White blood cells are manufactured in bone marrow — the spongy tissue inside some of your larger bones. A low white blood cell count usually is caused by:

1. Viral infections that temporarily disrupt the work of bone marrow
2. Certain disorders present at birth (congenital) that involve diminished bone marrow function
3. Cancer or other diseases that damage bone marrow
4. Autoimmune disorders that destroy white blood cells or bone marrow cells
5. Severe infections that use up white blood cells faster than they can be produced
6. Medications, such as antibiotics, that destroy white blood cells
7. Sarcoidosis (collections of inflammatory cells in the body)

Specific causes of a low white blood cell count include:

1. Aplastic anemia
2. Chemotherapy
3. HIV/AIDS
4. Hypersplenism (an abnormality of the spleen causing blood cell destruction)
5. Kostmann's syndrome (a congenital disorder involving low production of neutrophils)
6. Leukemia
7. Lupus
8. Malnutrition and vitamin deficiencies
9. Myelodysplastic syndromes
10. Myelokathexis (a congenital disorder involving failure of neutrophils to enter the bloodstream)
11. Radiation therapy
12. Rheumatoid arthritis and other autoimmune disorders
13. Tuberculosis (and other infectious diseases)

• Definition
• When to see a doctor

Jan. 11, 2018