Leukopenia

Leukopenia is a condition wherein the leukocyte count in the blood is low. Low WBC or White Blood Cells indicate decrease in disease fighting cells circulating in the blood. Some of the common causes for low WBC count:

Viral infections Any viral infections may disrupt bone marrow function for a short duration thus producing low counts of white blood cells. Infections like typhoid, influenza may lower the white blood cell count.

Congenital disorders may weaken bone marrow function, a WBC spectrum test can confirm any such congenital disorder.

Kostmann's syndrome is a congenital disorder wherein the neutrophil production is low.

Myelokathexis Neutrophils fail to enter the blood stream.

Infectious disease HIV destroys the WBC and leaves the person susceptible to infections.

Malnutrition

Vitamin or mineral deficiencies

Parasitic diseases

Autoimmune disorders may destroy white blood cells or bone marrow cells.

Aplastic anemia In this condition the bone marrow does not produce enough of any of the cells including white blood cells. This condition may set in all of a sudden or can develop and progress gradually. Few drugs, pregnancy, radiation therapy or chemotherapy can trigger this condition.

Lupus is an auto immune disease wherein the body fights with its own immune system thus destroying white blood cells.

Chemotherapy and radiation therapy are used to kill cancerous cells. They however destroy healthy white blood cells thus leaving the patient with low WBC count. This is one major reason why cancer patients are unable to fight diseases or infections in general.

Leukemia is a type of cancer wherein the body produces too many white blood cells that are abnormal. These white blood cells are not active white blood cells that can fight infections. People down with leukemia have low white blood cell count as their bone marrow is producing more of the abnormal white blood cells.

Cancer may also damage the bone marrow.

Hyperthyroidism An overactive thyroid can produce lower number of white blood cells. The medication used for thyroid can reduce the white blood cell count in the blood.

Liver disorder/Spleen disorder Hypersplenism, in which blood cells are destroyed prematurely by the spleen. An enlarged spleen also known as splenomegaly can trigger low white blood cell count.