What is a significant symptom of acute hemolytic reaction during a blood transfusion?

Acute hemolytic reactions during a blood transfusion are serious and can have life-threatening consequences. One of the hallmark symptoms of an acute hemolytic reaction is renal failure, specifically acute kidney injury. This occurs because the hemolysis of red blood cells releases hemoglobin into the bloodstream, which can precipitate in the renal tubules, causing obstruction and damage to the kidneys. The resulting renal failure is characterized by a decrease in urine output and a rise in blood urea nitrogen (BUN) and creatinine levels.

While other symptoms such as urticaria, dyspnea, or hives may occur in different types of transfusion reactions, they are more commonly associated with allergic reactions or febrile non-hemolytic transfusion reactions, rather than with acute hemolytic reactions. In contrast, the renal implications are particularly significant in the context of acute hemolysis, making renal failure a key and telling symptom of this serious condition.