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Endocrinology > Pituitary > Flashcards

Pituitary Flashcards

1
Q

Effect of somatostatin on GH

A

Inhibitory

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2
Q

Effect of somatostatin on TSH

A

Inhibitory

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3
Q

Effect of dopamine on prolactin

A

Inhibitory

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4
Q

In which 3 places can hypopituitarism be caused?

A

Hypothalamus, pituitary stalk and pituitary

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5
Q

What is Kallman’s syndrome?

A

Defect in gene KAL1 involved in making anosmin which is involved in olfactory system and migration of GNRH secreting neurons

Therefore causes GnRH deficiency - and hypogonadism
Also anosmia

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6
Q

What other hypothalamic problems can cause hypopituitarism?

A

Tumour, inflammation, infection (meningitis and TB) and ischaemia

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7
Q

Pituitary stalk origin of hypopituitarism?

A 
Trauma
Surgery
Mass lesion (craniopharyngioma) 
Meningioma
Carotid artery aneurysm
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8
Q

Pituitary origin of hypopituitarism?

A 
Tumour
Irradiation 
Inflammation 
Autoimmunity 
Infiltration - mets, haemochromatosis, amyloid 
Ischaemia - pit apoplexy (haemorrhage or infarction of a pituitary tumour) + Sheenhan's syndrome (pit necrosis following postpartum haermorrhage)
Skull base fracture 
Infection - meningitis, encephalitis
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9
Q

What type of tumours are pituitary tumours normally?

A

Benign adenomas

10% of all intracranial tumours

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10
Q

What are chromophobe tumours?

A 
70% 
Many are non-secretory 
Some cause hypopituitarism 
Half produce prolactin 
A few produce ACTH or GH
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11
Q

What do acidophil tumours produce?

A

GH, PRL

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12
Q

What do basophil tumours produce?

A

ACTH (Cushing’s)

LH, FSH, TSH - rarer

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13
Q

Local pressure effects in pituitary tumours

And hypothalamic effects

A

Headache,
Visual field defects - bitemporal hemianopia
Palsy of CN III, IV and VI
Diabetes Insipidus (post-pit)
Disturbance of hypothalamic centres of temp, sleep and appetite

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14
Q

If treated hypopituitarism what order do you need to give drugs?

A

Steroids (to treat Cushing’s) before levothyroxine

As levothyroxine can precipitate an adrenal crisis (addisonian crisis)

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15
Q

What is pituitary apoplexy?

A

Rapid enlargement of a pituitary tumour due to infarction or haemorrhage.

Can cause sudden severe headache and rapidly deteriorating visual function including double vision and vision loss.

Sometimes followed by acute hypopituitarism

Can be treated conservatively with hormone replacement but if bad visual loss then may need decompressive surgery

Need to give steroids to prevent Addisonian crisis

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16
Q

When give cabergoline?

A

Dopamine agonist given if prolactinoma

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17
Q

What is a craniopharyngioma?

A

Not strictly a pit tumour as it originates from Rathke’s pouch of hypothalamus - situated between pituitary and 3rd ventricle floor

Commonest intracranial tumour in childhood

Present with growth failure

But can present at any age - presentation mimics intrinsic pituitary lesion

Often calcified - can see calcification on xray in 50%

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18
Q

Order of deficiencies following pituitary tumour growth?

A

GH and gonadotropins usually affected first
Hyperprolactinaemia (loss of dopamine tonic inhibition) usually occurs early on as well
Then LH and FSH
TSH and ACTH usually affected last

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19
Q

What is panhypopituitarism?

A

Deficiency of all pituitary hormones - usually due to tumour, irradiation or surgery

Rarely are post-pituitary hormones affected

Can be if severe suprasellar extension to affect hypothalamus

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20
Q

How does hyperprolactinaemia present in women and men?

A

Women - usually presents earlier with menstrual disturbance

  • can also get galactorrhoea, low libido, weight gain and dry vagina

Men - later as erectile dysfunction or mass effects

  • also get galactorrhoea and loss of facial hair
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21
Q

What can raised prolactin levels cause?

A

Hypogonadism, infertility and osteoporosis

- by inhibiting GnRH production and therefore production of LH and FSH

22
Q

Causes of hyperprolactinaemia

A

Prolactinoma (very high prolactin levels likely to be this - >5000mu/L)
Compression of pit stalk
Use of dopamine antagonist

23
Q

Which endocrine disorder can cause increased prolactin secretion?

A

Hypothyroidism - increased TRH which stimulates prolactin secretion

24
Q

Drugs which can cause hyperprolactinaemia

A 
Metoclopramide
Haloperidol 
Anti-psychotics 
A-methyldopa 
Oestrogens
MDMA/ectasy
25
Q

Management of a microprolactinoma

A

Bromocriptine - dopamine agonist - shrinks tumour and restores menstrual cycle

26
Q

Macroprolactinoma management

A

Treat initially with dopamine agonist - surgery can be considered if visual problems

27
Q

How does GH act?

A

Binds to receptor in the liver which stimulates phosphorylation cascade leading to production of DNA transcription factors

28
Q

How is IGF-1 involved?

A

GH binding in the liver stimulates the secretion of IGF-1 which is involved in growth

Good measure of GH production and function

29
Q

GH/IGF-1 relation to glucose

A

Opposes the action of insulin

30
Q

Causes of short stature in children

A

Intrauterine complications
Systemic disorders, esp. small bowel disease
Hypothyroidism
Drugs esp. steroids for asthma
Emotional and psychological problems
Congenital problems eg. familial short stature

GH deficiency

31
Q

What does GH hyper-secretion cause?

A

Acromegaly - in adults

Gigantism - in children

32
Q

What is acromegaly most commonly caused by? Incidence?

A

Hyper-secretion from GH secreting pituitary adenoma 99%

3/million/year in UK

33
Q

Effects of GH hyper-secretion

A

GH stimulates bone and soft tissue growth through secretion of IGF-1

34
Q

Symptoms of acromegaly?

A 
Acroparesthesia
Amenorrhoea
Low libido
Sweating
Arthralgia
Backache
35
Q

Signs of acromegaly

A

Often precipitate diagnosis by 4 years

Growth of hands, jaw and feet (notice rings and shoes becoming tight) 
Coarsening of face and widening of nose 
Macroglossia 
Widely spaced teeth 
Puffy lips, eyelids and skin 
Skin darkening 
Laryngeal dyspnoea - OSA and snoring 
Goitre 
Carpal tunnel - 50%
36
Q

Complications of acromegaly

A

DM and impaired glucose tolerance

Vascular complications - hypertension, LVH, cardiomyopathy, arrhythmias

Increased risk of colon cancer

37
Q

What tests will be high in acromegaly?

A

Glucose, Calcium, Phosphate

Oral Glucose Tolerance Test - acromegalics will fail to suppress GH production

Serum IGF-1

Pituitary function tests - 9am cortisol, free T4 and TSH, LH, FSH, testosterone and prolactin

38
Q

How do you suppress GH secretion medically aka treatment of acromegaly? x3

A

Somatostatin analogue eg. Octreotide or lanreotide

Pegvisomant - GH receptor antagonist (doesn’t affect the tumour but can normalise IGF-1 levels)

Dopamine agonists - bromocriptine or cabergoline - only useful in mild disease or in combination with SSA’s

39
Q

Non-medical treatment for acromegaly?

A

1) Trans-sphenoidal surgery

2) Pituitary radiotherapy

40
Q

Other symptoms in acromegaly due to the pituitary adenoma

A

Hypopituitarism (hypogonadism, hypothyroidism, hypoadrenalism)
Visual disturbances - caused by optic chiasm compression (bitemporal heminopsia)

41
Q

What else is commonly produced by pituitary adenoma causing acromegaly

A

Prolactin therefore hyperprolactinaemia causing irregular periods, low libido and impotence

42
Q

Causes of female hypogonadism

A

Primary (problem with ovaries) eg. Turners or gonadal damage due to autoimmune or iatrogenic causes - FSH and LH will be high
Secondary eg. functional (stress, exercise, eating disorders), pituitary dysfunction or Kallamans - FSH and LH low

43
Q

Investigations in female hypogonadism

A

Oestradiol low

FSH and LH depends on cause

44
Q

How do you induce puberty in secondary female hypogonadism

A

Low dose ethyinylestradiol gradually increasing dose over puberty
Add cyclical progesterone (2 weeks of each month) when bleeding starts

45
Q

Inducing ovulation in secondary female hypogonadism

A

Pulsatile GnRH or gonadotrophin replacement therapy

46
Q

Causes of male hypogonadism

A

Primary eg. Klinefelters, cryptorchidism or gonadal damage from infection, trauma, iatrogenic etc - FSH and LH high

Secondary - pituitary/hypothalamic problems, Kallmans, - FSH and LH low or inappropriately normal

47
Q

Features of Kallmans

A

anosmia
GnRH low
Hypogonadism

48
Q

Features of Klinefelters

A

Intellectual dysfunction
XXY
Behavioural abnormalities
Hypogonadism

49
Q

Management of prepubertal male hypogonadism

A

Testosterone replacement (risk of prostate enlargement, polycythaemia and fluid retention)

50
Q

Management of secondary male hypogonadism

A

Gonadotrophin (hCG and FSH) replacement or pulsatile GnRH therapy

Endocrinology (8 decks)

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