ENDOCRINOLOGY - HYPERPITUITARISM

Question 1

What causes hyperpituitarism?

Answer 1

Pituitary adenoma - most often the cause
Ectopic production of pituitary hormones
Carcinoma

Question 2

Whats the most common cause of hyperpituitarism?

Answer 2

Pituitary adenoma

Question 3

What is a pituitary adenoma?

Answer 3

A benign tumour in the anterior pituitary that arises from a specific cell type

Question 4

How are pituitary adenomas classified?

Answer 4

They are classified by size:
<1cm micro adenomas
>1cm they are macroadenomas
They are also classified as functional or non-functional.

Question 5

Macroadenomas are more likely to compress surrounding structures. What structures may they compress and what are the consequences of this?

Answer 5

Meninges - headache
Optic nerve - bitemporal hemianopia
May compress other pituitary cells and interfere with their ability to make hormones

Question 6

Whats the difference between a functional and non-functional adenoma?

Answer 6

Functional adenomas secrete hormones
Non-functional adenomas do not

Question 7

Whats the most common type of pituitary adenoma?

Answer 7

Prolactinoma - tumour arising from lactotrophs

Question 8

What are the different types of pituitary adenoma?

Answer 8

Prolactinoma
Somatotrope derived adenoma
Coticotroph derives adenoma
Thyrotroph derived adenoma
Gonadotropin derives adenoma

Question 9

Whats the effect of somatotrope derived adenomas?

Answer 9

Gigantism and acromegaly

Question 10

Whats the effect of a corticotroph-derived adenoma?

Answer 10

It’s ACTH secreting so can cause Cushing disease

Question 11

Whats the effect of a Thyrotroph derived adenoma?

Answer 11

Secretes excess TSH which can cause hyperthyroidism signs

Question 12

Whats the effects of gonadotropin derived adenomas?

Answer 12

They are often clinically silent and non-functional but may cause hypogonadism
May also cause compression signs

Question 13

Whats the most frequent type of non-functional pituitary tumour?

Answer 13

Gonadotropin derived adenomas

Question 14

What are the potential complications of pituitary adenomas?

Answer 14

Mass effect
Pituitary apoplexy
Sella turcica erosion
Hormone-related diseases e.g. Cushing syndrome

Question 15

How do we diagnose pituitary adenomas?

Answer 15

Measure pituitary hormone levels
Gadolinium-enhanced MRI to image pituitary gland

Question 16

How do you treat non-functional pituitary adenomas?

Answer 16

Surgical removal but only if large enough to cause sympotms

Question 17

What usually inhibits and stimulates prolactin release?

Answer 17

Dopamine is a prolactin inhibiting factor
Thyrotropin releasing hormone stimulates its release

Question 18

What can cause hyperprolactinemia?

Answer 18

Physiological e.g. pregnancy or lactation
Prolactinoma
Hypothyroidism - as TRH stimulates its release
Medications e.g dopamine antagonists - most common cause
Damage or compression to hypothalamic-pituitary stalk

Question 19

What medications can cause hyperprolactinemia?

Answer 19

Dopamine antagonists e.g. metoclopramide, domperidone, phenothiazines and haloperidol
Oestrogens

Question 20

Why can damage to the hypothalamic-pituitary stalk cause hyperprolactinemia?

Answer 20

As dopamine can’t reach the lactotroph cells

Question 21

What are the symptoms of hyperprolactinemia?

Answer 21

Galactorrhoea, amenorrhoea and painful breasts in women
Gynaecomastia, erectile dysfunction, infertility, impotence or decreased libido in men
Compression symptoms if caused by prolactinoma

Question 22

What is a prolactinoma?

Answer 22

A benign tumour of the lactotroph cells in the pituitary gland that secretes excess prolactin

Question 23

What are micro and macroprolactinomas?

Answer 23

Microprolactinomas are <10mm and macroprolactinomas are >10mm

Question 24

Why do prolactinomas decrease oestrogen and testosterone?

Answer 24

As excess prolactin inhibits GnRH release which causes less FSH and LH

Question 25

Why does prolactinoma put you at risk for osteoporosis?

Answer 25

Decreased oestrogen means less inhibition on osteoclasts and less activation of osteoblasts

Question 26

What are the sympotms of prolactinomas?

Answer 26

Symptoms:
Vision problems, headaches
Women - galactorrhoea, amenorrhoea, vaginal dryness, brittle bones
Men - gynaecomastia, erectile dysfunction
Both - decreased libido and infertility

Question 27

How do you diagnose prolactinomas?

Answer 27

Elevated prolactin in blood
Sometimes TRH is elevated
MRI to visualise tumour

Question 28

How do you treat prolactinomas?

Answer 28

Dopamine agonists e.g. bromocriptine, cabergoline or quinagolide
Surgery for macroprolactinomas or those who fail medical therapy
Radiotherapy if above methods don’t work

Question 29

What does a prolactin >10,000mU/L suggest?

Answer 29

Macroadenoma

Question 30

What does a prolactin >5000mU/L suggest?

Answer 30

Prolactinoma