Low erythrocytes are conditions where the level of red blood cells in the body decreases to below the normal range. In the initial stages, this condition does not cause signs or symptoms, so it is only known after a blood test. Erythrocytes or red blood cells are produced in the bone marrow. These cells contain a protein called hemoglobin and function to deliver oxygen from the lungs to all organs and tissues of the body. You can find out the level of erythrocytes in the body by undergoing a complete blood test. Normal red blood cell levels in adult men are between 4.7-6.1 million / microliter (mcl), and in adult women it is 4.2-5.4 million / mcl. Whereas in children, normal erythrocyte levels are 4.1-5.5 million / mcl. What Makes Erythrocytes Low? Low erythrocyte levels can be caused by many factors, one of which is bleeding, for example due to an accident or surgery. Decreased levels of erythrocytes also often occur in pregnant women, due to the increasing amount of fluid in th...