Hypersecretion of anterior pituitary hormones

Question 1

what causes hyperpituitarism?

Answer 1

• autoimmune stimulation of TSH (Graves)
• isolated pit tumours (can also be ectopic)
• drugs like amiadrone

Question 2

what defects are usually associated with hyperpituitarism due to a tumour?

Answer 2

visual field defects e.g. bitemporal hemianopia (Optic chiasm proximity)
both eyes may be affected

Question 3

effect of excess ACTH

Answer 3

Cushing’s Disease

Question 4

effect of excess TSH

Answer 4

thyrotoxicosis

Question 5

effect of excess LH/FSH in children

Answer 5

precocious puberty in children

Question 6

effect of excess prolactin

Answer 6

hyperprolactinaemia

Question 7

effect of excess GH

Answer 7

gigantism, acromegaly

Question 8

what are the physiological causes of hyperprolactaemia?

Answer 8

pregnancy, breastfeeding

Question 9

describe the pathological causes of hyperprolactinaemia

Answer 9

prolactinoma ( micro adenoma <10mm)

• most common functioning pit. tumour making the hormone
• high prolactin suppresses GnRH pulsatility

Question 10

what is the effect of high prolactin on GnRH?

Answer 10

suppresses GnRH pulsatility

Question 11

what are the signs in women for hyperprolactinaemia?

Answer 11

galactorrhoea
secondary ammenorrhoea/oligomennorhoea
loss of libido
infertility

Question 12

what are the signs in men for hyperprolactinaemia?

Answer 12

galactorrhea (uncommon)
erectile dysfunction
loss of libido
infertility

Question 13

how can you switch off prolactin production?

Answer 13

dopamine from dopaminergic neurones bind to D2 receptors on lactotrophs to switch off prolactin secretion

Question 14

what is the treatment for hyperpituitarism?

Answer 14

• remove tumour causing it e.g.
  D2 receptor agonists (stimulate D2 receptors)
• surgery (trans- sphenoidal)
• radiation

first line of treatment given orally before surgery

Question 15

what is the effect of D2 receptor agonists?

Answer 15

decrease prolactin secretion and reduce tumour size

Question 16

what are the side effects of using D2 receptor agonists?

Answer 16

• nausea
• postural hypotension
• dyskinesia (loss of voluntary movement)
• depression (exhausted dopamine stores)
• pathological gambling, hypersexuality

Question 17

examples of D2 receptor agonists

Answer 17

bromocriptine

cabergoline

Question 18

what distinguishes gigantism and acromegaly

Answer 18

children get gigantism
adults get acromegaly

they are usually due to a benign GH secreting pit. adenoma

Question 19

describe the onset and death due to acromegaly

Answer 19

gradual but harmful onset
when left untreated, excess GH is associated with increased morbidity and mortality

death: CVS (60%), resp complications (25%) and cancer (15%)

Question 20

what features grow in acromegaly?

Answer 20

• periosteal bone
• cartilage
• fibrous tissue
• connective tissue
• internal organs like the liver

Question 21

what are the clinical features of acromegaly?

Answer 21

• hyperhidrosis
• polydipsia
• headache
• tiredness
• supraorbital ridge enlargement
• big nose, hands, feet
• thickened lips
• frontal bossing
• macroglossia
• prognathism (protrusion of lower jaw)
• carpal tunnel syndrome (leads to tingling fingers)
• barrel chest
• kyphosis

Question 22

diagnosis of acromegaly

Answer 22

photographs of the patient from before physical changes occurred

Question 23

how does acromegaly leads to the development of diabetes mellitus?

Answer 23

excess GH inhibits insulin

increased insulin resistance
impaired glucose tolerance
reduced uptake by muscles
DM

Question 24

what are the complications of acromegaly ?

Answer 24

• obstructive sleep apnoea due to soft tissue growth in the throat
• hypertension: GH mediated Na+ reabsorption
• cardiomyopathy: hypertension, DM, toxic effects of GH on myocardium
• cancer: colonic polyps

Question 25

alongside GH what else to acromegaly patients produce a lot of?

Answer 25

prolactin this mean a tumour is secreting both Gh and prolactin the hyperprolactinaemia will cause a secondary hypogonadism

Question 26

how is acromegaly diagnosed?

Answer 26

- GH is pulsatile - GH should drop in a healthy person as insulin rises with a glucose load - in acromegaly, there is a paradoxical rise in GH - an elevated serum IGF-1 can be measured

Question 27

how is acromegaly treated (first line)?

Answer 27

first line- surgery with trans-sphenoidal entry to remove tumour

Question 28

medication involved in acromegaly treatment?

Answer 28

somatostatin analogues or dopamine agonists

Question 29

how are somatostatin analogues used to treat acromegaly?

Answer 29

 Injected or administered in a monthly depot injection.  GI side effects common, e.g. nausea, diarrhoea, gallstones.  Reduces GH secretion and tumour size.  Also used as a pre-treatment before surgery (shrinks’ tumour).  Can be used post-operatively if not cured or whilst waiting for radiotherapy to take effect.

Question 30

example of somatostatin analogue

Answer 30

octreotide

Question 31

example of dopamine agonist

Answer 31

cabergoline

Question 32

why may glucose be found in the urine of acromegaly patients?

Answer 32

excess GH suppressed insulin so high glucose will remain high so needs to be expelled in the urine