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Endocrine system




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A 32-year-old man comes to his outpatient provider because of headaches that began five-months ago. The patient reports that the headaches are worse in the morning and improve over the day. In addition, the patient endorses reduced body hair. He does not use any medications. Temperature is 37.4°C (99.3°F), pulse is 68/min, respirations are 20/min, and blood pressure is 125/72 mmHg. Physical exam is notable for restricted peripheral vision and white watery discharge from the nipples. Further review of the patient’s history will most likely reveal which of the following findings?

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pituitary prolactinomas p. 335


pituitary prolactinomas p. 335


pituitary prolactinomas p. 335

Osteoporosis p. 472

pituitary prolactinomas p. 335

Pituitary prolactinomas p. 335


dopamine agonists for p. 334


With prolactinoma, prolactin refers to the endocrine hormone secreted by the pituitary gland and -oma refers to a tumor.

So a prolactinoma is a benign tumor, or adenoma, of the pituitary gland that secretes excess prolactin.

Normally, the pituitary is a pea-sized gland, hanging by a stalk from the base of the brain.

It sits just behind the eyes near something called the optic chiasm, which is where the optic nerves cross.

The anterior pituitary, which is the front of the pituitary gland, contains a few different types of cells, and each of which secretes a different hormone.

One group of cells in the anterior pituitary are called lactotrophs and they secrete prolactin.

Prolactin stimulates breast milk production.

Another group of cells are the gonadotrophs and they secrete two gonadotropic hormones - luteinizing hormone, or LH, and follicle-stimulating hormone, or FSH, both of which stimulate the ovaries in women which make estrogen and stimulate the testes in men which make testosterone.

Prolactin release is controlled by something called the hypothalamus, which is a structure at the base of the brain just above the pituitary gland.

It makes two key hormones, thyrotropin-releasing hormone which increases prolactin release, and dopamine, which inhibits the prolactin release and actually overrides the stimulatory effect of thyrotropin-releasing hormone.

That’s why dopamine is known as prolactin-inhibiting factor, and why it’s constantly released to prevent prolactin release in anyone that’s not pregnant.


A prolactinoma is a benign pituitary gland tumor that produces high levels of the hormone prolactin. Prolactin then suppresses the gonadotropin-releasing hormone resulting in symptoms like amenorrhea, galactorrhea, hypogonadism, gynecomastia, and erectile dysfunction in males. Treatment involves the use of dopamine agonist agents like bromocriptine which reduces the size of the tumor and lowers prolactin levels. In some cases, surgery or radiation therapy may also be required.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Harrison's Endocrinology, 4E" McGraw-Hill Education / Medical (2016)
  6. "Potential for long-term remission of microprolactinoma after withdrawal of dopamine-agonist therapy" Nature Clinical Practice Endocrinology & Metabolism (2006)
  7. "Demographic differences in incidence for pituitary adenoma" Pituitary (2010)

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