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Year 3 Endo > Pituitary Tumors > Flashcards

Pituitary Tumors Flashcards

1
Q

What are the 5 anterior pituitary cell types?

A 
Somatotrophs
Lactotrophs
Thytotrophs
Gonadotrophs
Corticotrophs
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2
Q

What does a tumour of somatotrophs cause?

A

Acromegaly

Too much GH

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3
Q

What does a tumour of lactotrophs cause?

A

Prolactinoma

Too much prolactin

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4
Q

What does a tumour of thyrotrophs cause?

A

TSHoma

Very rare

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5
Q

What does a tumour of gonadotrophs cause?

A

Gonadotrophinoma

Very rare

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6
Q

What does a tumour of corticotrophs cause?

A

Cushing’s disease
(Corticotroph adenoma)
Too much ACTH therefore too much cortisol

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7
Q

What is the difference between Cushing’s syndrome and disease?

A

Disease is due to a tumor

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8
Q

How do we classify pituitary tumour radiologically?

A

Size
Sellar or Suprasellar
Compressing optic chiasm or not
Invading cavernous sinus or not

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9
Q

What how do we classify pituitary tumour by size?

A

Microadenoma (<1cm)

Macroadenoma(>1cm)

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10
Q

What is a functional pituitary tumour?

A

Excess secretion of a specific pituitary hormone

e.g. prolactinoma

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11
Q

What is a non functional pituitary tumour?

A

No excess secretion of pituitary hormone

Non-functioning Adenoma

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12
Q

Is pituitary cancer common?

A

Pituitary carcinoma very rare

Mitotic index measured using Ki67 index - benign is <3%

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13
Q

Are pituitary tumours benign or malignant?

A

Pituitary adenomas can have benign histology but display malignant behaviour

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14
Q

How does hyperprolactinaemia shut down the HGP axis?

A

Prolactin binds to prolactin receptors on kisspeptin neurones in hypothalamus

Inhibits kisspeptin release

Decreases in downstream GnRH

Decreased LH/FSH

Decreased Testosterone and Oestrogen

Causes oligo-amenorrhoea, low libido, infertility and osteoporosis

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15
Q

What is the most common functional pituitary tumour?

A

Prolactinomas

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16
Q

What is the serum prolactin proportional to?

A

Tumour size

>5000mU/L

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17
Q

How does a prolactinoma present?

A 
Menstrual disturbance
Erectile dysfunction
Reduced libido
Galactorrhea (milk production from the breast)
Sub-fertility
18
Q

What are the physiological causes of an elevated prolactin?

A

Pregnancy/breastfeeding
Stress: exercise, seizure, venepuncture
Nipple/chest wall stimulation

19
Q

What are the pathological causes of an elevated prolactin?

A

Primary hypothyroidism
Polycystic ovarian syndrome
Chronic renal failure, prolactin secreted by the kidneys and cannot be excreted

20
Q

What are the iatrogenic causes of an elevated prolactin?

A

Antipsychotics
Selective serotonin re-uptake inhibitors
Anti-emetics
(all work by dopaminergic pathway which inhibits prolactin)

High dose oestrogen
Opiates e.g. morphine

21
Q

Can prolactin levels vary in a day?

A

No diurnal variation

Not affected by food

22
Q

What do you consider if someone has a mild prolactin elevation, no clinical features and you have reviewed their medication list?

A

Macroprolactin

Stress of venipuncture

23
Q

What is macroprolactin?

A

‘sticky prolactin’
a polymeric form of prolactin
an antigen-antibody comped of monomeric prolactin and IgG (normally <5% of circulating prolactin

Recorded on assay as elevation
No impact on life
Can reassure patient

24
Q

How do you exclude the stress of venepuncture?

A

Cannulated prolactin series

Sequential serum [prolactin] measurement 20 mins apart with an indwelling cannula to minimise venipuncture stress

25
Q

When do you conduct a pituitary MRI?

A

Only once you have confirmed a true pathological elevation of serum prolactin

26
Q

What is the first line treatment of prolactinoma?

A

Medical not surgical

Dopamine receptor agonists mainstay of treatments

Cabergoline

Safe in pregnancy

Aims to normalise serum prolactin and shrink prolactinoma

27
Q

How do dopamine receptor agonists work?

A

Dopamine from hypothalamic dopaminergic binds to receptor and inhibits prolactin

D2 agonists do the same

28
Q

What is the difficulty with acromegaly?

A

Often insidious presentation

Mean time to diagnosis from onset of symptoms = 10y

29
Q

What are the symptoms of acromegaly?

A

Sweatiness
Headache

Coarsening of facial features
- macroglossia
- prominent nose
Large jaw - prognathism
Increased hands and feet
Snoring and obstructive sleep apnea
Hypertension
Impaired glucose tolerance/ diabetes mellitus
30
Q

What is are the two mechanism of GH?

A

Via IGF-1 on the liver

Directly on muscle and bone

31
Q

How do we diagnose acromegaly?

A

GH pulsatile -so random measurement unhelpful

Elevated serum IGF-1

Failed suppression (paradoxical rise) of GH following oral glucose load tolerance test

Prolactin can be raised (co-secretion of GH and prolactin)

Carpal tunnel syndrom

32
Q

What is done once GH is confirmed to be in excess?

A

Pituitary MRI to visualise pituitary tumour

33
Q

How doe we treat acromegaly?

A

First line treatment is surgery

Trans-sphenoidal pituitary surgery

Aim to normalise serum GH and IGF-1

34
Q

What can you do to treat acromegaly medically?

A

Medical treatment prior to surgery to shrink tumour or if resection is incomplete

Somatostatin analogues

Dopamine agonists

Radiology (very slow)

35
Q

What are the symptoms of Cushing’s?

A 
Mental changes
Red cheeks
Moon face
Easy brushing 
Lemon on a stick 
etc.
36
Q

What causes Cushing’s?

A

Oral steroids
Pituitary depende Cushing;s disease (pituitary adenoma)
Ectopic ACTH (lung cancer)
Adrenal adenoma or carcinoma

37
Q

How do you investigate Cushing’s disease?

A

Elevated of 24h urine free cortisol - increased cortisol secretion

Elevation of late nigh cortisol - salivary or blood test - loss of diurnal rhythm

Failure to suppress cortisol after oral dexamethasone (exogenous glucocorticoid) - increased cortisol secretion

38
Q

What are non-functioning pituitary adenomas?

A

Don’t secrete any specific hormone

Often present with visual disturbance (bitemporal hemianopia)

39
Q

How can someone with a non-functioning pituitary adenoma present?

A

Hypopituitarism
Serum prolactin can be raised
(dopamine cannot travel down pituitary stalk from hypothalamus)

40
Q

How can you treat non-functioning pituitary adenomas?

A

Trans-sphenoidal surgery needed for larger tumours, particular if visual disturbance

3rd line: Sellar radiotherapy

Year 3 Endo (5 decks)

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