An experienced endocrinologist, Dr. Jane Schlecker treats patients with conditions like hyperprolactinemia and diabetes mellitus at her private practice in New York City. When a patient is diagnosed with hyperprolactinemia, it means he or she exhibits an excess of prolactin, which is a hormone that promotes milk production in women. It can arise from a variety of sources, including a prolactin-secreting tumor called a "prolactinoma," as a side effect of medication, or from a tumor growing near or on the pituitary gland.