Leukopenia is caused by a variety of medical issues including viral infections, autoimmune disorders, medications, aplastic anemia, chemotherapy, HIV, lupus, malnutrition and certain parasitic diseases, according to Mayo Clinic. The condition may also be caused by genetics.
Leukopenia is a medical condition in which a patient has a low white blood cell count, reports Mayo Clinic. Typically, if a patient has less than 4,000 white blood cells per microliter of blood, then he is diagnosed with leukopenia. This threshold number is only for adults, as children have a different threshold number that varies based on the age and sex of the child.