Which laboratory finding is most associated with acute intravascular transfusion reaction?

• A. Hyperkalemia
• B. Leukocytosis
• C. Hemoglobinemia
• D. Hypoglycemia

Answer: (C)

Intravascular hemolysis from an acute transfusion reaction happens when donor red cells are destroyed within the bloodstream due to recipient antibodies (often ABO incompatibility). The rapid breakdown releases free hemoglobin directly into the plasma, leading to hemoglobinemia. As this freely circulating hemoglobin is filtered by the kidneys, hemoglobinuria can follow. This intravascular destruction also elevates LDH and lowers haptoglobin, and the direct antiglobulin (Coombs) test is usually positive.

Among the options, hemoglobinemia best captures the primary laboratory change seen with this process. Hyperkalemia can occur from cell lysis, but it is not the defining or most characteristic finding. Leukocytosis points more toward infection or inflammation, and hypoglycemia is not typical in this setting.