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Ingestion of Acidic Foods Mimics Gastroesophageal Reflux During pH Monitoring

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Ingestion of acidic foods may produce artifactual drops in pH to < 4 that may be difficult to differentiate from a true acid reflux event. We aimed to evaluate intraesophageal pH changes during the ingestion of acidic food and describe the frequency and implications of acidic food ingestion on ambulatory pH monitoring. Ten normal volunteers (six females; mean age, 34) underwent combined impedance–pH testing with a pH electrode placed 5 cm above the lower esophageal sphincter. Each volunteer received 50 ml each of acidic foods in random order. Nadir and mean pH for 30 sec after ingestion of each substance were recorded. Subsequently 100 randomly selected reflux monitor diaries were reviewed, searching for ingestion of acidic foods, and 100 pH tracings were reviewed to evaluate the impact of including/excluding meal periods on percentage time pH < 4 and DeMeester scores. All foods produced abrupt drops to pH < 4, in 80% of cases exceeding 30 sec. During ambulatory pH monitoring 78% of patients recorded ingestion of at least 1 of the 10 tested substances during meals, the majority admitting ingesting carbonated beverages. Not excluding meal periods would have led to the misinterpretation of 6–16% of tracings, depending on the criteria used to identify abnormal acid exposure. We conclude that ingestion of acidic foods is frequent and carries the risk of overdiagnosing GERD. Current findings support the recommendations to carefully instruct patients to record all oral intake and to exclude meal periods from the analysis.

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  1. Wo JM, Castell DO: Exclusion of meal periods from ambulatory pH monitoring may improve diagnosis of esophageal acid reflux. Dig Dis Sci 39:1601–1607, 1994

    Article  PubMed  Google Scholar 

  2. Castell DO: Ambulatory monitoring in esophageal disease. Gastroenterology 3:40–44, 1990

    Google Scholar 

  3. Bollschweiler E, Feussner H, Holscher AH, Siewert JR: pH monitoring: the gold standard in detection of gastrointestinal reflux disease? Dysphagia 8:118–121, 1993

    PubMed  Google Scholar 

  4. Jamieson JR, Stein HJ, DeMeester TR, et al.: Ambulatory 24 hr esophageal pH monitoring: normal values, optimal thresholds, specificity, sensitivity, and reproducibility. Am J Gastroenterol 87:1102–1104, 1992

    PubMed  Google Scholar 

  5. Ter RB, Johnston BT, Castell DO: Does meal exclusion improve accuracy of esophageal pH monitoring? J Clin Gastroenterol 1:314–316, 1997

    Article  Google Scholar 

  6. Dobhan R, Castell DO: Prolonged intraesophageal pH monitoring with 16-hr overnight recording. Comparison with “24-hr” analysis. Dig Dis Sci 37:857–864, 1992

    Article  PubMed  Google Scholar 

  7. Tuttle SG, Ruffin F, Bettarella A: The physiology of heartburn. Ann Intern Med 55:292–300, 1961

    PubMed  Google Scholar 

  8. Hollander F: What is pH? Explanation of various measures of acidity employed in gastro-esophageal reflux. Gastroenterology 4:497–508, 1945

    Google Scholar 

  9. Shoenut JP, Duerksen D, Yaffe CS: Impact of ingested liquids on 24-hr ambulatory pH tests. Dig Dis Sci 4:834–839, 1998

    Article  Google Scholar 

  10. Bennett JR: pH measurements in the oesophagus. Baillieres Clin Gastroenterol 1:474–476, 1987

    Article  Google Scholar 

  11. Grande L, Pujol A, Ros E, Garcia-Valdecasas JC, Fuster J, Visa J, Pera C: Intraesophageal pH monitoring after breakfast + lunch in gastroesophageal reflux. J Clin Gastroenterol 10:373–376, 1988

    PubMed  Google Scholar 

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Correspondence to Amit Agrawal.

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Agrawal, A., Tutuian, R., Hila, A. et al. Ingestion of Acidic Foods Mimics Gastroesophageal Reflux During pH Monitoring. Dig Dis Sci 50, 1916–1920 (2005).

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