Flashcards in Drug Effects on the Hypothalamic Pituitary Axis Deck (64)
What stimulates the release of growth hormone?
Growth hormone releasing hormone (GHRH)
What inhibits the release of growth hormone?
Insulin-like growth factors (IGFs)
What carries out the functions of growth hormone?
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
What is a secondary growth hormone deficiency?
Growth hormone not secreted
What is a tertiary growth hormone deficiency?
No signal for growth hormone release from hypothalamus
What is another name for growth hormone?
What is the bioavailability of growth hormone aver oral administration?
How must growth hormone be administered?
Daily/multi-daily parenteral administration
Why must the dose of growth hormone be titrated to effect?
Because replacing physiologically regulated hormone
What hormone can growth hormone affect?
Can cause reduced T4 levels
What does activation of the GHRH receptor lead to biochemically?
What does the activation of the ghrelin receptor lead to biochemically?
What are the effects of both GHRH and ghrelin?
Synergistic effect on release of growth hormone
When is IGF-I administered?
Growth hormone insensitivity; eg: Laron dwarfism
Patients with anti-growth hormone Abs
What are the side effects of IGF-I therapy?
What do anti-growth hormone antibodies do?
Bind and inactivate growth hormone
What does too much growth hormone cause?
What is often a cause of acromegaly?
Growth hormone releasing tumours
What are the effects of too much growth hormone in adults?
Continued growth of
What are the effects of too much growth hormone in children?
Long bones don't stop growing
What are the treatment options for too much growth hormone?
- If relevant
- Not always large
- Can be anywhere
Reduce growth hormone release
- Somatostatin analogues
- Dopamine agonist
Inhibit growth hormone action
- Growth hormone antagonist
Why is somatostatin itself not often administered?
Has short half life
Do somatostatin analogues work on growth hormone secreting tumours?
Work on many because have somatostatin receptors
What is pegvisomant?
Growth hormone antagonist
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
Why is radioactively labelled somatostatin not used to ablate tumours?
Other cells also express somatostatin receptors
What other hormone does somatostatin affect?
How is somatostatin removed?