Prostaglandin D₂ metabolite is not a useful clinical indicator for assessing atopic dermatitis

Prostaglandin D₂ (PGD₂ ) plays an important role in atopic dermatitis (AD), and 11,15-dioxo-9α-hydroxy-2,3,4,5-tetranorprostan-1,20-dioicacid (PGDM) is a major metabolite of PGD₂ . We investigated the relationship between urinary PGDM levels and severity of paediatric AD. In total, 31 patients with AD and 21 healthy controls (HCs) without AD were recruited, and urinary PGDM levels were measured. Of the 31 patients with AD, 14 were reassessed for urinary PGDM after topical steroid therapy. There was no difference in urinary PGDM levels between patients with AD and HCs. Although there was a significant positive correlation between the SCORing Atopic Dermatitis (SCORAD) index and the serum level of thymus and activation-regulated chemokine (TARC), the urinary PGDM levels did not correlate with either SCORAD or serum TARC. Moreover, both SCORAD and serum TARC were significantly improved by topical steroid therapy; however, urinary PGDM levels were not changed. In conclusion, the level of urinary PGD₂ metabolites in children with AD is substantially the same as that in HCs even if the disease is severe.