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Pepsin Test Can Better Detect Aspiration Reflux, Chronic Lung Disease

by David Bronstein •

Dr. Kerschner stressed, however, that the need for more research should not obscure the importance of his team’s research. “I think we’ve added to the evidence that underdiagnosed AERD—what we call ‘silent aspiration’—is an important contributor to altered or diminished lung function and that you need a reliable test such as the Western blot pepsin assay that can accurately tell you that such a disease process is indeed taking place,” he said. “Well, you truly did not have such an assay until we completed our study.”

Pepsin: Where Does It Come From and Can It Be Treated?

When otolaryngologists consider the damaging effects of excess reflux of stomach contents, acid is usually thought to be the offending agent. Why, then, are researchers now looking at pepsin’s role in this process? The answer, to borrow a phrase from real estate, is location, location, location, according to experts in reflux disease.

Although acid is indeed the culprit in cases of gastroesophageal reflux disease (GERD), a growing body of evidence suggests that pepsin, an enzyme, is the substance that causes the most damage when the reflux extends beyond the upper esophagus and reaches the pharynx, larynx and lungs. Once present in sufficient amounts, studies have shown, pepsin can cause significant damage by adhering to laryngeal cells and breaking down proteins, among other injurious effects (published online November 10, 2011. Int J Otolaryngol. doi:10.1155/2012/646901). Thus, it’s not surprising that pepsin has been linked to serious lung disease, including acute exacerbations of idiopathic pulmonary fibrosis (Eur Respir J. 2012;39:352-358).

As for the theory that pepsin is a relatively unimportant local phenomenon—that is, something produced endogenously in the upper airways—“the literature is pretty clear on this: it shows that pepsin is produced only in the stomach,” Dr. Bishop said. “If you find it in the airways, you know that stomach contents, in some amount, are getting into those airways and potentially causing some damage.”

Assuming the recent work by Kerschner and colleagues linking pepsin to chronic pulmonary disease is confirmed in larger trials, the next question becomes, how should otolaryngologists treat a patient who has a positive pepsin test?

“I think such a result would make us refer patients not to increased acid suppression, but instead to antireflux surgery such as Nissen fundoplication, because remember, pepsin is not an acid—it’s an enzyme and is not affected by acid blocker therapy to any significant degree,” Dr. Bishop said.