Prolactin (PRL) plays a central role in a variety of reproductive functions. Initially, even though this hormone was recognized in relation to lactation in women, lately immense interest has been focused on prolactin with respect to its effect on reproduction. Hyperprolactinemia is a condition of elevated prolactin levels in blood which could be physiological, pathological, or idiopathic in origin. Similarly elevated prolactin levels could be associated with severe clinical manifestations on one side of the spectrum or be completely asymptomatic on the other side.
Unlike other tropic hormones secreted by the anterior pituitary gland, prolactin secretion is controlled primarily by inhibition from the hypothalamus and it is not subject to negative feedback directly or indirectly by peripheral hormones. It exercises self-inhibition by a counter-current flow in the hypophyseal pituitary portal system which initiates secretion of hypothalamic dopamine, as well as causes inhibition of pulsatile secretion of gonadotropin releasing hormone (GnRH). This negatively modulates the secretion of pituitary hormones responsible for gonadal function.