A white blood cell count of 247/mL means a white blood cell count of 0.247 x 10^9/L, which is more severe and classified as severely decreased. Leukocyte count generally refers to the number of white blood cells in the peripheral blood, under normal circumstances should be maintained within the range of 4,000 to 10,000/mL, once lower than 4,000/mL range (4 × 10^9/L), it is considered leukopenia, and 247/mL is significantly lower than the normal level of severe leukopenia, which needs to be taken seriously. Severe leukopenia can be seen in acute hematopoietic arrest, aplastic anemia, myelodysplastic syndromes, myelosuppressive phase after chemotherapy, and severe infections. It can lead to weakening of immunity of the patient, and is very likely to be life-threatening due to serious complications, so it is necessary to find out the cause as soon as possible under the guidance of a physician and receive standardized treatment.