What is the normal white blood cell count?

• A. 5,000 to 10,000/mm3
• B. 1,000 to 2,000/mm3
• C. 20,000 to 25,000/mm3
• D. 50,000 to 60,000/mm3

Answer: (A)

Normal white blood cell count reflects the typical number of immune cells circulating in a healthy adult’s blood. The commonly cited range is about 5,000 to 10,000 white blood cells per cubic millimeter (per microliter) of blood. Some laboratories use a slightly wider range, around 4,000 to 11,000, but 5,000 to 10,000 is a standard reference. Values below this range indicate leukopenia, which can point to bone marrow suppression or certain medical conditions, while values well above the range indicate leukocytosis, which can occur with infections, inflammation, stress, or hematologic disorders. This is why 5,000 to 10,000/mm3 is considered the normal range.