Psychogenic RAP seems to be associated with stress, apprehension or depression. Its pathophysiology is not clear. The factors that contribute to stress are relative, and patients sensitive to RAP seem to be easily stressed, either because of events at home (e.g., recent illness, financial problems, separation and loss) or at school (e.g., concerns about their performance, interrelationships with teachers and classmates). The RAP itself is more stressful because of new problems (e.g., frequent absences, isolation from classmates) or because it is mixed with pre-existing problems (e.g., peer confrontation). The history should begin with the initial pain episode, the frequency, nature, and location of the pain; the relationship to diet, bowel movements, and elimination; and the outcome of various treatments (e.g., changes in position, home therapy, OTC or prescription medications). Information obtained from the parents (or other persons caring for the child) is also helpful. Their differing opinions about the occurrence of abdominal pain and how it occurs can help to observe the impact of the family situation on the child and can help to provide an approach to the management of abdominal pain that satisfies the parents as well. The potential role of parental involvement together in the onset, persistence, and overcoming of pain is emphasized. Functional RAP is best diagnosed through a detailed history that identifies relevant symptoms or contributing factors (e.g., review of 24-hour diet to determine if food allergies or poor diet are the cause of pain, menstrual history, etc.). Functional RAP differentials include: poor diet, inadequate toilet training, constipation or stool retention and fecal incontinence due to the use of a regular potty (which may be too large for the child to fear falling), dysmenorrhea, intermenstrual pain, and lactose intolerance secondary to a physiologic decrease in lactase activity that occurs between 10 and 20 years of age in patients who tend to start with lactose intolerance because the pain occurs after 2 hours of breastfeeding or dairy products. Lactose intolerance is not suspected.