[Autoimmune hemolytic anemia: diagnosis and management]

Autoimmune hemolytic anemia (AIHA) is diagnosed in the presence of anemia, usually macrocytic and of variable intensity, reticulocytosis, and a positive direct and/or indirect antiglobulin test, after ruling out other types of hemolytic anemia. A positive direct antiglobulin test alone is not sufficient to diagnose AIHA and may be positive in many patients without anemia or negative in some patients with AIHA. AIHA may be classified into two major categories according to the optimal temperature of antibody activity: warm-reacting autoantibodies (usually IgG) optimal around 37 degrees C and cold-reacting autoantibodies, optimal at 4 degrees C (usually IgM). This classification guides the selection of tests and treatment. AIHA is widely reported to be associated with a variety of other diseases, although these associations are often fortuitous. A minimal set of useful investigations is appropriate since AIHA may be secondary to viral infections, lymphoid malignancies, or autoimmune disorders such as lupus. Transfusion should remain rare in AHAI, but close contact with the transfusion service is necessary if it is to succeed. As for many autoimmune and/or systemic diseases, numerous types of treatment have been proposed but have not been validated in controlled multicenter studies. These are necessary to improve the management of these rare disorders.