Can prolactin levels be decreased in a pituitary (Pituitary gland) adenoma?

From the Guidelines

Yes, prolactin levels can be decreased in patients with pituitary adenomas, particularly prolactinomas, through medical treatment with dopamine agonists, such as cabergoline, which is the preferred first-line therapy due to its superior effectiveness and lower adverse effect profile 1. The first-line therapy for reducing prolactin levels in patients with pituitary adenomas is dopamine agonists, which mimic dopamine's inhibitory effect on prolactin secretion.

• Cabergoline is generally preferred due to better efficacy, fewer side effects, and more convenient dosing, with a typical starting dose of 0.25mg twice weekly, gradually increasing to 0.5-1mg twice weekly as needed 1.
• Treatment with dopamine agonists typically leads to normalization of prolactin levels within weeks to months, along with tumor shrinkage in 60-70% of cases, and improvement of symptoms such as galactorrhoea, menstrual irregularities, and sexual dysfunction 1.
• Medication is usually continued for at least 2 years, with some patients requiring lifelong therapy, and side effects may include nausea, dizziness, and headache, which often improve with continued use or dose adjustments.
• For patients who don't respond to medical therapy or have other complications, such as cerebrospinal fluid leak or apoplexy, surgical removal of the adenoma may be necessary to reduce prolactin levels 1.
• It's worth noting that the effectiveness of dopamine agonists can vary depending on the size and type of the adenoma, as well as the patient's age and overall health, and that regular monitoring of prolactin levels and tumor size is necessary to adjust the treatment plan as needed 1.

From the FDA Drug Label

Clinically, bromocriptine mesylate significantly reduces plasma levels of prolactin in patients with physiologically elevated prolactin as well as in patients with hyperprolactinemia. The inhibition of physiological lactation as well as galactorrhea in pathological hyperprolactinemic states is obtained at dose levels that do not affect secretion of other tropic hormones from the anterior pituitary Bromocriptine mesylate is a nonhormonal, nonestrogenic agent that inhibits the secretion of prolactin in humans, with little or no effect on other pituitary hormones, except in patients with acromegaly, where it lowers elevated blood levels of growth hormone in the majority of patients Effective treatment with bromocriptine mesylate leads to a reduction in hyperprolactinemia and often to a resolution of the visual impairment

Prolactin Reduction in Pituitary Adenoma:

• Bromocriptine mesylate can decrease prolactin levels in patients with hyperprolactinemia, including those with pituitary adenoma.
• The reduction in prolactin levels can lead to a resolution of symptoms such as galactorrhea and visual impairment.
• Bromocriptine mesylate is a dopamine receptor agonist that inhibits the secretion of prolactin from the anterior pituitary, making it an effective treatment for hyperprolactinemic states, including pituitary adenoma 2, 2.

From the Research

Prolactin Decrease in Pituitary Adenoma

• Prolactinomas are the most common functional pituitary tumors, accounting for 40% of all pituitary adenomas 3.
• Medical treatment with dopamine agonists, mainly cabergoline, is considered the primary therapy for prolactinomas, with prolactin normalization achieved in 80-90% of cases 3, 4.
• Dopamine agonist therapy is the primary therapy for prolactin-secreting adenomas and usually results in normoprolactinemia, eugonadism, and tumor reduction 5.
• Cabergoline is superior to bromocriptine with regard to efficacy and tolerance 4, 5.
• A standardized, individualized, stepwise, dose-escalating regimen of cabergoline may normalize prolactin levels and reduce prolactinoma size in patients who were otherwise considered to be dopamine agonist resistant 4.
• Other therapeutic options for prolactinomas include temozolomide, aromatase inhibitors, the somatostatin receptor ligand pasireotide, peptide receptor radionuclide therapy, immune-checkpoint inhibitors, tyrosine-kinase inhibitors, or everolimus 3.

Treatment Outcomes

• Prolactin normalization is achieved in 80-90% of prolactinomas treated with cabergoline 3.
• Temozolomide is effective in 40-50% of treated lactotroph tumors showing at least a partial response 3.
• Dopamine agonists have been used off label in patients with acromegaly, Cushing disease, and nonfunctioning adenomas, with variable success rates 5.
• Withdrawal of cabergoline can be attempted in patients with normal prolactin levels on low doses of medication and evidence of radiographic tumor involution 5.