10: Hypothalamic-pituitary axis physiology, pituitary tumours, prolactinomas and acromegaly

Question 1

What is found superior to the pituitary gland?

Answer 1

Optic chiasm

Question 2

The pituitary gland is split into which parts?

Answer 2

Anterior and posterior pituitary gland

Question 3

What hormones are produced by the posterior pituitary?

Answer 3

ADH

Oxytocin

Question 4

Which hormones are produced by the anterior pituitary gland?

Answer 4

ACTH

TSH

FSH

LH

PRL

Growth hormone

Question 5

Which gland itself controls the pituitary gland?

Answer 5

Hypothalamus

Question 6

What are the effects of cortisol?

Answer 6

Increases blood glucose level

Increased lipogenesis

Increases immune response

Question 7

What is the main difference between prolactin release from the anterior pituitary and all the other hormones?

Answer 7

Dopamine inhibits constant prolactin secretion by the anterior pituitary

Question 8

What are the three clinical presentations you see in endocrinology?

Answer 8

Too much hormone

Not enough hormone

Gland is too big

Question 9

In which direction do pituitary tumours usually grow?

Answer 9

Superiorly

because inferiorly and laterally there are bones

Question 10

What structure tends to be compressed by pituitary tumours?

Answer 10

Optic chiasm

Question 11

If a pituitary tumour grows around the internal carotid artery, can it be cured surgically?

Answer 11

No, risk of rupturing artery too high

Question 12

What ENT symptom may patients present with if a pituitary tumour breaches the sphenoid sinus?

Answer 12

CSF leak from nose

Question 13

What dynamic tests would you do in the case of

a) too much hormone
b) too little hormone?

Answer 13

a) Too much > Suppression test

b) Too little > Stimuation test

Question 14

Diabetes insipidus involves a deficiency of what?

Answer 14

ADH

Question 15

What is the stimulation test for diabetes insipidus?

Answer 15

Water deprivation test

should stimulate the release of ADH

Question 16

What name is given to pituitary tumours

a) < 1cm
b) > 1cm

in diameter?

Answer 16

< or equal to 1cm diameter - MICROADENOMA

> 1cm diameter - MACROADENOMA

Question 17

What is a non-functioning pituitary adenoma?

Answer 17

A pituitary adenoma which doesn’t produce any hormone

Question 18

What can non-functioning pituitary adenomas compress?

Answer 18

Optic chiasm

CN III, IV & VI (optic, trochlear, abducent nerves)

Question 19

What endocrine conditions do non-functioning pituitary adenomas produce?

Answer 19

Not producing hormone, so deficiencies:

hypoadrenalism

hypothyroidism

hypogonadism

GH deficiency

Question 20

If a non-functioning pituitary adenoma affects the posterior pituitary, what endocrine condition can you get?

Answer 20

Diabetes insipidus

Question 21

At the optic chiasm, which optic nerves cross over and which ones stay on the unilateral side?

Answer 21

Temporal nerves stay on the same side

Nasal nerves cross over

Question 22

Which type of vision is lost in optic chiasm compression?

Answer 22

Temporal vision on both sides

bitemporal hemianopia

Question 23

What is the physiological function of prolactin?

Answer 23

Production of breast milk

Question 24

What are physiological causes for a raised prolactin?

Answer 24

Breastfeeding

Pregnancy

Stress

Sleep

Question 25

Which drugs cause raised prolactin?

Answer 25

**Dopamine antagonists** **Antipsychotic drugs**

Question 26

What is an example of a dopamine antagonist which raises prolactin?

Answer 26

**Metoclopramide**

Question 27

How do dopamine **agonists** affect prolactin levels?

Answer 27

**Suppress prolactin**

Question 28

**Which** thyroid-related **hormone** causes prolactin levels to rise?

Answer 28

**Thyrotropin releasing hormone (TRH)** so PRL is raised in hypothyroidism

Question 29

Which thyroid disease causes raised prolactin levels?

Answer 29

**Hypothyroidism** as TRH levels are raised to compensate

Question 30

What is a functioning adenoma which can cause raised prolactin?

Answer 30

**Prolactinoma**

Question 31

How would you investigate a suspected prolactinoma?

Answer 31

**Measure prolactin levels** **MRI scan of pituitary gland** **Visual field test** (for bitemporal hemianopia) Pituitary function test for other abnormalities

Question 32

Are prolactinomas surgically removed?

Answer 32

**No, high risk of damage to other structures**

Question 33

How is prolactinoma treated?

Answer 33

**Dopamine agonists** to inhibit prolactin secretion

Question 34

What is an example of a dopamine agonist used to treat prolactinoma?

Answer 34

**Cabergoline** 2x a week

Question 35

What condition is caused by **growth hormone excess**?

Answer 35

**Acromegaly**

Question 36

What is the presentation of acromegaly in children?

Answer 36

**Giantism**

Question 37

After epiphyseal fusion, which structures grow in acromegaly?

Answer 37

**Soft tissue** (skin, jaw, hands) **Cardiovascular structures** (hypertension, cardiac failure)

Question 38

Does the pituitary tumour itself cause **headaches** seen in acromegaly?

Answer 38

**NO** effect of vascular changes

Question 39

What are respiratory symptoms of acromegaly?

Answer 39

**Snoring** **Sleep apnoea**

Question 40

What is a classic respiratory presentation of acromegaly?

Answer 40

**Sleep apnoea**

Question 41

As GH is a stress hormone, what endocrine condition can it cause in the long term?

Answer 41

**Diabetes** due to hyperglycaemia

Question 42

As acromegaly is caused by a pituitary tumour, what optic problems can be involved?

Answer 42

**Visual field disturbance**

Question 43

Which tests are used to diagnose **acromegaly**?

Answer 43

**Measure IGF-1 levels** **Oral glucose tolerance test** **MRI pituitary**

Question 44

As acromegaly is caused by GH **excess**, what test is used to diagnose it?

Answer 44

**Glucose tolerance test** i.e a suppression test Normally GH will decrease in response to hyperglycaemia, in acromegaly it doesn't or it even increases

Question 45

How is acromegaly treated?

Answer 45

**Pituitary surgery** **Radiotherapy** **Somatostatin analogues**

Question 46

Which hormone **inhibits** the release of GH from the anterior pituitary and can be used in acromegaly pre and post-op?

Answer 46

**Somatostatin**

Question 47

Which symptom of acromegaly can be treated quickly using somatostatin analogues?

Answer 47

**Headache**

Question 48

How is somatostatin administered?

Answer 48

**Injections**

Question 49

Why does somatostatin cause GI side effects, particularly gall stones?

Answer 49

**Affects gut hormones inc. CCK, which controls gallbladder contraction**

Question 50

Why can dopamine agonists be used in acromegaly?

Answer 50

**Some pituitary tumours secrete both PRL and GH**

Question 51

If all attempts to treat acromegaly fail, which drug can be tried to treat it?

Answer 51

**GH antagonists** may increase GH by negative feedback, exacerbating the problem