Pituitary + Hypothalamus Flashcards
(34 cards)
How are the pituitary and hypothalamus connected?
Pituitary stalk/infundibulum
What are the two parts of the pituitary gland and what do they produce?
Anterior = adeno (glandular):
GH, ACTH, TSH, FSH, LH, PRL
Posterior = neuro (neural):
ADH, OXT (oxytocin)
What bone does the pituitary gland sit upon and what fossa is it within?
Sphenoid bone in sella turcica (Turkish saddle)
What structures are contained within the cavernous sinus?
Carotid arteries,
CN III, IV, V1, V2, VI
What paired hormones do the anterior pituitary hormones stimulate and where do they act upon?
TSH --> thyroxine (thyroid gland) ACTH --> cortisol (adrenal gland) GH --> liver/muscles PRL --> direct action FSH/LH --> reproductive glands
What organs do the posterior pituitary hormones act upon?
ADH - kidneys
OXT - lactation stimulation
Which hypothalamic hormones stimulate which pituitary hormones?
CRH --------- ACTH ------ cortisol TRH ---------- TSH -------- thyroxine GnRH -------- FSH/LH GHRH -------- GH DA - - - - - - PRL (negative control)
ADH/OXT are stored in the posterior pituitary after production in the hypothalamus
What test is used to measure cortisol production and how does it work?
Synacthen:
Give synthetic ACTH - looking for a rise in cortisol (indicates normal function of adrenals)
Check cortisol at 0,30,60 mins
What test is sued to measure GH levels and what are you looking for?
Insulin stress test:
Looking for a rise in GH and cortisol when insulin given in starvation state (check every 30 ins for 2/3 hours)
How is ADH production investigated?
Water deprivation test (over 8 hours), if urine concentration doesn’t increase = inadequate ADH production
What causes diabetes insipidus?
ADH insufficiency
How does diabetes insipidus present?
Polyuria, polydipsia, nocturia
How is diabetes insipidus diagnosed?
Water deprived test, serum osmolality, U&Es
What are the 2 types of diabetes insipidus and how are these differentiated on investigation?
Cranial (lack of ADH) or nephrogenic (unresponsive to existing ADH)
Vasopressin test:
after water deprivation give AVP and measure bodys response (if stop producing urine = cranial, if continue = nephrogenic)
How are the two forms of diabetes insipidus treated?
Cranial: desmopressin
Nephrogenic: Thiazide diuretic + NSAID
What is the main cause of SIADH?
Ectopic ADH production (from a paraneoplastic syndrome)
How does SIADH present?
Very vague symptoms depending upon severity
Causes hyponatraemia and hypo-osmolality (due to excess water)
How is SIADH investigated?
U&Es (hyponatraemia with hypoosmolality)
Urine dipstick (renal excretion of Na)
Concentrated urine
How is SIADH treated?
Treat underlying cause (as often a tumour)
furosemide infusion with slow Na to replace losses
Which side of the pituitary is panhypopituitarism most likely to affect and thus which hormones?
Anterior GH (growth failure/low mood) TSH (hypothyroidism) LH/FSH (hypogonadism) ACTH (hypoadrenalism) Prolactin (none)
What are the causes of panhypotiuitrarism?
Most likely tumours (either primary or secondary)
How does panhypopituitarism present?
Menstrual irregularities Gynaecomastia Abdominal obesity Loss of facial hair (M) Dry skin + hair Hypothyroid facial features
What is the main effect of low GH?
Low mood/depression
How is panhypopituitarism investigated?
Check all hormone levels: ACTH: cortisol - synacthen TSH: thyroxine - fT4 LH/FSH: sex hormones - testosterone/estradiol GH: IGF1 PRL: PRL
