Platelet Function Disorders in Bleeding Patients without Other Coagulopathies

Introduction:

We present a series of 105 patients referred for hematologic consultation to evaluate a clinical bleeding disorder. Little is known regarding the prevalence of non-genetic qualitative platelet disorders and which of these might respond to desmopressin.

Methods:

Patients were assessed over a two-year period, from December 2011 through December 2013. Patients, who were found to have neither von Willebrand's disease nor coagulation factor deficiencies, nor quantitative platelet defects, were tested for platelet function abnormalities by PFA-100 (Dade Behring, Marburg, Germany) and platelet aggregation and secretion studies using lumi aggregation (Chrono-Log Corp., Havertown, PA, USA). Selected patients with abnormal platelet function were given a trial of intravenous desmopressin to determine efficacy, and platelet function studies were repeated 2 hours later.

Results:

Of the 105 referred patients (26 males, age range 15-83 years; 79 females, age range 21-86 years), 67 with either normal (n=43) or abnormal (n=24) PFA-100 results were not evaluated further based on their clinical history and presentation. 18 patients with abnormal PFA-100 results, consisting of Collagen/ADP, Collagen/Epinephrine, or both, had platelet aggregation and secretion studies performed. 16 of these patients had abnormal platelet aggregation and secretion studies, while 2 patients had normal studies. In addition, 20 patients with normal PFA-100 results underwent platelet aggregation and secretion studies. Of these, 17 had abnormal platelet aggregation and secretion predominantly in response to two or more weak agonists, including ADP, epinephrine and/or arachidonic acid. Only 3 of these 20 patients had normal platelet aggregation and secretion. Of the 16 patients with both abnormal PFA-100 and abnormal platelet aggregation and secretion tests, 11 underwent subsequent pre- and post- desmopressin platelet function testing. 7 of the 11 patients showed improvement or complete normalization of at least one PFA-100 parameter, i.e., either Collagen/ADP, Collagen/Epinephrine, or both. However, results of platelet aggregation and secretion tests remained unchanged, irrespective of PFA-100 results.

Conclusions:

1. In the present study, platelet aggregation and secretion studies in patients with no other coagulopathies revealed platelet function defects in approximately 30% of the study cohort. Platelet function defects were in response to weak agonists, including ADP, epinephrine, and/or arachidonic acid.

2. Our data support the recent SCC ISTH recommendations against the use of PFA-100 for platelet function screening.

3. We recommend that the hematologist carefully assess the bleeding history, and, if significant, pursue platelet aggregation and secretion studies to identify potential platelet function defects.