pituitary Flashcards
pituitary hormone dysregulation: distinguish between primary and secondary disease states relating to pituitary function, recall the individual pituitary hormone deficiency and excess states that can occur and explain how these are diagnosed and treated
5 groups of anterior pituitary hormones
FSH/LH (follicle-stimulating hormone, leutinising hormone; both gonadotropins), prolactin (lactation post-partum), GH (growth hormone), TSH (thyroid-stimulating hormone; (make T3 and T4), ACTH (adrenocorticotropic hormone; make cortisol)
what disorder results in a secondary endocrine gland disease
when anterior pituitary gland hormone secretion is disordered (still receiving releasing/inhibiting hormone secreted by neurosecretory cells in hypothalamus (median eminence))
what disorder results in a primary endocrine gland disease
when endocrine gland (e.g. thyroid, gonads, adrenal cortex to release a primary hormone) is disordered
biochemical diagnosis of hypopituitarism: difficulties of using basal plasma concentrations of pituitary or target endocrine gland hormones
interpretation may be limited as pulsatile, undetectable cortisol (at night), T4 with a circulating half-life of 6 days (long half-life), cyclical FSH/LH, pulsatile GH/ACTH
biochemical diagnosis of hypopituitarism: why are stimulated (dynamic) pituitary function tests used and what do they consist of
we cause insulin-induced hypoglycaemia (<2.2mM) to stimulate GH and ACTH release, which are stress hormones (go up in terms of stress) so we can measure coristol; give TRH to stimulate and measure TSH and GnRH to stimulate and measure FSH and LH
biochemical diagnosis of hypopituitarism: radiological diagnosis
pituitary MRI may reveal specific pituitary pathology e.g. haemorrhage (apoplexy), adenoma; if an empty sella turcica (posterior bright spot on MRI not seen), then only thin rim of pituitary tissue seen as long-term hypopituitarism
replacement and check if ACTH deficient
hydrocortisone to mimic pulsatile release (more in morning, then over course of day); serum cortisol
replacement and check if TSH deficient
thyroxine; serum free T4 (body can convert to T3)
replacement and check if women LH/FSH deficient
HRT (E2 plus progestagen); symptom impovement, withdrawal bleeds
replacement and check if men LH/FSH deficient
testosterone; symptom improvement, serum testosterone (must induce sperm induction over short space of time)
replacement and check if GH deficient
GH; IGF1, growth chart (children)
define hyperpituitarism
excess pituitary hormone secretion
2 casues of hyperpituitarism
isolated pituitary tumours, ectopic (from non-endocrine tissue e.g. other tissue with hormone-producing tumour)
what is hyperpituitarism generally often associated with
visual field and other e.g. cranial nerve defects; endocrine-related signs and symptoms
effect of pituitary tumour on vision
as tumour grows (hyperplasia), it compresses optic chiasm, where fibres from nasal retinae cross (where light from temporal aspects of visual fields strikes), so causes bitemporal hemianopia
