Red blood cells normally live for 110 - 120 days. After that, they naturally break down and are usually removed from the circulation by the spleen.
Some diseases and processes cause red blood cells to break down too soon. This requires the bone marrow to make more red blood cells than normal. The balance between red blood cell breakdown and production determines how low the red blood cell count becomes.
Todd Gersten, MD, Hematology/Oncology, Palm Beach Cancer Institute, West Palm Beach, FL. Review provided by VeriMed Healthcare Network; Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.