What indicates a possible acute hemolytic reaction in a transfusion patient?

The presence of hemoglobinuria and a positive Direct Antiglobulin Test (DAT) are significant indicators of a possible acute hemolytic reaction in a transfusion patient. Hemoglobinuria refers to the presence of hemoglobin in the urine, which occurs when red blood cells (RBCs) are destroyed at an accelerated rate due to an immune reaction against transfused blood components. This destruction leads to the release of hemoglobin into the bloodstream, which is then filtered by the kidneys, resulting in a colored urine.

Additionally, a positive Direct Antiglobulin Test indicates that there are antibodies bound to the RBCs in circulation. This test is used to detect autoimmune hemolytic anemia and can provide evidence of an immune-mediated hemolytic process, which is characteristic of acute hemolytic transfusion reactions.

Both hemoglobinuria and a positive DAT work together to confirm the occurrence of hemolysis, thereby indicating a serious reaction requiring immediate medical intervention. In contrast, the other signs and symptoms mentioned might be associated with various transfusion reactions but do not specifically point to acute hemolysis with the same clarity as the combination of hemoglobinuria and a positive DAT.