24-Hour Gastric Acid Test refers to the monitoring of different pH values in the stomach and esophagus to reflect the changes in gastric acid, and is mainly used to confirm the diagnosis of gastroesophageal reflux disease (GERD) and other diseases. 24-Hour Gastric Acid Test is used to monitor the PH changes in the stomach and esophagus through a 24-hour ambulatory gastric acid monitor utilizing a guidewire with pH sensing, which is slowly inserted into the esophagus through the nasal cavity. The 24-hour gastric acid test is generally used to diagnose whether a person has GERD with a normal gastroscopy, and the monitoring method is less invasive. After the 24-hour test, the results should be interpreted under a doctor’s supervision, dietary adjustments should be made, smoking and alcohol should be stopped, and a regular routine should be followed.