Microcytosis or microcythemia[1] is a condition in which red blood cells are unusually small as measured by their mean corpuscular volume.
Microcytic anemia is not caused by reduced DNA synthesis[citation needed].
[citation needed] Red blood cells can be characterised by their haemoglobin content as well as by their size.
The normochromic cells have a normal concentration of haemoglobin, and are therefore 'red enough' while the hypochromic cells do not; thus the value of the mean corpuscular hemoglobin concentration.The most common cause of microcytosis is iron deficiency anemia.
Every time Hb synthesis being impaired in bone marrow microcytosis can occurs such as iron deficiency and Hb pathy may occur in fact when Hb production was impaired: size of each RBCs is decreased in early stage to save mean corpuscular Hb concentration : i.e. MCHC: so MCV is decreased as compensating mechanism.