An arterial blood gas test (ABG test) measures the levels of oxygen and carbon dioxide in the blood from an artery. This test helps evaluate lung function and the body's acid-base balance, which is crucial for maintaining various metabolic functions, such as energy production and enzyme activity. It is commonly used to diagnose and monitor conditions affecting the lungs, such as respiratory disorders, and to check the effectiveness of oxygen therapy. An ABG test provides important information about how well the lungs are delivering oxygen to the blood and removing carbon dioxide from it.