hypersecretion of anterior pituitary hormones

Question 1

what are the symptoms for hyperpituitarism associated with

Answer 1

excess production of adenohypophysial hormones

Question 2

what re the main causes of hyperpituitarism

Answer 2

isolated pituitary tumours - main or ectopic tumours - neuroendocrine tumour secrete peptide hormones similar to from anterior pituitary but not in the anterior pituitary eg carinoid tumour in the gut

Question 3

effect of a pituitary tumour on the optic chiasm and how this causes bitemporal hemianopia *

Answer 3

fibres that cross through the optic chiasm are what allows you to see the temporal fields

a pituitary mass stretches the optic chiasm causing bitemporal hemianopia, also invade the cavernous sinus so can squash the cranial nerves involved in sight - presents quite late because you can still get around

squash CN IV and VI = diplopia (double vision), III = ptosis (drooping/falling of upper eye lid)

eg in pic the optic chiasm is stretched - invasion into the cavernous sinus and therefore into th CN

can see the internal carotid arteries as 2 black circles

Question 4

how do you assess a bitemporal hemianopia *

Answer 4

use perimetry every time you see a flash you press a button

Question 5

what does excess ACTH cause *

Answer 5

cushing’s syndrome

Question 6

what does excess TSH cause *

Answer 6

thyrotoxicosis the thyroid gland is told to produce too much thyrotrope

Question 7

what does excess LH and FSH cause *

Answer 7

precocious puberty in children - too much LH, FSH -> testosterone and oestrogen

Question 8

what does excess prolactin cause *

Answer 8

hyperprolactinaemia

Question 9

what does excess GH cause *

Answer 9

gigantism in children - don’t have epiphysial bone closure acromegaly in adults - have epiphysial bone closure

Question 10

when is hyperprolactinaemia physiological

Answer 10

in pregnancy - preparation for lactation in breastfeeding

Question 11

when is hyperprolactinemia pathological and describe this *

Answer 11

prolactinoma - microadenomas <10mm in diameter

it is the most common functioning pit tumour high

prolactin supresses GnRH pulsatility - therefore teh GnRH is not able to stimultate the production of LH/FSH - this casues some of the symptoms

Question 12

clinical features of hyperprolactinoma in women *

Answer 12

galactorrhoea out of pregnancy

secondary amenorrheoa or obligomenorrhoea - becasue of shut down of LH and FSH

loss of libido - loss of LH FSH

infertility - because of abnormal periods, itself because of LH FSH

Question 13

clinical symptoms of hyperprolactinaemia for men *

Answer 13

galactorrhoea- unusual, have to also have abnormally high oestrogen, otherwise cant make the milk

loss of lipido, erectile dysfunction and infertility - becasue of loss of LH adn FSH -> loss of testosterone

Question 14

describe the principle of treatment for hyperprolactinaemia *

Answer 14

prolactin production is inhibited by dopamine

lactotrophs (in ant pit) have D2 receptors on the surface - dopamine from the hypothalamic dopaminergic neurons binds to these and inhibits prolactin production

therefore hyperprolactinaemia can be trated by supplying a dopamine agonist that can bind and stop prolactin production and reduce the size of the tumour

this is the 1st line treatment

eg bromocriptine and cabergoline

given by oral admin

Question 15

side effects of dopamine agonists *

Answer 15

nausea and vomiting (settles down), and postural hypotension are more common with bromocriptine

dyskinesias - uncontrolled involuntary movement

depression

pathological gambling, hypersexuality - impulse control disorder - dopamine stimulates the reward pathway in brain

Question 16

principles of diagnosis of hyperprolactinaemia *

Answer 16

usually diognosed relatively early because people notince when their periods are off, or lactation - women present earlier

Question 17

what is the main cause of excess GH

Answer 17

a benign growth hormone secreting pituitary adenoma

Question 18

describe gigantism *

Answer 18

when GH hypersecretion occurs in childhood - grow really tall, above the average

problem is it causes impaired glucose tolerance and therefore DM

Question 19

describe acromegaly *

Answer 19

insidious in onset

untreated, excess GH is releated to increased morbity and death

Question 20

How can acromegaly cause death *

Answer 20

increase cardiovascular disease 60% - increase cardiomyopathy (Big baggy heart), furrinmg up of the coronary arteries

resp complications 25% - obstructuve sleep apnoea because tongue etc gets bigger

cancer - 15% - supraphysiological level everyday - so have to have regular bowl screening and colonsocpies to check for polyps

Question 21

what grows in acromegaly

Answer 21

Soft tissue:

periosteal bone

cartilage

fibrous tissue

connective tissue

internal organs - cardiomegaly, splenomegaly, hepatomegaly

Question 22

descibe the clinical features of acromegaly *

Answer 22

subtle presentation - occur slowly so difficult to pick up

hyperhidrosis (excessive sweating), headache - hallmarks of active acromegaly

enlargement of supraorbital ridge, nose hands (spade shaped, square fingers), thick lips

general courseness of features

ring and shoe size increase

enlargarged tongue - macroglossia

mandible grows - protusion of lower jaw (prognathism) - gap between teeth

carpel tunnel syndrome - median nerve compression in bony tunnel in either wrist by the growth of soft tissue - pins and needles in hands

barrel chest

kyphosis - convex curvature of spine

painful joints - enlarged so rub together

Question 23

principle of diagnosis for acromegaly *

Answer 23

changes are subtle and over a long time - bring in an old picture to see if there is a difference

Question 24

what are the metabolic affects of acromegaly *

Answer 24

excess growth hormone stimulates increased endogenous glucose production and less glucose is taken into the muscles for storage

therefore the blood glucose conc rises so there is increased insulin secretion - leads to insulin resistance

• >impaired glucose tolerance
• > DM

Question 25

what are the clinical features for acromegaly *

Answer 25

obstructuve sleep apnoea - bone and soft tissue changes narrow the upper airway (larynx and pharynx) - collapse during sleep - dont get into REM sleep

hypertension - direct effect of GH or IGF1 on vascular tree, and GH increases Na and so water reabsorption from urine -> increase BP

cardiomyopathy - because of: DM, toxic effects of GH on myocardium - heart cant pump

increased risk of cancer - colonic polyps

Question 26

describe how prolactin and GH can be co-secreted in acromegaly and explain the furtehr effects of this *

Answer 26

tumour secret prolactin and GH

hyperprolactinaemia - cause secondary gonadism

Question 27

describe the GH axis

Answer 27

somatostatin and GHRH released from the hypothalamus

GH released by ant pit

GH act on liver

liver produce somatomedins - IGF1

Question 28

describe the diagnosis of acromegaly *

Answer 28

GH pulsitile - random measurement unhelpful

do dyanmic tests - because the hormones are on axis we can see if there is an apprpriatee response

measure IGF1 - if GH is always high there will be high IGF1 - clinical hallmark, also has a longer half life so can see what GH has been like recently

paradoxical rise in GH after oral glucose load (ie failed suppression which is normal)

MRI pituitary - show adenoma

Question 29

describe the treatment of acromegaly *

Answer 29

trans-sphenoidal surgery is sthe first line thrrough cribiform fascia, craniotomy if tumour is large

somatostatic analogues can shrink tumour and reduce GH - eg octerotide

dopamine agonists can work on 30% of teh adonomas - if they secrete prolactin too eg carbergoline

GHR antagonist - block the receptors pegvisomant, IGF1 will be controlled but GH will be high

radiotherapy - if surgeon can’t remove it all - side effect: hypopituitarism

Question 30

describe how presence of glucose in urine fits in with a diagnosis of acromegaly *

Answer 30

glucose in urine shows DM becasue it shows high blood glucose - that surpasses the glucose threshold of 10mmol/L meaning it is not reabvsorbed into the blood - it acts as an osmotic diuretic making the patient thirsty - this is becasue excess GH leads to type 2 DM

Question 31

describe somatostatin analogues *

Answer 31

endocrine cyanide

short acting injection/monthly depot

GI side effects becasue stop all enzymes - nausea, diarrhoea, gall stones

given pre-treatment - make surgeyr easier

given while waiting for radiation to take effect.

Question 32

how would you diagnose DM *

Answer 32

oral glucose test - come in fasting, have 75g glucose and measure glucose after 2hours >11.1 diabetes 7.8-11.1 impaired glucose tolerance - prediabetes (includes the fasting glucose as well)

simple fasting glucose- 6.1-7 impaired fasting glucose 7.1< diabetes

see if glucose is in the urine with a dipstick