We have identified causative factors contributing to marked mean corpuscular volume(MCV) change. We selected 38 patients who demonstrated changes in MCV of ≧10 fl within less than 30 days. Of the 38 patients, 27 had received blood transfusions and 6 had undergone allogeneic bone marrow transplantation within the previous 2 months. No definitive cause was detected in 5 patients. In conclusion, blood transfusion and bone marrow transplantation can result in substantial MCV change in a short time and can represent confounding factors for the MCV delta check method.

*1Department of Clinical Laboratory Medicine, Jichi Medical School, Kawachi-gun, Tochigi-pref. 329-0498