 There are situations that occur in vitro that we need to bear in mind when we look at abnormalities on our automated blood cell counting reports and one important such abnormality is cold agglutinants. Cold agglutinants are antibodies that are activated by cold temperature. Cold temperature only means temperatures below 37. So many patients example with lymphomas and other auto immune phenomena may have cold agglutinants and as their specimens sit on the bench waiting to be processed. The temperatures drop to room temperatures thus activating these cold agglutinants which then end up causing red blood cells to stick to each other and thereby present the automated blood cell counter with larger molecules and you will see on the count report higher RDWs, higher MCE HCs and higher RDWs which may look bizarre to you but that would be a clue to the doctor to remember that cold agglutinants may do so. Upon warming these changes will disappear that will be the key to resolving such changes.