White Blood Cells (WBC)
White blood cells (leukocytes) defend against infections and regulate immune responses. Count changes signal infection, inflammation, or blood disorders.
Normal ranges
Adults: 4.0–9.0 ×10⁹/L.
Units: ×10⁹/L
Causes of deviations
Low levels:
Viral infections, autoimmune disease, chemotherapy, bone marrow disorders.
High levels:
Bacterial infection, inflammation, stress, smoking, leukemia.
When to see a doctor
If persistently abnormal, or with fever, fatigue, or frequent infections.
This information is for educational purposes and does not replace medical advice.
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