The goal was to determine bile acids in human saliva using a sensitive ultraperformance liquid chromatography-tandem mass spectrometry analysis technique to identify quantitative variations in refractory gastroesophageal reflux disease (GERD) patients who were treated with proton pump inhibitors (PPIs) as compared to GERD controlled by proton pump inhibitor Saliva samples from two separate research were tested. The study compared the salivary microbiota of 20 healthy individuals and 20 patients with GERD symptoms who were treated with PPIs to assess any changes. In a follow-up exploratory study, saliva was collected from 34 patients with persisting GERD symptoms despite PPI therapy (refractory GERD), 30 healthy individuals, and 30 PPI-controlled GERD patients at 4 or more hours postmeal. Both healthy individuals and patients with PPI-controlled GERD had a total saliva bile acid increase for the first hour after eating a meal and returned to baseline levels four hours later in the meal-controlled pilot study. Researchers found no difference in bile acid levels between the 2 groups. The saliva from people with refractory GERD had significantly increased total bile acid levels when compared to healthy volunteers and patients on PPI therapy (P=0.0181). Bile acids might have been quantified in human saliva with a sensitive ultraperformance liquid chromatography-tandem mass spectrometry assay. An underlying disease may be indicated by increases above the threshold. The technique might have been utilized to investigate biliary reflux as a possible underlying cause of refractory GERD.