Initial Approach to Hemolysis Workup

Confirming Hemolysis

The initial workup for hemolysis should include complete blood count, reticulocyte count, peripheral blood smear, lactate dehydrogenase (LDH), haptoglobin, and bilirubin levels to establish the presence of hemolysis and differentiate between production defects and increased destruction, as recommended by the American Society of Hematology 1, 2
Peripheral blood smear examination is fundamental to identify abnormal red blood cell morphologies that may suggest specific causes of hemolysis, according to the American Journal of Hematology 1
The reticulocyte count is critical for assessing bone marrow erythropoietic activity and helps classify anemias based on production capacity, as stated by the American College of Physicians 2

If the direct antiglobulin test (DAT) is positive, further workup for autoimmune hemolytic anemia, drug-induced hemolysis, or alloimmune hemolysis is indicated, as recommended by the American Society of Clinical Oncology 3, 4
If DAT is negative, focus on non-immune causes such as membrane disorders, enzymopathies, or mechanical hemolysis, according to the American Journal of Hematology 1

Check for schistocytes on peripheral smear, which may indicate microangiopathic hemolytic anemia or mechanical hemolysis, as stated by the American Society of Clinical Oncology 3, 4
Assess for evidence of RBC destruction without anemia, which may indicate early stages of hemolytic processes, according to the American Society of Clinical Oncology 4

For suspected red cell enzyme deficiencies, measure specific enzyme activity and consider genetic testing, as recommended by the American Journal of Hematology 1
For suspected thrombotic microangiopathies, check ADAMTS13 activity and inhibitor titer, according to the American Society of Clinical Oncology 3, 4

The initial laboratory panel should include CBC with indices, reticulocyte count, peripheral blood smear, LDH, haptoglobin, bilirubin, and DAT, as recommended by the American Society of Hematology 1, 2
Interpret reticulocyte response: an elevated reticulocyte count suggests adequate bone marrow response to hemolysis, while a normal or low reticulocyte count with evidence of hemolysis suggests concurrent bone marrow suppression, nutritional deficiency, or autoimmune reaction against marrow precursors, according to the American College of Physicians 2
Based on DAT result, proceed with antibody identification, cold agglutinin testing, or drug-induced antibody testing if DAT is positive, as recommended by the American Society of Clinical Oncology 3, 4
Based on peripheral smear findings, consider thrombotic microangiopathies if schistocytes are present, according to the American Society of Clinical Oncology 3, 4