Author: MAI Medical Information Team ·
Updated: 2026-04-15 ·
Reviewed by: Medical Information Team ·
Sources: WHO, UpToDate, PubMed
White Blood Cell Count: Normal Range, High & Low WBC Explained
What Are White Blood Cells?
White blood cells (WBC, leukocytes) are a key part of your immune system. They fight infections caused by bacteria, viruses, and other pathogens. A WBC count is part of a standard Complete Blood Count (CBC) test.
WBC Normal Ranges
| Age Group | Normal Range (x109/L) |
|---|---|
| Adults | 4.0–11.0 |
| Children (6-17 yrs) | 4.5–13.5 |
| Infants | 6.0–17.5 |
High WBC (Leukocytosis)
Common causes: bacterial infection, inflammation, physical stress, allergic reactions, and in rare cases leukemia. A high count usually indicates your body is fighting an infection.
Low WBC (Leukopenia)
Common causes: viral infections, autoimmune diseases, bone marrow disorders, chemotherapy, and certain medications.
MAI Tip: If your WBC count is outside the normal range — don't panic. Upload your blood test to MAI and our AI will explain possible causes and whether additional tests are needed.
⚠️ Important: This article is for informational purposes only and does not constitute medical advice.
Always consult your doctor before making health decisions.
Sources: World Health Organization (WHO), UpToDate Clinical Reference, PubMed Medical Research Database.
Sources: World Health Organization (WHO), UpToDate Clinical Reference, PubMed Medical Research Database.
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