Δ-ALA may be increased in attacks of acute intermittent porphyria, hereditary coproporphyria, and porphyria variegata; evaluation of certain neurological problems with abdominal pain; diagnosis of lead or mercury poisoning. Urinary Δ-ALA is not a sensitive indicator of lead poisoning in children because it does not increase until blood lead concentration is 40 μg/dL, well above the recommended level <15 μg/dL. ALA is increased also in tyrosinemia.Porphobilinogen and δ-aminolevulinic acid are the tests of choice for acute intermittent porphyria. Recently the molecular lesions have been identified in a severely affected homozygote with δ-aminolevulinate dehydratase deficient porphyria.