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Flashcards in Pituitary Deck (22)
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1
Q

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

A

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

2
Q

If suspect corticotroph deficient, do what?

A

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

3
Q

If suspect too much ACTH?

A

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

4
Q

Adenomas most common in order:

A

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

5
Q

When do you have to intervene for a pituitary adenoma?

A

Symptoms
over 1cm
mass effect

6
Q

How do you differentiate between prolactinoma and stalk effect?

A

Small tumour and prolactinoma sx- probably prolactinoma

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

7
Q

Prolactinoma and planning a pregnancy?

A

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

8
Q

Symptoms of prolactinoma?

A

Hypogonadism
Infertility
Breast tenderness and discharge both sexes

9
Q

When high prolactin levels what should you FIRST check?

A

Is there a responsible drug?

Is the person hypothyroid ? TRH can stimulate prolactin release.

10
Q

Meds that increase prolactin?

A
Metoclopramide
SSRI
Morphine
Neuroleptics
Phenytoin
OCP
Ranitidine
Verapamil
Labetalol
11
Q

Most common cause of endogenous cushing syndrome?

A

Cushing disease

12
Q

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

A

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.

13
Q

Most common ca associated with acromegaly?

A

Thyroid cancer

Do colonoscopies from age 40

14
Q

Premature menopause vs PCOS

A

menopause increase FSH, low oestrogen

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

15
Q

Causes of hypoglycaemia:

A
Insulinoma (increase proinsulin:insulin ratio)
Self admin insulin
Self admin sulfonylurea (C peptide high)
Addisons
Alcohol
16
Q

Most common cause of pseudocushings?

A

Alcohol
Depression

Insulin stress test differentiates

17
Q

Biochemical abnormality in Cushings vs Addisons?

A

Cushings: hypokalaemia, metabolic acidosis

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

18
Q

Causes of raised prolactin?

A
Pregnancy
Hypothyroidism- TRH stimulates secretion
Drugs 
Stress
Pituitary stalk pressure 
Exercise, sleep
19
Q

If pituitary insufficiency- how do you monitor thyroid replacement?

A

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.)

20
Q

Describe vaptan MOA?

A

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.

21
Q

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

A

Hypercalcaemia

22
Q

What is the immune side effect of Ipilimumab?

A

Hypophysitis–>ACTH and TSH deficiency

Often need to give high dose steroids