Prolactinoma
About 30% of pituitary tumors produce a hormone called prolactin. Normally, prolactin is made by specialized pituitary cells called lactotrophs. Under normal circumstances, prolactin is secreted at the time of breast-feeding. Prolactin increases the production of breast milk and suppresses secretion of LH and FSH, causing loss of menstrual periods in a breast-feeding woman and protecting her from becoming pregnant at the time when all the energy is needed to feed the baby. The role of prolactin in men is not known. Prolactin secretion is regulated by a hypothalamic hormone called dopamine. Dopamine suppresses prolactin production, and any process that diminishes the production of dopamine or its flow to the pituitary may cause prolactin to rise.
Normally, blood levels of prolactin are below 20 ng/ml. They may change during the menstrual cycle, as a result of pain or simply throughout the day. This is why mildly elevated prolactin level (below 40 ng/ml) without appropriate symptoms should not necessarily be viewed as the evidence of a disease process: it needs to be repeated first.
Clinically, symptoms of prolactin excess are simply an exaggerated extension of prolactin's normal function. Instead of increasing milk production (galactorrhea) and suppressing menstrual periods (amenorrhea) in a breast-feeding woman, it will cause amenorrhea and galactorrhea without any relations to pregnancy or breast-feeding. In men, high levels of prolactin may cause hypogonadism: low blood testosterone levels, and decrease in sex drive (libido) and sexual function. Prolactinoma is a benign (non-cancerous) pituitary tumor composed of lactotrophs (prolactin-producing cells).
Most prolactinomas in women are small, less than 10 mm (1/2 inch) in diameter, but some may be larger, up to 3-5 cm (2 inches) in diameter. In men, many prolactinomas are already large at the time of diagnosis. The larger the tumor, the higher the prolactin.
Large tumors may press on the optic nerves causing loss of vision or occupy cavernous or sphenoid sinuses. Large pituitary tumors often cause headache.
| Service Name | Appointment |
|---|---|
| Adult Neurosurgery - Pituitary and Neuroendocinology Center | 734-936-5020 |
