Increased Mean Corpuscular Volume Erythrocyte Macrocytosis Increased MCV High MCV SCDO:1000626 Larger than normal size of erythrocytes. Macrocytosis refers to a mean cell volume (MCV) greater than 100 fL. If macrocytosis is an isolated abnormality, the amount of hemoglobin in the cell increases proportionately, so the mean cell hemoglobin concentration (MCHC) remains within normal limits. Sufficient HP:0005518 Abnormal Mean Corpuscular Volume