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ESA 2 - MEH > 8. Pituitary disorders > Flashcards

8. Pituitary disorders Flashcards

1
Q

What is the most common cause of pituitary malfunction?

A

benign tumour (adenoma)

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2
Q

Are pituitary tumours usually ‘functional’ or ‘non-functioning’? What is the difference?

A
  • most are non-functioning: don’t produce hormone themselves but can cause hypopituitarism (underproduction) due to physical pressure from growing tumour on glandular tissue
  • functional tumours are rarer: can cause hyperpituitarism (overproduction)
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3
Q

What are the symptoms of pituitary adenomas? Explain why these occur.

A

pressure on surrounding structures causes:

  1. headache
  2. visual problems
  3. eye mov. probs.
  4. vomiting and nausea
  5. symptoms associated with either underproduction (non-functioning) or overproduction (functional) of pituitary hormones
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4
Q

Which 3 investigations are performed when a pituitary tumour is suspected?

A

i. MRI scan: delineation of anatomy, size and topographical location of pituitary or parapituitary mass
ii. assessment of visual field defects

iii. assessment of endocrine function to determine any hormonal excess/deficiency:
- measuring hormone levels in blood
- staining sections from a biopsy of the tumour with antibodies for the relevant hormone

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5
Q

Which symptoms indicate lateral or superior growth of tumour?

A

lateral growth:

  • headaches (compression of nerves Va and Vb)
  • eye mov. probs. (compression of nerves III, IV or VI)

superior growth:
- visual probs. (compression of optic nerve)

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6
Q

What are the possible causes of hypopituitarism? Which is most common?

A

Most common:
1. pituitary adenoma (mass effects)

Rarer causes:

  1. radiation therapy
  2. inflammatory disease
  3. head injury
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7
Q

Which hormones are lost first in hypopituitarism?

A

typically a progressive loss of AP function with GH and FSH/LH 1st to be affected

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8
Q

Which term is used to describe deficiency of all AP hormones?

A

panhypopituitarism

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9
Q

In which cases would secretion of ADH and oxytocin from PP be affected?

A
  1. if tumour affects hypothalamic function

2. if inflammatory process is involved

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10
Q

What are the typical causes of GH deficiency in adults or children?

A

adults: mass effects from pituitary adenoma
children: usually idiopathic but can involve specific gene mutations and autoimmune inflammation

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11
Q

What are the symptoms of GH deficiency in adults?

A

often quite subtle:

  1. decreased exercise tolerance
  2. decreased muscle strength
  3. increased body fat
  4. reduced sense of “well-being”
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12
Q

What are the effects of prenatal GH deficiency?

A

usually has little effect on foetal growth

if severe can cause hypoglycaemia and jaundice

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13
Q

What are the effects of GH deficiency in childhood?

A

poor growth and short stature

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14
Q

What is the treatment for GH deficiency?

A

recombinant GH

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15
Q

What are the symptoms of gonadotropin deficiency from a pituitary adenoma?

A

women:

  • lack of libido
  • infertility
  • oligoamenorrhea/amenorrhea

men:

  • lack of libido
  • impotence
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16
Q

What is diabetes insipidus?

A

ADH deficiency

17
Q

What are the possible causes of ADH deficiency?

A
  1. hypothalamic tumour
  2. pituitary tumour that has extended into hypothalamus
  3. cranial radiotherapy
  4. pituitary surgery
  5. autoimmune infiltration
  6. infections such as meningitis
18
Q

What are the 2 main effects of ADH deficiency?

A
  1. excess secretion of dilute urine… dehydration

2. increased sensation of thirst (polydipsia)

19
Q

What are the 3 main conditions caused by a hypersecreting pituitary adenoma?

A
  1. prolactin excess
  2. GH excess: gigantism or acromegaly
  3. ACTH excess: Cushing’s syndrome
20
Q

How is prolactin secretion by AP lactotropes regulated?

A

i) PRH stimulates secretion

ii) PIH (dopamine) inhibits secretion - dominates

21
Q

What are the symptoms of hyperprolactinaemia?

A
  1. galactorrhea (unexplained milk production, rare in men)
  2. gynecomastia (hard breast tissue)
  3. hypogonadism (diminished activity of testes/ovaries)
  4. amenorrhea
  5. erectile dysfunction
22
Q

Why is hypogonadism a symptom of hyperprolactinaemia?

A

increased plasma prolactin… increased dopamine due to neg. feedback… decreased GnRH… decreased FSH/LH

23
Q

Name 4 possible causes for hyperprolactinaemia.

A
  1. hypersecreting pituitary adenoma (prolactinoma) - most common cause
  2. non-functioning pituitary adenoma (‘stalk effect’)
  3. physiological causes: pregnancy, suckling, stress and exercise
  4. dopamine antagonist drugs, inc. antipsychotics (e.g. haloperidol) and antidepressants (e.g. clomipramine)
24
Q

How can one differentiate between a prolactinoma and a non-functioning pituitary adenoma?

A
  • hypersecreting prolactinoma: prolactin >5000 mU/L

- non-functioning adenoma: prolactin <5000 mU/L

25
Q

What is the treatment for prolactinoma and a non-functioning pituitary adenoma?

A
  • prolactinoma: dopamine R agonists, e.g. cabergoline

- non-functioning pituitary adenoma: trans-phenoidal surgery (or radiotherapy)

26
Q

What is acromegaly and which is diagnosis often late?

A
  • GH excess caused by hypersecreting pituitary adenoma (typically large so also associated with local mass effects)
  • effects of increased GH and IGF-1 receptor activation often take several years to manifest as change in physical appearance
27
Q

What are the symptoms of acromegaly?

A

gradual change in physical features:

  1. broad nose, coarse facial features, thick lips and prominent supraorbital ridge
  2. enlargement of hands and feet
  3. excessive sweating and greasy skin

local mass effects:

  1. headaches
  2. visual field defects
  3. other cranial nerve palsies
28
Q

Which condition is caused by excess GH secretion in childhood?

A

gigantism

29
Q

What are the long-term complications of GH excess if untreated?

A
  1. diabetes mellitus and hypertension (as GH antagonises the actions of insulin)
  2. some forms of cancer, e.g. colon or thyroid (due to increased IGF-1)
  3. irreversible body changes
  4. premature cardiovascular death
30
Q

Which biochemical tests are used to diagnose acromegaly?

A
  1. oral glucose tolerance test: failure to suppress GH <1ug/L
  2. elevated IGF-1 level
  3. GH day curve: elevated mean GH
31
Q

What are the treatment options for agromegaly?

A
  1. trans-sphenoidal surgery
  2. radiotherapy: external beam (multiple short bursts over several wks) or gamma knife (high conc. over single time)
  3. drug therapy
32
Q

Which drugs can be used to treat acromegaly?

A
  1. GH R antagonists, eg pegvisomant
  2. dopamine R agonists, eg cabergoline - some efficacy in decreasing GH (but much higher dose than for prolactinoma)
  3. synthetic somatostatin analogs, eg octerotide

ESA 2 - MEH (42 decks)

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