RESUMEN
OBJECTIVES: To identify the occurrence and the causes of platelet refractoriness in oncohematologic patients. INTRODUCTION: Platelet refractoriness (unsatisfactory post-transfusion platelet increment) is a severe problem that impairs the treatment of oncohematologic patients and is not routinely investigated in most Brazilian services. METHODS: Forty-four episodes of platelet concentrate transfusion were evaluated in 16 patients according to the following parameters: corrected count increment, clinical conditions and detection of anti-platelet antibodies by the platelet immunofluorescence test (PIFT) and panel reactive antibodies against human leukocyte antigen class I (PRA-HLA). RESULTS: Of the 16 patients evaluated (median age: 53 years), nine (56 percent) were women, seven of them with a history of pregnancy. An unsatisfactory increment was observed in 43 percent of the transfusion events, being more frequent in transfusions of random platelet concentrates (54 percent). Platelet refractoriness was confirmed in three patients (19 percent), who presented immunologic and non-immunologic causes. Alloantibodies were identified in eight patients (50 percent) by the PIFT and in three (19 percent) by the PRA-HLA. Among alloimmunized patients, nine (64 percent) had a history of transfusion, and three as a result of pregnancy (43 percent). Of the former, two were refractory (29 percent). No significant differences were observed, probably as a result of the small sample size. CONCLUSION: The high rate of unsatisfactory platelet increment, refractoriness and alloimmunization observed support the need to set up protocols for the investigation of this complication in all chronically transfused patients, a fundamental requirement for the guarantee of adequate management.