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Homeostasis > Pituitary Disease > Flashcards

Pituitary Disease Flashcards

1
Q

Describe the location of the pituitary gland?

A
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2
Q

Arterial supply of the pituitary gland?

A
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3
Q

Anterior Pit Hormones?

A
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4
Q

Hormone regulation in the anterior pit?

A
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5
Q

Thyroid Reg?

A
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6
Q

gonadotrophin reg?

A
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7
Q

growth hormone reg?

A

IGF mediates it

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8
Q

Oxytocin causes?

A

Uterine contraction. It is stimulaterd by distension of the cervix.

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9
Q

Posterior Pit hormones?

A

Oxytocin

ADH

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10
Q

What inhibits AVP/ADH?

A

a decrease in plasma osmolality (not thirsty)

Thirsty (high plasma orsmolalitt).

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11
Q

Exampples of pituitary and parapituitary tummours?

A

Pit - Pituitary Adenoma

Parapituitary tumours (craniopharyngiomas, meningiomas)

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12
Q

Causes of hypopituitarism?

A

Pituitary (Pituitary adenoma) and parapituitary tumours (e.g. craniopharyngiomas, meningiomas)
Post-pituitary surgery
Post-radiotherapy to the pituitary or general irradiation to the brain (e.g in the treatment of childhood leukaemia)
Infarction (loss of blood supply) – ‘pituitary apoplexy’ (e.g. Sheehan’s syndrome)
Infiltration/inflammation e.g. sarcoidosis, lymphocytic hypophysitis (autoimmune)
Infection e.g. TB
Trauma e.g. head injury
Congenital
Functional e.g. psychosocial deprivation, weight loss, anorexia nervosa, athlete’s syndrome

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13
Q

Features of hypopituitarism?

A

Often non-specific:
Lack of energy
Fatigue
Weight gain

Related to specific hormone deficiencies
GH deficiency
LH/FSH deficiency
TSH and ACTH deficiency
Alterations in PRL secretion
Oxytocin,AVP deficiency

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14
Q

Gonadotropin Deficiency?

A
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15
Q

ADH/AVP deficiency clinical symptoms?

A

Deficiency of AVP leads to cranial diabetes insipidus
Polyuria (large volumes of dilute urine >3L/24 h), polydypsia
Not usually seen with pituitary tumours (but can occur as a complication of pituitary surgery)
Commoner with inflammatory diseases (e.g. sarcoidosis, hypophysitis) or other tumours (e.g. craniopharyngioma

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16
Q

how to investigate hypopituitarism?

A

Measurement of the basal pituitary or target gland hormones
Free T4, TSH, PRL, LH, FSH, testosterone (men) or oestradiol (women), IGF-1 and cortisol/ACTH
Stimulation test needed to confirm GH and cortisol deficiency
Insulin stress test (which will assess both)
If contraindicated synacthen test for cortisol deficicency and appropriate stimulation test for GH

17
Q

adequate stress test?

A
18
Q

when to measure synacthen test?

A

measure cortisol before and 30 mins after.

19
Q

how to investigate posterior dysfunction?

A

If clinically indicated, water deprivation test
Deprive of fluid for up to 8 hours
Measure plasma and urine osmolality and urine volume
Desmopressin (AVP analogue) given at the end if needed to distinguish between cranial and nephrogenic diabetes insipidus
Normal body response as osmolality and thirst etc goes up is to try to conserve water:
AVP secretion will rise and the urine will become concentrated (osmolality >800)
If cranial diabetes insipidus, urine will fail to concentrate and the patient will continue to pass large volumes of urine

20
Q

Urine Osmolality?

A
21
Q

how much does growth hormone cost?

A

£3000/year

22
Q

benefits of growth hormone replacmenet?

A

Improves quality of life (NICE approved)
Reduces fat mass and increases lean muscle mass
Benefical effect on lipids

23
Q

hormone replacments?

A

Thyroxine (tablets)
Hydrocortisone (tablets)
Testosterone (men; gels, patches, injections)
Oestrogen (women; oral contraceptive pill or HRT)
DDAVP (‘desmopressin’) if cranial diabetes insipidus (nasal spray or tablets)

24
Q

commonest cause of hypopituitarism?

A

Pituitary tumours

Benign and slow growing

Up to 10% of the population affected (incidental MRI findings increasingly common) but most will never come to clinical attention
Cause problems through:
Hormone excess syndromes
Hormone deficiency syndromes (already discussed)
Local pressure effects

25
Q

Local pressure effects of a pituitary tumour?

A

Headaches
If upward extension towards optic nerves then visual disturbance:
Loss of visual acuity
Visual field defects (outer part of vision – bitemporal hemianopia)
If sideways extension:
Cranial nerve palsies

26
Q

How to classify pituitary tumours?

A

Size
Microadenoma (<1cm)
Macroadenoma (>1cm)
Hormone-secreting or not
Prolactinoma (commonest, approx 40%)
Non-functioning (commonest needing surgery) 20-30%
Acromegaly (GH tumours) 10-15%
Cushing’s disease (ACTH tumours) 10-15%
TSHoma and true LH/FSH secreting tumours (causing clinical hormonal excess) very rare
Hypopituitarism is unusual in microadenomas but common in macroadenomas

27
Q

when do the pituitary tumurs commonly present?

A

midle-late life

28
Q

second commonest pituitary tumpur?

A

non functioning pituitary tumour

29
Q

if large adeonma what should you do?

A

surgery + radiotherapy

30
Q

symptoms of porlactin excess?

A

Women

Oligomenorrhoea/amenorrhoea

Galactorrhoea

Infertility

Hirsutism/acne*

Men
Reduced libido
Impotence
Infertility
Galactorrhoea*

31
Q

symptoms of enlarged tumour?

A

Headache
Visual failure
Cranial nerve palsies

32
Q

symptoms of pituitary hormone deficiency?

A

Microprolactinoma - usually normal
Macroprolactinoma - varying degrees of hypopituitarism

33
Q

causes of hyperprolactinaemia?

A

Stress (venepuncture?) Pregnancy Lactation

Anti-emetics e.g. metoclopramide, domperidone, prochlorperazine
Phenothiazines e.g. chlorpromazine
Antidepressants

34
Q

pathological causes of hyperprolactinaemia?

A

Primary hypothyroidism
Pituitary tumours Prolactinoma Growth hormone-secreting (30% acromegalics) Non-functioning (stalk compression)
PCOS (10%)
Hypothalamic lesions (rare) e.g. sarcoidosis
Chest wall stimulation e.g. post-herpes zoster
Liver or renal failure

35
Q

levels of prolactin?

A

macroprolactinomas tend to have much higher readings (e.g. >10,000; normal <500-600)
MRI scan

36
Q

treat prolactinaemia?

A

Drugs – bromocriptine or cabergoline
Very effective in normalising prolactin levels (85-90% patients) and restoring normal menstrual periods/ovulation etc
If not tolerated or macroprolactinoma not shrinking, then surgery may be considered but rarely needed

37
Q

features of acromegaly?

A

Coarse facial features
Enlargement of supraorbital ridges
Soft tissue thickening e.g. lips
Separation of teeth
Prognathism
Macroglossia
Enlargement of the hands and feet
Headaches
Excessive sweating
Hypertension
Impaired glucose tolerance/type 2 diabetes
Goitre

38
Q

treatment for pituitary tumour?

A

Surgery (transsphenoidal) usually first line
‘Cure’ depends on tumour size principally but also skill of surgeon
50% cure for macroadenomas
80-90% cure for microadenomas

Homeostasis (22 decks)

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