Differentiating gastroparesis from functional dyspepsia is no longer sufficient

We read with interest the commentary by Camilleri and Talley on whether gastroparesis and functional dyspepsia (FD) are ‘really ‘interchangeable’ diseases’.1 Their significant efforts to improve the reliability of gastric emptying testing will strengthen both care and trials. However, we submit that their careful analysis also serves as a starting point for deeper inquiry, because differentiation by emptying testing alone is no longer sufficient. It is now widely accepted that both FD and gastroparesis labels reflect umbrella syndromes grouping diverse underlying pathophysiologies. These underlying mechanisms are shared by both syndromes, but vary between individual patients. Some are motor, some are sensory, some overlap. They include interstitial cell of Cajal (ICC) deficits, impaired accommodation, autonomic and pyloric dysfunction, antral hypomotility, immune activation, hypersensitivity and gut-brain axis dysregulation.2 Several such factors may delay gastric emptying, but delayed emptying is specific to none of them. Emptying is thus best appreciated as an integrative measure of gastric function, and while clinically important, only captures one disease axis among many. Confronting these overlapping and heterogeneous mechanisms is essential, because it helps explain decades of …