What is the normal RBC (red blood cell) count range?

• A. 2-4 x10^6/µL
• B. 3-5 x10^6/µL
• C. 4-6 x10^6/µL
• D. 5-7 x10^6/µL

Answer: (C)

RBC count measures how many red blood cells are in a microliter of blood. In adults, a normal reference range is roughly 4 to 6 million cells per microliter. This window ensures there are enough cells to carry oxygen to tissues without making the blood too viscous. Values below suggest anemia or blood loss, while values above can indicate polycythemia, dehydration, or adaptation to high altitude. While labs may vary slightly, 4–6 x 10^6/µL is the range that best represents a healthy adult in routine practice.