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Endocrinology > Pituitary disorders > Flashcards

Pituitary disorders Flashcards

1
Q

Pituitary tumours tend to be…?

A

Adenomas - benign tumour of glandular epithelial tissue

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2
Q

What is a macro-adenoma?

A

Tumour bigger than 1cm

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3
Q

What is a micro-adenoma?

A

Tumour smaller than 1cm

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4
Q

What causes a pituitary tumour to present?

A

Mass effect of tumour, pressure on local structures

Abnormality in pituitary function

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5
Q

Which structures can be compressed by a pituitary tumour?

A

Optic chiasm

Cranial nerves 3+4

Cranial nerve 5

Cranial nerve 6

Internal carotid artery

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6
Q

What will be compressed by a pituitary tumour growing superiorly?

A

The optic chiasm

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7
Q

What are the consequences of a compressed optic chiasm?

A

Bitemporal hemi-anopia - visual field loss

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8
Q

Which structures can be compressed by a pituitary tumour growing laterally?

A

Cranial nerves 3+4

Cranial nerves 5

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9
Q

What are the consequences of compressed cranial nerves 3+4?

A

Double vision

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10
Q

What are the consequences of compressed cranial nerves 5?

A

Pain

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11
Q

What is a non-functioning pituitary tumour?

A

Tumour cells do not produce any biologically active hormones

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12
Q

What is a functional pituitary tumour?

A

Tumour cells produce biologically active hormones

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13
Q

If a non-functioning pituitary tumour secretes hormones, they will be…?

A

Inactive, not biologically active!

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14
Q

What causes abnormality of pituitary function in a non-functioning pituitary tumour?

A

Tumour prevents tropic hormones from hypothalamus
reaching anterior pituitary gland

Or due to pressure of tumour on glandular tissue in anterior pituitary

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15
Q

What does abnormality of pituitary function lead to?

A

Hypo- or hyper-secretion or hormones

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16
Q

What is hypopituitarism?

A

Insufficient anterior pitutiary hormone production

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17
Q

What is panhypopituitarism?

A

Deficiency of all anterior pituitary hormones

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18
Q

In a non-functional pituitary tumour where hypothalamic tropic hormones can’t reach the anterior pituitary gland, which hormones are hypo-secreted? Why?

A 
TSH
GH
ACTH
FSH
LH

Loss of stimulating hormones from hypothalamus

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19
Q

In a non-functional pituitary tumour where the hypothalamic tropic hormones can’t reach the anterior pituitary gland, which hormone is hyper-secreted? Why?

A

Prolactin

Loss of inhibitory hormone PRIH/dopamine from hypothalamus

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20
Q

What is the order by which the hormones become deficient?

A

Growth hormone

FSH, LH

TSH, ACTH

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21
Q

What are the consequences of growth hormone deficiency in children?

A

Pituitary dwarfism - proportionate type of dwarfism

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22
Q

What are the consequences of growth hormone deficiency in teens?

A

Delayed or no sexual development

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23
Q

What are the consequences of growth hormone deficiency in adults?

A

Muscle weakness

Increased body fat

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24
Q

Why is growth hormone deficiency difficult to detect?

A

Because growth hormone is secreted in a pulsatile manner throughout the day

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25
Q

How is growth hormone deficiency treated?

A

Giving recombinant growth hormone

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26
Q

What are the consequences of FSH, LH deficiency in teenagers?

A

Delayed puberty

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27
Q

What are the consequences of FSH, LH deficiency in adults?

A

Females - oligomenhorrea, amenhorrea

Males - impotence

Both sexes - loss of sexual characteristics e.g. pubic hair, axillary hair, loss of libido, infertility

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28
Q

What are the consequences of TSH deficiency?

A

Hypothyroidism symptoms

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29
Q

What is particular about hypothyroidism caused by a pituitary adenoma?

A

TSH will be low as well as thyroid hormones

Because even though there’s less negative feedback of the anterior pituitary, it can’t produce TSH

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30
Q

What is hyperpituitarism?

A

Excessive secretion of hormones from anterior pituitary gland

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31
Q

Which hormones are commonly over-secreted by a functional pituitary tumour?

A

Prolactin

GH

ACTH

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32
Q

Which hormones are rarely over-secreted by a functional pituitary tumour?

A

TSH

LH, FSH

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33
Q

What is a prolactinoma?

A

A prolactin-secreting pituitary tumour

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34
Q

Which secretes more prolactin - a macro-prolactinoma or a micro-prolactinoma?

A

Macro-prolactinoma

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35
Q

What does a prolactinoma cause?

A

Hyperprolactinaemia - high levels of prolactin in the blood

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36
Q

What are the symptoms of hyperprolactinaemia in women?

A

Gynecomastia - hard breast tissue

Galactorrhea - abnormal milk production

Amenhorrea

Hypogonadism - reduced activity of ovaries

37
Q

What are the consequences of hyperprolactinaemia in men?

A

Hypogonadism - reduced activity of testes

Erectile dysfunction

38
Q

Are macro-prolactinomas more common in men or women? Why?

A

Men
realise symptoms later
tumour grows in the meanwhile

39
Q

Why does hyperprolactinaemia cause hypogonadism?

A

High prolactin means hypothalamus secretes more dopamine
due to negative feedback

Dopamine also inhibits GnRH release from hypothalamus
Less LH and FSH released from anterior pituitary

40
Q

Which symptoms of a prolactinoma do men tend to present with?

A

Symptoms due to mass effect of tumour

e.g. headaches, double vision, visual field loss

41
Q

What do non-functioning pituitary tumours and prolactinomas have in common?

A

Both give increase in prolactin

42
Q

How are non-functioning pituitary tumours distinguished from prolactinomas?

A

Prolactin <5000
due to disinhibition of prolactin
by non-functioning pituitary tumour

Prolactin >5000
due to secretion of prolactin
by prolactinoma

43
Q

Why is it important to distinguish between prolactinomas and non-functioning pituitary tumours?

A

Because prolactinomas are treated medically

But non-functioning pituitary tumours are treaed surgically

44
Q

How is prolactinoma treated?

A

Dopamine agonists

45
Q

What is an example of a dopamine agonist?

A

Cabergoline

46
Q

What do dopamine agonists do?

A

Stimulate D2 receptor

47
Q

What is the result of treating a prolactinoma with dopamine agonists?

A

Dopamine inhibits prolactin secretion

Tumour will shrink in size

48
Q

Do men or women present later with prolactinomas? Why?

A

Men

have no periods so realise symptoms later

49
Q

What are some physiological causes of hyperprolactinaemia?

A

Pregnancy, suckling

50
Q

What are some medical causes of hyperprolactinaemia?

A

Anti-pysychotic drugs

Anti-depressants

51
Q

What is an example of dopamine antagonists?

A

Anti-psychotic drugs

52
Q

What is the cause of acromegaly?

A

Pituitary adenoma secreting growth hormone

53
Q

How are the symptoms of acromegaly brought about?

A

Increased GH

Increased IGF-1

54
Q

How long does it take for the symptoms of acromegaly to present?

A

Several years

55
Q

What are the signs of acromegaly?

A 
Broad nose
Coarse facial features
Thick lips
Prominent supraorbital ridge
Enlargement of hands and feet
56
Q

How are blood tests used to confirm acromegaly?

A

Elevated GH
Failure to suppress GH with glucose

Elevated IGF-1

57
Q

How is acromegaly treated?

A

Surgery to remove adenoma

Radiation therapy

Dopamine agonists

Somatostatin analogues

GH receptor antagonists

58
Q

How can dopamine agonist treat acromegaly?

A

Reduces GH secretion

59
Q

Give an example of a GH receptor antagonist?

A

Pegvisomant

60
Q

What is the consequence of growth hormone excess during childhood? Why?

A

Gigantism
epiphyseal plates have not yet closed
bones continue to grow in length

61
Q

What can cause a deficiency in ADH?

A

Hypothalamic tumour

Pituitary tumour that has extended upwards into hypothalamus

Infection, autoimmune conditions

62
Q

What is the function of ADH?

A

Increases expression of aquaporin channels in kidneys

giving increased reabsorption of water

63
Q

What happens in ADH deficiency?

A

Lack of aquaporin channels in kidneys
reduced reabsorption of water
more urine produced, dilute urine

64
Q

What are the consequences of ADH deficiency?

A

Larger quantities of dilute urine

Dehydration

Increased thirst

65
Q

What is ADH deficiency called when the consequences arise?

A

Diabetes insipidus - cranial type

66
Q

What is another type of diabetes insipidus? What causes it?

A

Nephrogenic type

Caused by kidney disease
kidneys don’t respond to ADH, resistant to it

67
Q

What are some of the complications of diabetes insipidius?

A

Hypernatraemia - high sodium levels

68
Q

How is cranial diabetes insipidus treated?

A

Desmopressin - acts as replacement of ADH

69
Q

How is desmopressin given?

A

Nasal spray

Tablets

Injections

70
Q

What is apoplexy?

A

Stroke - sudden vascular event

71
Q

What is a pituitary apoplexy?

A

Suddent vascular event in pituitary tumour

72
Q

What are the types of pituitary apoplexy? How are they different?

A

Haemorrhage - bleeding within tumour

Infarction - lack of blood supply, ischaemia giving cell death

73
Q

How does pituitary apoplexy present?

A

Sudden onset headache

Bitemporal hemi-anopia

Double vision

Hypopituitarism

74
Q

What are the consequences of a functional pituitary tumour secreting TSH?

A

Hyperthyroidism symptoms, thyrotoxicosis

75
Q

What is particular about hyperthyroidism caused by a pituitary adenoma?

A

TSH levels remain raised with raised thyroid hormone levels too
Because pituitary adenoma isn’t inhibited by raised thyroid hormone levels, still secretes TSH

76
Q

What is measured in a blood test when a pituitary tumour is suspected?

A

Free T4, TSH

LH, FSH
Testosterone in men
Oestriadiol in women

Serum prolactin

77
Q

Which dynamic blood tests are carried when a pituitary tumour is suspected?

A

GH, IGF1

9am cortisol - cortisol is highest in morning

78
Q

What are the two types of dynamic assessments of HP axes?

A

Stimulation test

Suppression test

79
Q

When is a stimulation test used?

A

When suspect a hormone deficiency

80
Q

How does a stimulation test work?

A

Try and stimulate release of a particular hormone

81
Q

How are the results of a stimulation test interpreted?

A

If hormone levels don’t increase

means hormone deficiency

82
Q

When is a suppression test used?

A

When suspect a hormone excess

83
Q

How does a suppression test work?

A

Try and suppress the release of a particular hormone

84
Q

How are the results of a suppression test interpreted?

A

If hormone levels don’t decrease

means hormone excess

85
Q

What is the stimulation test for GH deficiency?

A

Give insulin
person becomes hypoglycaemic
growth hormone should increase

86
Q

What is the suppression test for GH excess?

A

Give glucose
person becomes hyperglycaemic
growth hormone should decrease

87
Q

What imaging techniques are used when investigating a pituitary tumour?

A

MRI

88
Q

What other tests are done when investigating a pituitary tumour?

A

Assessing visual fields - bi-temporal hemi-anopia

Endocrinology (14 decks)

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