Not stopping a PPI in time prior to certain tests
For certain tests, it is important to be aware that PPIs may influence the results. First, in patients suspected of having GORD who are scheduled for ambulatory pH-monitoring, which aims to determine the presence of abnormal oesophageal acid exposure, reflux frequency and symptom association with reflux episodes, we believe PPIs should be stopped 7 days in advance.15 This follows from a study by Hemmink et al., in which it was shown that testing off a PPI results in a higher diagnostic yield than testing on a PPI.15 This approach is adopted by the American College of Gastroenterology guideline on GORD, stating that as a true diagnostic test (for abnormal acid exposure) and for evaluation before considering surgery in a patient with NERD, an off therapy test is recommended.16 In patients who have refractory reflux symptoms, testing on or off a PPI is sometimes the subject of debate. Performing pH-monitoring combined with impedance in patients who have persistent reflux symptoms and previously documented GORD on a PPI, may be useful to evaluate PPI efficacy, adherence and association of complaints with non-acidic reflux.16
Second, PPIs have a suppressing effect on H. pylori, and testing for H. pylori while taking a PPI can give a false-negative result. This holds for the stool antigen test, urea breath test, rapid urease test, histology and culture; with the exception of serology. For these tests, it is advised to stop PPI therapy at least 2 weeks prior to testing to allow H. pylori to repopulate the stomach and increase the chance of a positive test.17
Third, in patients suspected of having a gastrinoma, it is important to realize that PPIs may influence test results when measuring gastrin and chromografin A levels. However, since withdrawal of PPIs in patients with possible Zollinger–Ellison syndrome can lead to serious complications and stopping PPI is not always necessary, the decision to stop should be made on an individual basis.18
The general advice for patients on a PPI who need to stop their medication for 1 or 2 weeks, is to temporarily switch to H2 antagonists or antacids.
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