Endo 2: Hypersecretion of adenohypophysial hormones

Question 1

Overall causes of hyperpituitarism. What is it associated with

Answer 1

Pituitary tumour or ectopic (i.e. cancer producing pituitary hormones).

It’s associated with visual field defect due to compression of overlying optic chiasm or other cranial nerve defects (due to compression of the nerves in the wall of the choroid plexus).

And endorcrine-related signs and symptoms

Question 2

Specific effect of a large pituitary gland on vision and how this is assessed

Answer 2

Compresses optic chiasm by growth of SUPRASELLAR tumour. The fibres that cross over at the optic chiasm are those from the nasal retina. The light rays that hit the nasal retina are those from the periphery. So you get bitemporal heminopia (because vision lost on the temporal side). Assess with perimetry

Question 3

What is the result of excess of each of the pituitary hormones?

Answer 3

ACTH: cushing's
TSH: thyrotoxicosis 
FSH/LH: precocious puberty in kids
Prolactin: hyperprolactinaemia
Somatotrophin: Gigantism/acromegaly

Question 4

Physiological and pathological cause of hyperprolactinaemia. What other hormone is affected by this

Answer 4

Phys: pregnancy and breastfeeding
Path: prolactin secreting adenoma (prolactinoma). It’s the most common function pituitary tumour. GnRH is suppressed

Question 5

Presentation of hyperprolactinaemia in M and F

Answer 5

F: galactorreah even when not pregnant, secondary amenorreah/oligomenorrhoea, infertility, loss of libido
M: galactorreah (less common since appropriate steroid background usually inadequate), loss of libido, erectile dysfunction, infertility

Question 6

Regulation of prolactin secretion?

Answer 6

Under constant inhibition from dopaminergic neurons in the hypothalamus- level increases when dopamingergic neurons suppressed

Question 7

Treatment for hyperprolactinaemia

Answer 7

MEDICAL TREATMENT FIRST LINE. Give D2-receptor agonists (to stimulate dopaminergic neurons to release dopamine which inhibits prolactin release AND it reduces tumour size). e.g cabergoline and bromocriptine oral administration

Question 8

Side effects of dopamine receptor agonists

Answer 8

cabergoline: depression, nausea and vomiting, postural hypotension, dyskinesia, pathological gambing

Question 9

2 effects of excess GH

Answer 9

childhood: gigantistm
adulthood: acromegaly

Question 10

What usually causes excess GH

Answer 10

benign growth hormone secreting pituitary adenoma

Question 11

How do symptoms progress of too much GH?

Answer 11

Gradually- insidious on onset

Question 12

What causes the increase in morbidity and mortality in acromegaly

Answer 12

Cardiovascular disease (60%) as sugar is increased by GH so diabetes and there is also HTN, respiratory complications (25%), cancer (15%)

Question 13

What grows in acromegaly

Answer 13

periosteal bone, cartilage, fibrous tissue, connective tissue, orgnans (cardiomegaly, splenomegaly, hepatomegaly etc.)

Question 14

Clinical features of acromegaly

Answer 14

MAIN: excessive sweating and headache.
Also: Enlargement of superorbital ridges, nose hands and feet (SPADE SHAPED HANDS), thickening of lips and coarseness of features, macroglossia, mandible grows causing protrusion of lower jaw (prognathism), carpal tunnel syndrome (compresses median nerve), barrel chest and hyphosis

Question 15

Metabolic effects of acromegaly

Answer 15

Increases blood glucose levels, decreased muscle glucose uptake, leading to insulin resistance and T2DM

Question 16

Complications of acromegaly

Answer 16

Obstructive sleep apnea
Hypertension
Cardiomyopathy
Cancer

Question 17

Why does acromegaly cause obstructive sleep apnea

Answer 17

due to soft tissue changes in the neck casues collapse during sleep

Question 18

Why does acromegaly cause hypertension

Answer 18

direct effect of GH and IGF-1 on vascular tree and GH mediated renal sodium reabsorption

Question 19

Why does acromegaly cause cardiomypathy

Answer 19

hypertension, DM, toxic effects of GH on myocardium`

Question 20

Why does acromegaly cause cancer. Which regular test is required.

Answer 20

increased cell growth e.g. colonic polyps, regular colonoscopy needed

Question 21

Which hormone often cosecreted with GH

Answer 21

Prolactin (may relect tumour secreting prolactin and GH) - so may get secondary hypergonadism due to hyperprolactinaemia

Question 22

How to diagnose acromegaly

Answer 22

Not GH as pulsatile

1. IGF-1 blood test (increased serum IGF implies it)
2. Oral glucose tolerance test (see tutorial questions for how this works)

Question 23

Treatment for acromegaly

Answer 23

1. Surgical removal of pituitary tumour (transphenoidal)
2. Somatostatin agalogues e.g. octreotide (increase release of hypothalamic SS which inhibits GH secretion) and perhaps dopamine agonists e.g. cabergoline (as prolactin often cosecreted)
3. Radiotherapy

Question 24

Outline the regulation of GH secretion

Answer 24

GHRH releasing neurons from hypothalamus main stimulation
Inhibition from SS.

GH causes release of SOMATOMEDINS e.g. mostly IGF1 and a bit of IGF2 from liver

Question 25

Outline how somatostatin analogues work and what it would be used for

Answer 25

For treatment of acromegaly (increased GH): ‘endocrine cyanide’- reduces GH secretion and tumour size. Injected or monthly depot

USE: pre-treatment before surgery to make resection easier, post operatively if not cured or whilst waiting for radio to take effect.

Question 26

Side effects of somatostatin

Answer 26

Nausea, diarroea, gall stones (also suppresses CCK release etc)