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Block 7 - Endocrine, Nutrition, Reproductive Health > 7.02 Pituitary Tumour > Flashcards

7.02 Pituitary Tumour Flashcards

1
Q

What are the phases of growth in humans?

A

Prenatal growth
Postnatal growth - infantile phase (first three years of life), childhood growth (3 to puberty) and pubertal growth spurt

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2
Q

Growth velocity of infantile phase of growth

A

Rapidly decelerating

Largely dependent on nutrition, genetics and endocrine hormones

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3
Q

Childhood growth velocity

A

Slowly decelerating

Regulated by genetic factors and GH

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4
Q

Pubertal growth spurt

A

28cm males, 25 cm females

Dependent upon sex steroids and GH

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5
Q

Where are GH receptors present?

A

In most tissues of the body, particularly liver

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6
Q

Weight gain velocity during infancy

A

Rapid (birth weight triples by 1 year)

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7
Q

Peak bone mineral velocity during puberty

A

Lags behind peak growth velocity by about 1 year. Causes a transient declie in mone mineral per bone volume, leading to an increased susceptibility of fractures

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8
Q

Pituitary fossa

A

Depression on upper surface of sphenoid bone

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9
Q

Sellar diaphragm

A

Sheet of dura that stretches over the clinoid processes. The centre has a small opening where the pituitary stalk sits

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10
Q

What is on the floor of the cavernous sinus?

A

V2, V ganglion, V3

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11
Q

Where does the carotid plexus distribute its fibres?

A

Deep structures (eye and LPS)

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12
Q

Origin of the neurohypophysis

A

Floor of diencephalon

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13
Q

Origin of adenohypophysis

A

Roof of the embryonic pharynx

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14
Q

What are the three “pars” of the anterior pituitary?

A 
Pars distalis (most of AP)
Pars intermedia (internediate part between AP and PP)
Pars tuberalis (sheath extendig from pars distalis and wrapping around the pituitary stalk)
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15
Q

What does prolactin do in males (normally)?

A

It increases testosterone binding in the prostate and formation of androgen receptor complexes

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16
Q

B FLAT

A

Basophilic cells of the AP: FSH, LH, ACTH, TSH

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17
Q

Where are oxytocin and vasopressin made?

A

The hypothalamus

Supraoptic and paraventricular nuclei

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18
Q

Vascular supply of the PG

A

Branches of the ICA

Superior hypophyseal arteries - infindubulum, which connects to AP via hypophyseal portal system

Inferior hypophyseal arteries - neural lobe of AP

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19
Q

Hypophyseal portal system

A

Venules connecting capillaries in the median eminence

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20
Q

Does the AP receive a direct blood supply?

A

No. It depends on the hypophyseal portal system

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21
Q

Microadenoma

A

<1cm diameter

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22
Q

Macroadenoma

A

> 1cm diameter

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23
Q

What is known about mutations in pituitary adenomas?

A

Evidence of monoclonality, oncogene activation, G protein mutations (for non-functioning pituitary adenomas)

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24
Q

When do pressure effects of the tumour occur?

A

When the tumour is a macroadenoma

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25
Q

What symptoms result from compression or invasion of adjacent structures by the tumour?

A

headache (stretching of dura)
CSF obstruction & hydrocephalus (large tumours)
visual disturbances (optic compression)
CSF rhinorrhoea (erosion of sella turcica)
III, IV or VI palsies

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26
Q

How is GH release co-ordinated?

A

GH secretion is co-ordinated by a synchronous decrease in somostatin tone and release of GHRH from the hypothalamus.

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27
Q

Presenting symptoms of a prolactinoma in men

A

Men usually present with impotence or symptoms of hypogonadism. Galactorrhoea occurs in about 20%.

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28
Q

What types of prolactinomas (micro or macro_) are common in (a) men and (b) women?

A

The majority of prolactinomas in women are microadenoams, whereas in men they are more frequently macroadenomas

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29
Q

When would coma occur as a presenting symptom of raised ICP?

A

This is usually a late stage presentation, but occasionally a rapid herniation of the brain can cause coma as the first presentation.

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30
Q

How does a tumour cause hypopituitarism?

A

If normal pituitary tissue is destroyed by the tumour
Iatrogenically, as a consequence of Tx
Compression of the pituitary stalk, causing disruption of delivery of hormones from HTH

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31
Q

What is the order of loss of pituitary hormone secretion?

A

Prolactin, Gonadotophins, GH, TSH, ACTH

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32
Q

Carniopharyngioma

A

Arises from remnants of Rathke’s pouch (roof of mouth that gives rise to AP). A congenital malformation which grows at variable rates, forming cysts as they enlarge.

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33
Q

Most common presentation of craniopharyngioma

A

Increased ICP

Usually present in middle childhood

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34
Q

What are the main pituitary tumours

A 
From most common to least common:
Non-functioning adenoma
Prolactinoma
Combined GH/prolactin producing adenoma
Thyrotrope adenoma
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35
Q

Non-functioning adenomas can stain positive for what?

A

Glycoprotein hormones, e.g. gonadotrophins, LH/FSH/TSH (the beta-subunit) BUT they are either non-secretory or only secrete biologically inactive hormones (i.e. subunits)

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36
Q

What do you need to remember about secretory tumours and other hormones?

A

A secretory adenoma can cause a deficiency of the other pituitary hormones

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37
Q

Gigantism

A

Caused by GH secreting adenoma in childhood, before epiphyseal closure

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38
Q

Gonadotrope adenomas

A

Women have no symptoms
Men may have sexual dysfunction or gynacomastia
Children may have precocious puberty

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39
Q

What is the classic triad of increased ICP that could possibly be due to a brain tumour (or other space occupying lesion)?

A

Headaches, vomiting, papilloedema

40
Q

In children, when might the visual problems associated with increased ICP be drawn to one’s attention?

A

When they are having trouble in school

Children might not complain about vision problems until they are nearly blind

41
Q

Papilloedoema

A

Transmission of ICP along the optic nerve sheath, causing venous congestion and swelling

42
Q

Headache

A

Due to tension on dura or blood vessels

Headache tends to increase gradually ove time and is worst on waking when ICP is highest

43
Q

Vomiting

A

Distortion/ischaemia in areas of the medulla involved with vomiting (area postrema). More common in children, and may be very sudden in onset

44
Q

Can ICP be high in the absence of papilloedema?

A

Yes. The anatomy of the optic sheath may not allow for the transmission of pressure

45
Q

What are the late signs in increased ICP?

A

Disturbances of consciousness, oculomotor function disturbances (suggests that intracranial adaptive capacity has become exhausted)

46
Q

Other signs of intracranial masses

A

Disturbed function of the structures involved in the tumour
e.g. reduced pituitary function
If cortex is involved, focal or generalised epilepsy may occur

47
Q

Severe short stature is associated with which diseases?

A

Primary disorders of bone (e.g. achondroplasia) or bone metabolism (osteogenesis imperfecta)

48
Q

Psychological consequences of short stature?

A

There is a positive correlation between lack of self-esteem, depression, underachievement and shortness of stature

BUT recent studies show few psych consequences in children and adolescence and sometimes health professionals rate child as having more problems than the child demonstrates

49
Q

Things that a short child might do

A

Elicit behaviours more appropriate for their “height age” than actual age.
Coping with teasing by clowning around/joking
Self-sufficiency and independence may suffer (unless physical environment is adjusted to height level)

50
Q

Effect of early maturation in girls

A

May benefit in contrast to the late-maturing girl

51
Q

Effect on late maturation in boys

A

Less poised, less relaxed, more restless

52
Q

What is normal short stature?

A

Short stature that is not a consequence of endocrine disorder. Endocrine therapies are not necessary

53
Q

Is blood pressure affected at normal levels of vasopressin release?

A

No

54
Q

What can diabetes insipidus be caused by?

A

Destruction of cell bodies in hypothalamus
Mutation in vasopressin gene

Results in increased secretion of ADH

NB destruction or removal of the pituitary will not remove the source of vasopressin

55
Q

What happens if the thirst mechanism is disrupted?

A

Circulatory collapse - this can be fatal

56
Q

Actions of oxytocin

A

Uterine contractions at birth (neuroendocrine reflex), milk let-down (suckling), coitus, behavioural effects

57
Q

Germinoma

A

Tumour of germ cell origin

A child is more likely to have a tumour of germ-cell origin or a low-grade astrocytoma from an adjacent structure than a ptiuitary adenoma

Investigations: alphafoetoprotein and beta HCG in CSF/serum as markers of germ-cell origin tumour

58
Q

Treatment of pituitary macroadenomas - options

A

Surgery, radiotherapy, drugs

Must be treated because they have demonstrated they have a capacity to grow

59
Q

Radiation therapy

A

Used in patients with recurrent or incompletely excised tumours

60
Q

Surgery

A

Mostly trans-sphenoidal surgery

Trans-cranial if they have extended into other parts

61
Q

Drugs

A

Prolactinoma: cabergoline (DA Agonist)
GH adenoma: octreotide (somatostatin analogue)
ACTH: ketoconazole (usually reserved for patients unsuitable for surgery or with recurrent tumours after radiation)

62
Q

Circadian rhythms

A 
Endogenously produced biological rhythms
Repetitive oscillations (1 cycle per 24 hours)
Maintained under constant conditions
63
Q

Circadian system

A

Co-ordinates physioloigcal and behavioural activities of brain and body

64
Q

Activities influenced by the circadian system

A

Sleep-wake timing, thermoregulation, respiratory function, CV function, alertness, neurocognitive performance, immune function, endocrine function, GIT function, renal function

65
Q

The circadian system is a wake-promoting system that works in opposition to the …

A

… homeostatic sleep system

66
Q

Where is the “circadian pacemaker”

A

suprachiasmatic nuclei of anterior HTH

67
Q

Zeitberger

A

Environmental cue

Strongest is the light-dark cycle

68
Q

Retinohypothalamic tract

A

Involved in phototransduction from retina to suprachiasmatic nucleus

69
Q

Zeitbergers other than light

A

Melatonin, exercise, social cues

70
Q

Circadian disruption

A

Occurs due to misalignment in timing of circadian system relative to environmental light-dark cycle

71
Q

Melatonin

A

Secreted by the pineal gland

Modulated by sympathetic innervation from the pineal gland

72
Q

How is melatonin synthesis stimulated at night?

A

Neurons in SCN receive (absence of) light info from retina, and synthesise melanin

73
Q

How is melatonin synthesis suppressed during the day?

A

Suppression of sympathetic neurons in SCN

74
Q

Is melatonin affected by sleep deprivation?

A

No. Melatonin secretion occurs independent of sleep-wake status

75
Q

Measuring melatonin

A

Blood and saliva
Primary metabolite is excreted in urine

Must be determined in dim lights because it is sensitive to light exposure

76
Q

Can melatonin promote regulation of sleep?

A

Yes. Nightly onselt of melatonin occurs around the same time as the nightly increase in sleepiness and sleep propensity.

Administration of melatonin during the day makes a person sleepy

77
Q

Cortisol is different from melatonin as it is influenced by …

A

the circadian system
sleep-wake behaviour AND
stress

78
Q

What is the morning peak in cortisol related to?

A

Sleep termination. When sleep offset is delayed, so is the peak in cortisol. So during 24 hour sleep deprivation, cortisol levels tend to be elevated compared to normal

79
Q

Circadian rhythms

A 
Endogenously produced biological rhythms
Repetitive oscillations (1 cycle per 24 hours)
Maintained under constant conditions
80
Q

Circadian system

A

Co-ordinates physioloigcal and behavioural activities of brain and body

81
Q

Activities influenced by the circadian system

A

Sleep-wake timing, thermoregulation, respiratory function, CV function, alertness, neurocognitive performance, immune function, endocrine function, GIT function, renal function

82
Q

The circadian system is a wake-promoting system that works in opposition to the …

A

… homeostatic sleep system

83
Q

Where is the “circadian pacemaker”

A

suprachiasmatic nuclei of anterior HTH

84
Q

Zeitberger

A

Environmental cue

Strongest is the light-dark cycle

85
Q

Retinohypothalamic tract

A

Involved in phototransduction from retina to suprachiasmatic nucleus

86
Q

Zeitbergers other than light

A

Melatonin, exercise, social cues

87
Q

Circadian disruption

A

Occurs due to misalignment in timing of circadian system relative to environmental light-dark cycle

88
Q

Melatonin

A

Secreted by the pineal gland

Modulated by sympathetic innervation from the pineal gland

89
Q

How is melatonin synthesis stimulated at night?

A

Neurons in SCN receive (absence of) light info from retina, and synthesise melanin

90
Q

How is melatonin synthesis suppressed during the day?

A

Suppression of sympathetic neurons in SCN

91
Q

Is melatonin affected by sleep deprivation?

A

No. Melatonin secretion occurs independent of sleep-wake status

92
Q

Measuring melatonin

A

Blood and saliva
Primary metabolite is excreted in urine

Must be determined in dim lights because it is sensitive to light exposure

93
Q

Can melatonin promote regulation of sleep?

A

Yes. Nightly onselt of melatonin occurs around the same time as the nightly increase in sleepiness and sleep propensity.

Administration of melatonin during the day makes a person sleepy

94
Q

Cortisol is different from melatonin as it is influenced by …

A

the circadian system
sleep-wake behaviour AND
stress

95
Q

What is the morning peak in cortisol related to?

A

Sleep termination. When sleep offset is delayed, so is the peak in cortisol. So during 24 hour sleep deprivation, cortisol levels tend to be elevated compared to normal

Block 7 - Endocrine, Nutrition, Reproductive Health (5 decks)

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