Endo - Pituitary Tumour Flashcards

1
Q

What is the outcome of a functioning somatotrophic tumour?

A

acromegaly

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2
Q

What is a functioning lactotroph tumour called?

A

prolactinoma

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3
Q

What is a functioning thyrotroph tumour called?

A

TSHoma

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4
Q

What is a functioning gonadotroph tumour called?

A

Gonadotrophinoma

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5
Q

What is a corticotroph tumour called?

A

Cushing’s Disease (corticotroph adenoma)

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6
Q

How do you classify a pituitary tumour by size?

A

→ microadenoma = < 1 cm

→ macroadenoma = > 1 cm

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7
Q

How do you classify a pituitary tumour radiologically?

A

→ sellar or suprasellar
→ compressing optic chiasm or not
→ invading cavernous sinus or not

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8
Q

How do you classify a pituitary tumour by function?

A

→ excess secretion of hormone

→ no excess secretion of hormone = non-functioning adenoma

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9
Q

How do you classify a pituitary tumour by benign or malignancy?

A

→ carcinoma very rare
→ mitotic index measured using Ki67 index (benign is <3%)
→ pituitary adenoma can have benign histology + malignant behaviour

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10
Q

What the effect of hyperprolactinaemia on the gonadotrophin hormones?

A

→ Prolactin binds to prolactin receptors on kisspeptin neurons in hypothalamus
→ Inhibits kisspeptin release
→ decreases downstream homrone cascade e.g. less GRH, LH + FSH, testosterone + oestrogen

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11
Q

What is the most common functioning pituitary adenoma?

A

prolactinoma

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12
Q

What is the size of the prolactinoma usually proportional to?

A

serum prolactin

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13
Q

How does the prolactinoma present?

A
→ Menstrual disturbance
→ Erectile dysfunction
→ Reduced libido
→ Galactorrhoea
→ Subfertility
→ Oligo-amenorrhoea
→ Osteoporosis
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14
Q

What are the alternative physiological cause of elevated prolactin?

A

→ pregnancy / breastfeeding
→ stress (exercise, seizure, venepuncture)
→ nipple/chest wall stimulation

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15
Q

What are the alternative pathological causes of elevated prolactin?

A

→ primary hypothyroidism
→ polycystic ovarian syndrome
→ chronic renal failure

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16
Q

What are the alternative iatrogenic (drug-related) causes of elevated prolactin?

A
→ antipsychotics
→ SSRIs
→ anti-emetics
→ high dose oestrogen
→ opiates
17
Q

How do you confirm true elevation of serum prolactin?

A

→ no diurnal variation
→ not affected by food
→ consistent with clinical features

18
Q

What are the 2 possible explanations if a mild prolactin elevation has no consistency with clinical features + the medical history has been reviewed?

A

→ macroprolactin

→ stress

19
Q

What is macroprolactin?

A

→ “sticky prolactin”
→ a polymeric form of prolactin
an antigen–antibody complex of monomeric prolactin + IgG (normally <5% of circulating prolactin)
→ Recorded on assay as elevation of prolactin – needs alternative method to confirm (macroprolactin screening test)

20
Q

Why can stress cause a false positive elevation in serum prolactin?

A

→ stress of venepuncture (unsure why)

→ measure 20 minutes apart with indwelling cannula to minimise venepuncture stress

21
Q

What’s the next step after a true elevation of prolactin has been confirmed?

A

pituitary MRI

22
Q

How is prolactinoma treated?

A

→ first-line = medical
→ dopamine receptor agonists
e.g. CABERGOLINE
(bromocriptine doesn’t work as well) (also safe in preganancy)
→ aim to normalise serum prolactin + shrink prolactinoma

23
Q

How do dopamine receptor agonists work?

A

→ dopamine receptor agonists mimic the dopamine released from hypothalamic dopaminergic neurones
→ inhibits release of prolactin from lactotrophs

24
Q

What is the result of excess GH in children? Why?

A

gigantism

→ growth plates still active

25
Q

What is the result of excess GH in adults? Why?

A

acromegaly

→ growth plates are closed

26
Q

What are the symptoms of acromegaly?

A
→ Sweatiness
→ Headache
→ Coarsening of facial features
→ Macroglossia (huge tongue)
→ Prominent nose
→ Large jaw - prognathism
→ Increased hand and feet size
→ Snoring & obstructive sleep apnoea
→ Hypertension
→ Impaired glucose tolerance/diabetes mellitus
27
Q

How is acromegaly diagnosed? What test is done to confirm acromegaly?

A

→ measure GH after oral glucose load
→ serum GH levels should decrease in normal person
→ serum GH has paradoxical increase in acromegalic (prolactin often increases too)
→ should also have elevated serum IGF-1

28
Q

What is done after excess GH is confirmed?

A

pituitary MRI

29
Q

Why is it important to treat acromegaly?

A

→ increased risk of DM

→ increased cardiovascular risk

30
Q

How is acromegaly treated?

A

→ first-line = surgical
→ trans-sphenoidal pituitary surgery
→ aim to normalise serum GH + IGF-1
→ Can use medical treatment prior to surgery to shrink tumour or if surgical resection incomplete e.g. Somatostatin analogues eg octreotide – ‘endocrine cyanide’ or Dopamine agonists eg cabergoline (GH secreting pituitary tumours frequently express D2 receptors

31
Q

What is Cushing’s syndrome vs. Cushing’s disease?

A

→ both = too much cortisol or other glucocorticoid

→ Cushing’s disease is due to specifically a pituitary adenoma

32
Q

What are causes of Cushing’s?

A
ACTH dependent
→ adrenal adenoma or carcinoma
→ taking steroids by mouth
ACTH independent
→ pituitary dependent Cushing's disease
→ ectopic ACTH (lung cancer)
33
Q

What are the symptoms of Cushing’s?

A
→ mental changes
→ red cheeks
→ fat pads
→ striae
→ easy bruising
→ moon face
→ centripetal obesity
→ hypertension, etc...
34
Q

What clinical investigation results indicate Cushing’s Disease?

A

→ elevation of 24hr urine free cortisol (due to excess cortisol)
→ elevation of late night cortisol (loss of diurnal rhythm)
→ failure to suppress cortisol after oral dexamethasone (oral glucocorticoid) (should be supressed due to negative feedback)

35
Q

What’s next after determining elevated cortisol levels?

A

measure ACTH to determine whether cause is ACTH dependent/independent

36
Q

What are non-functioning pituitary adenomas?

A

→ don’t secrete any specific hormone
→ often present with visual disturbance (bitemporal hemianopia)
→ can present w hypopituitarism
→ serum prolactin could be raised if dopamine can travel down from hypothalamus

37
Q

How are non-functioning pituitary adenomas treated?

A

trans-sphenoidal surgery is needed for larger tumours, especially for the visual disturbance