Esophageal pH monitoring developed a dependable external reference electrode. Using this technique to monitor esophageal acid exposure patients for periods up to 24 hours, DeMeester and Johnson were able to identify the most important parameters of esophageal acid exposure, and they developed a composite pH score to quantify gastroesophageal reflux. The initial 24-hour pH studies required hospitalization until the introduction of microcircuits in the 1980s that allowed portable esophageal pH monitoring in an outpatient setting. Gastroesophageal reflux disease (GERD) is a common disease in western countries. In the United States, 7% of the population experiences heartburn daily and 44% at least once a
Fecal pH test Fecal pH test A fecal pH test is one where a specimen of feces is tested for acidity in order to diagnose a medical condition. Human feces is normally acidic. An acidic stool can indicate a digestive problem such as lactose intolerance or a contagion such as "E. coli" or rotavirus, or overgrowth of the acid producing bacteria (such as lactic acid bacteria for instance). The average pH for a healthy person is a pH of 6.6. The test is fast and can be performed in a doctor's office. A patient must not be receiving antibiotics. At least half a