Hypersecretion of Anterior Pituitary Hormones

Question 1

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

Answer 1

Pituitary adenoma

Question 2

What visual defect is associated with pituitary adenoma?

Answer 2

Bitemporal hemianopia

Question 3

State the disease resulting from hypersecretion of:

a. Corticotrophin
b. Thyrotrophin
c. Gonadotrophin
d. Prolactin
e. Somatotrophin

Answer 3

a. Cortictrophin
Cushing’s disease

b. Thyrotrophin
Thyrotoxicosis

c. Gonadotrophins
Precocious puberty in children

d. Prolactin
Hyperprolactinaemia

e. Somatotrophin
Gigantism/Acromegaly

Question 4

What is the usual cause of hyperprolactinaemia?

Answer 4

Prolactinoma

Most commonly microadenomas (< 10 mm)

Question 5

State the symptoms of hyperprolactinaemia.

Answer 5

Loss of libido

Infertility

Galactorrhoea (rarely occurs in males as well)

Oligomenorrhoea/amenorrhoea Impotence (in men)

Question 6

State two physiological causes of hyperprolactinaemia.

Answer 6

Pregnancy

Breast feeding

Question 7

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

Answer 7

Children – gigantism

Adults – acromegaly

Question 8

What are the most serious complications of excess growth hormone?

Answer 8

Cardiovascular problems (majority) and respiratory problems

This is mainly due to organ growth

Question 9

State some common clinical manifestations of acromegaly.

Answer 9

Prognathism

Enlarged supraorbital ridges

Enlarged soft tissue

Hyperhydrosis

Carpal tunnel syndrome (due to excessive cartilaginous growth)

General coarseness of features

Hypertension

Question 10

What are the metabolic effects of acromegaly?

Answer 10

Increased insulin response to oral glucose leading to insulin resistance

This causes impaired glucose tolerance (in 50%) and diabetes mellitus (in 10%

Question 11

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

Answer 11

Suppression test

Question 12

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

Answer 12

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 13

State some of the treatments for acromegaly.

Answer 13

Transsphenoidal Hypophysectomy

Radiotherapy

Chemotherapy:
 Octreotide (somatostatin analogue)
 Bromocriptine and Cabergoline (dopamine receptor agonists)

Question 14

What are the clinical uses of octreotide?

somatostatin analogue

Answer 14

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 15

Describe the administration, distribution and metabolism of octreotide.
(somatostatin analogue)

Answer 15

Octreotide is administered SC or IM 3/day

It is retained in extracellular fluid

Half-life = 2-4 hours

Question 16

State some of the side effects of octreotide.

somatostatin analogue

Answer 16

GI tract disturbance (because somatostatin is produced by the small intestine as well)

Initial reduction in insulin secretion causing hyperglycaemia (octreotide inhibits the production of insulin by the beta cells)

Rarely gallstones

Question 17

What is used to treat hyperprolactinaemia?

Answer 17

Dopamine agonists – bromocriptine and cabergoline

Question 18

Describe the pharmacokinetics and side-effects of bromocriptine.
(dopamine receptor agonists)

Answer 18

Administered orally 1/day

Heavily plasma protein bound

Half-life = 7 hours (hepatic metabolism)

Side effects: 
 Nausea/vomiting/abdominal cramps 
 Dyskinesias
 Psychomotor excitation 
 Postural hypotension 
 Vasospasm in fingers and toes

Question 19

State some other uses of bromocriptine.

dopamine receptor agonists

Answer 19

Suppression of lactation

Cyclical benign breast tumours (and cyclic breast pain)

Also used in acromegaly but doesn’t have the same beneficial effect on tumour size

Parkinson’s disease

Question 20

Describe the pharmacokinetics and side-effects of cabergoline.
(dopamine receptor agonists)

Answer 20

Taken orally 1-2/week

Half-life = > 45 hours

Side effect: same as bromocriptine but less pronounced