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MEH > Lecture 16 > Flashcards

Lecture 16 Flashcards

1
Q

What is the most common cause of pituitary malfunction?

A

Bengin tumour= Adenoma

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2
Q

How common are disorders of the pituitary gland?

A

Rare

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3
Q

What are the 2 types of pituitary tumours?

A

Non-functioning: Do not produce any hormone. Result in inadequate production of one or more pituitary hormones due to physical pressure on glandular tissue

Functional: Cause problems with overproduction of one or more of the pituitary hormones

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4
Q

How do pituitary tumours affect the patient clinically?

A

Non-functioning: headaches, visual problems (compression of optic nerve), vomiting, nausea

Functional: systemic effects of the over secreted hormone

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5
Q

How would you investigate/diagnose a suspected pituitary tumour?

A
  1. Locate the anatomy, size and location of mass- MRI scan
  2. Assess visual field defects
  3. Assess endocrine function by measuring levels of hormones in blood (excess/deficiency)
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6
Q

What is hypopituitarism and its causes?

A 
Insufficient pituitary hormone production
Causes:
-pituitary adenoma
-radiation therapy
-inflammatory disease
-head injury
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7
Q

In what order are the pituitary hormones lost?

A

GH and LH/FSH lost first, then TSH and ACTH, lastly PRL
ADH and oxytocin are only significantly affected if tumour affects hypothalamic function/inflammatory process is involved

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8
Q

What is panhypopituitarism?

A

Deficiency of all anterior pituitary hormones

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9
Q

What does GH deficiency in adults/children result in?

A

Adults

  • decrease in tolerance to exercise
  • decreased muscle strength
  • increased body fat
  • reduced sense of well-being

Children

  • poor growth
  • short stature
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10
Q

Why is GH deficiency hard to diagnose?

A

GH secretion is pulsatile

requires direct and indirect measurements

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11
Q

What are the causes of GH deficiency in children?

A
  • idiopathic (unknown)
  • gene mutations in GHRH receptor
  • autoimmune inflammation
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12
Q

Does GH deficiency have any effect on fetal growth?

A

Little

-can result in hypoglycaemia/jaundice

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13
Q

How do you treat GH deficiency?

A

GH is manufactured by recombinant DNA technology

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14
Q

What does a gonadotropin deficiency cause?

A
  • lack of libido (sexual desire)
  • infertility
  • infrequent periods (oligomenorrhea)
  • no periods (amenorrhea)
  • impotence (erectile dysfunction/failure to orgasm)
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15
Q

What causes a deficiency of ADH?

A
  • hypothalamic tumour
  • pituitary tumour that has extended up into the hypothalamus
  • cranial radiotherapy
  • pituitary surgery
  • autimmune infiltration
  • infections (meningitis)
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16
Q

What does insufficient ADH release lead to?

A

Excess excretion of dilute urine resulting in dehydration, and an increasedsensation of thirst (polydipsia)
=DIABETES INSIPIDUS

17
Q

What are the 3 main conditions caused by excess pituitary hormone production due to hypersecreting pituitary adenoma?

A
  • prolactin excess
  • growth hormone excess
  • ACTH excess
18
Q

What does excess secretion of ACTH cause?

A

Cushing’s syndrome

19
Q

What dominates the function/secretion of prolactin?

A

Inhibition of prolactin secretion by dopamine dominates

20
Q

What is the most common form of pituitary disorder?

A

Hyperprolactinaemia (high prolactin level in blood)

21
Q

What are the symptoms of hyperprolactinaemia?

A
  • galactorrhoea (unexplained milk production-rare in men)
  • gynecomastia (hard breast tissue)
  • hypogonadism (diminshed activity of testes/ovaries)
  • amenorrhea (no period)
  • erectile dysfunction
22
Q

Why does hypogonadism arise from hyperprolactinaemia?

A
  • high levels of dopamine due to negative feedback from increased plasma prolactin
  • high levels of dopamine inhibits GnRH/LH/FSH secretion from anterior pituitary
23
Q

What is the most common cause of hyperprolactinaemia?

A

Prolactinoma- pituitary adenoma which secretes prolactin

-pregnancy, suckling, stress, exercise, drugs, antidepressants can also cause it

24
Q

How do you treat prolactin excess?

A
  • dopamine receptor agonists (cabergoline)
  • trans-sphenoidal surgery (access pituitary through nose)
  • radiotherapy
25
Q

What do growth hormone secreting adenomas cause and how?

A

-headache
-visual field defects
-cranial nerve palsies
(they are usually large)

Direct actions of GH itself and via stimulation of IGF-1 production

26
Q

How long does GH excess take to manifest?

A

Several years (can be up to 6 years)

27
Q

What are some changes in physical appearance in GH excess?

A
  • broad nose
  • coarse facial features
  • thick lips
  • prominent supraorbital ridge (crest bone on frontal lobe of skull)
  • enlargement of hands and feet
  • skin is greasy with excessive sweating
  • deepening of voice (hypertrophy of soft tissue in upper airways)
28
Q

What is the condition where there is excessive GH secretion in children (before fusion of epiphyseal plates)?

A

Gigantism

rarely develops now due to early diagnosis and treatment

29
Q

What does GH antagonise?

A

The actions of insulin

therefore diabetes mellitus may develop

30
Q

What have the increase in IGF-1 levels in GH excess been associated with?

A

Some forms of cancer

31
Q

What are the 3 treatment options for patients with acromegaly (too much GH in adults)?

A
  • surgery to remove adenoma
  • radiation therapy
  • drug therapy
32
Q

How can you reduce GH levels with drugs?

A
  • Dopamine receptor agonists
  • somatostatin which limits GH secretion has limited use due to short half life, but synthetic somatostatin analogs have been developed which produce prolonged suppression of GH secretion
  • antagonists of GH receptor (pegvisomant) is the most recent treatment
33
Q

In what nucleus of the hypothalamus is ADH made?

A

Supraoptic nucleus

34
Q

In what nucleus of the hypothalamus is oxytocin made?

A

Paraventricular nucleus

35
Q

What is pituitary apoplexy?

A

Sudden vascular event in a pituitary tumour

MEH (22 decks)

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