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BRS2 - Endocrinology > Hypopituitarism > Flashcards

Hypopituitarism Flashcards

1
Q

Name the 5 main cell types of the anterior pituitary gland

A 
Somatotrophs
Thyrotrophs
Lactotrophs
Gonadotrophs
Corticotrophs
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2
Q

Name the 6 main hormones released from the anterior pituitary

A

Growth hormone (somatotrophin)
TSH (thyroid stimulating hormone, thyrotrophin)
Prolactin
LH/FSH (luteinising hormone/follicle stimulating hormone)
ACTH (adrenocorticotrophic hormone, corticotrophin)

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3
Q

What’s the main difference in tissue type between the anterior and posterior pituitary gland?

A

The anterior pituitary comprises endocrine tissue whereas the posterior pituitary is composed of neural tissue

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4
Q

What does the anterior pituitary gland need to release hormones that the posterior pituitary does not? Why?

A

The anterior pituitary needs a blood supply to release its hormones whereas the posterior pituitary does not. This is because the posterior tissue is made of neural tissue vs anterior pituitary’s endocrine tissue.

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5
Q

What hormone do the somatotrophs secrete?

A

GH (somatotrophin)

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6
Q

What hormone do the lactotrophs secrete?

A

Prolactin

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7
Q

What hormone do the thyrotrophs secrete?

A

TSH (thyroid stimulating hormone, thyrotrophin)

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8
Q

What hormones do the gonadotrophs secrete?

A

LH, FSH

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9
Q

What hormone do the corticotrophs secrete?

A

ACTH (adrenocorticotrophic hormone, corticotrophin)

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10
Q

How do hypothalamic-releasing/inhibiting factors reach the anterior pituitary?

A

They travel in the hypothalamic-pituitary portal circulation (and down the pituitary stalk)

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11
Q

What do hypothalamic-releasing/inhibiting factors do in regards to the anterior pituitary?

A

Regulate anterior pituitary hormone production

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12
Q

What glands do LH/FSH stimulate?

A

Gonads - testes + ovaries

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13
Q

What gland does TSH stimulate?

A

Thyroid gland

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14
Q

What gland does ACTH stimulate?

A

Adrenal gland (cortex)

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15
Q

What is the main action of LH/FSH on the gonads?

A

Stimulate the release of sex hormones (testosterone, oestrogen)

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16
Q

What is the main action of TSH on the thyroid gland?

A

Stimulate the release of thyroxine

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17
Q

What is the main action of ACTH on the adrenal cortex?

A

Stimulate the release of cortisol

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18
Q

What are the three main glands affected in anterior pituitary failure?

A

Thyroid
Adrenal cortex (cortisol)
Gonads

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19
Q

What are the two main groups of disease that could cause failure of the thyroid, adrenal cortex or the gonads?

A

Primary disease

Secondary disease

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20
Q

Differentiate primary and secondary anterior pituitary failure.

A

Primary - gland itself fails

Secondary - no/reduced signals from hypothalamus or anterior pituitary gland

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21
Q

What is primary hypothyroidism?

A

Low thyroid hormone levels due to destruction of the thyroid gland

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22
Q

What is the main problem in primary hypothyroidism?

A

Destruction of the thyroid gland resulting in reduced thyroid hormone production

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23
Q

What is the main cause of primary hypothyroidism?

A

Autoimmune destruction of the thyroid gland

24
Q

What would we find when checking blood hormone levels in someone with primary hypothyroidism?

A

TSH high
T3/T4 low
TRH high (but don’t measure TRH)

25
Q

Why does TSH increase in primary hypothyroidism?

A

Low T3/T4 levels feedbacks to the hypothalamus and pituitary gland

Results in increased TRH secretion

Results in increased stimulation of TSH release

No negative feedback so TSH levels remain high

26
Q

What is secondary hypothyroidism?

A

Low thyroid hormone levels due to an underactive pituitary gland or pituitary gland failure (or hypothalamus)

27
Q

A pituitary tumour damaging thyrotrophs is a cause of what disease?

A

Secondary hypothyroidism

28
Q

What would we find when checking blood hormone levels in someone with secondary hypothyroidism?

A 
TSH low (because can't make TSH)
T3/T4 low
29
Q

Why do T3/T4 levels fall in secondary hypothyroidism?

A

Can’t make TSH

No stimulation of thyroid hormones to produce/release T3/T4

30
Q

ACTH regulates cortisol AND aldosterone secretion from the adrenal cortex. True or False?

A

FALSE!

Aldosterone is regulated by the renin-angiotensin system

31
Q

What regulates aldosterone production/secretion?

A

Aldosterone is regulated by the renin-angiotensin system

32
Q

What is the main problem in primary hypoadrenalism?

A

Damage to the adrenal glands causing reduced adrenal hormone production/secretion, e.g. autoimmune destruction of the adrenal cortex

33
Q

What is secondary hypoadrenalism?

A

ACTH deficiency due to pituitary or hypothalamic causes (or prolonged glucocorticoid administration)

34
Q

What would we find when checking blood hormone levels in someone with primary hypoadrenalism?

A

Cortisol low
ACTH high
(don’t measure CRH but it would also be high)

35
Q

What would we find when checking blood hormone levels in someone with secondary hypoadrenalism?

A

ACTH low - because can’t make ACTH

Cortisol low

36
Q

What condition might a pituitary tumour damaging corticotrophs cause?

A

Secondary hypoadrenalism

37
Q

What condition might the autoimmune destruction of the adrenal gland cause?

A

Primary hypoadrenalism - addison’s disease (primary adrenal failure)

38
Q

Name a potential cause of primary hypogonadism?

A

E.G.

Destruction of testes (e.g. mumps)
Destruction of ovaries (e.g. chemotherapy)

39
Q

Why does ACTH increase in primary hypoadrenalism?

A

Low cortisol levels feedbacks to the hypothalamus and pituitary gland

Results in increased CRH secretion

Results in increased stimulation of ACTH release

No negative feedback so ACTH levels remain high

40
Q

What would we find when checking blood hormone levels in someone with primary hypogonadism?

A

Testosterone or Oestrogen - low
LH/FSH - high
(GnRH - would also be high BUT we don’t measure this)

41
Q

Why do LH/FSH increase in primary hypogonadism?

A

Low testosterone/oestrogen levels feedback to the hypothalamus and pituitary gland

Results in increased GnRH secretion

Results in increased stimulation of LH & FSH release

No negative feedback so LH & FSH levels remain high

42
Q

What condition might be caused by a pituitary tumour damaging gonadotrophs?

A

Secondary hypothyroidism

43
Q

What would we find when checking blood hormone levels in someone with secondary hypogonadism?

A

Can’t make LH/FSH
LH/FSH levels - fall
Testosterone/oestrogen - fall

–> LH/FSH - low & testosterone/oestrogen - low

44
Q

What’s more common - congenital or acquired hypopituitarism?

A

Acquired causes are much more common

Congenital causes are very rare

45
Q

What mechanism usually underlies congenital hypopituitarism?

A

Mutations - of transcription factor genes needed for normal anterior pituitary development, e.g. PROP1 mutation

46
Q

What are some typical clinical findings in someone with congenital hypopituitarism?

A

Deficient in GH + at least 1 more anterior pituitary hormone

Short stature

Hypoplastic anterior pituitary gland on MRI

(Last two findings because have had low growth hormone since birth)

47
Q

List at least 3 acquired causes of hypopituitarism

A

Tumours, e.g. adenomas, metastases, cysts
Radiation (hypothalamic/pituitary damage)
Infection, e.g. meningitis
Traumatic brain injury
Pituitary surgery
Inflammatory (hypophysitis)
Pituitary apoplexy - haemorrhage (or less commonly infarction)
Peri-partum infarction (Sheehan’s syndrome)

48
Q

How many axis might hypopituitarism affect?

A

One axis, several or all

49
Q

What part of the pituitary gland does hypopituitarism describe?

A

Often describes anterior pituitary dysfunction

Certain processes, esp. inflammation (hypophysitis) or surgery, can cause posterior pituitary dysfunction too

50
Q

What is panhypopituitarism?

A

Total loss of anterior + posterior pituitary function

51
Q

What is the term for total loss of anterior & posterior pituitary function?

A

Panhypopituitarism

52
Q

Why can radiotherapy cause hypopituitarism?

A

Radiotherapy involves treatment with radiation. The pituitary gland and hypothalamus are both sensitive to radiation.

53
Q

How can treatment of acromegaly cause hypopituitarism?

A

Treatment can involve radiotherapy direct to the pituitary gland which is sensitive to radiation. This can cause pituitary damage, resulting in pituitary dysfunction.

54
Q

How can treatment of nasopharyngeal carcinoma result in hypopituitarism?

A

Treatment can involve radiotherapy which can cause indirect damage to the pituitary which is sensitive to radiation. This can cause pituitary dysfunction, resulting in hypopituitarism.

55
Q

What does the extent of hypopituitarism induced by radiotherapy depend on?

A

The total dose of radiotherapy delivered to the hypothalamo-pituitary axis (Gy).

56
Q

How can radiotherapy affect the pituitary gland?

A

It can cause radiotherapy induced hypopituitarism because the pituitary (and hypothalamus) is sensitive to radiation.

BRS2 - Endocrinology (1 decks)

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