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)

3rd decade of life (mean age at diagnosis usually 40–45 year

Question 2

etio of acromegaly

Answer 2

Benign growth hormone-secreting pituitary adenoma (> 95% of cases)

hypothalamic tumors

paraneoplastic syndromes

Question 3

NORMAL AXIS OF GH

Answer 3

hypothalamus secretes GhRH

pituitary secreses GH

liver synthesises
IGF-1

acts on IGF-1 and insulin receptors

effect of IGF-1 on insulin receptors:
pathological glucose tolerance caused by binding to insulin receptors

effect of IGF-1 on IGF-1 receptors:
causes growth of bone, cartilage, skeletal muscle, skin, soft tissue, and organs

↑ secretion of somatostatin from the hypothalamus → ↓ serum GH and IGF-1 (negative feedback)

Question 4

pathophys of gh in pit adenoma

Answer 4

1)acromegaly sx
Overproduction of GH →
abnormally high serum IGF-1 levels → overstimulation of cell growth and proliferation

2) mass effect
-Tumor mass compresses optic nerve→ blurred vision/ bitemporal hemianopsia
-hyperprolactinemia
d/2 damage to pit stalk by tumor

3)hypogondism
hypopituitarism of other pituitary hormones:
gonadotropins → ↓ LH and FSH → ↓ estrogen and testosterone → infertility & amenorhoea &

Question 5

sx of acromegaly

Answer 5

MASS EFFECT
- (bitemporal hemianopsia),
♀: secondary amenorrhea, galactorrhea,
♂: Erectile dysfunction, decreased libido, ↓ testicular volume

SOFT TISSUE
hyperhidrosis by enlarged sweat glands

Deepening of the voice, macroglossia & obstructive sleep apnea

Carpal tunnel syndrome from connective tissue proiferation in tendon sheath

SKELETAL sx

Large skull, coarsened features: enlarged nose, forehead, and jaw
diastema (gap tooth)
Widened hands, fingers, and feet

CDV sx

• LVH
• cardiomyopathy

ORGAN ENLARGEMENT
-kidneys & thyroid

Question 6

dg

Answer 6

hormone test
-elevated serum IGF-1

OGTT

• measure baseline GH after 2hrs of intake of 75g glucose
• UNSUPRESSED GH indicates acromegaly
• supressed gh rules out acromegaly

MRI
-for visible mass on pituitary
abscence shows extrapituitary cause

Question 7

rx of pituitary adenoma

Answer 7

Surgery: transsphenoidal adenomectomy (thru the nose)

RADIATION THERAPY W/ GAMMA KNIFE

medication:
SOMATOSTATIN ANALOG
(ocreotide/ lanreotide)

dopamine agonist for hyperprolactinoma

Question 8

complication of pituitary adenoma

Answer 8

Cardiovascular complications (cause death) (CHF, hypertension, arrhythmia, valvular disease, hypertrophy)

Diabetes mellitus