What laboratory findings may indicate hemolysis in a transfusion reaction?

Unconjugated bilirubin levels rise in cases of hemolysis, which can occur during a transfusion reaction. When red blood cells break down, hemoglobin is released and subsequently metabolized in the liver. The breakdown of hemoglobin leads to an increase in unconjugated bilirubin as the liver processes the excess hemoglobin resulting from the hemolytic process. This is particularly significant because elevated levels of unconjugated bilirubin not only indicate increased red blood cell destruction but also serve as a marker for assessing the extent of hemolysis and confirming a transfusion reaction.

The other choices do not directly correlate with the monitoring of hemolysis due to transfusion. A low platelet count may indicate thrombocytopenia but does not specifically signify hemolysis. High creatinine levels could suggest renal impairment, possibly due to hemolytic uremic syndrome, but this is a secondary effect rather than a direct indicator. An increased white blood cell count could suggest an inflammatory response but is also not specific for hemolysis following transfusion. Thus, unconjugated bilirubin is the clear marker indicating hemolysis in this context.