[Test of refractory gastroesophageal reflux disease]

It should be considered that the causes of refractory gastroesophageal reflux disease (GERD) are multifactorial. Esophageal manometry study is useful when we make distinguish patients with esophageal motility disorders from those with refractory GERD. Endoscopic ultrasonography is also performed to observe the thickness of esophageal wall which represents the disturbance of esophageal motor function. Esophageal pH monitoring is useful to detect the acid clearance disturbance and phenomenon of nocturnal acid breakthrough. Both are occurred at night, and are recently considered to be responsible for refractory GERD. Catheter-free pH monitoring system, Bravo, makes it possible to measure esophageal pH under quite physiological conditions. Genotype of CYP2C19 is sometimes checked in patients with PPI resistance GERD. Intra-gastric pH with omeprazole and lansoprazole depends on patient's genotype of CYP2C19. Monitoring of 24-hour bilirubin, Bilitec, is also useful to detect duodeno-gastro-esophageal reflux.