Pituitary

Question 1

When do water deprivation test, what are you aiming to do?

Answer 1

Get serum osmolarity over 300 and ensure urine concentrates to over 600

Question 2

If suspect corticotroph deficient, do what?

Answer 2

SynACTHen - NOT in acute pit failure)- can the adrenals respond normally?

ITT- if BSL under 2.2 then should be able to release GH and ACTH as part of stress response- gold standard

Glucagon stimulation test- should increase plasma cortisol once fall in glucose.

*note very rare to just see ACTH deficiency on its own! WIll usually be other things like LH/FSH, GH, TSH first. Will not see hyperpigmentation or salt craving. Often will see hypercalcaemia

Question 3

If suspect too much ACTH?

Answer 3

Urine Free cortisol over 3 x ULN

24 h UFC

Low dose DST- dex should inhibit CRH: 1mg at 11pm–>measure at 8am- should be cortisol under 50

Salivary cortisol - 11pm but does not confirm

Dexamethasone/CRH to differentiate cushings and pseudocushings

If indeterminate ACTH levels then do 8mg overnight DST or 48 hour high dose DST- if supressed to below 50% baseline, it suggests a pituitary source. Will not suppress in ectopic ACTH

Question 4

Adenomas most common in order:

Answer 4

Nonfunctioning (stain for FSH)–>prolactinomas–>GH–>ACTH–>TSH or FSH (not usually both)

Question 5

When do you have to intervene for a pituitary adenoma?

Answer 5

Symptoms
over 1cm
mass effect

Question 6

How do you differentiate between prolactinoma and stalk effect?

Answer 6

Small tumour and prolactinoma sx- probably prolactinoma

Large tumour and up to 10x increase prolactin- probably prolactinoma

Question 7

Prolactinoma and planning a pregnancy?

Answer 7

Small, under 1cm- stop the dop agonist
Examine visual fields during pregnancy and with a 6wk post partum MRI

If big, think abour prepreg surgery
watch visual fields and give bromocriptine if become compromised or just continue bromocriptine during pregnancy
Steroids if vision threatened
Post partum MRI

Question 8

Symptoms of prolactinoma?

Answer 8

Hypogonadism
Infertility
Breast tenderness and discharge both sexes

Question 9

When high prolactin levels what should you FIRST check?

Answer 9

Is there a responsible drug?

Is the person hypothyroid ? TRH can stimulate prolactin release.

Question 10

Meds that increase prolactin?

Answer 10

Metoclopramide
SSRI
Morphine
Neuroleptics
Phenytoin
OCP
Ranitidine
Verapamil
Labetalol

Question 11

Most common cause of endogenous cushing syndrome?

Answer 11

Cushing disease

Question 12

What should you do if acromegaly and a poor surgical candidate?

Answer 12

Somatostatin analogue-
octreotide
Lanreotide

surgical cure is defined as supression of GH after 75mg glucose load
If normalise IGF-1 , there is a survival benefit.

Question 13

Most common ca associated with acromegaly?

Answer 13

Thyroid cancer

Do colonoscopies from age 40

Question 14

Premature menopause vs PCOS

Answer 14

menopause increase FSH, low oestrogen

PCOS high LH, high LH:FSH, FSH normal or low, high estrogen

Question 15

Causes of hypoglycaemia:

Answer 15

Insulinoma (increase proinsulin:insulin ratio)
Self admin insulin
Self admin sulfonylurea (C peptide high)
Addisons
Alcohol

Question 16

Most common cause of pseudocushings?

Answer 16

Alcohol
Depression

Insulin stress test differentiates

Question 17

Biochemical abnormality in Cushings vs Addisons?

Answer 17

Cushings: hypokalaemia, metabolic acidosis

Addisons: hyperkalaemia, metabolic acidosis
loss aldosterone. Also sodium reabsorption is linked to H secretion

Question 18

Causes of raised prolactin?

Answer 18

Pregnancy
Hypothyroidism- TRH stimulates secretion
Drugs 
Stress
Pituitary stalk pressure 
Exercise, sleep

Question 19

If pituitary insufficiency- how do you monitor thyroid replacement?

Answer 19

fT4

Dont need to treat plolactin deficiency
GH replacement controversial in adulta
Consider HRT or OCP unless hx prostate or breast Ca
Glucocort replacement (not mineralocorticoid as adrenal cortex is intact)- so give hydrocort over pred/cortisone acetate often- which have mineral effects.)

Question 20

Describe vaptan MOA?

Answer 20

Prevent ADH binding to receptor on basolateral membrane V2–> AQP2 not phosphorylated and located to luminal membrane–>increase plasma sodium concentration, create more dilute urine.

Question 21

What other biochem abnormality do you see in isolated ACTH deficiency?

Answer 21

Hypercalcaemia

Question 22

What is the immune side effect of Ipilimumab?

Answer 22

Hypophysitis–>ACTH and TSH deficiency

Often need to give high dose steroids