Diagnostic Approach for Autoimmune Hemolytic Anemia

Initial Diagnostic Workup

The American College of Physicians recommends evaluating patients for symptoms including weakness, paleness, jaundice, dark-colored urine, fever, inability to perform physical activity, and heart murmur 1
A detailed history should be obtained with special consideration of new medications and insect, spider, or snake bites 1
A complete blood count (CBC) with evidence of anemia and macrocytosis should be performed 1
Peripheral blood smear to identify evidence of hemolysis should be conducted 1
Reticulocyte count (typically elevated) should be assessed 1
Lactate dehydrogenase (LDH) (elevated) should be measured 1
Haptoglobin (decreased or absent) should be evaluated 1
Bilirubin (direct and indirect) - elevated indirect (unconjugated) bilirubin should be assessed 1
Free hemoglobin assessment should be performed 1

The test should be performed before initiating any treatment 1
Indirect antiglobulin test to detect free autoantibodies in serum should be conducted 1
Autoimmune serology to identify underlying autoimmune disorders should be performed 1

Evaluate for viral and bacterial (especially mycoplasma) causes of hemolysis 1
Consider HIV, hepatitis testing 1
Paroxysmal nocturnal hemoglobinuria screening should be performed 1
If no obvious cause is found, consider bone marrow analysis and cytogenetic analysis to evaluate for myelodysplastic syndromes 1
Glucose-6-phosphate dehydrogenase assessment should be conducted 1
Evaluation for methemoglobinemia should be performed 1
Protein electrophoresis and cryoglobulin analysis should be conducted 1
Workup for bone marrow failure syndrome if refractory, including B12, folate, copper, parvovirus, iron studies, and thyroid function should be performed 1

Secondary AIHA can be associated with underlying conditions such as lymphoproliferative disorders 2
Infections can also cause secondary AIHA 1

Evaluate common drug causes including ribavirin, rifampin, dapsone, interferon, cephalosporins, penicillins, NSAIDs, quinine/quinidine, fludarabine, ciprofloxacin, lorazepam, diclofenac, etc. 1

False-normal PK enzyme activity levels may occur due to markedly increased reticulocyte count 3
Recent blood transfusions can also cause false-normal PK enzyme activity levels 1
Incomplete removal of platelets and leukocytes can lead to false-normal PK enzyme activity levels 3
Autoantibody titers and specificity may vary during the course of disease; seronegative individuals at diagnosis may express conventional autoantibodies later 2
Repeated testing may be necessary if initial results are negative but clinical suspicion remains high 2
Comprehensive autoimmune serology workup may not be available in all laboratories; consider sending samples to reference laboratories in cases of diagnostic uncertainty 2