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

Endocrine Week 3 2017/18 > 10: Hypothalamic-pituitary axis physiology, pituitary tumours, prolactinomas and acromegaly > Flashcards

Flashcards in 10: Hypothalamic-pituitary axis physiology, pituitary tumours, prolactinomas and acromegaly Deck (51)
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1
Q

What is found superior to the pituitary gland?

A

Optic chiasm

2
Q

The pituitary gland is split into which parts?

A

Anterior and posterior pituitary gland

3
Q

What hormones are produced by the posterior pituitary?

A

ADH

Oxytocin

4
Q

Which hormones are produced by the anterior pituitary gland?

A

ACTH

TSH

FSH

LH

PRL

Growth hormone

5
Q

Which gland itself controls the pituitary gland?

A

Hypothalamus

6
Q

What are the effects of cortisol?

A

Increases blood glucose level

Increased lipogenesis

Increases immune response

7
Q

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

A

Dopamine inhibits constant prolactin secretion by the anterior pituitary

8
Q

What are the three clinical presentations you see in endocrinology?

A

Too much hormone

Not enough hormone

Gland is too big

9
Q

In which direction do pituitary tumours usually grow?

A

Superiorly

because inferiorly and laterally there are bones

10
Q

What structure tends to be compressed by pituitary tumours?

A

Optic chiasm

11
Q

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

A

No, risk of rupturing artery too high

12
Q

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

A

CSF leak from nose

13
Q

What dynamic tests would you do in the case of

a) too much hormone
b) too little hormone?

A

a) Too much > Suppression test

b) Too little > Stimuation test

14
Q

Diabetes insipidus involves a deficiency of what?

A

ADH

15
Q

What is the stimulation test for diabetes insipidus?

A

Water deprivation test

should stimulate the release of ADH

16
Q

What name is given to pituitary tumours

a) < 1cm
b) > 1cm

in diameter?

A

< or equal to 1cm diameter - MICROADENOMA

> 1cm diameter - MACROADENOMA

17
Q

What is a non-functioning pituitary adenoma?

A

A pituitary adenoma which doesn’t produce any hormone

18
Q

What can non-functioning pituitary adenomas compress?

A

Optic chiasm

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

19
Q

What endocrine conditions do non-functioning pituitary adenomas produce?

A

Not producing hormone, so deficiencies:

hypoadrenalism

hypothyroidism

hypogonadism

GH deficiency

20
Q

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

A

Diabetes insipidus

21
Q

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

A

Temporal nerves stay on the same side

Nasal nerves cross over

22
Q

Which type of vision is lost in optic chiasm compression?

A

Temporal vision on both sides

bitemporal hemianopia

23
Q

What is the physiological function of prolactin?

A

Production of breast milk

24
Q

What are physiological causes for a raised prolactin?

A

Breastfeeding

Pregnancy

Stress

Sleep

25
Q

Which drugs cause raised prolactin?

A

Dopamine antagonists

Antipsychotic drugs

26
Q

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

A

Metoclopramide

27
Q

How do dopamine agonists affect prolactin levels?

A

Suppress prolactin

28
Q

Which thyroid-related hormone causes prolactin levels to rise?

A

Thyrotropin releasing hormone (TRH)

so PRL is raised in hypothyroidism

29
Q

Which thyroid disease causes raised prolactin levels?

A

Hypothyroidism

as TRH levels are raised to compensate

30
Q

What is a functioning adenoma which can cause raised prolactin?

A

Prolactinoma

31
Q

How would you investigate a suspected prolactinoma?

A

Measure prolactin levels

MRI scan of pituitary gland

Visual field test (for bitemporal hemianopia)

Pituitary function test for other abnormalities

32
Q

Are prolactinomas surgically removed?

A

No, high risk of damage to other structures

33
Q

How is prolactinoma treated?

A

Dopamine agonists

to inhibit prolactin secretion

34
Q

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

A

Cabergoline 2x a week

35
Q

What condition is caused by growth hormone excess?

A

Acromegaly

36
Q

What is the presentation of acromegaly in children?

A

Giantism

37
Q

After epiphyseal fusion, which structures grow in acromegaly?

A

Soft tissue (skin, jaw, hands)

Cardiovascular structures (hypertension, cardiac failure)

38
Q

Does the pituitary tumour itself cause headaches seen in acromegaly?

A

NO

effect of vascular changes

39
Q

What are respiratory symptoms of acromegaly?

A

Snoring

Sleep apnoea

40
Q

What is a classic respiratory presentation of acromegaly?

A

Sleep apnoea

41
Q

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

A

Diabetes

due to hyperglycaemia

42
Q

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

A

Visual field disturbance

43
Q

Which tests are used to diagnose acromegaly?

A

Measure IGF-1 levels

Oral glucose tolerance test

MRI pituitary

44
Q

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

A

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

45
Q

How is acromegaly treated?

A

Pituitary surgery

Radiotherapy

Somatostatin analogues

46
Q

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

A

Somatostatin

47
Q

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

A

Headache

48
Q

How is somatostatin administered?

A

Injections

49
Q

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

A

Affects gut hormones inc. CCK, which controls gallbladder contraction

50
Q

Why can dopamine agonists be used in acromegaly?

A

Some pituitary tumours secrete both PRL and GH

51
Q

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

A

GH antagonists

may increase GH by negative feedback, exacerbating the problem