It generates the cell counts, hemoglobin, and hematocrit from a centrifuged specimen. These are light, portable instruments made by Becton Dickinson. The rest of this discussion does not apply to this type of instrument. Cold agglutinins - low red cell counts and high MCVs can be caused by a decreased number of large red cells or red cell agglutinates. If agglutinated red cells are present, the automated hematocrits and MCHCs are also incorrect.
Cold agglutinins cause agglutination of the red cells as the blood cools.
Cold agglutinins can be present in a number of disease states, including infectious mononucleosis and mycoplasma pneumonia infections. If red cell agglutinates are seen on the peripheral smear, warm the sample in a 37 degrees C heating block and mix and test the sample while it is warm. Strong cold agglutinins may not disperse and need to be redrawn in a pre-warmed tube and kept at body temperature. Fragmented or very microcytic red cells these may cause red cell counts to be decreased and may flag the platelet count as the red cells become closer in size to the platelets and cause an abnormal platelet histogram. The population is visible at the left side of the red cell histogram and the right end of the platelet histogram.