**4.3 Pathophysiological differences**

Esophageal mucosa is more resistant to acid attacks, a critical pH is 4.0, cell death and mucosal injury occur below this point. Laryngeal mucosa damage occurs at a pH of 5.0 with short-term exposure. Laryngeal epithelium is up to 100 times more sensitive to pepsin damage than esophageal tissues, and according to some authors, it seems that pepsin plays a key role in the pathogenesis of laryngopharyngeal reflux [16]. Up to 50 GER episodes per day are considered within the normal range; however, LPR more than 3 times a week can lead to pathological changes in the laryngopharyngeal region [17]. GERD is associated with a higher body mass index (BMI), which is not observed in LPR [18]*.* As can be observed, GERD and LPR have some different etiological and pathogenic features, as shown in **Table 1**.

