Biologic responses to DDAVP in 26 patients with type 1 VWD. Changes of FVIII:C (U/dL) and VWF:RCo (U/dL) are shown for each patient before and 30 minutes, 2 hours, and 4 hours after DDAVP administration. BT results expressed in minutes are reported only before and 2 hours after DDAVP. Limits of FVIII:C, VWF:RCo, and BT used in this study to define responsiveness (see “Criteria for biologic response to DDAVP”) are shown by the zone indicated in gray. Patients responsive (•) and unresponsive (○) to DDAVP.