Acromegaly

Question 1

What is acromegaly?

Answer 1

Condition in which benign pituitary adenomas lead to an excess secretion of growth hormone (GH) and insulin-like growth factor 1 (IGF-1)

Question 2

What is the physiology of GH secretion?

Answer 2

Hypothalamus secretes GHRH → ↑ secretion of GH → GH induces IGF-1 synthesis → ↑ serum IGF-1 via liver synthesis

Question 3

What are the effects of IGF-1?

Answer 3

Binds to IGF-1 and insulin receptors → stimulation of cell growth and proliferation, inhibits programmed cell death

Question 4

What are the clinical features of acromegaly?

Answer 4

(Mass effect) Headache, vision loss (bitemporal hemianopsia), cranial nerve palsies
(In women) Oligomenorrhea, secondary amenorrhea, galactorrhea, vaginal atrophy
(In men) Erectile dysfunction, decreased libido, ↓ testicular volume
(MSK) enlarged nose, forehead, and jaw (macrognathia) with diastema
Widened hands, fingers, and feet
(Cardiovascular) hypertension (∼ 30% of cases), left ventricular hypertrophy, cardiomyopathy
(Organ enlargement)

Question 5

How is acromegaly diagnosed?

Answer 5

(Hormone analysis) ↑ Serum IGF-1 concentration

Conduct OGTT and measure IGF-1 2 hours after. If IGF-1 secretion not suppressed then acromegaly confirmed

Question 6

What is the treatment for acromegaly?

Answer 6

(Trans-sphenoidal surgery) first-line treatment for acromegaly
(Medication) Dopamine agonists (for example bromocriptine); Somatostatin analogue (e.g., octreotide, lanreotide); GH receptor antagonists (e.g., pegvisomant)
(Radiotherapy) If above fails