Gastric analysis (basal acid output) measures the amount of acid secreted by the stomach in baseline conditions. The most common uses for the test are:

• To diagnose pernicious anemia (caused by a deficiency of vitamin B12 as a result of a stomach problem) or achlorhydria (a lack of stomach acid)
• Pre-and post-operative tests of acid reducing surgery
• To diagnose Zollinger-Ellison syndrome and evaluate elevated serum gastrin levels (a condition in which too much acid is produced)
• Pre-and post-acid suppressing therapy (to assess adequacy of the drug dose)