Use

This test is useful for the confirmation of a diagnosis of acute intermittent porphyria (AIP). AIP is an inherited disorder resulting from enzyme defects in the heme biosynthetic pathway, specifically diminished erythrocyte activity of porphobilinogen deaminase (PBGD), also known as uroporphyrinogen I synthase or hydroxymethylbilane synthase (HMBS). Onset typically occurs during puberty or later, with symptoms such as severe abdominal pain, peripheral neuropathy, and psychiatric issues. Accurate and timely diagnosis is crucial as acute episodes can be fatal and the condition is inherited in an autosomal dominant manner. More than 80% of individuals with a deficiency variant in the HMBS gene remain asymptomatic. Biochemical diagnosis is best made by increased urinary excretion of porphobilinogen and enzyme activity measurement in erythrocytes.