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Flashcards in Pituitary physiology Deck (48):
1

What hormone produced in the hypothalamus stimualtes the release of ACTH?

CRH

2

What hormone produced in the hypothalamus stimulates release of TSH?

TRH

3

What hormone produced by the hypothalamus stimualtes release of LH/ FSH?

GnRH

4

What hormone produced by the hypothalamus inhibits the release of prolactin?

dopamine

5

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

6

What is synacthen?

synthetic ACTH

7

Who shouldnt be given an insulin stress test?

patients with cardiac histories or epilepsy

8

How do insulin stress tests work?

supposed to induce severe hypoglycaemia and stimulate growth hormone and ACTH as part of the stress mechanism

9

What is a microadenoma defined as?

less than or equal to 1cm

10

What is a macroadenoma defined as?

greater than 1cm

11

What are physiological causes of raised prolactin?

breast-feeding; pregnancy; stress; sleep

12

What drugs can cause a raised prolactin?

dopamine antagonists; antipsychotics;antidepressants

13

What are pathological causes of raised prolactin?

hypothyroidism; stalk lesions; prolactinoma

14

What are the symptoms of a raised prolactin in females?

galactorrhoea; menstrual irregularity; ammenorrhoea; infertility

15

Who has the earlier presentation, males of females?

females

16

What are the sympomts of raised prolactin in males?

impotence; visual field abnormal; headache; anterior pituitary malfunction

17

How does hypothyroidism cause a raised prolactin?

no thyroxine so no negative deedback so high levels of TRH which also stimualtes PRL

18

What is homonymous hemianopia?

complete loss of vision in one side

19

What is the treatment for prolactinoma?

drugs- dopamine agonist: cabergoline

20

What is acromegaly caused by?

GH excess

21

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

22

What causes the headaches in acromegaly?

hyperdynamic blood supply

23

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

24

What is the treatment for acromegaly?

pituitary surgery; external radiotherpathy to ptiuitary fossa

25

What are the effects of somatostatin analogues in acromegaly (octreotide)?

reduces GH; shrinks tumour; relieves headaches and improves op outcomes

26

What are the SE of somatostatin analogues?

local stinging (injection); flatulence; diarrhoea; abdo pain; gastritis; gallstones

27

Why do gallstones occur with somatostatin analogues?

inhibiti GB contraction and theres a risk of biliary colic

28

What is pegvisomant?

a GH antagonist which binds to the GH receptor to block GH activity

29

What is the follow up for acromegaly?

cancer surveillance-colon; CVS risk factors; sleep apnoea; check otehr pituitary hormones

30

What causes Cushings syndrome?

excess cortisol

31

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

32

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

33

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)

34

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)

35

What is the tes for too much steroid?

suppression test- exogenous oral high dose steroid eg dexamethasone --low serum cortisol

36

What is the difference between Cushing's disease and Cushing's syndrome?

cushings disease when caused by a pituitary problem

37

What are the causes of Cushing's syndrome?

adrenal adenoma; ectopic- thymus; lungl pancreas; pseudo- alcohol and depression and steroid medication

38

What is the action of metyrapone?

block cortisol production

39

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

40

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

41

How is GH given?

daily SC injection

42

What are the risks of testosterone replacement?

postate enlargement; polycythaemia; hepatitis (only for oral)

43

Does testosterone replacement cause prostate cancer?

no- but may make it grow so do PR exam and PSA (prostate specific antigen)

44

What are the features seen in familial diabetes insipidus?

diabetes insipidus; diabetes mellitus; optic atrophy; deaf

45

How is DI diagnosed?

water deprivation test

46

What is the treatment for DI?

desmopressin

47

What are the rare causes of DI?

tumour; sarcoid; radiation; meningitis

48

What are you trying to get in a water deprivation test?

a urine/serum osmolality ratio of greater than 2