From the Guidelines
Hemolytic labs are ordered when a patient develops a fever during a blood transfusion to determine if the fever is caused by a hemolytic transfusion reaction, which is a potentially life-threatening complication, with a risk of fatal hemolysis estimated to range from 1.3 to 1.7 per million transfused RBC units 1. When a patient develops a fever during transfusion, the transfusion should be immediately stopped, the IV line kept open with normal saline, and these labs drawn promptly. The labs typically include:
- Direct antiglobulin test (DAT)
- Plasma free hemoglobin
- Haptoglobin
- Lactate dehydrogenase (LDH)
- Bilirubin
- Urinalysis for hemoglobinuria Hemolytic transfusion reactions occur when the recipient's antibodies attack donor red blood cells, causing them to rupture and release hemoglobin into the circulation, which can trigger fever, back pain, hypotension, and in severe cases, disseminated intravascular coagulation (DIC) and acute kidney injury 1. The lab tests help differentiate between immune-mediated hemolytic reactions, which are typically more severe, and other causes of transfusion reactions such as febrile non-hemolytic reactions or allergic reactions, allowing for appropriate management of the patient, with the estimated risk for death due to hemolysis being 1:1 250 000 or 8 per 10 million RBC units 1. It is essential to note that the risk of fatal hemolysis is relatively low, but the consequences can be severe, making prompt identification and management crucial to prevent morbidity and mortality. Key points to consider:
- The risk of hemolytic transfusion reactions is estimated to be 1.3 to 1.7 per million transfused RBC units
- The risk of fatal hemolysis is estimated to be 1:1 250 000 or 8 per 10 million RBC units
- Prompt identification and management of hemolytic transfusion reactions are crucial to prevent morbidity and mortality
- The lab tests help differentiate between immune-mediated hemolytic reactions and other causes of transfusion reactions, allowing for appropriate management of the patient.
From the Research
Hemolytic Labs During Blood Transfusion
When a patient develops a fever during a blood transfusion, hemolytic labs are ordered to investigate the cause of the fever and to rule out a hemolytic transfusion reaction.
- Hemolytic transfusion reactions can be life-threatening and are often caused by the administration of incompatible blood products 2.
- Fever is a common presenting symptom of hemolytic transfusion reactions, as seen in a study of 23 cases of delayed hemolytic transfusion reaction, where fever was the most frequent presenting symptom 3.
- Hemolytic labs, such as the direct antiglobulin test, can help diagnose hemolytic transfusion reactions by detecting antibodies against red blood cells 3.
Importance of Hemolytic Labs
Hemolytic labs are crucial in determining the cause of fever during blood transfusion, as they can help distinguish between a hemolytic transfusion reaction and other causes of fever, such as infection 4.
- A study of a 2-year-old boy who developed fever during a red blood cell transfusion found that the fever was caused by an infection with Enterobacter cloacae, rather than a hemolytic transfusion reaction 4.
- Another study found that premedication with acetaminophen or diphenhydramine did not significantly reduce the risk of febrile or allergic reactions during blood transfusion 5.
Diagnostic Approach
The diagnostic approach to a patient with fever during blood transfusion should include hemolytic labs, as well as other tests to rule out infection or other causes of fever 6, 2, 3, 4, 5.
- The results of these tests can help guide treatment and ensure the safe continuation of the blood transfusion.