Acute Porphyrias

Porphyrias are a group of eight metabolic disorders characterized by defects in heme biosynthesis. Porphyrias are classified into two major categories: 1) the acute or inducible porphyrias and 2) the chronic cutaneous porphyrias. The acute hepatic porphyrias are further classified into acute intermittent porphyria (AIP), hereditary coproporphyria, variegate porphyria, and porphyria due to severe deficiency of delta-aminolevulinic acid (ALA) dehydratase (ALADP).

AIP is the most common, and ALADP is the least common acute porphyria. The clinical presentations of acute porphyrias are nonspecific. There are no pathognomonic signs or symptoms. The most frequent presenting symptom is abdominal pain, but pain in the chest, back, or lower extremities may also occur. Hyponatremia is the most common electrolyte abnormality during acute attacks, and hypomagnesemia is also common. Both are risk factors for development of seizures, which occur in ∼ 20-30% of acute attacks.

Once suspected, the diagnosis of porphyria can be rapidly established by checking random urinary porphobilinogen. Initial management of acute porphyria includes discontinuation of all potentially harmful drugs and management of symptoms. Acute attacks should be treated emergently with intravenous heme and glucose to avoid considerable morbidity and mortality. Acute attacks last a few days, and the majority of patients are asymptomatic between attacks. Prognosis is good if the condition is recognized early and treated aggressively.