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Path - Chempath > Pituitary > Flashcards

Pituitary Flashcards

1
Q

What are the 6 hormones produced by the anterior pituitary?

A 
GH 
Prolactin 
TSH 
LH, FSH
ACTH
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2
Q

What hormone stimulates GH production?

A

GHRH

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3
Q

What hormone stimulates /suppresses prolactin?

A

TRH stimulates

dopamine suppresses

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4
Q

What hormone stimulates LH, FSH

A

LHRH

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5
Q

What hormone stimulates ACTH?

A

CRH

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6
Q

Why do people with hypothyroidism commonly have hyperprolactinaemia?

A

Low T4 > positive feedback onto TRH > high TRH

TRH also stimulates prolactin

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7
Q

What are symptoms of hyperprolactinaemia?

A

galactorrhea

amenorrhoea

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8
Q

What types of prolactinoma can you get in terms of size?

A

micro adenoma = <1cm

macro adenoma = >1cm

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9
Q

What visual field defect is caused by a prolactinoma?

A

Bilateral hemianopia

Due to compression of optic chiasm

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10
Q

What visual testing is done for bilateral hemianopia?

A

Humphreys test

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11
Q

When is a prolactinoma considered inoperable?

A

when it is in very close contact with the carotid arteries

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12
Q

Define prolactinoma

A

An adenoma of the pituitary producing excess prolactin

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13
Q

What prolactin results do you get with a prolactinoma?

A

x10 higher than upper limit for prolactin

so 6000

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14
Q

What testing is important if a prolactinoma is suspected

A

Testing pituitary to see if it responds to metabolic stress by producing ACTH, GH

so perform a COMBINED PITUITARY FUNCTION TEST -

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15
Q

What does a CPFT involve?

A

Give 3 stimuli:

  • hypoglycaemia
  • TRH
  • LHRH
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16
Q

What must you be aware of before performing a CPFT ‘

A

That hypoglycaemia is DANGEROUS

Therefore ensure that there are no cardiac RF (ECG normal) and no history of epilepsy

17
Q

What occurs to the patient when blood glucose drops below 1.5 mol/L

A

Neuroglycopoenia - patient loses consciousnes, becomes confused or aggressive

18
Q

How do you rescue a patient with severe hypoglycaemia?

A

50mL 20% dextrose IV

19
Q

What is the dose of insulin you must give in CPFT?

A

0.15 units/kg

20
Q

What hormone must be replaced urgently if ALL pituitary hormones are reduced?

A

HYDROCORTISONE

To replace cortisol

21
Q

What cortisol levels need to be reached for a CPFT to be normal?

A

Cortisol >550

22
Q

What GH levels need to be reached for a CPFT to be normal?

A

GH >10

23
Q

What hormones need to be given if pituitary function is suppressed?

A

hydrocortisone
Thyroxine
Oestrogen
GH

24
Q

What is front line treatment for a prolactinoma?

A

A dopamine agonist (bromocriptine/cabergoline)

This willl shrink the size of the tumour

25
Q

Other than a prolactinoma, what other tumour can cause increased prolactin?

A

a LARGE NON FUNCTIONING tumour

26
Q

How does a large non functioning tumour cause hyperprolactinaemia?

A

It compresses the pituitary stalk

Thereby prevents dopamine from reaching the pituitary

27
Q

How do you treat a large non functioning tumour?

A

SURGERY

They will NOT respond to dopamine agonist

28
Q

How do you distinguish a prolactinoma from a non functioning tumour?

A

SIZE & PROLACTIN RATIO

A LARGE non functioning tumour (size detected by bitemporal hemianopia) will cause moderate increase in prolactin (around 3000)

A SMALL prolactinoma can cause MASSIVE increase in prolactin

29
Q

What steroids can be given in ACTH / cortisol replacement=

A

Hydrocortisone - current front line

Predisolone - potent steroid, longer half life, currently being trialled

30
Q

How do you test acromegalY?

A

Oral glucose tolerance test (as glucose suppresses GH)

IGF-1 levels

31
Q

How do you test GH deficiency in children?

A

Random plasma GH
Exercise then test GH (exercise causes GH release)

Do NOT do a GH stimulation test right away

After these you can try INSULIN TOLERANCE TEST

32
Q

How do you treat acromegaly?

A

Octreotide (suppresses GH)
Cabergoline (if tumour is co-secreting prolactin)
Pituitary surgery
Pituitary radiotherapy

Path - Chempath (23 decks)

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