American Association of Critical-Care Nurses (AACN) Certification Practice Test

What is the normal percentage range of eosinophils in the blood?

1. 1%

2. 3%

3. 5%

4. 10%

The correct answer is: 3%

The normal percentage range of eosinophils in the blood is typically around 1% to 4% of the total white blood cell count, though some references may round this to approximately 3%. Eosinophils are a type of white blood cell that play a crucial role in the body’s immune response, particularly in combating parasitic infections and in allergic reactions. When evaluating eosinophil levels, medical professionals often consider various factors, including the patient's overall health, symptoms, and medical history. While individuals may occasionally have a percentage as high as 5% in specific situations, this is not the standard range for healthy individuals. The higher percentages listed in the incorrect choices would indicate either an abnormal increase in eosinophils due to infections, allergic responses, or other medical conditions. Thus, identifying the normal range is essential for evaluating potential health issues and guiding clinical decisions.