacks before puberty or after age 40 years may be triggered by a major provocation, such as new use of phenobarbital or estrogens. Attacks generally last for 3 to 7 days. 

The usual sequence of events in attacks of AIP is as follows:

  1. Abdominal pain
  2. Psychiatric symptoms
  3. Peripheral neuropathies

The abdominal pain often is epigastric and colicky in nature; it is severe and lasts for several days. Constipation or vomiting may also occur. Severe abdominal pain of short (< 1 d) duration or chronic abdominal pain is unusual. Diffuse pain, especially in the upper body, may also be observed.

Patients can have a wide variety of psychiatric symptoms. Depression is very common. Usually, patients have concurrent neurologic or abdominal symptoms. A Swedish study documented a fourfold increased risk of schizophrenia or bipolar disorder in patients with AIP. The risk in relatives of individuals with AIP was increased twofold, suggesting common genetic influences with these diseases. [12]

Peripheral neuropathies tend to be predominantly motor and can mimic Guillain-Barré syndrome. The weakness usually starts in the lower limbs and ascends, but neuropathies can be observed in any nerve distribution. Autonomic neuropathies that produce hypertension and tachycardia may also occur.

Central nervous system signs may include the following:

  • Seizures
  • Delirium
  • Cortical blindness
  • Coma

Skin manifestations are not a feature of AIP attacks, as they are of other forms of porphyria (eg, porphyria cutanea tarda). 

Between attacks, patients may be completely free of symptoms. However, emerging evidence points to chronic manifestations as a feature in 20-64% of patients with AIP. In a study of patients with frequent attacks of AIP, 18 of the 19 patients interviewed also described chronic symptoms, which were often disabling. Key chronic symptoms were pain, nausea, fatigue, and features of neuropathy (eg, tingling and numbness). [13]


Physical Examination

Vital signs during attacks of acute intermittent porphyria (AIP) include the following:

  • From 30-80% of patients have tachycardia
  • Fever can be present in some patients
  • Hypertension is observed in half of patients and may persist between attacks

Neurological manifestations are as follows:

  • Usually, the neuropathy is a motor neuropathy that is more predominant in the lower limbs
  • Areflexia often is present on examination
  • Any nerve can be involved, and cranial neuropathies also are observed
  • Patients also may have cortical blindness

Despite the intense pain, the findings on abdominal examination often are nonspecific. Skin examination is noncontributory; unlike many other porphyrias, AIP is not associated with a skin rash.