Flashcards in Pituitary physiology Deck (48):
What hormone produced in the hypothalamus stimualtes the release of ACTH?
What hormone produced in the hypothalamus stimulates release of TSH?
What hormone produced by the hypothalamus stimualtes release of LH/ FSH?
What hormone produced by the hypothalamus inhibits the release of prolactin?
What are dynamic tests?
if theres too much hormone- do test that tries to suppress the hormone; is theres too little hormone- do test that tries to stimulate the hormone
What is synacthen?
Who shouldnt be given an insulin stress test?
patients with cardiac histories or epilepsy
How do insulin stress tests work?
supposed to induce severe hypoglycaemia and stimulate growth hormone and ACTH as part of the stress mechanism
What is a microadenoma defined as?
less than or equal to 1cm
What is a macroadenoma defined as?
greater than 1cm
What are physiological causes of raised prolactin?
breast-feeding; pregnancy; stress; sleep
What drugs can cause a raised prolactin?
dopamine antagonists; antipsychotics;antidepressants
What are pathological causes of raised prolactin?
hypothyroidism; stalk lesions; prolactinoma
What are the symptoms of a raised prolactin in females?
galactorrhoea; menstrual irregularity; ammenorrhoea; infertility
Who has the earlier presentation, males of females?
What are the sympomts of raised prolactin in males?
impotence; visual field abnormal; headache; anterior pituitary malfunction
How does hypothyroidism cause a raised prolactin?
no thyroxine so no negative deedback so high levels of TRH which also stimualtes PRL
What is homonymous hemianopia?
complete loss of vision in one side
What is the treatment for prolactinoma?
drugs- dopamine agonist: cabergoline
What is acromegaly caused by?
What are the symptoms of acromegaly?
giant (before epiphyseal fusion); thickened soft tissues; HT; cardiac failure; headaches; snoring/sleep apnoea; DM; local pituitary effeects (visual fields ;hypopituitarism; early CV death; colonic polyps and colon cancer
What causes the headaches in acromegaly?
hyperdynamic blood supply
How is acromegaly diagnosed?
IGF1 meausred; GTT (suppression test)- GH should suppress to less than 0.4 after glucose but in acromegaly there is no suppession
What is the treatment for acromegaly?
pituitary surgery; external radiotherpathy to ptiuitary fossa
What are the effects of somatostatin analogues in acromegaly (octreotide)?
reduces GH; shrinks tumour; relieves headaches and improves op outcomes
What are the SE of somatostatin analogues?
local stinging (injection); flatulence; diarrhoea; abdo pain; gastritis; gallstones
Why do gallstones occur with somatostatin analogues?
inhibiti GB contraction and theres a risk of biliary colic
What is pegvisomant?
a GH antagonist which binds to the GH receptor to block GH activity
What is the follow up for acromegaly?
cancer surveillance-colon; CVS risk factors; sleep apnoea; check otehr pituitary hormones
What causes Cushings syndrome?
What are the ymtpoms of Cushing's syndrome?
protine loss- myopathy, wasting; osteoporosis- fractures; thin skin- striae, bruising; altered carbohydrate/lipid metabolism; DM; obesity; altered psyche ; hypertension and oedema; virilism; hirsutism; acne; oligo/amenorrhoea
Why does Cushing's syndrome cause hypertension?
glucocorticoids bind to mineralocorticoid receptors, usually in the kidneys, an enzyme inactivates cortisol so that it is mainly aldosterone that regulates sodium balance, but with the excess cortisol, the enzyme is overwhelmed and cortisol causes sodium retention
What is the cause of virilism; hirsutism; acne; oligo/amenorrhoea?
excess androgen- small amounts of androgen are also produced in the zona fasciculata (in addition to its main source from the zona reticularis)
How can you differentiate between Cushing's and obesity?
Cushing's patients will have in addition: thin skin; proximal myopathy; frontal balding in women; conjuctival oedema (chemosis); osteoporosis (obesity usually protects against)
What is the tes for too much steroid?
suppression test- exogenous oral high dose steroid eg dexamethasone --low serum cortisol
What is the difference between Cushing's disease and Cushing's syndrome?
cushings disease when caused by a pituitary problem
What are the causes of Cushing's syndrome?
adrenal adenoma; ectopic- thymus; lungl pancreas; pseudo- alcohol and depression and steroid medication
What is the action of metyrapone?
block cortisol production
What are the symptoms of anterior hypopituitarism?
menstrual irregularities; infertility; impotence; gynaecomastia; abdo obesity; loss of facial hair; loss of exillary and pubic hair; dry skin and hair; hypothyroid faces; growth retardation
What are the functions of GH in adults?
improves well being and QOL; decreaases abdo fat; increases muscle mass, strength, exercise capacity and stamina; improves cardiac function; decreases cholesterol and increases LDL; increase bone density
How is GH given?
daily SC injection
What are the risks of testosterone replacement?
postate enlargement; polycythaemia; hepatitis (only for oral)
Does testosterone replacement cause prostate cancer?
no- but may make it grow so do PR exam and PSA (prostate specific antigen)
What are the features seen in familial diabetes insipidus?
diabetes insipidus; diabetes mellitus; optic atrophy; deaf
How is DI diagnosed?
water deprivation test
What is the treatment for DI?
What are the rare causes of DI?
tumour; sarcoid; radiation; meningitis