The importance of detecting pepsin to diagnose reflux

August 3, 2021

Gastro-oesophageal reflux disease (GORD) occurs when excessive amounts of stomach contents – including acid, bile, pepsin and digested food and drink – enter the lower oesophagus, causing symptoms such as heartburn and indigestion. Medication for reflux, such as proton pump inhibitors (PPIs), suppress stomach acid and help to relieve these ‘classic’ reflux symptoms.

However, sometimes reflux can extend much further, with stomach contents reaching beyond the upper oesophagus into the pharynx, larynx, airways and even the middle ear, causing damage to these sensitive areas. This is referred to as laryngopharyngeal reflux (LPR), extra-oesophageal reflux (EER), silent reflux or airways reflux. Symptoms can include hoarseness, sore throat, voice disorders, chronic coughing and asthma. PPIs are often ineffective at treating reflux that reaches beyond the lower oesophagus, suggesting stomach acid may not be the cause. Many researchers believe pepsin is to blame.

What is pepsin and how is it involved in reflux?


Pepsin was one of the first enzymes to be discovered. In 1836, Theodor Schwann identified an acidic substance that was able to convert nitrogen-based foods into water-soluble materials, and named it pepsin, from the Greek word for ‘digestion’. It is now known to play a role in the first stage of the breakdown of food, in which proteins are cleaved into peptides. Pepsin should only be found in the stomach, and so if it is identified in the upper GI tract, then it must have been refluxed. As the squamous cells that line the oesophagus are very sensitive, and there is little mucus to protect them, pepsin can cause significant damage to these tissues. The surface cells of the larynx and airways are even more sensitive to injury by pepsin. PPIs do not affect the production of pepsin, and so are ineffective against reflux symptoms caused by the enzyme.

Why detect pepsin?

Identifying pepsin outside of the stomach allows clinical diagnosis of reflux in patients suffering from atypical symptoms. It has been identified in the saliva of patients with reflux laryngitis, in the breath of those with lung disease, and even in the middle ear of glue ear sufferers. Since pepsin can have damaging effects to tissues exposed to it long term – including weakening protective proteins and damaging Golgi apparatus and mitochondria – it is important to identify pepsin reflux.

Detecting pepsin in saliva samples helps clinicians to pinpoint the cause of complex query reflux in patients where traditional subjective clinical indices (such as the Reflux Symptom Index (RSI) and Reflux Finding Score (RFS)) are often inconclusive.

Why use Peptest?

PeptestPeptest is a simple lateral flow test that measures pepsin in saliva samples. It has been shown to be an excellent biomarker for detecting airway reflux and LPR, with an overall sensitivity of 76.4 %. Traditional tests for reflux are invasive, time consuming, resource heavy and costly but Peptest offers an accurate, painless and inexpensive option. The test clearly indicates the presence of pepsin to differentiate between GORD, LPR and other conditions that present as reflux. Since it also provides a quantitative measurement of pepsin in the sample, there is also the potential to use it for monitoring treatment efficacy.

Peptest, having a greater ability to diagnose LPR than other diagnostic methods such as RSI and RFS, serves as a useful adjunct to diagnosing pathological LPR by GPs, ENT specialists, gastroenterologists and allergists.

Find out more about PEPTEST

About BIOHIT HealthCare

BIOHIT HealthCare is a Finnish biotech company, headquartered in Helsinki, that specialises in the development, manufacture and distribution of kits and assays for the screening, diagnosis and monitoring of digestive diseases. Its core disease focus areas include stomach health and dyspepsia, reflux and acid dysregulation, Inflammatory Bowel Disease (IBD), functional gastrointestinal disorders (FGID), Irritable bowel syndrome (IBS), and gut microbiota dysbiosis. Innovating for Health

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