Leukopenia primarily depends on the extent of the decrease in white blood cells, which can be classified into mild, moderate, and severe levels.

Mild leukopenia generally means less than 4.0 X 10⁹/L, and if granulocytes are decreased, it typically means an absolute value of granulocytes less than 2.0 X 10⁹/L. A lack of granulocytes indicates a more severe condition, usually less than 0.5 X 10⁹/L. For patients with mild leukopenia, special preventive measures are generally not necessary. However, for moderate and severe leukopenia, the greatest risk is an increased chance of infection, as white blood cells are a marker of our ability to defend against external threats. With fewer of these defensive guards, the probability of resisting infections and the chance of acquiring infections significantly increase. Therefore, for patients with moderate leukopenia, their rate of infection increases, and it is important to take precautions, reduce visits to public places, maintain hygiene, and eliminate chronic infectious foci.

For patients with severe leukopenia, aseptic isolation measures should be adopted. For patients who have infections, it is crucial to find sensitive antibiotics, preferably broad-spectrum antibiotics. If there is a concurrent fungal or viral infection, antifungal or antiviral medications should also be used, as the decrease in white blood cells can destroy a person's immune capacity, lowering immunity and increasing the chance of infections and the invasion of pathogenic bacteria, which in severe cases could even lead to sepsis or septic shock.