Editing Red blood cell (section)

=== Separation and blood doping ===
Red blood cells can be obtained from [[whole blood]] by [[centrifugation]], which separates the cells from the [[blood plasma]] in a process known as [[blood fractionation]]. [[Packed red blood cells]], which are made in this way from whole blood with the plasma removed, are used in [[transfusion medicine]].<ref>{{cite web|url=http://www.aabb.org/resources/bct/Documents/coi0809r.pdf|title=Circular of Information for Blood and Blood Products|publisher=American Association of Blood Banks, American Red Cross, America's Blood Centers|access-date=1 November 2010|url-status=dead|archive-url=https://web.archive.org/web/20111030212757/http://www.aabb.org/resources/bct/Documents/coi0809r.pdf|archive-date=30 October 2011}}</ref> During [[blood donation|plasma donation]], the red blood cells are pumped back into the body right away and only the plasma is collected.

Some athletes have tried to improve their performance by [[blood doping]]: first about 1&nbsp;litre of their blood is extracted, then the red blood cells are isolated, frozen and stored, to be reinjected shortly before the competition. (Red blood cells can be conserved for 5 weeks at {{convert|−79|C|F|disp=or}}, or over 10 years using cryoprotectants<ref>{{cite book | vauthors = Valeri CR | chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK233117/| chapter = Frozen Red Cell Technology| veditors = Sparacino L, Manning FJ | title = Blood Groups and Red Cell Antigens |date=8 February 1996|publisher=National Academies Press (US)|via=www.ncbi.nlm.nih.gov}}</ref>) This practice is hard to detect but may endanger the human [[cardiovascular system]] which is not equipped to deal with blood of the resulting higher [[viscosity]]. Another method of blood doping involves injection with [[erythropoietin]] to stimulate production of red blood cells.  Both practices are banned by the [[World Anti-Doping Agency]].