What is the normal reference range for platelet counts in 10^9/L?

• A. 25-50
• B. 150-400
• C. 200-500
• D. 2000-4000

Answer: (B)

Understanding the normal platelet count range helps distinguish healthy variation from potential bleeding or clotting concerns. In most adults, platelets fall roughly between 150 and 450 x 10^9/L. This range is used because it covers the majority of healthy individuals and keeps clinicians alert to counts that are too low (risk of bleeding) or too high (risk of thrombosis or underlying disease).

Among the given options, 150-400 x 10^9/L best matches the typical reference interval many labs use, capturing the lower bound of normal and a reasonable upper bound for everyday practice. The other ranges either miss lower-end values that are still normal for some people (too high or too low for a true normal range) or describe values far outside the expected normal spectrum.