Force monitoring of clot retraction during DDAVP therapy for the qualitative platelet disorder of uraemia

The qualitative platelet disorder of uraemia results in decreased primary haemostatic capacity which can result in significant blood loss during invasive procedures. Treatments of the disorder tend to be empirical and include measures such as aggressive dialysis, conjugated oestrogens, and use of DDAVP. Improvement in platelet function is typically monitored by repeated bleeding times. The variability of the bleeding time is an all too recognized limitation of its usefulness. We report here the case of a 35-year old male with end stage renal disease who presented with intractable bleeding secondary to peptic ulcer disease and haemorrhagic gastritis. Platelet function tests including bleeding time, platelet aggregation studies, and clot retraction measurements were monitored before and after intravenous administration of DDAVP (0.3 microgram/kg). The bleeding time which had been 8 min before DDAVP did not change. Platelet aggregation studies revealed improved aggregation by both collagen and adenosine diphosphate. Clot retraction forces were dramatically enhanced after DDAVP. Pre-DDAVP clots containing 72 x 10(9) platelets per 1 and 1 g fibrinogen per 1 produced 90 dynes/cm2 of force at 800 s post-thrombin addition. Identical clots formed with blood drawn 2 h post-DDAVP produced 750 dynes/cm2. The DDAVP dose was repeated after 8 h with obvious slowing of blood loss. The marked effect of DDAVP on clot retraction may allow monitoring of DDAVP therapy utilizing this technique.