Most frequent type of hyperfunctioning pituitary adenoma, accounts for 30% of all recognized pituitary adenomas.
Prolactinomas are the most common secretory tumor accounting for 60% of all pituitary adenomas and more than 75% of pituitary adenomas in women.
Micro prolactinomas have a female: male ratio of 20:1, are usually stable and slow growing, with continue growth after diagnosis in less than 15% of cases.
Most patients with a pituitary mass and a serum prolactin level exceeding 150 ng/ millimeter are found to have a prolactinoma.
A prolactin level of more than 250 ng/mL is usually diagnostic of a macroprolactinoma, and the tumor mass usually correlates with the serum prolactin level.
Approximately 99% of patients with serum prolactin levels greater than 250 µg per liter have prolactinoma.
Large prolactinomas measuring greater than 10 mm in diameter are aggressive lesions and account for less than 5% of prolactin tumors that are characterized by very high prolactin levels of greater than 1000 ng/mL and the male: female ratio of 9:1.
Prolactinomas are generally larger in men, with higher prolactin levels and and more aggressive.
A benign adenoma tumor of the pituitary gland that produces a hormone called prolactin.
Uncontrolled replication of lactotroph cells are the most common type of pituitary tumor.
It is the most common type of functioning pituitary tumor.
Prolactinomas account for approximately 25-30% of all pituitary adenomas.
Symptoms relate to too much prolactin in the blood or those caused by pressure of the tumor on surrounding tissues: headaches of vision changes as the tumor compresses other structures.
Prolactin can affect the ability to produce other hormones such as reducing production of testosterone in men, and even more rarely make produce gallactorrhea in men.
Oligomenorrhea occurs in approximately 93% of women with prolactin secreting pituitary adenomas, and approximately 85% of these women have galactorrhea.
Hypogonadism is a consequence of hyperprolactinemia, and may cause infertility in both women and men.
In women hyperprolactinemia may cause a shorter luteal phase, contributing to infertility.
People with hyperprolactinemia have skeletal fragility, increased rates of fractures, which are most likely due to hypogonadism secondary to hyperprolactemia.
30 % of people with hyperprolactinemia have vertebral fractures.
The pituitary gland sits in the sella turcica.
Prolactin stimulates the breast to produce milk.
Prolactin has other functions such as regulation of mood.
Prolactin levels are usually higher during pregnancy and after childbirth.
Following delivery of a baby prolactin levels normalize in a few weeks after breastfeeding is discontinued.
Each time milk is dispursed, prolactin levels rise; to maintain milk production.
Prolactin in males is responsible for the sexual refractory period after orgasm and excess levels can lead to erectile dysfunction.
Prolactinoma s are classified as a microprolactinoma (<10 mm diameter) or macroprolactinoma (>10 mm diameter).
Microprolactinomas are much more common than macroprolactinomas.
Symptoms associated with prolactinoma are divided into those that are caused by increased prolactin levels or mass effect.
Symptoms of increased prolactin levels include:
Amenorrhea
Galactorrhea
Loss of axillary and pubic hair.
Hypogonadism
Gynecomastia
Erectile dysfunction
Symptoms caused by mass effect include:
Bitemporal hemianopsia
Vertigo
Nausea, vomiting
The cause of pituitary tumors is unknown.
Experiencing stress can significantly raise prolactin levels.
Most pituitary tumors are sporadic.
The majority of moderately raised prolactin levels of up to 5000IU/mL are not due to microprolactinomas but other causes.
Causes of excess prolactin include the effects of some prescription drugs, other pituitary tumours, normal pregnancy and breastfeeding.
The chemical Bisphenol-A has been shown to lead to hyperprolactinaemia and growth of prolactin-producing pituitary cells.
Testing prolactin blood levels in women with unexplained galactorrhea or irregular menses or infertility, and in men with impaired sexual function and, in rare cases, milk secretion is appropriate.
Magnetic resonance imaging (MRI), which is the most sensitive test for detecting pituitary tumors and determining their size.
Treatment efforts: return prolactin secretion to normal, reduce tumor size, correct any visual abnormalities, and restore normal pituitary function.
With the treatment prolactin levels should be normalized, sexual function and fertility restored, galactorrhea halted, and the tumor mass eliminated or reduced, while pituitary function is retained.
Prolactinomas are non-cancerous.
Exercise can significantly reduce stress and, thereby, prolactin levels.
With very large tumors, only partial reduction of the prolactin levels may be possible.
Dopamine normally inhibits prolactin secretion.
Treatment with bromocriptine, cabergoline or Quinagolide drugs that act like dopamine,and are dopamine agonists.
Dopamine agonists shrink the tumor and return prolactin levels to normal in approximately 80% of patients.
Bromocriptine and cabergoline are approved for treating hyperprolactinemia and prolactinomas.
These drugs, activate D2 dopamine receptors on pituitary lactotrophs, decreasing serum prolactin and shrinking the adenoma.
Bromocriptine is associated with nausea and dizziness and hypotension in patients with already low blood pressure readings.
Bromocriptine treatment is started slowly, and Prolactin levels often rise again in most people when the drug is discontinued.
Bromocriptine is safe to use during pre-conception, but should be discontinued in pregnancy for microprloactinomas.
In patients with macroprolactinomas and pregnancy, the tumor may enlarge and abut the optic chiasm, and should be continued in these cases.
If the prolactin levels remain normal, the drug may be reduced or discontinued.
Dopamine agonist therapy is continued indefinitely in patients whose adenomas do not completely regress with therapy.
Withdrawal of dopamine agonist can be attempted for patients who attain normal prolactinemia and complete tumor aggression after at least two years of treatment.
There is an increased success of remission of prolactin levels after discontinuation in patients having been treated for at least 2 years prior to cessation of bromocriptine.
Because bromocriptine requires daily dosing the drug is rarely used.
Cabergoline associated with side-effects: nausea and dizziness, but are less common and less severe than with bromocriptine.
Cabergoline has a long half-life of the drug (4–7 days), and may cause hypotension.
Cabergolin administed once a twice a week low is prolactin levels in about 83% of patients and normalizes macro prolactinomas in approximately 65% of patients with normalization of prolactin levels and reduction in tumor mass.
Hyperprolactinemia remits in up to 20% of patients after tapering and discontinuation of Cabergoline.
Surgery is considered if medical therapy cannot be tolerated or if it fails to reduce prolactin levels, restore normal reproduction and pituitary function, or reduce tumor size.
Medical therapy that is only partially successful should be continued, and combined with surgery or radiation treatment, if needed.
Surgical results depend a on tumor size and prolactin level.
In patients with micro prolactinomas, transphenoidal resection results in normal prolactin levels in 71% of patients, and initial cure rates may exceed 90% when resection is performed by high-volume surgeons.
About 50% of macroprolactinomas remit, and persistent, postoperative hyperprolactinemia arises from tumor remnants.
The use of dopamine agonists and the long-term risk of postoperative recurrence have discouraged surgery is a primary treatment for macro prolactinomas.
As expected the higher the prolactin level the lower the chance of normalizing serum prolactin.
Surgery corrects prolactin levels in 80% of patients with a serum prolactin less than 250 ng/ml.
With large tumors that cannot be completely surgically removed, drug therapy may be able to return serum prolactin to the normal range after surgery.
Surgical series show that 20 to 50% of prolactinomas treated by surgery will recur, usually within five years.
95% of cases of microprolactinoma tumor will not show any signs of growth after a 4 to 6-year period.
Macroprolactinomas often require more aggressive treatment otherwise they may grow.
Regular monitoring to detect any changes in the tumor is recommended.
Hyperprolactinemia can cause reduced estrogen production in women and reduced testosterone production in men.
After successful medical therapy women can have a normal pregnancy.
The pituitary enlarges and prolactin production increases during normal pregnancy in women without pituitary disorders.
Women with prolactin-secreting tumors may experience further pituitary enlargement during pregnancy.
Damage to the pituitary or eye nerves occurs in less than one percent of pregnant women with prolactinoma.
The risk of damage to the pituitary or eye nerves is greater in pregnant women with large tumors.
Estimates of damage to pituitary it eye nerves isvas high as 25% with large lesions.
For women who complete a successful pregnancy, the likelihood of further successful pregnancies are extremely high.
As soon as a patient with prolactinoma is pregnant, it is advised to stop taking bromocriptine or cabergoline.
Bromocriptine or cabergoline treatment may be renewed after delivery īand additional treatment may be required if the patient develops symptoms from growth of the tumor during pregnancy.
Patients with prolactinoma treated with bromocriptine or cabergoline may also take oral contraceptives, and Ppost-menopausal estrogen replacement is safe in patients with prolactinoma treated with medical therapy or surgery.
Autopsy studies indicate that 6-25% of the U. S. population have small pituitary tumors.
Forty percent of these pituitary tumors produce prolactin.
Most pituitary tumors are not considered clinically significant.
Significant pituitary tumors affect the health of approximately 14 out of 100,000 people.
Some growth hormone (GH)–producing tumors also co-secrete prolactin.
Sizes range from microadenomas to large lesions with mass effect.
Majority of lesions are composed of weakly acidophilic or chromophobic cells.
Using immunohistochemical stains identify prolactin within secretory granules in the cytoplasm of the cells.
Have a tendency to have dystrophic calcifications with psammoma bodies to extensive calcification of the entire mass.
Microadenomas can secrete enough prolactin to cause hyperprolactinemia and serum concentrations correlate with the size of the adenoma.
Increased prolactin levels causes amenorrhea, galactorrhea, infertility and decreased libido.
About 50% of women and 35% of men have galactorrhea and both suffer with reduced bone density, often associated with sex steroid hormone deficiency and an increased risk of vertebral fractures.
Diagnosis, especially between ages of 20-40, is easier to make in women than men because of the likelihood of abnormal menses.Underlies the diagnosis of amenorrhea in almost 25% of cases.
Diagnosis in postmenopausal women and men may be delayed to the point that the lesion may be a macroadenoma before diagnosis.