Acute intermittent porphyria with seizures. Anticonvulsant medication-induced metabolic changes.

Abstract

ACUTE intermittent porphyria (AIP) is a rare inborn error of metabolism characterized chemically by an excessive excretion of the porphyrin precursors δ-aminolevulinic acid (ALA) and porphobilinogen (PBG). It is transmitted as an autosomal dominant but rarely do the clinical symptoms of abdominal pain and neurologic dysfunction manifest themselves until after puberty. The site of the metabolic lesion is unknown but numerous hypotheses exist. 1 Some of these include enhanced activity of ALA synthetase, the rate-controlling enzyme in porphyrin biosynthesis, 2,3 impairment of terminal oxidation, 4 a defect in glycine metabolism, 5 and many others. An experimental form of the disease can be induced in animals by a wide variety of drugs, including especially the barbiturates. 6 This report concerns a 7-year-old girl who, after three years' treatment with anticonvulsants, developed an acute neurologic illness. At this time the urine was found to contain elevated amounts of porphyrins and PBG. Subsequent