Autoimmune Hemolytic Anemia
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Introduction
Autoimmune Hemolytic Anemia (AIHA) is a condition in which antibodies are made against red blood cells. There are many potential causes.
The Case of...
Causes and Risk Factors
warm agglutinins: IgG
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cold agglutinins: IgM
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IgG-mediated
- ABO-incompatibility
- idiopathic
- neoplastic
- infections
autoimmune hemolytic anemia (AIHA) - cold IgM, warm IgG
- diagnose via spherocytes and the direct antiglobulin test (DAT)
- cleared by splenic macrophages
Pathophysiology
IgM-mediated destruction is usually post-infectious. IgM antibodies cross-react with RBC antigens. In the cold, or in the distal circulation (where temperatures are cooler), antibodies bind and attract complement. RBCs are directly lysed or cleared following C3 coating.
Signs and Symptoms
- history
- physical exam
History
Acute anemia can result, leading to:
- fatigue
- shortness of breath
- pallor
Physical Exam
Jaundice and splenomegaly can result.
Physical exam should include investigation for malignancy, ie looking for lymphadenopathy.
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
A complete blood count can reveal:
- anemia
Other tests include:
- increased reticulocyte count
- increased bilirubin, urine bilinogen, LDH
- free hemoglobin in the serum
- methemalbuminemia
- urine hemoglobin, hemosiderin
Antiglobulin tests (Coomb's tests)
- warm immune hemolysis: antibodies
- cold hemolysis: complement
Diagnostic Imaging
Differential Diagnosis
Treatments
The underlying cause should be treated.
Corticosteroids, splenectomy, or immunisuppression should be considered for IgG-mediated disease.
Avoidance of cold exposure can be helpful for patients with IgM-mediated disease.
Consequences and Course
Resources and References
Topic Development
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