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March 25, 1983

The Coombs Test and Autoimmune Hemolytic Anemia

Author Affiliations

Nassau Hospital Mineola, NY

JAMA. 1983;249(12):1564-1565. doi:10.1001/jama.1983.03330360018013

To the Editor.—  In a recent review, Schreiber wrote that the Coombs test can detect as few as 1,500 molecules of IgG per erythrocyte but that about 2,000 molecules of IgG per erythrocyte were necessary to augment the clearance of IgG-coated RBCs (1982; 248:1380). He concluded that "the antiglobulin test is a sensitive, albeit crude, method for the detection of antibody on the erythrocyte surface."However, approximately 2% to 5% of all patients with autoimmune hemolytic anemia (AHA) will have a negative Coombs test result,1 and a recent edition of a hematology textbook states that "the greatest shortcoming of the antiglobulin test is its relative insensitivity."2 As reported by Mollison and Hughes-Jones,3 as few as ten anti-Rh antibodies can shorten the RBC survival substantially. However, at least 500 molecules of antibodies per erythrocyte must be present to give a positive reaction by the Coombs reagent.1 Thus,