Pituitary Flashcards

1
Q

Does pituitary failure cause hypotension?

A

Pituitary failure does NOT cause hypotension, it’s the loss of aldosterone that causes hypotension (if the pituitary gland fails, you can still produce aldosterone because the adrenal glands are intact)

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2
Q

Hypothalamic and anterior pituitary hormones

A
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3
Q

What are the signs of pituitary failure?

A
  • Galactorrhoea
  • Amenorrhoea
  • Bitemporal hemianopia (if >1cm macroadenoma is the cause pressing on optic chiasm)
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4
Q

What is the cause of a very high prolactin? >6,000

A
  • it must be a prolactinoma this is the only cause of such a high prolactin
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5
Q

Is high prolactin/prolactinoma a problem?

A
  • This is normally not too much of a problem, but if it interferes with the production or axis of the other pituitary hormones, this can become a problem, so you need to test for the other hormonespituitary function testing
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6
Q

What is in an CPFT? “triple test”

A
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7
Q

What things should we ensure during a CPFT?

A
  • Check glucose regularly
  • Ensure an adequate hypoglycaemia (<2.2mM)
  • If severe hypoglycaemia occurs (or unconsciousness), rescue patient with 50mL of 20% dextrose
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8
Q

How do we carry out a CPFT?

A

Fast patient overnight

Ensure good IV access

Weigh pt. and calculate dose of insulin required (0.15U/kg i.e. 70kg woman = 10.5U)

Mix and IV. Inject the following (patient may vomit on injection):

  • Insulin 0.15U/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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9
Q

Contraindications of inducing hypoglycaemia?

A
  • Cardiac risk factors (ECG normal, no angina, etc.)
  • History of epilepsy
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10
Q

Effects of hypoglycaemia (2)

A
  • sympathetic activation occurs → aggression (if patient needs glucose, this may be difficult so IV access helps)
  • 2) when very low (<1.5mM), neuroglycopaenia may occur (patient loses consciousness / becomes confused)
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11
Q

CPFT results

what is a normal response stress testing result?

A
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12
Q

How do we treat an abnormal response stress testing?

A

URGENThydrocortisone replacement (fludrocortisone is not necessary as adrenals should still be able to make aldosterone as it is independent of the HPA)

Total therapy (ordered):

  • Hydrocortisone replacement
  • Thyroxine replacement
  • Oestrogen replacement
  • GH replacement
  • (Cabergoline or Bromocriptine (Dopamine agonists)) – if prolactinoma is the cause of the failure → shrinks tumour)
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12
Q

How do we treat an abnormal response stress testing?

A

URGENThydrocortisone replacement (fludrocortisone is not necessary as adrenals should still be able to make aldosterone as it is independent of the HPA)

Total therapy (ordered):

  • Hydrocortisone replacement
  • Thyroxine replacement
  • Oestrogen replacement
  • GH replacement
  • (Cabergoline or Bromocriptine (Dopamine agonists)) – if prolactinoma is the cause of the failure → shrinks tumour)
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13
Q

Bitemporal hemianopia aka non-functioning pituitary adenoma → how does this lead to hyperprolactinaemia

A

Prolactin is high (~2,800) but MUCH lower than in prolactinoma (>6,000)

  • Adenoma presses on pituitary stalk
  • Dopamine prevented from reaching anterior pituitary
  • No -ve inhibition on prolactin release
  • Hyperprolactinaemia
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14
Q

Bitemporal hemianopia aka non-functioning pituitary adenoma mx

A
  • Hydrocortisone replacement
  • Thyroxine replacement
  • Oestrogen replacement
  • GH replacement
  • Cabergoline or Bromocriptine – brings down prolactin and allows women to ovulate and men to be fertile
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15
Q

Steroid replacement: prednisolone vs hydrocortisone

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)
16
Q

Acromegaly testing

A
17
Q

Acromegaly mx

A
  • Pituitary surgery (the best treatment option)
  • Pituitary radiotherapy
  • Cabergoline
  • Octreotide (somatostatin analogue; good at reducing the size of the tumour)
18
Q

Acromegaly signs and sx

A
19
Q

symptoms of high prolactin

A

Symptoms include irregular or absent menstrual periods, infertility, menopausal symptoms (hot flashes and vaginal dryness), and, after several years, osteoporosis (thinning and weakening of the bones). High prolactin levels can also cause milk discharge from the breasts

20
Q

Causes of high prolactin

A