Medical Laboratory Scientist (MLS) ASCP Practice Exam 2025 - Free Practice Questions and Study Guide

The normal range for partial pressure of oxygen (pO2) in blood gas analysis is widely accepted to be between 80-100 mmHg at sea level. This range reflects the amount of oxygen dissolved in the plasma and is indicative of the efficiency of pulmonary gas exchange. An arterial pO2 within this range suggests that the body is adequately oxygenating blood.

Choosing the range of 85-105 mmHg is correct because it captures the accepted normal physiological variation due to factors such as altitude and individual health status, while still being primarily representative of normal pO2 levels. Values below this range may indicate hypoxemia, while values above may suggest hyperoxia, both of which can have clinical significance.

Other ranges provided do not encompass the standard normal range accurately. For instance, the ranges of 70-80 mmHg and 80-90 mmHg fall short of capturing the wider normal pO2, particularly in healthy individuals at sea level. The range of 105-115 mmHg reflects elevated oxygen levels that are not typically seen in a healthy population under normal conditions. Thus, the chosen range offers the best approximation of normal arterial oxygen levels.