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ENDOCRINOLOGY > 1b Pituitary Tumours > Flashcards

1b Pituitary Tumours Flashcards

1
Q

What is a functioning tumour of the somatotrophs called?

A

Acromegaly

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2
Q

what is the most common pit adenoma

A

Gonadatrophs, prolactinomas, GH

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3
Q

Why are prolactinomas in men bigger?

A

Less likely do present earlier - women looses her menses and produces more breast milk

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4
Q

What is a functioning tumour of the thyrotrophs called?

A

TSHoma

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5
Q

What is a functioning tumour of the lactotrophs called?

A

prolactinoma

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6
Q

What is a functioning tumour of the gonadotrophs called?

A

gonadotrophinoma

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7
Q

What is a functioning tumour of the Corticotrophs called?

A

Cushings Disease

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8
Q

What is a functioning tumour of the corticotrophs called?

A

Corticotroph adenoma

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9
Q

What is the name for a radiologically small and large pituitary tumour?

A

Microadenoma and macroadenoma

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10
Q

What are the two functional classifications for tumours?

A

excess hormone secretion or not (non-functioning adenoma

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11
Q

Are pituitary tumours generally malignant?

A

No

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12
Q

Describe how hyperprolactinaemia leads to the associated symptoms?

A

Prolactin binds to prolactin
receptors on kisspeptin
neurons in hypothalamus

Inhibits kisspeptin release.

Decreases in downstream
GnRH/LH/FSH/T/Oest
Oligo-amenorrhoea/Low
libido/Infertility/Osteoporosis

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13
Q

What is serum prolactin proportional to in prolactinomas?

A

The size of the tumour

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14
Q

What is the hormonal presentation of prolactinomas?

A

low GnRH, low FSH and low LH

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15
Q

What are the clinical symptoms of prolactinoma?

A

Menstrual disturbance
* Erectile dysfunction
* Reduced libido
* Galactorrhoea
* Subfertility

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16
Q

What is Galactorrhoea?

A

Breasts producing milk outside pregnancy

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17
Q

why is Galactorrhoea more common in women?

A

Need oeastrogen to prime the breats for lactation

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18
Q

What are three physiological causes of elevated prolactin

A
  • Pregnancy/breastfeeding
  • Stress: exercise, seizure, venepuncture
  • Nipple/chest wall stimulation
19
Q

Why is prolactin levels higher in pregnancy?

A

Lactotrophs undergo hypertrophy

20
Q

What are the pathological causes of elevated prolactin?

A
  • Primary hypothyroidism - stimulates prolactin
  • Polycystic ovarian syndrome
  • Chronic renal failure - cannot destroy prolactin
21
Q

Why does primary hypothyroidism cause elevated prolactin?

A

thyroid gland not working, therefore not producing thyroxine, so TSH rises which stimulates prolactin release

22
Q

How should a prolactinoma be investigated?

A

MRI - look for pituitary tumour

23
Q

What is the first line treatment of prolactinoma?

A

Cabergoline - dopamine receptor agonist

24
Q

How do dopamine receptor agonists reduce prolactin and shrink prolactinomas?

A

Dopamine is the off switch for prolactin, therefore dopamine binds to the D2 receptors on the lactotrophs and reduces prolactin production - can also used dopamine agonists like Cabergoline

25
Q

Where does the dopamine come from?

A

The dopaminergic neurones

26
Q

What is the difference between acromegaly and giganticism?

A

acromegaly is in adults, gigantism in children

27
Q

What is the problem with insidious prsentation of acromegaly?

A

long time between symptoms appearing and mean time to diagnosis

28
Q

What are some clinical symptoms of acromegaly?

A

Sweatiness
* Headache
* Coarsening of facial features
* Macroglossia
* Prominent nose
* Large jaw - prognathism
* Increased hand and feet size
* Snoring & obstructive sleep
apnoea
* Hypertension
* Impaired glucose
tolerance/diabetes mellitus

29
Q

What are the two mechanisms of growth hormone action?

A

direct and indirect

Direct = growth hormones acting on tissues
Indirect = GH act on liver, which makes IGF-1 which then acts on other body tissues

30
Q

How do you diagnose acromegaly?

A

Failed suppression (‘paradoxical
rise’) of GH following oral
glucose load – oral glucose
tolerance test
then MRI

31
Q

Why are random measurements of growth hormone not useful?

A

GH is pulsatile so random measurements are unhelpful

32
Q

Why is it important that acromegaly must be treated?!!!!!!

A

Increased cardiovascular risk in untreated
acromegaly

33
Q

What is the first line treatment of acromegaly?

A

First-line treatment is surgical – trans-sphenoidal
pituitary surgery

34
Q

what is the medical treatment to do before surgery for treating acromegaly?(2)

A

Somatostatin analogues eg octreotide –
‘endocrine cyanide’
Dopamine agonists eg cabergoline (GH
secreting pituitary tumours frequently express
D2 receptors)

35
Q

What are the clinical features of Cushings?

A
  • Red Striae
  • Buffalo humps
  • Lemon on sticks - centripedal obesity
  • Moon face
  • Proximal Myopathy - cannot get up from squat
  • Easily bruising
36
Q

What us Cushings Syndrome?

A

Too much cortisol

37
Q

What are the common causes of Cushings Syndrome?

A

Causes of Cushing’s syndrome
* Taking steroids by mouth (common)
* Pituitary dependent Cushing’s
disease (pituitary adenoma)
* Ectopic ACTH (lung cancer)
* adrenal adenoma or carcinoma

38
Q

What is cushings Disease?

A

pituitary dependant adenoma

39
Q

What are ACTH dependant causes of Cushings?

A

ACTH dependent
* Cushing’s disease (corticotroph
adenoma)
* Ectopic ACTH (lung cancer)

40
Q

What are ACTH indepedant causes of Cushings?

A

ACTH dependent
* Taking steroids by mouth
(common)
* Adrenal adenoma or carcinoma

41
Q

What would you see in an investigation of Cushings?

A
  1. Elevation of 24h free urine cortisol
  2. Elevation of late night cortisol 12am
  3. Failure to suppress cortisol after oral dexamethasone so increased cortisol secretion
42
Q

What do you do when hypercortisolism is confirmed?

A

Measure ACTH - if high then pituitary MRI, CTH dependant

43
Q

What are the main effects of non-functioning pituitary adenomas

A

visual disturbances - bitemporal hemianopia

44
Q

What are the hormonal affects of non-functioning pituitary adenomas?

A

Can present with hypopituitarism
* Serum prolactin can be raised
(dopamine can’t travel down
pituitary stalk from hypothalamus)

ENDOCRINOLOGY (20 decks)

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