Pituitary Physiology & Pathology

Question 1

What do the hypothalamus & pituitary to stimulate cortisol/adrenaline release?

Answer 1

hypothalamus - CRH

pituitary - ACTH

Question 2

What do the hypothalamus & pituitary to stimulate thyroxine?

Answer 2

hypothalamus - TRH

pituitary - TSH

Question 3

What do the hypothalamus & pituitary to stimulate oestraodiol & testosterone?

Answer 3

hypothalamus - GRH

pituitary - LH/FSH

Question 4

What do the hypothalamus & pituitary to stimulate growth?

Answer 4

hypothalamus - GHRH
pituitary - GH
Liver - IGF1

Question 5

How does the hypothalamus control prolactin?

Answer 5

Dopamine is released and inhibits prolactin secretion

Question 6

What two hormones are stored in the posterior pituitary?

Answer 6

ADH & Oxytocin

Question 7

What is the aim of dynamic tests?

Answer 7

Act to suppress/stimulate a hormone, if a pathology is present no change will occur

Question 8

Name three dynamic test

Answer 8

• synacthen
• insulin stress test/prolonged glucagon test
• water deprivation test

Question 9

Describe syacthen test

Answer 9

Normal cortisol rises by 150 and reaches 500 in response to synthetic ACTH. In pathology, cortisol will not rise - indicating a problem with the adrenal cortex

Question 10

How does an insulin stress test work?

Answer 10

Causes a hypo & forces the hypothalamus to produce cortisol & GH

Question 11

When is an insulin stress test contraindicated?

Answer 11

Epilepsy & angina

Question 12

What can be used instead of an insulin stress test?

Answer 12

Prolonged glucagon test

Question 13

What is a water deprivation test used to diagnose?

Answer 13

Diabetes insipidus - overnight test

Question 14

Name the origin of the anterior pituitary

Answer 14

Rathke’s pouch

Question 15

Describe the histology of the posterior pituitary

Answer 15

Extension of neural tissue consists of modified glial cells & axonal processes

Question 16

Name the main cause of adrenocortical hypersecretion

Answer 16

Cushing’s syndrome

Question 17

What are the three hormones types produced by the adrenal gland?

Answer 17

• glucocorticoids
• mineralocorticoids
• androgens

Question 18

Explain the impact excess cortisol

Answer 18

protein loss (proximal myopathy, osteoporosis, striae, thin skin) 
altered carb/lipid metabolism (diabetes, obesity)
altered psych (psychosis/depression)

Question 19

What is the consequence of excess mineralocorticoid?

Answer 19

Hypertension & oedema (conjunctival)

Question 20

How will excess androgen present?

Answer 20

Virilism, hirsutism, acne, oligo/amenorrhoea

Question 21

Name three screening tests for Cushing’s

Answer 21

• overnight dexamethasone suppression test
• urine free cortisol
• diurnal cortisol variation

Question 22

Describe the screening suppression test for Cushings

Answer 22

1mg dexamethasone (inhibits ACTH and reduces cortisol)<50 next morning = normal 
>130 next morning = abnormal

Question 23

What is meant by ‘diurnal variation’?

Answer 23

Physiologically cortisol peaks in the morning when you wake up and by midnight it is undetectable

Question 24

What is the definitive test for Cushing’s?

Answer 24

2 day 2mg/day dexamethasone

- cortisol after 6 hours after last dose <50 = no cushings >130 = cushing’s

Question 25

Name four causes of Cushing’s Syndrome

Answer 25

• Pituitary
• Adrenal adenoma/carcinoma
• Ectopic ACTH production
• Pseudo

Question 26

What is the most common cause of Cushing’s?

Answer 26

Steroid Therapy

Question 27

What would happen if the cause of Cushing’s is a pituitary pathology?

Answer 27

50% suppression in high dose dexamethasone suppression test

Question 28

In pituitary disease how would Cushing’s present in a CRH stimulation test?

Answer 28

50% increase in ACTH

20% increase in cortisol

Question 29

How is pituitary pathology Cushing’s treated?

Answer 29

Hypophysectomy & radiotherapy

Question 30

How is adrenal pathology Cushing’s treated?

Answer 30

Adrenalectomy

Question 31

What drugs can be used to treat Cushing’s?

Answer 31

Somatostatin analogue (inhibits release of ACTH)
Ketoconazole (inhibits enzyme - prevent rise in ACTH)
Metyrapone (glucocorticoid synthesis inhibitor)

Question 32

State the hormones in the anterior pituitary that are affected in pan hypopituitarism

Answer 32

• growth hormone
• TSH
• LH/FSH
• ACTH

Question 33

What is the effect of pan hypopituitarism on the posterior pituitary?

Answer 33

Diabetes Insipidus

Question 34

State the three main causes of pan hypopituitarism

Answer 34

Tumours
Iatrogenic
Systemic Disease

Question 35

What systemic diseases can cause pan hypopituitarism?

Answer 35

• granulomatous (TB, sarcoidosis)
• vascular (polyarteritis)
• trauma
• autoimmune
• infections

Question 36

What specific autoimmune condition causes pan hypopituitarism?

Answer 36

Sheenan - secondary necrosis due to post partum haemorrhage

Question 37

How does pan hypopituitarism present?

Answer 37

Menstrual irregularities, infertility, impotence, gynaecomastica, lack of facial/axillary/pubic hair, abdominal obesity, dry skin & hair, hypothyroid face, growth retardation

Question 38

How is pan hypopituitarism diagnosed?

Answer 38

synacthen test & insulin tolerance test

Question 39

What is the treatment for pan hypopituitarism?

Answer 39

Hormone replacement therapy

Question 40

Describe growth hormone replacement therapy

Answer 40

Given daily by subcutaneous injection, very beneficial to wellbeing & general health

Question 41

Describe testosterone replacement

Answer 41

IM, skin gel - may cause prostate enlargement so regular PR exam is required
Other risks - polycythameia (high RBC) & hepatitis (only for oral tablets)