Porphobilinogen (PBG), Quantitative, 24-Hour Urine

Urine (24-hour), frozen and protected from light

3 mL aliquot

1 mL aliquot (Note: This volume does not allow for repeat testing.)

Plastic 24-hour urine container with 30 mL of 30% glacial acetic acid (Labcorp No. 23301) (optional preservative, but required if ordered with Δ-ALA) and amber plastic frozen transport tube and cap (Labcorp No. 78656).

Appropriate test to rule out acute intermittent porphyria (AIP) and other acute attack types of porphyrias associated with neurologic and/or psychiatric symptoms. Detect porphyrias and porphyrinurias. Acute intermittent porphyria is characterized by excretion of porphobilinogen and delta aminolevulinic acid in urine during acute attacks, but not during latency. Increased urine values are seen in the intoxication porphyrias (heavy metals, halogenated solvents, certain drugs).

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Ion-exchange chromatography/spectrophotometry

0.0−1.5 mg/24 hours

Acute attacks of acute intermittent porphyria are precipitated by drugs, including barbiturates, hydantoins, hormones, infection, and diet. The most common symptom of acute intermittent porphyria is abdominal pain. The most common sign is tachycardia.¹ Subjects with the porphyrias may pass urine the color of port wine. The term porphyria derives from the Greek “porphyria,” an expression for the color purple.¹ Quantitative porphobilinogen will pick up many but not all patients with acute intermittent porphyria in the latent period.