Anemia can be defined as a reduction in hemoglobin (less than 13.5 g/dL in men; less than 12.0 g/dL in women) or hematocrit (less than 41.0% in men; less than 36.0% in women) or red blood cell (RBC) count. The terms hemoglobin and hematocrit are more commonly used than RBC count in day-to-day clinical practice. BACKGROUND. Apheresis donors are routinely evaluated with a complete blood count (CBC). Low red blood cell mean corpuscular volume (MCV) values (<80 fL) in the presence of an acceptable hemoglobin (Hb; ≥12.5 g/dL) could be due to iron deficiency or hemoglobinopathy. The etiology of a low MCV in a healthy apheresis donor population was assessed. The complete blood cell count (CBC) is one of the most frequently ordered laboratory tests, but some values included in the test may be overlooked. This brief review discusses 3 potentially underutilized components of the CBC: the red blood cell distribution width (RDW), the mean platelet volume (MPV), and the nucleated red blood cell (NRBC) count. These results have unique diagnostic Alteration in other hematological parameters such as hemoglobin (HG), hematocrit (HCT), mean corpuscular volume (MCV) ,mean corpuscular hemoglobin (MCH), white blood cell (WBC) count and platelet count is associated with thyroid dysfunction is observed as well , but all changes return to normal if an euthyroid (normal) state is obtained MCV is part of complete blood count—a routine screening test that analyzes the other two blood components, white blood cells, and platelets. MCV is an indicator of reduced red blood cell circulation in the body, as seen in anemia and vitamin B12, and folic acid deficiencies. Normal MCV in adults ranges from 80-100 fL. CBC: The Basics of Red Cells •Red cell size distribution width: degree of variation in erythrocyte size, a coefficient of variation •A high RDW indicates a large variation in size of RBCs If the MCV is normal and the RDW is high, there is a mixture of large and small RBCs If the RDW is normal and the MCV is high, the RBCs are likely all pWb2N. Complete blood count (CBC) reference intervals are essential for effectively diagnosing diseases, screening blood donors, and assessing overall health. However, critical accuracy gaps exist in the reference intervals that are currently used in China. Most available reference intervals for laboratory tests are outdated or adopted from the

high red blood cell count but low mcv and mch