Low white blood cell count refers to a decrease in the number of white blood cells.
The normal white blood cell count is 4-10×10/L, and may vary slightly depending on the individual testing facility and testing method, the normal reference range for white blood cells. A white blood cell count below 4×10/L is usually specified as leukopenia, which is a low white blood cell count.
There are many causes of leukopenia. Common causes include infectious diseases especially viral infections such as influenza, measles, viral hepatitis, chickenpox, rubella, cytomegalovirus, and other viral infections. Some bacterial infections such as Mycobacterium typhi, Mycobacterium tuberculosis, and sepsis can also cause leukopenia, which may also occur when the patient is old and frail, has chronic wasting disease, or is a patient with advanced malignancy combined with a serious infection.
Other causes include hematologic disorders (such as certain types of anemia, some types of leukemia, malignant histiocytosis, etc.), physicochemical radiation, side effects of certain medications (such as certain thyroid medications, diabetes medications, antibiotics, antipyretics, etc.), autoimmune system disorders, and other causes that may cause leukopenia.