Diclofenac-induced antibodies against RBCs and platelets: two case reports and a concise review

BACKGROUND: Diclofenac has frequently been implicated as the cause of immune hemolytic anemias and less frequently of immune thrombocytopenia. The presence of the causative antibodies has only been demonstrated in patients with immune hemolytic anemia, but not yet in patients with thrombocytopenia. The cases of two patients in whom diclofenac simultaneously induced antibodies against platelets and RBCs are reported. STUDY DESIGN AND METHODS: The investigation was carried out with standard serologic tests for detection of antibodies against platelets and RBCs. The patients' sera were tested in the presence and absence of diclofenac and its metabolites. RESULTS: One of the two patients developed severe hemolysis and significant thrombocytopenic purpura. The other patient developed significant thrombocytopenia but no hemolysis. Both patients had a positive DAT and drug- and/or metabolite-dependent antibodies against RBCs and platelets. CONCLUSION: Based on our findings and those of other investigators, we believe that diclofenac leads to the production of antibodies against RBCs and/or platelets.