Plasma, salivary, and urinary oxytocin in anorexia nervosa: a pilot study.

Although oxytocin (OT) has the potential to be an informative biomarker of social functioning in patients with eating disorders, the burden of invasive blood draws or lumbar punctures limits OT study. Salivary and urinary OT measurements may be advantageous, as they require less invasive sampling techniques which could be conducted in a wider variety of settings. Yet, the degree to which the concentration of OT in these fluids is correlated with blood levels is uncertain, as is the impact of vomiting on salivary secretion of OT. Therefore, we compared contemporaneously sampled OT concentration in blood, saliva, and urine from twenty women acutely ill with anorexia nervosa. Salivary OT was positively correlated with plasma OT in patients with no history of self-induced vomiting (r=0.89), but correlation was lower in those with recent history of self-induced vomiting (r=0.42). Urinary and plasma OT were not well-correlated(r=0.13), suggesting preliminarily that collection of plasma OT remains the method of choice. Self-induced vomiting in eating disorders may limit the applicability of salivary sampling for OT.