Red blood cell distribution width Red blood cell distribution width Red blood cell distribution width (RDW or RDW-CV or RCDW and RDW-SD) is a measure of the range of variation of red blood cell (RBC) volume that is reported as part of a standard complete blood count. Usually red blood cells are a standard size of about 6-8 μm in diameter. Certain disorders, however, cause a significant variation in cell size. Higher RDW values indicate greater variation in size. Normal reference range of RDW-CV in human red blood cells is 11.5-14.5%. If anemia is observed, RDW test results are often used together with mean corpuscular
Hematopoietic stem cell Hematopoietic stem cell Hematopoietic stem cells (HSCs) are the stem cells that give rise to other blood cells. This process is called haematopoiesis.<ref name="Birbrair n/a–n/a"></ref> This process occurs in the red bone marrow, in the core of most bones. In embryonic development, the red bone marrow is derived from the layer of the embryo called the mesoderm. Hematopoiesis is the process by which all mature blood cells are produced. It must balance enormous production needs (the average person produces more than 500 billion blood cells every day) with the need to precisely regulate the number of each blood cell type