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BRS 1b > 3.1 Hypopituitarism > Flashcards

3.1 Hypopituitarism Flashcards

1
Q

How does the hypothalamus cause the anterior pituitary to release hormones?

A

hypothalamo-hypophysial portal system

  1. Axon terminals of hypothalamic neurosecretory cells release hormones (RH and IHs) into the hypothalamo-hypophysial portal system.
  2. The RH and IHs travel in the portal system to the anterior pituitary.
  3. The RH and IHs stimulate or inhibit the release of hormones from the anterior pituitary cells.
  4. Anterior pituitary hormones leave the gland via the blood.
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2
Q

Why does the anterior pituitary need a blood supply?

A

To release stored hormones into circulation and gland itself.

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3
Q

Which glands can fail?

A

Thyroid
Gonads
Adrenal Cortex (cortisol)
Pituitary (whole gland itself)

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4
Q

What is primary failure?

A

Gland itself fails

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5
Q

What is secondary failure?

A

No signals from hypothalamus or anterior pituitary

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6
Q

What are the 5 endocrine cell types in the anterior pituitary?

A
  1. Somatotrophs
  2. Lactotrophs
  3. Thyrotrophs
  4. Gonadotrophs
  5. Corticotrophs
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7
Q

What hormones are produced by somatotrophs, what are the target cells of these hormones, and what do these hormones stimulate?

A

Produces - growth hormones (somatotrophin)
Target cells - general body tissues (especially liver)
Stimulates - growth

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8
Q

What hormones are produced by lactotrophs, what are the target cells of these hormones, and what do these hormones stimulate?

A

Produces - prolactin
Target cells - breast tissue
Stimulates - milk production

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9
Q

What hormones are produced by thyrotrophs, what are the target cells of these hormones, and what do these hormones stimulate?

A

Produces - thyrotropin (thyroid stimulating hormone)
Target cells - thyroid gland
Stimulates - T3 and T4 production

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10
Q

What hormones are produced by gonadotrophs, what are the target cells of these hormones, and what do these hormones stimulate?

A

Produces - LH & FSH
Target cells - testes (males), ovaries (females)
Stimulates - testosterone, oestrogen, progesterone

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11
Q

What hormones are produced by corticotrophs, what are the target cells of these hormones, and what do these hormones stimulate?

A

Produces - Adrenocorticotrophic hormone (ACTH)
Target cells - Adrenal Cortex
Stimulates - Cortisol production

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12
Q

What is total loss of anterior and posterior pituitary function called?

A

panhypopituitarism

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13
Q

What is inflammation of the anterior pituitary called?

A

hypophysitis

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14
Q

What is tertiary failure?

A

failure caused by hypothalamic dysfunction, however not referred to as hypothalamic factors cannot be measured in the blood stream

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15
Q

What could cause secondary hypothyroidism/hypoadrenalism/hypogonadism?

A

Pituitary tumour

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16
Q

What could cause primary hypothyroidism?

A

Autoimmune destruction of thyroid

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17
Q

What could cause primary hypoadrenalism?

A

Autoimmune destruction of adrenal cortex (e.g. Addison’s disease)

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18
Q

What could cause primary hypogonadism?

A

Trauma
Mumps (testes)
Chemotherapy (ovaries)

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19
Q

What would T3/4 and TSH be in primary hypothyroidism?

A

T3/4 - low

TSH - high (no negative feedback)

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20
Q

What would T3/4 and TSH be in secondary hypothyroidism?

A

TSH - low

T3/4 - low (as no TSH)

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21
Q

What would cortisol and ACTH be in primary hypoadrenalism?

A

ACTH - high

Cortisol - low

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22
Q

What would cortisol and ACTH be in secondary hypoadrenalism?

A

ACTH - low

Cortisol - low

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23
Q

What are the symptoms of FSH/LH deficiency?

A

Reduced libido
Secondary amenorrhoea
Erectile dysfunction
Reduced pubic hair.

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24
Q

What are the symptoms of ACTH deficiency?

A

Fatigue

NB not a salt losing crisis (renin-angiotensin)

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25
Q

What are the symptoms of TSH deficiency?

A

Fatigue

26
Q

What are the symptoms of GH deficiency?

A

Reduced quality of life

NB short stature only in children

27
Q

What are the symptoms of prolactin deficiency?

A

inability to breastfeed

28
Q

Is hypopituitarism usually congenital or acquired?

A

Acquired is much more common.

Congenital is much more rare.

29
Q

How would you diagnose congenital hypopituitarism? (3)

A
  • deficiency in GH and at least 1 more anterior pituitary hormone
  • short stature
  • hypoplastic (underdeveloped) anterior pituitary gland on MRI
30
Q

What is congenital hypopituitarism caused by?

A

Usually due to mutations of transcription factor genes needed for normal anterior pituitary development.
–> PROP1 mutation

31
Q

What are some acquired causes of hypopituitarism?

A 
Tumours (e.g. adenoma)
Radiation
Infection (e.g. meningitis)
Traumatic brain injury
Pituitary surgery
Inflammation (hypophysitis)
Pituitary apoplexy (haemorrhage or infarction)
Peri-partum infection (Sheehan's syndrome)
32
Q

Why can radiotherapy induce hypopituitarism?

A

Pituitary and hypothalamus both sensitive to radiation.

33
Q

What kind of radiation can cause hypopituitarism?

A

Direct to the pituitary e.g. acromegaly
AND
Indirect e.g. nasopharangeal carcinoma

34
Q

What affects the degree of hypopituitarism?

A

Extent depends on the total dose of radiotherapy delivered to the hypothalamo-pituitary axis.

35
Q

Which hormones are most affected by radiotherapy?

A

GH and gonadotrophins most sensitive

36
Q

How does radiotherapy affect PRL levels?

A

PRL can increase after radiotherapy - due to loss of hypothalamic dopamine

37
Q

How long does risk of hypopituitarism last after radiotherapy, how can we mitigate this?

A

10 years

Annual assessment

38
Q

What is Sheehan’s syndrome?

A

Post partum hypopituitarism

39
Q

How is Sheehan’s sydrome caused?

A

Anterior pituitary enlarges during pregnancy (lactotroph hyperplasia)
Post partum haemorrhage
Causing hypotension
Which leads to pituitary infarction

40
Q

In which areas is Sheehan’s syndrome more common?

A

Developing countries

41
Q

What is usually not affected in Sheehan’s syndrome?

A

Posterior pituitary

42
Q

What are the symptoms of Sheehan’s?

A 
Lethargy
Anorexia
Weight Loss
Failure of lactation
Failure to resume menses post-delivery
43
Q

What are the symptoms of pituitary apoplexy?

A

severe sudden onset headache
visual field defect - e.g. bitemporal hemianopia caused by compressed optic chiasm
Cavernous sinus involvement may lead to diplopia (IV, VI), ptosis (III)

44
Q

What is diplopia?

A

Double vision

45
Q

What is ptosis?

A

Drooping of the upper eyelid

46
Q

What could cause pituitary apoplexy?

A 
Pituitary tumours (adenomas) - may be first presentation and often is dramatic in presentation.
Can be precipitated by anti-coagulants
47
Q

How is hypopituitarism diagnosed radiologically?

A 
Pituitary MRI (CT so good at delineating)
Look for empty sella - thin rim of pituitary tissue
48
Q

Why must caution be taken when interpreting basal plasma hormone concentrations?

A

Cortisol - highest in the morning
T4 - circulating half life is 6 days
FSH/LH - cyclical in women
GH/ACTH - pulsatile

49
Q

What does dynamic pituitary function in the diagnosis of hypopituitarism involve? (for each hormone)

A

ACTH & GH are stress hormones
Hypoglycaemia (<2.2 mM) = stress
So to measure GH and ACTH release (ACTH release measured by cortisol levels)
Insulin - induced hypoglycaemia stimulated

TRH stimulates TSH release

GnRH stimulates FSH & LH release

50
Q

Outline the treatment of GH deficiency according to NICE guidance.

A

Confirm GH deficiency on dynamic pituitar function test.
Assess quality of life (QoL) using specific questionnaire.
Daily injection

51
Q

How is improvement in GH deficiency measured?

A

Improvement in QoL using same questionnaire

Plasma IGF-1 levels

52
Q

Outline the treatment of TSH deficiency.

A

Replace with once daily levothyroxine.

Aim for fT4 above middle of the reference range.

53
Q

Outline the treatment of ACTH deficiency

A

Replace cortisol rather than ACTH
But diffucult to mimic diurnal variation of cortisol
Treat using synthetic glucocorticoids (2 options in the UK)
Either: Prednisolone once daily AM (3mg)
Hydrocortisone 3x daily (10mg, 5mg, 5mg)

54
Q

Outline the treatment of PRL deficiency

A

There is none as prolactin is the only negative feedback hormone

55
Q

Why do patients with ACTH deficiency have special ‘sick day rules’

A

Patients with ACTH deficiency (or Addison’s primary adrenal failure) are at risk of ‘adrenal crisis’ triggered by intercurrent illness.

56
Q

What are symptoms/features of an adrenal crisis? (4)

A 
Dizziness
Hypotention
Vomiting
Weakness
--> can result in collapse and death
57
Q

Patients who take replacement steriods (prednisolone, hydrocortisone) must be told sick day rules. What are they?

A

Steroid alert pendant/bracelet
Double steroid dose (glcocorticoid not mineralocorticoid) if fever/intercurrent illness
If unable to take tablets (i.e vomiting), inject IM or come straight to A&E

58
Q

Outline the treatment of FSH/LH deficiency for men, with no fertility required.

A

Replace testosterone - topical or intramuscular

Measure plasma testosterone

59
Q

Why does replacing testosterone not restore sperm production?

A

This is dependent on FSH

60
Q

Outline the treatment of FSH/LH deficiency for men, with fertility required.

A

Induction of spermatogenesis by gonadotropin injections.
Measure testosterone and semen analysis
Sperm production may take 6-12 months

Best response to treatment if secondary hypogonadism has developed after puberty.

61
Q

Outline the treatment of FSH/LH deficiency for women, with no fertility required.

A

Replace oestrogen - oral or topical

Will need additional progesterone if intact uterus to prevent endometrial hyperplasia

62
Q

Outline the treatment of FSH/LH deficiency for women, with fertility required.

A

Can induce ovulation by carefully timed gonadotropin injections.
Then IVF

BRS 1b (25 decks)

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