Oxytocin levels in response to pituitary provocation tests in healthy volunteers.

Neither the arginine infusion nor the oral macimorelin test stimulates plasma oxytocin levels, whereas there was an increase with high variance upon hypertonic saline infusion. As a predictable rise in most participants is required for a reliable pituitary provocation test, none of the investigated pituitary provocation tests can be recommended diagnostically to identify patients with an oxytocin deficiency.