Since internists, pediatricians, and family practitioners all see patients with gastrointestinal symptoms, they all are called upon to diagnose and treat lactose intolerance. If their attempts to diagnose and treat do not result in adequate clinical benefit, patients usually will be referred to a gastroenterologist, an internist or pediatrician specially trained in diseases of the gastrointestinal tract. These specialists will be able to diagnose and treat causes of symptoms other than lactose intolerance.