Effect of aging on desmopressin-induced VWF responses. The effects of increasing age on plasma VWF:Ag levels after desmopressin administration were assessed in combined subgroups of patients with low VWF and type 1 VWD in whom plasma VWF levels increased ≥30 IU/dL. Plasma VWF:Ag were determined prior to desmopressin administration (T0), and at 1 (T + 1), 4 (T + 4), and 24 (T + 24) hours after desmopressin administration. The mean and standard deviations are depicted; n = 171 before desmopressin administration; n = 164 at 1 hour; n = 123 at 4 hours; and n = 98 at 24 hours after desmopressin administration. Significantly increased VWF responses were observed at 1, 4, and 24 hours after desmopressin administration with increasing age at the time of desmopressin trial. P values are outcomes of linear regression analysis with the presented age groups included as independent variable. ns, not significant.