The association of the serotonin metabolite, 5-HIAA, to the lysosomal enzyme N-acetyl-beta-glucosaminidase.

Twenty-one medication-free patients with generalized anxiety disorder (GAD) collected urine samples for 5-hydroxyindoleacetic acid (5-HIAA) and N-acetyl-beta-glucosaminidase (NAG). Nine patients with no comorbid psychiatric diagnosis showed a significant association between 5-HIAA and NAG, r = -0.683, p = 0.04. The possibility that NAG could be a marker for serotonin metabolism is discussed.