From the Guidelines
Diagnosing hemolytic anemia requires a comprehensive approach that includes a thorough clinical history and physical examination, followed by specific laboratory tests to identify the underlying cause, as outlined in the most recent guideline update 1. The diagnostic work-up should start with a history and physical examination, considering new drugs, insect, spider, or snake bites, and proceed with blood chemistry, CBC with evidence of anemia, macrocytosis, and evidence of hemolysis on peripheral smear, including LDH, haptoglobin, bilirubin, reticulocyte count, and free hemoglobin 1. Key laboratory tests include:
- Disseminated intravascular coagulation (DIC) panel
- Autoimmune serology
- Paroxysmal nocturnal hemoglobinuria (PNH) screening
- Direct and indirect bilirubin, direct agglutinin test, and bone marrow analysis if no obvious cause is found
- Evaluation for viral or bacterial causes of hemolysis
- Protein electrophoresis and cryoglobulin analysis
- Workup for bone marrow failure syndrome if refractory, including B12, folate, copper, parvovirus, iron, and thyroid infection
- Glucose-6-phosphate dehydrogenase level
- Assessment of common drug causes and methemoglobinemia 1. The most critical step is to systematically evaluate each patient using these guidelines to determine the specific cause of hemolytic anemia, which then directs the appropriate treatment approach, prioritizing morbidity, mortality, and quality of life as outcomes 1.
From the Research
Diagnostic Steps for Hemolytic Anemia
The diagnosis of hemolytic anemia involves several steps, including:
- Laboratory tests to confirm hemolysis, such as reticulocytosis, increased lactate dehydrogenase, increased unconjugated bilirubin, and decreased haptoglobin levels 2
- A peripheral blood smear to identify abnormal red blood cell morphologies 2
- The direct antiglobulin test to differentiate immune causes from nonimmune causes 2, 3
- Classification of hemolytic diseases into hemoglobinopathies, membranopathies, enzymopathies, immune-mediated anemias, and extrinsic nonimmune causes 2
Laboratory Evaluation
The laboratory evaluation of anemia begins with a complete blood count and reticulocyte count 4, 5
- The anemia is then categorized as microcytic, macrocytic, or normocytic, with or without reticulocytosis 5
- Examination of the peripheral smear and a small number of specific tests confirm the diagnosis 5
- Hemolytic markers, such as increased reticulocytes, elevated lactate dehydrogenase, reduced haptoglobin, and unconjugated hyperbilirubinemia, are used to guide the differential diagnosis and monitor treatment of hemolytic conditions 3
Specialized Testing
Genetic testing, such as Sanger sequencing or next-generation sequencing, may be recommended if conventional laboratory tests are unable to detect the underlying cause of hemolysis 6