Differential White Blood Cell Count (diff count)
A Differential White Blood Cell Count (diff count) is a blood test that determines the percentage of each type of white blood cell (leukocyte) present in the blood. This test provides valuable information about the composition of the immune system and can help diagnose various conditions. The types of white blood cells counted in a differential count typically include neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Here’s how a differential count is used to evaluate different aspects of health:
- Infection: A differential count can help identify the specific type of infection or illness present. For example, an increased percentage of neutrophils (neutrophilia) often indicates a bacterial infection, while an increased percentage of lymphocytes (lymphocytosis) can suggest a viral infection.
- Inflammation: Inflammatory conditions can lead to changes in the differential count. For instance, an increase in the percentage of monocytes (monocytosis) may be seen in chronic inflammatory conditions or autoimmune diseases.
- Allergic Reactions: Elevated eosinophils (eosinophilia) may indicate an allergic reaction or parasitic infection. Eosinophils play a role in the body's response to allergens and parasites.
- Immune System Disorders: Abnormalities in the distribution of white blood cell types can be indicative of underlying immune system disorders. For instance, a decrease in lymphocytes (lymphopenia) may occur in conditions such as HIV/AIDS or other immunodeficiency disorders.
- Bone Marrow Disorders: Certain disorders affecting the bone marrow, such as leukemia or myelodysplastic syndromes, can cause abnormalities in the differential count. These abnormalities may include the presence of immature or abnormal white blood cells.
- Monitoring Treatment: Differential counts may be monitored over time to assess the effectiveness of treatment for infections, inflammatory conditions, or other medical issues.