2 - Hypersecretion of anterior pituitary hormones

Question 1

What is the usual cause of hypersecretion of anterior pituitary hormones?

Answer 1

Pituitary adenoma

usually benign tumours but can cause problems physically by pushing on the anterior pituitary

Question 2

Give some other causes of hypersecretion of anterior pituitary hormones?

Answer 2

(can be ectopic in origin) - non-endocrine tissue (neuroendocrine)
e.g. vasopressin producing lung tumours

Question 3

What is a common defect that comes with hypersecretion of anterior pituitary hormones that is not directly caused by the hyper secretion?
How are these caused?

Answer 3

visual field defects

the tumour can have an effect on structures that are close to the pituitary (optic chaism may be squashed by a tumour)

Question 4

What visual defect is associated with pituitary adenoma?

Answer 4

Bitemporal hemianopia

Question 5

State the disease resulting from hypersecretion of:

a. Cortictrophin
b. Thyrotrophin (rare)
c. Gonadotrophins
d. Prolactin
e. Somatotrophin (GH)

Answer 5

a. Cushing’s disease
b. Thyrotoxicosis
c. Precocious puberty in children
d. Hyperprolactinaemia
e. Gigantism/Acromegaly

Question 6

What is the usual cause of hyperprolactinaemia?

Answer 6

Prolactinoma

Most commonly microadenomas (< 10 mm)

Question 7

How is prolactin secretion regulated?

Answer 7

(lactotrophs produce prolactin)
- regulated by dopamine (from hypothalamic dopaminergic neurones)
- under constant inhibition by dopamine
- dopamine binds to D2 receptors on lactotrophs
(this suppresses prolactin)

Question 8

How can hyperprolactinaemia be treated?

surgery is not the first line of treatment

Answer 8

DOPAMINE RECEPTOR AGONIST

Question 9

Give the drug name that is used to treat hyperprolactinaemia?

Answer 9

cabergoline (or bromocriptine)

Question 10

What are the side effects of dopamine receptor agonists?

Answer 10

nausea and vomiting
postural hypotension
dyskinesias
DEPRESSION
pathological gambling

Question 11

State two physiological causes of hyperprolactinaemia.

Answer 11

Pregnancy

Breast feeding

Question 12

What does excess growth hormone cause in children and in adults?

Answer 12

Children – gigantism

Adults – acromegaly

Question 13

What is excess of somatotrophin usually due to?

Answer 13

a benign growth hormone secreting pituitary adenoma

not cancerous, but physically disturbs the pituitary

Question 14

What are the most serious complications of excess growth hormone?

Answer 14

Cardiovascular problems (majority) and respiratory problems 
This is mainly due to organ growth

Question 15

State some common clinical manifestations of acromegaly.

Answer 15

Prognathism
Enlarged supraorbital ridges 
Enlarged soft tissue 
Hyperhydrosis 
Carpal tunnel syndrome (due to excessive cartilaginous growth)
General coarseness of features
Hypertension
Headache (cardinal feature)

Question 16

What are the metabolic effects of acromegaly?

Answer 16

Increased insulin response to oral glucose leading to insulin resistance
This causes impaired glucose tolerance (in 50%) and diabetes mellitus (in 10%)

Question 17

What are the other complications that can arise from acromegaly?

Answer 17

• obstructive sleep apnoea
• hypertension
• cardiomyopathy
• increased risk of cancer
• diabetes (metabolic)

Question 18

What type of test is used to diagnose a hyperpituitary disorder?

Answer 18

Suppression test

Question 19

What test is used to diagnose acromegaly and how are the results interpreted?

Answer 19

Glucose-induced suppression of growth hormone secretion

Giving glucose should cause a decrease in growth hormone release in a normal individual
In someone with acromegaly, giving glucose will cause a PARADOXICAL rise in growth hormone release

Question 20

State some of the treatments for acromegaly.

Answer 20

• SURGERY - Transsphenoidal Hypophysectomy
• Radiotherapy (may become hypopituitary)
• Chemotherapy: (used in prep for surgery)
—–> somatostatin analogue (Octreotide)
—–> dopamine receptor agonists (Bromocriptine and Cabergoline)

Question 21

What is ocreotide? What type of drug is it? What is it used to treat?

Answer 21

a somatostatin analogue
used to treat acromegaly (excess of growth hormone)
NOTE: it inhibits lots of peptides and isn’t specific to just GH

Question 22

What are the clinical uses of octreotide? (when is it used?

Answer 22

It can be used short-term before surgery to shrink the size of the pituitary adenoma
It can be used long-term if it can’t be controlled by other means
It is used as a treatment for other neuroendocrine tumours e.g. carcinoid tumours

Question 23

State some of the side effects of octreotide.

Answer 23

GI tract disturbance (because somatostatin is produced by the small intestine as well) - nausea, diarrhoea, rarely gallstones
Initial reduction in insulin secretion causing hyperglycaemia (octreotide inhibits the production of insulin by the beta cells)

Question 24

Describe which neurones cross over at the optic chiasm

Answer 24

fibres from the nasal part of the retina cross over

the temporal hemiretina stay on the same side

Question 25

What are the symptoms of hyperproactinaemia in men and women?

Answer 25

WOMEN: galactorrhoea, secondary amenorrhoea (or oligomenorrhoea), loss of libido, infertility
MEN: loss of libido, erectile dysfunction, infertility

NOTE that men do not usually experience galactorrhoea

Question 26

Why is it uncommon for hyperprolactinaemic men to experience galactorrhea?

Answer 26

you need an appropriate steroid background

Men don’t have enough oestrogen to prime the breast and produce milk

Question 27

What grows in acromegaly?

Answer 27

• Periosteal bone
• Cartilage
• Fibrous tissue
• Connective tissue
• Internal organs (cardiomegaly, splenomegaly, hepatomegaly, etc.)