Abstract
Seventy-nine platelet transfusions to 73 thrombocytopenic patients with cancer were analyzed to determine whether a platelet count obtained one hour after transfusion could help differentiate between alloimmunization and other clinical factors that result in rapid platelet destruction. These transfusions were selected because 18- to 24-hour increments were inadequate in response to fresh, random donor platelets. A corrected count increment (CI) (CI=[posttransfusion count—pretransfusion count]×body surface area [sq m]/platelets transfused×1011) at one hour of 10×103/μL or greater was associated with absence of lymphocytotoxic antibody, whereas increments of less than 10×103/μL were generally associated with high levels of strongly cytotoxic antibody. HLA-matched transfusions produced no improvement in increments when the previous one-hour CI had been 10×103/μL or greater, whereas in the other group significantly better increments were obtained. A one-hour posttransfusion count is a simple test that correlates well with the presence of antibody against HLA antigens, is valuable in predicting the need for HLA-matched platelets, and helps avoid wasteful, empirical use of such transfusions.(JAMA 243:435-438, 1980)