Bleeding times, von Willebrand activities, and platelet retentions were examined before and following d-DAVP in 13 uremic patients. Shortening of the bleeding time from 16.6 +/- 2.2 (SEM) to 6.8 +/- 0.7 min was seen in six patients. However, bleeding times remained greater than or equal to 20 min in the remaining seven individuals. The only baseline parameter that correlated with response to d-DAVP was the amount of blood loss (mg/min) during the bleeding time test. Responders had normal blood loss values averaging 6.2 +/- 1.5 mg/min. By contrast, these values were elevated in 6/7 of the non-responders and averaged 28.4 +/- 5.9 mg/min (P = 0.01). Von Willebrand activities increased following d-DAVP in the responders but not in the non-responders. Platelet retention was uniformly low in all patients and improved from 21.0 +/- 7.0% to 75.0 +/- 7.9% (P = less than 0.001) following d-DAVP in responders but not non-responders. To further define the retention abnormality in uremia, the two-stage platelet retention assay was performed prior to d-DAVP. Most of the patients (9/12) had both first- and second-phase abnormalities. Therefore, the retention defect in uremia appears to be more complex than that seen in von Willebrand's disease (2nd phase abnormality only). Nevertheless, d-DAVP seems to improve platelet rheology in uremic individuals whose von Willebrand activities increase with d-DAVP.