A low white blood cell count of 3.8 x 10^9/L needs to be judged as serious depending on the specific cause and condition. It is usually less serious if it is only some viral infection, while it is more serious if it is caused by blood system diseases, etc.
The normal value of white blood cells is (4~10) x 10^9/L, so 3.8 x 10^9/L is a low level. If the white blood cell count is consistently below 4.0 x 10^9/L it is considered leukopenia. In most cases, leukopenia is the result of neutropenia.
Common causes of leukopenia include certain viral infections such as influenza, viral hepatitis, chickenpox, and gram-negative infections such as typhoid fever; hematologic disorders such as aplastic anemia; certain medications such as chloramphenicol; and autoimmune disorders such as systemic lupus erythematosus and hypersplenism.
The specific severity of the disease can only be determined by further examination after identifying the cause of the disease. It is recommended to consult a doctor in time for standardized diagnosis and treatment.