Background: Cold agglutinin disease; is a rare autoimmune hemolytic anemia caused by IgM antibodies (rarely IgA or IgG) against polysaccharide antigens on erythrocytes at low temperatures. As the cold activated antibodies cause degeneration and autoagglutination in the erythrocytes membrane, the erythrocyte count may be low and the hemoglobin value may be too high to be incompatible with the erythrocyte count.Case report:A 81-year-old male patient was admitted to the Internal Medicine Hematology Clinic. Patient requested hemogram test can not be worked on otomatize hemogram analyzer. Agglutinated erythrocytes were observed when the hemogram tube was examined. Considering the prediagnosis of cold agglutinin disease, the sample was kept at 37°C for 15 minutes. Upon the observation that the agglutinins were lost in the tube, the measurement on the count of erythrocyte and the hemoglobin/hematocrit ratio were considered to be correct and confirmed. IgG kappa and IgM lambda biclonal gammopathy was detected in the immunofixation electrophoresis study. In addition, the patient's blood group analysis was performed tube at room temperature and tube bathed at 37°C for 15 minutes. O Rh (+) results were obtained in both studies.

Results: When the discordance of the parameters is noticed and the agglutination is observed in the tube at room temperature, cold agglutinin disease should be considered and the sample should be kept at 37 °C in the benmari. Then the sample should be worked on the hemogram analyzer immediately.