Red blood cell
Another antibody-mediated condition that can affect complete blood count results is red blood cell agglutination. This phenomenon causes red blood cells to clump together because of antibodies bound to the cell surface. Red blood cell aggregates are counted as single cells by the analyzer, leading to a markedly decreased red blood cell count and hematocrit, and markedly elevated MCV and MCHC. Often, these antibodies are only active at room temperature (in which case they are called cold agglutinins), and the agglutination can be reversed by heating the sample to . Samples from people with warm autoimmune hemolytic anemia may exhibit red cell agglutination that does not resolve on warming.