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Y3M - Diabetes & Endocrinology > Pituitary Assessment & Hyperprolactinaemia > Flashcards

Pituitary Assessment & Hyperprolactinaemia Flashcards

1
Q

Location of the pituitary.

A

Size of a pea and sits in the pituitary fossa in the sella turcica at the base of the brain.

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2
Q

Origins of the pituitary.

A

Anterior is an up-growth of gut.

Posterior is a down-growth of primitive brain tissue.

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3
Q

What is found superior to the pituitary?

A

Optic chiasm

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4
Q

What is found lateral to the pituitary gland?

A

Cavernous sinus

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5
Q

Give the 5 pituitary axes.

A

Growth axis

Adrenal axis

Gonadal axis

Thyroid axis

Prolactin axis

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6
Q

Secretion manner of GH

A

Pulsatile

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7
Q

When are the peak pulses of GH?

A

During REM sleep

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8
Q

Explain the action of GH

A

Acts on the liver to produce IGF-1

Also acts directly on its receptor to stimulate musculoskeletal growth in children.

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9
Q

Marker of GH activity.

A

IGF-1

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10
Q

Positive and negative control of GH.

A

+ve control by GHRH

-ve control by somatostatin

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11
Q

Secretion manner of ACTH

A

Circadian rhythm

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12
Q

Highest conc and lowest of ACTH/cortisol.

A

Highest in the morning around 8-9

Lowest at midnight.

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13
Q

Secretion manner of GnRH.

A

Pulsatile which will stimulate FSH and LH

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14
Q

What inhibits FSH and LH?

A

Testosterone

Oestrogen

Prolactin

(TRH indirectly)

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15
Q

TRH stimulates TSH release.

What else does it stimulate?

A

Prolactin release.

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16
Q

Effects of prolactin on other hormones.

A

Direct inhibitory effect on LH and FSH.

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17
Q

Give examples of functioning pituitary tumours.

A

GH Acromegaly (Chromophobe or Acidophil)

Cushings disease from ACTH (Basophil or Chromophobe)

Prolactinoma from PRL (Chromophobe or Acidophil)

TSHoma

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18
Q

Hormone levels in a non-functioning pituitary tumour.

A

All usually go down except for prolactin which will go up.

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19
Q

How do non-functioning pituitary tumours usually present?

A

Hypopituitarism and compression of local structures.

Compression of optic chiasm leading to bitemporal hemianopia.

Hyperprolactinaemia

Headache

Palsy of cranial nerves III, IV, VI.

Erosion through floor of sella leading to CSF Rhinorrhoea

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20
Q

What examination is essential for patients with pituitary tumours?

A

Visual field

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21
Q

Basal tests of pituitary tumour.

A

Prolactin

TSH

LH and FSH

Testosterone

Cortisol

IGF-1

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22
Q

When can TSH and Prolactin be checked?

A

Any time of day as they don’t fluctuate much.

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23
Q

Why should both fT4 and TSH be checked in suspected secondary hypthyroidism?

A

Because TSH is usually normal.

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24
Q

When should LH and FSH be checked in women?

A

1st 5 days of the menstrual cycle.

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25
Q

When should LH and FSH as well as basal testosterone be checked in men?

A

At 0900 in the fasting state.

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26
Q

When should cortisol be checked when deficiency is suspected?

A

At 0900

27
Q

What is a good marker to measure in order to find GH abnormalities?

A

IGF-1.

Low levels suggest deficiency

High levels suggest excess.

28
Q

What dynamic tests are used to assess pituitary function?

A

Synacthen test

Insulin tolerance test

29
Q

Explain synacthen test.

A

To assess primary adrenal failure.

Also useful to assess pituitary ACTH reserve.

30
Q

Why is synacthen predominantly use for primary adrenal failure and not secondary to pituitary?

A

Because after two weeks of ACTH deficiency atrophy of the adrenal cortex leads to an inadequate response to synacthen.

31
Q

Should synacthen test be used in an acute situation?

A

No it cannot assess ACTH reserves in an acute situation such as pituitary apoplexy and immediately post-pituitary surgery.

32
Q

What is the gold standard to test ACTH and GH reserves?

A

Insulin Tolerance test (ITT)

33
Q

Explain insuline tolerance test.

A

Insulin indiced hypoglycaemia will put significant physiological stress on the body.

If frank hypoglycaemia is achieved with symptoms, ACTH and GH will rise accordingly.

34
Q

When is insulin tolerance test contraindicated?

A

Ischaemic heart disease (coronary ischaemia)

Epilepsy (seizures)

35
Q

Imaging choice of pituitary gland.

A

MRI

36
Q

Definition of pituitary macro-adenoma.

A

> 1 cm

37
Q

Definition of pituitary micro-adenoma.

A

< 1 cm

38
Q

What imaging can be used in case a patient is unable to have an MRI?

A

CT

39
Q

What are some uprising functional imaging concerning functionaly of the lesion?

A

PET and fMRI

40
Q

Give broad causes of hyperprolactinaemia.

A

Pituitary

Physiological

Hypothalamic

Medication

Analytical

Secondary

41
Q

Give pituitary causes of hyperprolactinaemia.

A

Prolactinoma (functioning)

Non-functioning pituitary tumour

Hypophysitis

Stalk section

Infiltrative disease

42
Q

Give physiological causes of hyperprolactinaemia.

A

Pregnancy

Breast stimulation

Stress

43
Q

Give hypothalamic causes of hyperprolactinaemia.

A

Tumours

Infiltrative disease

44
Q

Give medication that can cause hyperprolactinaemia.

A

Antipsychotics

Antiemetics

Antihypertensives

Oestrogen

45
Q

Secondary causes of hyperprolactinaemia.

A

Renal failure

Primary hypothyroidism (Leading to high levels of TRH)

Adrenal insufficiency

Polycystic ovary syndrome (PCOS)

46
Q

What levels of prolactin suggests a large pituitary tumour actively secreting prolactin aka prolactinoma?

A

> 5000 miU/L of prolactin

47
Q

What does a pituitary tumour with a prolactin level of lower than 5000 miU/L suggest?

A

Non-functioning adenoma compressing the pituitary stalk.

48
Q

What are the most common pituitary tumours?

A

Micro-prolactinomas

49
Q

Men vs Women micro-prolactinomas

A

More common in women.

50
Q

Clinical features of micro-prolactinomas.

A

Menstrual disturbance or hypogonadism in men

Galactorrhoea

Infertility might be the only feature that shows

51
Q

How is PCOS distinguished from a prolactinoma?

A

By the presence of androgenic symptoms like hirsutism in PCOS.

Also by less elevated prolacitn levels < 1000 miU/L.

Absence of pituitary lesion on MRI

52
Q

Men vs women in macro-prolactinoma.

A

More common in men than women.

53
Q

Explain the Hook effect in macro-prolactinoma investigation.

A

When levels of prolactin are extremely high the immuno-assay can give inaccurately low results.

54
Q

How is the Hook effect dealt with?

A

Dilute the sample to achieve a more accurate result.

55
Q

Treatment of prolactinomas.

A

D2 agonists such as cabergoline (most common) or bromocriptine.

56
Q

Frequency of dosage of cabergoline vs bromocriptine.

A

Cabergoline is once or twice weekly.

Bromocriptine given daily.

Cabergoline is generally tolerated better.

57
Q

Common side effects of prolactinoma treatment.

A

Nausea

Postural hypotension

Rarely psychiatric disturbances

58
Q

What is the risk of D2 agonist treatment in macro-prolactinomas?

A

In 15% of cases D2 agonist treatment of macro-prolactinomas can cause CSF leak due to rapid reduction in size of the lesion.

This gives a potential risk for meningitis.

59
Q

What is a risk of a high cumulative dose of dopamine agonists in Parkinsons?

A

Cardiac valve abnormalities.

Not a concern for prolactinoma doses.

60
Q

Investigations of hyperprolactinaemia.

A 
Basal PRL (Non-stressful venepuncture between 09.00 and 16.00h)
Do a pregnancy test,TFT, U&Es,
MRI pituitary might be done if other causes are ruled out.
61
Q

What is pituitary apoplexy?

A

Rapid pituitary enlargement from a bleed into a tumour.

This may cause mass effects, CVS collapse and death.

Suspect this if there is an acute onset of headache, meningism, decreased GCS, opthalmoplegia/visual field defect.

62
Q

Treatment of pituitary apoplexy.

A

Urgent steroids (Hydrocortisone IV 100mg)

Fluid balance

+/- cabergoline if prolactinoma

+/- surgery.

63
Q

The pituitary’s relationship to cranial nerves.

A

Y3M - Diabetes & Endocrinology (17 decks)

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