Objective: The main objective of this work was to study plasma oxytocin concentration of children with psychosomatic recurrent abdominal pain and children with organic abdominal disease producing pain. Another objective was to study plasma oxytocin in children with psychosomatic recurrent pain over time and its relationship to other associated symptoms such as somatic pains and appetite.
Design: The concentration of oxytocin in plasma (fasting morning sample) was measured by radioimmunoassay in 48 children with abdominal pain, 32 of whom had psychosomatic recurrent abdominal pain according to previously defined criteria. Oxytocin levels were assessed in a separate group of 15 children with inflammatory bowel disease with abdominal pain and in a control group of 79 healthy school children.
Results: Plasma oxytocin concentration was significantly lower in children with recurrent abdominal pain of psychosomatic origin (P < 0.0001) and in the group of children with inflammatory bowel disease (P < 0.001) compared to controls. There was no difference between oxytocin levels of children with psychosomatic abdominal pain and those with inflammatory bowel disease. When repeated after one year, children with psychosomatic abdominal pain had an increase in mean plasma oxytocin level (P < 0.05). No relationship was found between specific symptoms and plasma oxytocin.
Conclusions: Plasma oxytocin level is low in patients with abdominal pain of psychosomatic origin and inflammatory bowel disease. Measurement of plasma oxytocin may be of some help in the differential diagnosis of recurrent abdominal pain, but does not differentiate between psychosomatic abdominal pain and pain associated with inflammatory bowel disease.