Low white blood cells are not necessarily a blood disorder. There are many conditions other than blood disorders that can cause a decrease in white blood cells, such as viral infections, drug intoxication, hypersplenism, etc. In addition, ionising radiation, antipyretic and analgesic drugs, and anti-tumour cytotoxic drugs can all cause a decrease in the number of white blood cells.
If multiple tests are abnormal, further tests such as peripheral blood sorting, bone marrow aspiration (with cytomorphology, genetic tests, etc.), and even imaging are required to clarify whether the disease is haematological.