Drug Effects on the Hypothalamic Pituitary Axis Flashcards Preview

MD1 Endocrine > Drug Effects on the Hypothalamic Pituitary Axis > Flashcards

Flashcards in Drug Effects on the Hypothalamic Pituitary Axis Deck (64)
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1

What stimulates the release of growth hormone?

Ghrelin
Growth hormone releasing hormone (GHRH)

2

What inhibits the release of growth hormone?

Somatostatin
Insulin-like growth factors (IGFs)

3

What carries out the functions of growth hormone?

IGFs

4

What happens in growth hormone insensitivity?

High growth hormone levels
Liver doesn't secrete IGF in response to growth hormone
No negative feedback of IGF to growth hormone release

5

What is a secondary growth hormone deficiency?

Growth hormone not secreted

6

What is a tertiary growth hormone deficiency?

No signal for growth hormone release from hypothalamus

7

What is another name for growth hormone?

Somatotropin

8

What is the bioavailability of growth hormone aver oral administration?

Zero

9

How must growth hormone be administered?

Daily/multi-daily parenteral administration

10

Why must the dose of growth hormone be titrated to effect?

Because replacing physiologically regulated hormone

11

What hormone can growth hormone affect?

Can cause reduced T4 levels

12

What does activation of the GHRH receptor lead to biochemically?

Elevates cAMP

13

What does the activation of the ghrelin receptor lead to biochemically?

Elevates Ca

14

What are the effects of both GHRH and ghrelin?

Synergistic effect on release of growth hormone

15

When is IGF-I administered?

Growth hormone insensitivity; eg: Laron dwarfism
Patients with anti-growth hormone Abs

16

What are the side effects of IGF-I therapy?

Muscle hypertrophy
Sometimes hypoglycaemia

17

What do anti-growth hormone antibodies do?

Bind and inactivate growth hormone

18

What does too much growth hormone cause?

Acromegaly

19

What is often a cause of acromegaly?

Growth hormone releasing tumours

20

What are the effects of too much growth hormone in adults?

Continued growth of
- Hands
- Feet
- Cartilage
- Nose
- Ears

21

What are the effects of too much growth hormone in children?

Long bones don't stop growing
Organ damage

22

What are the treatment options for too much growth hormone?

Remove tumour
- If relevant
- Not always large
- Can be anywhere
Reduce growth hormone release
- Somatostatin analogues
- Dopamine agonist
Inhibit growth hormone action
- Growth hormone antagonist

23

Why is somatostatin itself not often administered?

Has short half life

24

Do somatostatin analogues work on growth hormone secreting tumours?

Work on many because have somatostatin receptors

25

What is pegvisomant?

Growth hormone antagonist

26

What is one way of finding a growth hormone secreting tumour?

Use radioactively labelled somatostatin analogue
Somatostatin receptors internalised > take peptide ligand with them
Can be imaged by in vivo receptor scintigraphy

27

Why is radioactively labelled somatostatin not used to ablate tumours?

Other cells also express somatostatin receptors

28

What other hormone does somatostatin affect?

Reduces TSH

29

How is somatostatin removed?

Enzymatic cleavage
Renal elimination

30

What is octreotide?

Somatostatin analogue