Endo - Hypopituitarism Flashcards
What is hypopituitarism?
lack of pituitary function that can cause secondary failure of other glands
What other glands can hypopituitarism effect?
Thyroid, adrenal cortex, gonads
What is primary hypothyroidism? Effects on hormone levels?
→ damage or lack of function of thyroid
→T4 / T3 decrease, TSH increase
What is secondary hypothyroidism? Effects on hormone levels?
→ damage to pituitary thyrotrophs
→ T3 + T4 decrease, TSH decrease
What is primary hypoadrenalism? Effects on hormone levels?
→ damage or lack of function of adrenal cortex
→ low levels of cortisol
→ normal to high levels of ACTH
What is secondary hypoadrenalism? Effects on hormone levels?
→ damage to pituitary corticotrophs
→ ACTH decreases, cortisol decreases
What is secondary hypogonadism? Effects on hormone levels?
→ damage to pituitary gonadotrophs
→ LH + FSH decreases, testosterone + oestrogen decreases
What is primary hypogonadism? Effects on hormone levels?
→ damage or lack of function of gonads
→ low levels of testosterone + oestrogen
→ normal to high levels LH + FSH
What is a very rare cause of hypopituitarism?
→ congenital
What is congenital hypopituitarism caused by?
Mutations of transcription factor genes needed for anterior pituitary development e.g. PROP1
What symptoms does congenital hypo pituitarism present with?
→ deficiency of GH + at least 1 other AP hormone
→ short stature
→ hypoplastic (underdeveloped) AP gland on MRI
What are 8 causes of acquired hypopituitarism?
Hint: TRIP TIPP
Traumatic brain injury
Radiation
Infection
Pituitary surgery
Tumours
Inflammatory (Hypophysitis)
Pituitary Apoplexy
Peri-partum Infarction
What is total loss of anterior + posterior pituitary function called?
Panhypopituitarism
What is most likely to cause panhypopituitarism?
Pituitary surgery + inflammation (hypophysitis)
How does radiotherapy induce hypopituitarism?
→ pituitary + hypothalamus very sensitive to radiation
→ can be direct e.g. treating acromegaly
→ indirect eg treating nasopharyngeal carcinoma
What parts of the pituitary are most sensitive to radiation?
Somatotrophs + gonadotrophs
What hormone’s production can increase after radiotherapy? Why?
Prolactin
→ hypothalamic dopamine not produced due to radiation + damage
How long can the risk of hypopituitarism persist after radiotherapy?
10 years
How does hypopituitarism present with FSH/LH?
→ reduced libido
→ reduced pubic hair
→ secondary amenorrhoea (women)
→ erectile dysfunction (men)
How does hypopituitarism present with ACTH + TSH?
→ fatigue
How does hypopituitarism present with GH?
→ reduced quality of life
→ short stature in children
How does hypopituitarism present with prolactin?
→ inability to breastfeed
What is another name for peri-parturm infarction?
Sheehan’s syndrome
What is the pathogenesis of Sheehan’s syndrome?
→ anterior pituitary enlarges during pregnancy due to lactotroph hyperplasia
→ haemorrhage / loss of blood during pregnancy = hypotension
→ pituitary infarction occurs (posterior usually not affected)
What are symptoms of Sheehan’s syndrome?
→ lethargy + anorexia + weight loss (TSH, ACTH and GH deficiency) → failure to lactate (prolactin deficiency) → failure to resume menstruation (LH + FSH deficiency)
What is pituitary apoplexy?
intra pituitary haemorrhage (or less commonly an infarction)
What pre-existing condition is commonly associated with pituitary apoplexy?
Pituitary adenoma
What can increase the likelihood of pituitary apoplexy?
Anti-coagulants
What are symptoms of pituitary apoplexy?
→ severe sudden onset headache
→ visual field defect e.g. bitemporal hemianopia
(due to compressed optic chiasm)
→ cavernous sinus involvement may lead to diplopia (double vision,IV, VI) + ptosis (droopy eyelid, Ill)
How do you diagnose hypopituitarism radiologically?
MRI
Why is MRI better than CT at identifying hypopituitarism?
→ CT not very good at delineating pituitary gland
→ MRI can reveal specific pituitary pathology
Why do you have to be careful when measuring cortisol?
Diurnal rhythm so depends on time of day
→ highest in the morning
Why do you have to be careful when measuring T4?
Circulates with a half life of 6 days
Why do you have to be careful when measuring FSH/LH?
Cyclical in women
Why do you have to be careful when measuring GH + ACTH?
pulsatile release
How do you measure GH + ACTH release to determine a functioning pituitary?
Induce hypoglycaemia stress w INSULIN
→ causes GH + ACTH release
What is the name of the test that measures GH + ACTH?
Dynamic Pituitary Function Test
What anterior pituitary hormone isn’t treated?
Prolactin deficiency
How is GH deficiency treated?
Daily injection (administered after DPF test and QOL questionnaire)
How is the response to GH treatment measured?
→ improvement in QOL
→ plasma IGF-1
How is TSH deficiency treated?
Daily Levothyroxine, aiming for fT4 above the middle of reference range
How is ACTH deficiency treated?
Replace cortisol with synthetic glucocorticoids
prednisolone or hydrocortisone
What are the sick day rules for ACTH deficiency?
Take double dose of glucocorticoids
→ when sick body normally produces more cortisol
How is FSH/LH deficiency treated in men (no fertility)?
replace testosterone (topical gel or intra muscular) → does not restore sperm production
How is FSH/LH deficiency treated in men (who want fertility)?
Gonadotrophin injections
→ best if hypogonadism is after puberty
→ may take 6-12 months til sperm
How is FSH/LH deficiency treated in women (who want fertility)?
Carefully timed gonadotrophin injections (IVF) can induce ovulation
How is FSH/LH deficiency treated in women (no fertility)?
→ oestrogen (oral tablets or topical gel)
→ progesteron if uterus intact (to prevent endometrial hyperplasia)
