The anemia of SLE is warm-antibody mediated, Coombs’ positive, and is characterized by extravascular hemolysis. In extravascular hemolysis, as erythrocytes pass through the spleen, antibodies that are attached to the cell membrane are removed. Loss of a portion of the cell membrane results in loss of the normal biconcave shape and evolution to a spherical shape. Associated laboratory findings include hyperbilirubinemia and decreased haptoglobin. Cold agglutinins are associated with mycoplasma infections, lymphoid neoplasms, and paroxysmal cold hemoglobinuria.
