From the Guidelines
For a hemolytic anemia work-up, essential initial labs should include a complete blood count (CBC) with peripheral smear, reticulocyte count, lactate dehydrogenase (LDH), haptoglobin, and direct Coombs test (direct antiglobulin test or DAT), as recommended by the most recent guidelines 1. When ordering labs for hemolytic anemia, it is crucial to prioritize tests that help distinguish between immune and non-immune causes of hemolysis. The direct Coombs test detects antibodies already bound to red blood cells, indicating immune-mediated hemolysis occurring in the circulation. While the provided evidence does not explicitly mention the indirect Coombs test as a necessary initial test, in clinical practice, both direct and indirect Coombs tests are often considered because they provide complementary information. However, the most recent and highest quality study 1 only mentions the direct antibody test (Coombs test), suggesting its priority in the initial workup. Additional useful tests include:
- Bilirubin (total and direct)
- Urinalysis to check for hemoglobinuria
- Coagulation studies
- Hemoglobin electrophoresis if a hemoglobinopathy is suspected These tests help guide appropriate treatment and distinguish between different causes of hemolysis. The pattern of abnormalities—such as elevated LDH and reticulocytes with decreased haptoglobin—confirms hemolysis, while the Coombs tests specifically help identify immune-mediated mechanisms 1. In the context of real-life clinical medicine, prioritizing the direct Coombs test along with other essential labs is a practical approach for the initial workup of hemolytic anemia, considering the information provided by the most recent study 1.
From the Research
Essential Initial Labs for Hemolytic Anemia Work-up
- Complete blood count (CBC) to categorize the anemia as microcytic, macrocytic, or normocytic, with or without reticulocytosis 2
- Reticulocyte count to reflect erythropoietic activity and help differentiate between decreased erythropoiesis and increased erythrocyte degradation 3
- Peripheral blood smear to identify abnormal red blood cell morphologies 4
- Lactate dehydrogenase (LDH), unconjugated bilirubin, and haptoglobin levels to confirm hemolysis 4
- Direct antiglobulin test (direct Coombs test) to differentiate immune causes from nonimmune causes 4, 2
Direct and Indirect Coombs Tests
- The direct Coombs test is essential in the work-up of hemolytic anemia to identify antibody-mediated destruction of red blood cells 4, 2
- There is no clear indication in the provided studies that both direct and indirect Coombs tests should be ordered initially, but the direct Coombs test is mentioned as a crucial test in differentiating immune causes from nonimmune causes 4, 2