From the Guidelines
Prolactin is increased in prolactinoma. A prolactinoma is a benign tumor of the pituitary gland that produces excessive amounts of the hormone prolactin, leading to elevated serum prolactin levels, often significantly higher than normal ranges 1. Normal prolactin levels are typically below 25 ng/mL in women and below 20 ng/mL in men, but in patients with prolactinomas, levels can range from mildly elevated (50-200 ng/mL) in microadenomas to markedly elevated (often >200 ng/mL and sometimes >1000 ng/mL) in macroadenomas.
Key Points
- The increased prolactin causes various symptoms including galactorrhea (inappropriate milk production), menstrual irregularities and infertility in women, and decreased libido and erectile dysfunction in men.
- Treatment typically involves dopamine agonists like cabergoline or bromocriptine, which reduce prolactin secretion by binding to dopamine receptors on the tumor cells, as dopamine naturally inhibits prolactin release 1.
- These medications not only normalize prolactin levels but often shrink the tumor size as well, with cabergoline being the dopamine agonist of choice given its superior effectiveness and lower adverse effect profile.
Management
- Dopamine agonists are the first-line therapy for reducing serum prolactin concentrations and inducing tumor shrinkage in patients with prolactinoma, with cabergoline being the preferred option due to its longer half-life and greater affinity for the dopamine receptor 1.
- The use of dopamine agonists has been shown to induce normalization of prolactin levels, tumor shrinkage, resolution of visual field defects, normalization of menses, fertility, and sexual function, and resolution of galactorrhoea in a significant proportion of patients with prolactinoma.
From the Research
Prolactin Levels in Prolactinoma
- Prolactin levels are increased in prolactinoma, as indicated by the definition of hyperprolactinemia, which is commonly found in patients with prolactin-secreting pituitary adenoma (prolactinoma) 2.
- Serum prolactin levels above 200 microg/L are typically associated with a prolactin-secreting pituitary adenoma (prolactinoma) 2.
- The goal of treatment for prolactinoma is to reduce serum prolactin levels and tumor dimensions, which can be achieved with dopamine agonists in about 80% to 90% of patients 3.
Treatment and Prolactin Levels
- Dopamine agonists, such as bromocriptine, cabergoline, and quinagolide, are effective in reducing prolactin levels and tumor size in patients with prolactinoma 2, 4, 5.
- In some cases, prolactin levels may not be fully normalized with dopamine agonist therapy, and alternative treatments such as surgery or radiotherapy may be necessary 5, 6, 3.
- The management of dopamine agonist-resistant prolactinomas includes switching to a different dopamine agonist, dose escalation, or considering alternative treatments such as surgery or radiotherapy 5.