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 porphobilinogen may be caused also by variegate porphyria or hereditary coproporphyria. Increased urine values are seen in the intoxication porphyrias (heavy metals, halogenated solvents, certain drugs).