The donation of blood is presented to the public as an altruistic service in which one human helps another. At the same time, the donor receives some help for himself. In the process of blood donation, a medical history is taken, an extremely short physical examination is done, and the donor's blood is studied by various tests. Although this is by no means the equivalent of a complete physical examination performed by a physician, it sometimes can be helpful in discovering early disease or other medical findings which could be pertinent to the donor's health.