A blood cell disorder is when there is a problem with your red blood cells, white blood cells, or platelets-the smaller cells that circulate and are necessary for clot formation. The soft tissue that makes up your bones, or bone marrow, is where all three types of cells grow. Oxygen is carried to the tissues and organs of your body by red blood cells. Your body uses white blood cells to fight infections. Platelets aid in blood clotting. The formation and function of one or more of these blood cell types are impaired by blood cell disorders.