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a path 3 > CHEMPATH: Pituitary > Flashcards

CHEMPATH: Pituitary Flashcards

1
Q

Does pituitary failure cause hypotension?

A

No - you still have aldosterone so you do NOT get hypotension.

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2
Q

What is the BP in Addison’s disease?

A

Low

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3
Q

What are the 6 hormones in the anterior pituitary?

A
  • GHRH –> GH
  • TRH –> TSH, prolactin
  • Dopamine – > lowers prolactin
  • LHRH/GnRH –> LH, FSH
  • CRH –> ACTH
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4
Q

Why does primary hypothyroidism cause hyperprolactinaemia?

A

Because TRH stimulates its production

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5
Q

What is a macroadenoma?

A

pituitary tumour >1cm

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6
Q

What are some symptoms of pituitary failure e.g. due to macroadenoma?

A
  • Galactorrhoea
  • Amenorrhoea
  • Bitemporal hemianopia
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7
Q

If the prolactin is >6,000, what is the diagnosis?

A

Prolactinoma is the only cause of such a high prolactin

NB: make sure that the patient is not pregnant

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8
Q

How do you test temporal vision?

A

Humphreys 30-2 test - if the blind spot is not black then this is a false negative and they must have looked at the light

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9
Q

What is shown below?

A

Development of bitemporal hemianopia in a pituitary adenoma

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10
Q

What is a normal prolactin level?

A

<600

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11
Q

What is the CPFT?

A

Combined pituitary function test - “triple test”

You give… to induce hypoglycaemic stress:

  • GnRH/LHRH –> causes LH/FSH rise
  • TRH –> causes TSH and prolactin release
  • Insulin (hypoglycaeemic stress)
    • increases CRF –> increased ACTH –> increased cortisol –> increased glucose
    • increased GHRH –> increased GH –> increased glucose
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12
Q

What are the risks of CPFT and how is this managed? What is the target level for hypoglycaemia?

A

Can be dangerous due to risk of hypoglycaemia, so must have good IV acess so that you can give glucose if they become hypoglycaemic. Give 50mL of 20% glucose and patient will wake up in about 5 min.

However, you must ensure adequate hypoglycaemia <2.2mM

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13
Q

What is the method for the CPFT?

A
  • Fast patient overnight
  • Ensure good IV access
  • Weight pt. and calculate dose of insulin required (0.15units/kg i.e. 70kg woman = 10.5units)
  • Mix and IV. Inject the following (patient may vomit on injection):
    • Insulin 0.15 units/kg
    • TRH 200mcg
    • LHRH/GnRH 100mcg
  • Take bloods at 0, 30 and 60 minutes of glucose, cortisol, GH, LH, FSH, TSH, prolactin and T4
  • Take bloods at 90 and 120 minutes of glucose, cortisol and GH
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14
Q

Interpret these CPFT results.

A

Normal.

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15
Q

Interpret these CPFT results.

A

Pituitary macroadenoma (functioning) - abnormal, requires replacement of all hormones but hydrocortisone is urgent as you need this to respond to stress.

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16
Q

What is the management of the previous patient with abnormal CPFT?

A
  • URGENT hydrocortisone replacement (fludrocortisone is not necessary as adrenals should still be able to make aldosterone as it is independent of the HPA)
  • Total therapy (ordered):
    1. Hydrocortisone replacement
    2. Thyroxine replacement
    3. Oestrogen replacement
    4. GH replacement
    5. (Cabergoline or Bromocriptine – if prolactinoma is the cause of the failure –> shrinks tumour)
      • Dopamine agonists
17
Q

If the patient (female) only presents with bitemporal hemianopia, what is the diagnosis?

A

Non-functioning pituitary adenoma

18
Q

What are the prolactin levels in non-functining pituitary adenoma vs prolactinoma?

A

Prolactin is high (~2000) but lower than in prolactinoma.

19
Q

Name 2 dopamine agonists.

A
  • Bromocriptine (3 times a day)
  • Carbegoline (once a week)
20
Q

Interpret these CPFT results. What is the pathophysiology?

A

Disconnection hyperprolactinaemia (non-functioning pituitary adenoma).

  • Adenoma presses on pituitary stalk
  • Dopamine prevented from reaching anterior pituitary
  • No -ve inhibition on prolactin release
  • Hyperprolactinaemia
21
Q

Do you need to use rescue therapy in CPFT in disconnection hyperprolactinaemia?

A

No because they rescue themselves with adrenaline

22
Q

What is the management of non-functioning pituitary adenoma?

A

This still cuts off all the hypothalamic releasing hormones.

  1. Hydrocortisone replacement
  2. Thyroxine replacement
  3. Oestrogen replacement
  4. GH replacement
  5. Cabergoline or Bromocriptine – brings down prolactin and allows women to ovulate and men to be fertile
23
Q

What type of prolactinaemia occurs in disconnection hyperprolactinaemia?

A

Secondary hyperprolactinaemia

This is also often caused by psychiatric drugs.

24
Q

Which of these does a patient with disconnection hyperprolactinaemia not need and why?

  • Fludrocortisone
  • Hydrocortisone
  • Thyroxine
  • Oestrogen
  • GH
A

Fludrocortisone - not a pituitary hormone, not affected in pituitary conditions.

25
Q

Do you need to give carbegoline/bromocriptine in disconnection hyperprolactinaemia?

A

No treatment as this is non-functioning. However, in some it may be preferred…

Carbegoline is a dopamine agonist and it will not shrink the tumour - but this brings down the prolactin and allows women to ovulate and men to be fertile.

26
Q

Should you use prednisolone or hydrocortisone for steroid replacement in pituitary failure?

A
  • Hydrocortisone is used as a steroid replacement in pituitary failure (BD or TDS)
  • However, prednisolone is more potent with a longer half-life that is more resistant to degradation
  • Prednisolone can be given OD and matches circadian rhythm better (will be used more in future)
27
Q

What is the diagnosis?

(Case presentation - 28yo, 2cm pituitary adenoma, bitemporal hemianopia, high persistent GH)

A

Acromegaly

28
Q

What dynamic test is used for acromegaly? How is this done?

A

OGTT

  • (75g of glucose - measure glucose in 2 hours)
    • GH should drop with glucose
    • In acromegaly, you get a paradoxical rise in GH with glucose administration
29
Q

Apart from OGTT, what else can be used for acromegaly?

A

Serum IGF-1

30
Q

What is the best treatment for acromegaly? What are the other treatment options?

A
  • Pituitary surgery (the best treatment option)
  • Pituitary radiotherapy
  • Cabergoline
  • Octreotide (somatostatin analogue; good at reducing the size of the tumour)
31
Q

What is this?

A

Adrenals

a path 3 (89 decks)

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