Acromegaly

Question 1

What is acromegaly ?

Answer 1

It is the continued growth of boney extremities and projections due to excess growth hormone or somatotropin.

Question 2

What is Gigantism ?

Answer 2

It is the acromegaly equivalent seen in children. The children are unusually tall.

Question 3

What are the stimuli for the hypothalamus to release GHRH ?

Answer 3

• Low blood glucose
• Lack of food.
• Increased exercise or increased sleep
• Increased stress or trauma.

Question 4

What are the anterior pituitary cells responsible for releasing growth hormone in response to GHRH ?

Answer 4

Somatotrophs.

Question 5

What are the components of negative feedback that regulate GH release ?

Answer 5

• When there is too much GH it signals the hypothalamus to cease secreting GHRH.
• When GH reaches the liver, bones, and muscles they release somatomedians which inhibit the Somatotrophs of the anterior pituitary from secreting the GH.
• GH and somatomedians also signal the hypothalamus secrete somatostatin which inhibit the somatotrophs in the adenohypophysis.

Question 6

How does excess GH cause diabetes in patients with acromegaly ?

Answer 6

By inhibiting the cellular uptake of glucose from the plasma.

Question 7

What is the indirect effect of GH ?

Answer 7

It stimulate kidneys, muscles, bones, and liver to produce more somatomedian C which promotes cellular metabolism, cell division and inhibit cell death.

Question 8

What is the most common cause of acromegaly ?

Answer 8

pituitary adenoma that causes the somatotrophs to release more GH and also increase insulin like growth factor 01.

Question 9

What are the rare cause of acromegaly ?

Answer 9

Hypothalamic tumours that cause excess release of GHRH or ectopic tumours in other parts of the body that release GH.

Question 10

What is Wermer syndrome ?

Answer 10

It is the MEN1 that includes pituitary adenoma involving the somatotrophs, pancreatic tumours, and parathyroid adenomas.

Question 11

What are the diagnostic markers of acromegaly ?

Answer 11

Elevated levels of Insulin like growth factor 01 and GH after administering a large of dose of glucose. MRI can then be used to confirm pituitary adenoma.

Question 12

What are the treatments in acromegaly ?

Answer 12

• Trans-sphenoidal resection of the pituitary adenoma.
• Radiation therapy
• Somatostatin analogues to inhibit the somatotrophs.
• GH receptor agonists to prevent GH from binding to target tissues.