When should a clinician perform gastric analysis?
D004381:Duodenal Ulcer / Q000175:diagnosis; D005744:Gastric Acid / Q000378:metabolism*; D006801:Humans; D010437:Peptic Ulcer / Q000175:diagnosis*; D013276:Stomach Ulcer / Q000175:diagnosis / Q000378:metabolism / Q000601:surgery; D014628:Vagotomy