hyposecretion of anterior pituitary hormones Flashcards
different parts of pituitary
anterior (glandular) and posterior (neural- derived from diencephalon)
anterior pituitary hormones
FSH/LH prolactin GH TSH ACTH
classification of disorders
primary endocrine is issue with endocrine gland, secondary is issue with anterior pituitary
define panhypopituitarism
decreased production of all anterior pituitary hormones
cause and features of congenital panhypopituitarism
rare, due to mutation of T.F genes= deficient in GH and at least 1 other hormone leads to short status and hypoplastic (small) anterior pit on MRI
causes of acquired panhypopituitarism
tumours- hypothalamic (squashes pituitary) or pituitary (adenomas/cysts) radiation- causes pituitary damage, especially GH (not so much TSH) infection eg meningitis traumatic brain injury infiltrative disease (usually affecting pituitary stalk) inflammatory (autoimmune) pituitary apoplexy (due to haemorrhage) peripartum infection (sheehans syndrome)
presentation of panhypopituitarism
symptoms due to deficient hormones: FSH/LH- secondary hypogonadism= low libido + secondary amenorrhoaea/erectile dysfunction ACTH- secondary hypoadrenalism= fatigue TSH- secondary hypothyroidism = fatigue
sheehans sydrome cause
post partum hypopituitarism due to a post partum haemorrhage, which causes hypotension, and because anterior pituitary already enlarged during pregnancy due to more lactotrophs anyway, gland likely to die by infarcation
presentation of sheehans syndrome
lethargy, anorexia and weight loss due to TSH/ACTH lactation (breastfeeding) deficiency due to low prolactin lack of periods post delivery (due to low FSH/LH) posterior not usually affected
pituitary apoplexy
intra-pituitary haemorrhage (bleeding into the gland) /infarction, often due to patients already with pituitary adenomas anti-coagulants can cause this by increasing risk of bleeding
presentation of pituitary apoplexia DIAGRAM
there is gap between optic chiasm and pituitary gland- in an adenoma there is no gap, so it can cause visual field defect (bitemporal hemianopia), as chiasm is squash MAIN presentation is severe sudden headache cavernous sinus has nerves and arteries, there, so adenoma can squash them and cause diplopia (double vision) and ptosis
problem with biochemical diagnosis of hypopituitarism
measuring basal levels of hormones is limited as: cortisol changes throughout the day (high in the morning), T4 has a half life of 6 days, FSH/LH is cyclical, and GH/ACTH is pulsatile
correct way of bichemical diagnosis
stimulated pituitary function tests- ACTH+GH are stress hormones that raise blood glucose, so an insulin induced hypoglycaemia causes GH and ACTH release TRH and GnRH also given to stimulate TSH/FSH+LH release
radiological diagnosis of hypopituitarism DIAGRAM
MRI given to reveal haemorrhage, adenoma etc can see an EMPTY SELLA, with just a stalk and a thin rim of tissue
deficient hormones, replacement and check
ACTH- hydrocortisone, check serum cortisol TSH- thyroxine, check serum T4 women LH/FSH- HRT, should cause withdrawal bleeds men LH/FSH- testosterone, serum testosterone GH- GH, check IGF1/growth chart in children
growth hormone deficiency
children- causes short stature (2SDs below mean height, or abnormal growth on predicted percentile) adults- effects more complex
causes of short stature
genetic (downs/turners/prader willi) syndrome emotional trauma systemic disease eg cystic fibrosis malnutrition and malabsorption (coelia) endocrine (cushings, hypothyrodism, GH deficiency) skeletal dysplasias (osteogenesis imperfecta/achondroplasia)
causes of short stature in children
issue with hypothalamus- prader willi (less GHRH) issue with APG- pituitary dwarfism (low GH) issue with GH receptor on liver- laron dwarfism (low IGF1/2 from liver)
detecting short statures in children
use growth charts and monitor height
causes of acquired GH deficiency in adults
trauma pituitary tumour./surgery cranial radiotherapy
diagnosis of GH deficiency
not random GH, give provactive challenge like insulin (if GH doesn’t reach 3mcg/L, deficient) GHRH+ arginine- tests whether GH can be made glucagon weirdly as well which would stimulate GH release exercise after tests, measure GH at specific time points before and after
growth hormone therapy and benefits
prepare using human recombinant GH, and administer daily, adjusting dose to IGF-1 improved body composition with lower waist circumference, better lipid profile, better bone mineral density
GH deficiency in adults presentation
lower lean mass, muscle, and increased fat, LDL and lower HDL
risks of GH therapy
increased risk of cancer, although no data shows this expensive
