PANCE Blueprint Endocrinology (7%)

Pituitary adenoma and neoplasm (Lecture)

Patient will present as → a 31-year-old woman who complains of irregular, infrequent menstrual periods. On further questioning, she complains of headaches, fatigue, and breast discharge. She takes ibuprofen only occasionally. The serum prolactin level is 380 μg per L.

Pituitary adenomas are benign tumors of the anterior pituitary that derive from one of the five types of pituitary hormone-producing cells

  • Common presentations associated with pituitary adenoma (may involve multiple endocrine abnormalities)
  • Pituitary adenomas < 1 centimeter are called microadenomas, whereas those > 1 centimeter are called macroadenomas
Classification of Pituitary Adenomas
Tumor Type Secretory Product(s) Relative Frequency (%)
Prolactinoma (Galactorrhea)

  • Women present with amenorrhea, galactorrhea, infertility, decreased libido
↑ Prolactin 50
Somatotroph adenoma (acromegaly & gigantism) ↑ Growth Hormone (GH) 10
Corticotroph adenoma (Cushing's disease) ↑ ACTH 5
Thyrotroph adenoma (Hyperthyroidism) ↑ TSH 1
Gonadotroph adenoma ↑ LH ↑ FSH 3
Non-Secreting Adenoma α alpha -subunit 34


Diagnosis is made by MRI - look for sellar lesions/tumors

  • Endocrine studies: Prolactin, GH, ACTH, TSH, FSH, LH

Treatment is often surgical

  • Transsphenoidal surgery: management of choice for removal of ACTIVE or compressive tumors
  • Medical management is the first line for prolactinomas - Dopamine inhibits prolactin release - Cabergoline or Bromocrpitine (dopamine acgonists)
  • Acromegaly: TSS + Bromocriptine (dopamine decreases GH production)

osmosis Osmosis


Prolactinoma is a prolactin secreting tumor of the pituitary gland. This tumor is the most common adenoma of the pituitary gland. These tumors are benign but can cause symptoms due to elevated prolactin levels in the blood or by compression of nearby structures. Prolactin is the hormone that stimulates the breast to produce breast milk. Therefore, elevated prolactin levels are usually seen during pregnancy and after childbirth. Pathologic secretion of prolactin from prolactinomas can cause galactorrhea in women although rare in men because of insufficient breast tissue. Prolactin also inhibits the release of gonadotropin releasing hormone. Normally, GnRH stimulates the release of FSH and LH from the anterior pituitary, which plays an important role in the synthesis of sex hormones. Increased prolactin can therefore cause decreased levels of sex hormone in men and women, leading to impotence and amenorrhea, respectively. Enlargement of the tumor can lead to compression of the optic chiasm resulting in bitemporal hemianopia. Dopamine physiologically suppresses prolactin secretion and is used in the treatment of prolactinomas.

Play Video + Quiz

Question 1
A 22-year old female comes to your clinic complaining of breast secretions. Her periods have been absent and she complains of decreased sex drive. On examination there is definite galactorrhea. her blood pressure is 138/78 and there are no abnormalities on PE. What is the most likely diagnosis?
anorexia nervosa
Question 1 Explanation: 
This patient has hyperprolactinemia, most likely from a pituitary microadenoma or macroadenoma. The combination of galactorrhea, amenorrhea, infertility, and decreased libido is almost certainly the result of a prolactinoma.
Question 2
Of the following, what would be the best serum test to order?
Question 2 Explanation: 
A prolactinoma can be confirmed by a serum prolactin level test. A level of serum prolactin of 300 ng/ mL or more is almost always the result of a pituitary adenoma (in the absence of pregnancy).
Question 3
What is the best treatment for this patient?
transsphenoidal resection
Question 3 Explanation: 
Treatment is controversial, but because of a high rate of recurrence with surgery, initial therapy with cabergoline or bromocriptine is the best choice. Treatment with dopamine agonists is not curative; it does, however, reduce the prolactin level, reduce the tumor mass, and increase fertility. Side effects include nausea and vomiting, an increase in liver enzymes, and an increase in serum uric acid.
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References: Merck Manual · UpToDate

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