Macrocytosis is a condition where red blood cells are larger than normal.

[1] These enlarged cells, also known as macrocytes, are defined by a mean corpuscular volume (MCV) that exceeds the upper reference range established by the laboratory and hematology analyzer (usually >110 fL).

[2] Upon examination of a peripheral blood smear under microscope, these macrocytes appear larger than standard erythrocytes.

[3] The presence of macrocytosis can indicate a range of conditions, from benign, treatable illnesses to more serious underlying disorders.

[5] These conditions can affect the production and development of red blood cells, leading to their enlargement.