1) Hyposecretion of from APG Flashcards
Define panhypopituitarism:
reduced production of ALL APG hormones
What is the anterior pituitary gland also called and what type of tissue is it made up of?
APG=adenohypophysis (glandular)
What is the posterior pituitary gland also called and what type of tissue is it made up of?
PPG=neurohypophysis (neural)
5 APG hormones:
ACTH (cortisol) FSH/LH (oestrogen/testosterone) GH Prolactin TSH (T3/4)
How are APG hormones stimulated + actually released?
1) Hypothalamus secretes releasing/inhibiting hormones
2) APG secretes APG hormone into blood
3) APG hormone stimulates endocrine gland to secrete primary hormone
2 types of APG disease:
Primary disease-issue with endocrine gland
Secondary disease-issue with APG
Summarise the hypothalamic pituitary thyroid axis:
1) TRH released from hypothalamus
2) TRH stimulates TSH release from APG into bloodstream–>thyroid gland
3) Thyroid gland secretes T3 + 4
4) T3 + 4 negatively feedback on both hypothalamus + PG
2 possible causes of panhypopituitarism with examples:
Congenital
- genetic mutation
- deficient in GH + another hormone
- short stature
- hypoplastic (shrunken PG)
Acquired
- pituitary apoplexy
- tumour
- trauma
- infection
What is pituitary apoplexy and what is it a sign of?
pituitary infarction/haemorrhage
sign of pituitary adenoma
What does presentation of panhypopituitarism depend on?
Which hormone(s) are deficient
How would an FSH/LH deficiency present?
secondary hypogonadism e.g. low libido, secondary ammenorrhoea, erectile dysfunction
How would an ACTH deficiency present?
secondary hypoadrenalism=fatigue
How would a TSH deficiency present?
Secondary hypothyroisim =fatigue
What is sheehan’s syndrome and what is it caused by?
Panhypopituitarism specifically post partum haemorrhage
Caused by hypotension-poor PG perfusion
What happens to the PG during pregnancy?
Enlarges due to lactotroph hyperplasia
What could happen if the PG enlarges?
Compression of optic chiasm
2 symptoms of a bitemporal hemniaopia?
Loss of peripheral vision
Headache
2 ways panhypopituitarism is diagnosed?
Stimulated pituitary function tests
Pituitary MRI
Why must stimulated pituitary function tests be carried out, why can’t we just measure plasma conc of the APG hormones?
Hormone levels fluctuate throughout the day Cortisol-changes in the day Thyroxine-half life GH + ACTH=pulsatile FSH/LH=cyclical
How do we test for each of the APG hormones in a stimulated pituitary function test?
GH & ACTH are stress hormones so we induce hypoglycaemia
TSH is given to measure thyroixine
FSH/LH are given to measure oestrogen/progesterone/testosterone levels
How is hypopituitarism treated specifically for each APG hormone?
ACTH=hydrocortisone
FSH/LH=HRT (oestrogen + progesterone/testosterone)
GH=GH
TSH=thyroxine
Why is hormone treatment not 100% effective?
Tablets release the hormone steadily not at different levels in response to need
What stimulates + inhibits GH release from the APG?
Inhibits=somatostatin
Simulates=GnRH
What does GH stimulate?
IGF-1 release from liver
3 types of GH deficiency + the condition they cause?
Issue with hypothalamus=Prader Willi syndrome
Issue with APG (secondary disease)=pituitary dwarfism
Issue with GH receptor=laron dwarfism
What is the issue in normal dwarfism?
Skeletal
5 causes of GH deficiency?
Trauma Surgery Tumour Radiotherapy Cranial
Causes of short stature?
Short parents Endocrine Genetic e.g. turners/downs/prader willi Malnutrition/Malabsorption e.g. coeliac Emotional deprivation Puberty delay FGR/SGA Significant illness-inflammation blocks IGF-1 signalling
How is short stature diagnosed?
Falling off centile charts
How is GH deficiency diagnosed?
GH provocation tests-do/give things that should normally increase GH levels
e.g. excercise/insulin/GnRH
If levels dont increase=GH deficiency
What does insulin do to GH levels normally?
Increases them
4 symptoms of GH deficiency?
1) reduced lean mass + muscle strength
2) increased adiposity
3) decreased HDL & increased LDL
4) reduced Qual
How is GH treated + how is treatment monitored?
GH injections daily
Monitor by measuring IGF-1
2 disadvantages of GH therapy?
Expensive
Cancer??
