Chempath 22: Pituitary

Question 1

Why is blood pressure low in Addison’s disease ?

Answer 1

Low aldosterone levels

less aldosterone binds to mineralocorticoid receptors in collecting duct. Less Na+ reabsorbed so less water reabsorbed

Question 2

List the hormones that are released by the Anterior pituitary gland ?

Answer 2

GH
Prolactin 
TSH
LH
FSH
ACTH

Question 3

The hypothalamus releases TRH which acts on the anterior pituitary causing release of ……… and ……….

Answer 3

TSH

Prolactin

Question 4

Dopamine causes reduced secretion of ……….. That’s why the drug Cabergoline or ………… can be used to treat a …………..

Answer 4

Prolactin
Bromocriptine
Prolactinoma

Question 5

Why do people with hypothyroidism get hyperprolactinaemia ?

Answer 5

In primary hypothyroidism the Hypothalamus secretes more TRH which causes increased TSH and prolactin release.

Question 6

How does hyperprolactinaemia cause infertility ?

Answer 6

Prolactin has a negative feedback loop with GnRH which means it can switch off release of FSH and LH.

Question 7

Post partum haemorrhage can cause infarction of the pituitary. This is known as ………… syndrome.

Answer 7

Sheehans.

Question 8

Transphenoidal hypophysectomy is the surgery to treat a ………

Answer 8

Prolactinoma in the optic chiasm

Question 9

Which hormones are released by the hypothalamus and pituitary in response to hypoglycaemia ?

Answer 9

CRF - ACTH

GHRH - GH

Question 10

Describe pituitary function testing?

Answer 10

Use a combined rapid anterior pituitary panel (CPFT):

• Induce hypoglycaemia (fasting + insulin) and measure if levels of GH and Cortisol rise.
• Give TRH and measure if Prolactin and TSH levels rise
• Give GnRH and see if LH and FSH levels rise

Question 11

Which pituitary hormone should be replaced most urgently in case of pituitary failure?

A)TSH
B)LH & FSH
C)Cortisol
D)Prolactin
E)Aldosterone

Answer 11

C) Cortisol

Cortisol must be replaced with Hydrocortisone urgently as it is required to respond to stress and maintain cell integrity and electrolyte balance.

Aldosterone should still be produced by the adrenals

Question 12

Explain why secondary hyperprolactinaemia requires surgery ?

Answer 12

Secondary hyperprolactinaemia is most commonly caused by a non functioning pituitary adenoma. This blocks Dopamine from causing negative feedback on prolactin release. This does not respond to Bromocriptine so requires surgery.

Question 13

In slow growing children you should initially do a plasma ……. level. Otherwise an ……….. test can be done to see if …… levels rise.

Answer 13

GH
exercise
GH

Question 14

Which syndrome is associated with adrenal failure due to haemorrhage into the adrenals?

This is mainly caused by ………infection

Answer 14

Waterhouse-friderichsen syndrome

N.meningitidis (meningococcal infection)

Question 15

Acromegaly is diagnosed using the …………………… and …………. test

Answer 15

Oral glucose tolerance test

IGF-1 level

Question 16

What hormones secreted from the hypothalamus cause anterior hormone release

Answer 16

GHRH - GH
Dopamine - ve prolactin 
TRH - TSH and prolactin 
LHRH - LH, FSH 
CRH - ACTH

Question 17

How many people with pituitary failure present

Answer 17

Galactorrhoea or amenorrhoea

If macroadenoma - bitemporal hemianopia

Question 18

When do you suspect a prolactinoma

Answer 18

Prolactin > 6000

Question 19

Dangers of inducing hypoglycaemia

Answer 19

Check no cardiac RF
ECG must be normal
BG <2.2 stimulates the pituitary

If severe hypoglycaemia - rescue with 50mL of 20% dextrose

Question 20

contraindications for the CPFT

Answer 20

ischaemic heart disease
epilepsy
untreated hypothyroidism

Question 21

side effects of CPFT

Answer 21

sweating, palpitations, loc
rarely - convulsions with hypoglycaemia
trh injection - may experience transient symptoms of metallic taste in the mouth, flushing, nausea