Platelet transfusion refractoriness is most commonly due to what?

• A. Alloantibodies to HLA or platelet antigens
• B. Bacterial sepsis
• C. Iron deficiency
• D. Splenomegaly

Answer: (A)

Platelet transfusion refractoriness happens when the expected rise in platelet count after transfusion does not occur. The most common reason is immune-mediated destruction from alloantibodies against donor HLA antigens or against platelet-specific antigens. After prior exposure to non-self HLA or platelet antigens through transfusions or pregnancy, a patient can develop antibodies that bind to transfused platelets, marking them for clearance by the spleen and reticuloendothelial system. This rapid destruction leaves few platelets circulating, so the count doesn’t rise as it should. While nonimmune factors like splenomegaly (sequestration of platelets), bacterial sepsis, or iron deficiency can affect platelet dynamics, they are not the primary, most frequent cause of refractoriness.