Acromegaly Flashcards
What is acromegaly?
Acromegaly is a condition caused by excessive growth hormone (GH) secretion.
What is the most common cause of unregulated growth hormone secretion in acromegaly?
A pituitary adenoma, which can be microscopic or large enough to compress local structures.
Can acromegaly be caused by conditions other than pituitary adenomas?
Yes, very rarely, acromegaly can be secondary to cancers like lung or pancreatic cancer, which secrete ectopic growth hormone-releasing hormone (GHRH) or growth hormone (GH).
What visual defect is associated with pituitary tumours in acromegaly?
Bitemporal hemianopia, which is a loss of the outer half of vision in both eyes.
What are some common clinical features of acromegaly caused by growth hormone excess?
- Prominent forehead (frontal bossing)
- Coarse skin
- Large nose
- Macroglossia (large tongue)
- Large hands and feet
- Prognathism (large protruding jaw)
What additional features may be present in acromegaly?
- Hypertrophic heart
- Hypertension
- Type 2 diabetes
- Carpal tunnel syndrome
- Arthritis
- Colorectal cancer
What is a common exam tip for diagnosing acromegaly in the PACES exam?
When a patient presents with bilateral carpal tunnel syndrome, consider acromegaly as the underlying cause, as it is often linked with this condition.
What is the most reliable test for diagnosing acromegaly?
Measuring insulin-like growth factor-1 (IGF-1) levels in a blood sample, as it reflects the growth hormone level and is typically raised in acromegaly.
How is the growth hormone suppression test conducted?
A patient consumes a 75g glucose drink, and growth hormone is measured at baseline and 2 hours later. The glucose should suppress growth hormone levels; failure to do so indicates acromegaly.
What imaging is used to diagnose a pituitary adenoma in acromegaly?
MRI of the pituitary gland, although small adenomas may be difficult to detect.
What is the definitive treatment for acromegaly caused by pituitary adenomas?
Trans-sphenoidal surgery, which removes the pituitary tumour through the nose and sphenoid bone.
How is acromegaly caused by ectopic hormones treated?
Treatment typically involves surgical removal of the ectopic tumour.
What are the medical treatment options for acromegaly if surgery is not suitable?
- Pegvisomant (growth hormone receptor antagonist, daily subcutaneous injection)
- Somatostatin analogues (e.g., octreotide, block growth hormone release)
- Dopamine agonists (e.g., bromocriptine, block growth hormone release)
What is somatostatin’s role in acromegaly treatment?
Somatostatin, also known as growth hormone-inhibiting hormone, blocks growth hormone release from the pituitary gland.
How does dopamine affect growth hormone secretion?
Dopamine inhibits growth hormone release, but it is less effective than somatostatin.
