Prolactinomas
Prolactinomas are uniformly benign tumors comprised of prolactin secreting cells found in the pituitary gland, located approximately 1.5 inches behind the bridge of the nose. Prolactinomas retain their responsiveness to the inhibitory effects of dopamine; therefore, their origin still remains somewhat nebulous. Hypotheses include: reduced dopamine concentrations in the pituitary portal system and vascular isolation of the tumor that precludes dopamine inhibition. Some have reported prolactinomas in 12% to 25% of women with secondary amenorrhea; however, the actual incidence is somewhat less. The incidence of prolactinomas in women with galactorrhea but regular menses is quite low. A pituitary microadenoma (tumor less than 1cm in diameter) or hyperplasia is the cause of hyperprolactinemia in most patients. In over one-third of women with hyperprolactinemia, a radiologic abnormality consistent with an adenoma is found. In the remainder, simple hyperplasia of the pituitary lactotrophs is assumed to be the cause. Most of these abnormalities are microadenomas (less than 1 cm), and patients can generally be reassured of a benign course of disease. Ergot alkaloids are the mainstay of therapy. In the United States, bromocriptine was approved for use in the United States to treat hyperprolactinemia caused by a pituitary adenoma. The ergot alkaloids increase dopamine levels, thus decreasing prolactin levels. Macroadenomas are pituitary tumors greater than 1 cm in size. Bromocriptine is the best initial and potentially long-term treatment option for macroadenomas, but transphenoidal surgery may be required. Reproductive endocrinologist have broad experience in evaluating and treating prolactinomas.
