White blood cells help the body fight infections. The Mayo Clinic indicates that the normal range for a white blood cell count often varies. However, a count below 3,500 per microliter of blood may elicit further evaluation from your physician. Leukopenia refers to the white blood count falling under the normal range and several reasons contribute to this occurrence. Low blood count may have specific causes such as an autoimmune disorder, cancer or a viral infection. Short-term causes include allergic reactions or medications.
Aplastic Anemia
Blood disorders such as aplastic anemia prevent white blood cells from regenerating. The National Heart Lung and Blood Institute indicates that aplastic anemia not only prevents the red blood cells from regenerating but also prevents platelets and white blood cells from making enough new blood cells to prevent infection, clot and carry oxygen to the body. Damage to the stem cells causes the blood cells from reproducing in a normal fashion. This disorder gets worse over time and requires treatment due to the seriousness of the condition.
Cancer
Certain cancers, such as leukemia, cause extremely low white blood cell counts. Leukemia starts in the white blood cells, preventing the bone marrow from producing normal white blood cells. The Mayo Clinic indicates leukemia occurs as a mutation in DNA, eventually causing abnormal cell growth to crowd out healthy blood cells. Differing types of leukemia exist. They impact the white blood cell count either through excessive abnormal production or extremely low production. Medical intervention offers testing and diagnostics to treat the symptoms of leukemia.
Medications
The Mayo Clinic indicates that some medications destroy white blood cells and damage bone marrow. Although medications offer treatment for various ailments, the risk of damage to the white blood cell count causes concern. Careful physician monitoring of the white blood cell count provides a means for preventing extensive damage to blood cells. Chemotherapy drugs often have toxic effects, resulting in decreased white cell levels. Immunosuppressive medications also kill white blood cells as part of the attempt to prevent organ rejection after a transplant.
