Personalized medicine in functional gastrointestinal disorders: Understanding pathogenesis to increase diagnostic and treatment efficacy

Table 1 Commonly encountered gastrointestinal diseases and their phenotypic presentations (symptoms and pathophysiology) and management principles

Disease phenotype	Symptoms	Pathophysiology	Diagnosis	Treatment options or selections
Functional dyspepsia	Postprandial fullness, early satiety; Epigastric pain, epigastric burning	Alterations in gastric emptying and/or gastric accommodation	Gastric emptying study; Gastric accommodation studies (SPECT, MR imaging)	Reduced GE and/or GA → prokinetic or gastric relaxants; Normal GE and GA → central pain modulator
Outlet dysfunction constipation	Constipation, abdominal pain	Pelvic floor dyssynergia	Anorectal manometry with balloon expulsion test; MR defecography	Pelvic floor rehabilitation with biofeedback training
Slow transit constipation	Constipation, abdominal pain	Decreased colonic motility	Colon transit studies with radiopaque markers or scintigraphy or wireless motility capsule	Prokinetic agents; Secretory + stimulant laxatives; Total colectomy with ileo-rectal anastomosis
Bile acid diarrhea	Diarrhea; Abdominal pain	Increased bile acid synthesis/ decreased bile acid absorption	Total fecal bile acids; Fecal bile acid composition; Serum 7-α-hydroxy-4-cholesten-3-one	Bile acid binders

GE: Gastric emptying; GA: Gastric accommodation; SPECT: Single-photon emission computed tomography; MR: Magnetic resonance.