4 - pituitary Flashcards
what does
a) anterior
b) posterior
pituitary secrete?
a) GH, LH/FSH, ACTH, TSH, prolactin
b) ADH & oxytocin
what makes prolactin unique from the other hormones made in anterior pituitary?
- it’s controlled by inhibition of hypothalamus, hypothalamus makes dopamine which inhibits prolactin secretion
- prolactin is direct target - it’s secreted from anterior pituitary and directly acts on target tissues whereas all the others have intermediate to act on e.g. TSH then on thyroid for T3&4, ACTH acts on adrenal which makes cortisol etc
what are the baseline pituitary function tests? (the ones that should be done as basic to test pituitary function)
- 9am cortisol (IMPORTANT). normal = less than 400
- thyroid profile (TSH, fT3&T4)
- prolactin
- LH/FSH, oestradiol or testosterone
- IGF-1
*basically test a bunch of the functions of pituitary (makes sense)
what test is done to assess pituitary & adrenal function?
synacthen test = give synthetic ACTH
*if chronic pituitary problem then adrenal gland atrophied so won’t respond to ACTH stimulus (by making cortisol). therefore shows function of pituitary & adrenal
note - won’t work if acute pituitary failure as adrenal gland not atrophied yet
what is gold standard test for adrenal insufficiency or hypopituitarism?
insulin stress test - give insulin to make hypoglycaemic, this should stimulate cortisol + growth hormone secretion
what is hypopituitarism? what happens to what hormones?
when pituitary gland not making enough
- low GH = growth failure
- low TSH = secondary hypothyroidism
- low LH/FSH = hypogonadism
- low ACTH = secondary hypoadrenal
also ADH deficiency so arginine vasopressin deficiency (diabetes insipidus)
what are some causes of hypopituitarism?
- pituitary tumours
- non-pituitary brain tumours
- brain injury or trauma
- iatrogenic e.g. pituitary surgery
- granulomatous disease & hypophysitis
- vascular
- infection
- idiopathic
- genetic
what is presentation of ACTH deficiency?
chronic = fatigue, pallor, anorexia, weakness
acute = weakness, dizziness, nausea, vomiting, shock
*in kids = delayed puberty, failure to thrive
what is presentation of TSH deficiency?
tiredness, cold intolerance, constipation, hair loss, dry skin, hoarseness, cognitive slowing
*in kids = growth + development impairment
what is presentation of LH/FSH deficiency? in females and males
females = oligomenorrhea, loss of libido, dyspareunia, infertility
males = loss of libido, erectile dysfunction, reduced sexual hair growth
*in kids = delayed puberty
what is presentation of GH deficiency?
decreased muscle mass, visceral obesity, fatigue, decreased quality of life, impairment of attention + memory
*in kids impaired growth
what is result of ADH deficiency?
polyuria + polydipsia (as ADH conserves water + osmolality)
what is management of hypopituitarism if deficient in
a) cortisol
b) T4
c) oestrogen or testosterone
d) GH
e) ADH
a) hydrocortisone - 15-25mg per day
b) thyroxine - 100-150mg per day
c) HRT female or testosterone male
d) GH replacement, high in kids and low or none in adults
e) desmospray or desmopressin tablets
what side effects to watch out for in testosterone replacement?
monitor as polycythaemia and prostate enlargement (not cancer but can make prostate symptoms)
what are the main pituitary tumours (that can cause hypopituitarism)?
non functioning tumour = gonadotroph
functioning = prolactinomas (commonest), acromegaly, cushing’s disease, TSHoma
what size is microadenoma and macroadenoma?
microadenoma= less than 1cm
macroadenoma = more than 1 cm
what pituitary tumour radiological classification?
modified knosp classification