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Basal Acid Output (BAO)

This is an invasive test performed on the stomach in order to measure acidity. The test measures the Basal Acid Output (BAO, the normal minute to minute amount of acid being produced) and the Maximal Acid Output (MAO, the largest amount of acid produced by the stomach). In gastrinoma, the BAO is generally more than 60% of the MAO, or greater than 10 mmol/hour, demonstrating a significant excess of acid production.