Vitamin A levels and transplant outcomes. (A) Free vitamin A levels in patient plasma 30 days posttransplant are in a narrow range and normally distributed with a median value of 1.296 ng/mL. (B) Vitamin A levels below the median are associated with increased incidence of grades 2-4 GVHD (38.6% vs 12.4% at 100 days, P = .0008). (C) Vitamin A levels below the median are associated with increased incidence of GI GVHD (30.4% vs 7% at 100 days, P = .002). (D) TRM was also increased in patients with vitamin A levels below the median compared with patients with vitamin A levels above the median (17.7% vs 7.4% at 1 year, P = .03).