Chronic Cough Due to Gastroesophageal Reflux Disease: Laboratory Testing
A number of potential risk factors for GERD have been identified. These include the following: drugs such as alendronate, oral corticosteroids, bronchodilators such as inhaled (32-adrenergic agonists and theophylline in some studies, progesterone, calcium channel-blocking agents,anticholinergic agents, morphine, and meperidine; obesity; smoking; vigorous exercise,; alcohol; caffeine in some studies; fatty foods, chocolate, carminatives, and irritating foods such as citrus juices and tomato products; prolonged gastric intubation; lung transplanta-tion; following pneumonectomy and peritoneal dialysis; and a variety of respiratory diseases such as asthma and obstructive sleep apnea. While it is not known what their presence means from a diagnostic standpoint in the evaluation of cough, the failure to correct or eliminate risk factors may assume importance during treatment. This will be discussed in the “Treatment” section. Based on a small genome-wide scan of families affected by severe pediatric GERD, followed by haplotying and by pairwise and multipoint linkage analyses based on epidemiologic studies, it is possible that GERD, in the future, may one day be found to be a genetically determined disease, and that genetic testing may be able to predict who is at risk for GERD and its varied presentations. this
Depending on the information that is sought, there are a variety of laboratory tests from which to choose. For example, the results of esophageal manometry to assess for a hypotensive lower esophageal sphincter and barium esophagography to assess for the presence of a hiatus hernia may suggest that there is the potential for GERD. While barium esophagography results may suggest that there is mucosal injury, esophagoscopy with mucosal biopsy can confirm it. Intraesophageal hydrochloric acid infusion while monitoring symptoms (ie, the Bernstein test) may reveal esophageal mucosal acid sensitivity. Barium esophagography, radionuclide esophageal scintigraphy, and esophageal pH monitoring can assess for GER events. Dual esophageal and pharyngeal simultaneous pH monitoring can evaluate for gastropharyngeal GER events and their potential to cause laryngopharyngeal injury, and the risk of aspiration. A radionuclide gastric-emptying study with solids has the potential to assess for GERD that may be contributed to by delayed gastric emptying.