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Autoimmune hemolytic anemia

Background

Overview

Definition
AIHA is an acquired disorder where the immune system produces antibodies against RBC antigens, leading to hemolysis.
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Pathophysiology
The pathophysiology of AIHA involves warm antibody-mediated and cold agglutinin disease. In warm type, IgG antibodies bind to RBCs at normal body temperature, leading to their destruction primarily in the spleen and liver. Cold type involves IgM antibodies that bind to RBCs at colder temperatures, typically in the extremities, causing destruction mainly in the peripheral circulation.
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Epidemiology
The prevalence of AIHA in the US is estimated at 17 per 100,000 population.
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Disease course
Clinically, AIHA usually presents with fatigue and other constitutional symptoms due to anemia. Other signs and symptoms may include jaundice due to the breakdown of RBCs and shortness of breath. Physical examination may reveal pallor, hepatosplenomegaly, and jaundice.
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Prognosis and risk of recurrence
The prognosis of AIHA can vary widely. It can run a chronic course with severe intermittent exacerbations. The response to treatment can also influence the prognosis.
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Guidelines

Key sources

The following summarized guidelines for the evaluation and management of autoimmune hemolytic anemia are prepared by our editorial team based on guidelines from the First International Consensus Meeting (FICM 2020), the American Society for Apheresis (ASFA 2019), and the British Society for Haematology (BSH 2017).
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Screening and diagnosis

Diagnosis: as per FICM 2020 guidelines, obtain direct antiglobulin test (C3d+), a cold agglutinin titer and bone marrow examination (at least by histology and flow cytometry) for the diagnosis of cold agglutinin disease.
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Classification and risk stratification

Assessment of thrombotic risk
As per FICM 2020 guidelines:
Take into account the risk of thrombotic events (both venous and arterial), mostly during acute hemolytic flares and in splenectomized patients.
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Obtain assessment of general thrombotic risk factors in patients with AIHA: age > 70 years, active cancer, previous VTE, reduced mobility, already known thrombophilic condition, recent trauma and/or surgery, heart and/or respiratory failure, acute infection.
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Diagnostic investigations

Initial assessment
As per FICM 2020 guidelines:
Assess for signs of acrocyanosis in patients with cold agglutinin disease.
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Obtain baseline values of LDH, bilirubin, haptoglobin, reticulocyte count, and review of peripheral smear (looking for spherocytes in warm AIHA, RBC aggregation in cold agglutinin disease, and schistocytes to exclude thrombotic microangiopathies) in all patients with AIHA.
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  • Direct antiglobulin test

  • Direct agglutination test

  • Cold agglutinin test

  • Donath-Landsteiner test

  • Evaluation for underlying cause

  • Assessment of related conditions

Medical management

Management of primary warm AIHA, indications
As per FICM 2020 guidelines:
Initiate treatment in patients with warm AIHA in the setting of symptomatic anemia.
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Consider obtaining monitoring (watchful waiting) in rare patients with mild and stable anemia.
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  • Management of primary warm AIHA (first-line therapy)

  • Management of primary warm AIHA (second-line therapy)

  • Management of primary warm AIHA (third-line therapy)

  • Management of primary warm AIHA (refractory cases)

  • Management of primary warm AIHA (emergency management)

  • Management of primary cold AIHA (indications)

  • Management of primary cold AIHA (avoidance of cold)

  • Management of primary cold AIHA (first-line therapy)

  • Management of primary cold AIHA (second-line therapy)

  • Management of primary cold AIHA (other therapies)

  • Management of primary cold AIHA (emergency management)

  • Management of mixed AIHA

  • Management of paroxysmal cold hemoglobinuria

  • Management of drug-induced AIHA

  • Management of secondary AIHA (lymphoproliferative disorders)

  • Management of secondary AIHA (solid organ neoplasms)

  • Management of secondary AIHA (immune dysregulations)

  • Management of secondary AIHA (infections)

  • Management of Evans syndrome

  • Thromboprophylaxis

  • Management of corticosteroid side effects

Nonpharmacologic interventions

Folic acid supplementation
As per FICM 2020 guidelines:
Initiate folic acid supplementation in patients with active hemolysis.
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Monitor hematinic in case of reticulocytosis, or if anemia worsens.
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Therapeutic procedures

Blood transfusion
As per BSH 2017 guidelines:
Administer transfusion with ABO, Rh and K matched red cells if anemia is life-threatening in the time required for full compatibility testing.
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Consider using a blood warmer for transfusion in patients with cold AIHA (cold agglutinin disease, mixed AIHA and paroxysmal cold hemoglobinuria).
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Surgical interventions

Splenectomy, indications: as per FICM 2020 guidelines, offer splenectomy as a third-line treatment option in patients with primary warm AIHA, based on the individual assessment of the benefit over risk ratio.
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  • Splenectomy (preoperative evaluation)

  • Splenectomy (postoperative care)

Specific circumstances

Pediatric patients: as per BSH 2017 guidelines, include LFTs in the evaluation of pediatric patients with AIHA.
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  • Pregnant patients (evaluation)

  • Pregnant patients (antenatal care)

  • Pregnant patients (postnatal care)