Urine porphobilinogen (PBG) is useful for the evaluation of neurologic and/or psychiatric symptoms to exclude acute porphyrias such as acute intermittent porphyria (AIP).

Porphobilinogen is measured in patients with symptoms that suggest acute intermittent porphyria, [9, 10] variegate porphyria, or hereditary coproporphyria. Patients with an elevated porphobilinogen levels can undergo further testing to determine the subtype of porphyria present.