transitive verb. 1  To keep up or carry on; continue: maintain good relations. 2  To keep in an existing state; preserve or retain: maintain one's composure. 3  To keep in a condition of good repair or efficiency: maintain two cars.
Anemia is usually classified based on the size of RBCs, as measured by the mean corpuscular volume (MCV). Anemia can be microcytic (MCV typically less than 80 Î¼m3 [80 fL]), normocytic (80 to 100 Î¼m3 [80 to 100 fL]), or macrocytic (greater than 100 Î¼m3 [100 fL]).
Usually red blood cells are a standard size. Certain disorders, however, cause a significant variation in cell size. Higher RDW values indicate greater variation in size. Normal range in human red blood cells is 11 - 15%. If anemia is observed, RDW test results are often used together with MCV results to figure out what the cause of the anemia might be. It is mainly used to differentiate between iron deficiency anemia, in which RDW is elevated, and other microcytic anemias.