[Determination of normal values of extraesophageal reflux in 24-h two-channel pH testing].

Extraesophageal reflux (EER) causes multiple diseases of the upper aerodigestive tract. EER is diagnosed by two-channel pH testing. However, little data exist about normal values. Therefore, we performed ambulatory two-channel pH testing in healthy volunteers and determined normal values for the number of reflux episodes, fraction, and reflux area index. These values were determined for pH </=4 as commonly used as well as for pH </=5 because pepsin is still generated at a pH of 5. In 40 healthy volunteers, ambulatory 24-h two-channel pH testing was performed. Asymptomatic gastroesophageal reflux was excluded by the DeMeester index. Ten subjects with a DeMeester score >14.72 were excluded from the evaluation. In the other patients, the mean number of reflux episodes was 2.6+/-0.9 (95(th) percentile 4.4), the fraction of pH </=4 was 0.1+/-0.04% (95(th) percentile 0.2), and the reflux area index was 3.8+/-1.5 (95(th) percentile 6.8). Data for the threshold of pH </=5 were 10 times higher.