Acromegaly

Question 1

What is growth hormone (GH) controlled by? [4]

Answer 1

1. GHRH stimulates GH secretion
2. somatostatin inhibits GH secretion
3. ghrelin stimulates GH secretion
4. high blood glucose inhibits GH secretion

Question 2

How does GH exert its action [3]

Answer 2

1. directly - on tissues such as liver, muscles, bone or fat
2. indirectly - stimulate the liver to produce insulin-like growth factor (IGF-1) / which then stimulates growth in skeletal muscle, cartilage and bone

Question 3

What is acromegaly? [3]

Answer 3

excessive GH secretion / most commonly due to a pituitary tumour / resulting in the enlargement of bones in the hands, feet and face

Question 4

What is gigantism [4]

Answer 4

excessive GH production / before puberty in children / before the fusion of the epiphyseal (growth) plates / resulting in excessive growth and height

Question 5

What are the causes of acromegaly? [3]

Answer 5

1. benign GH-producing pituitary tumour (99%)
2. ectopic GH-releasing hormone from a carcinoid tumour (<1%)

~5% of cases associated with MEN-1 gene

Question 6

What is the pathophysiology of acromegaly? [6]

Answer 6

1. increased GH / leads to increased secretion of IGF-1 / which stimulates skeletal and soft tissue growth
2. local tumour expansion / leads to compression of surrounding structures / leading to headaches and visual field loss

Question 7

What are the symptoms of acromegaly? [7]

Answer 7

1. Headaches
2. Acral enlargement
3. Malocclusion
4. Visual field defects
5. Acroparaesthesia
6. Gonadal dysfunction - amenorrhoea, decreased libido
7. Sweating excessively

Question 8

What are the signs of acromegaly? [6]

Answer 8

1. growth of hands and feet
2. prognathism (protrusion of jaw)
3. coarsening face with wide nose
4. macroglossia (big tongue)
5. skin darkening and acanthosis nigricans
6. carpal tunnel syndrome

Question 9

What are the complications of acromegaly? [5]

Answer 9

1. impaired glucose tolerance (40%)
2. diabetes mellitus (15%)
3. obstructive sleep apnoea
4. vascular problems - hypertension, LV hypertrophy, cardiomyopathy, arrythmias, ischaemic heart disease, stroke
5. increased risk of colon cancer

Question 10

What can you expect to find when testing for acromegaly? [2]

Answer 10

1. increased glucose, calcium and phosphate levels

2. increased GH and IGF-1 levels

Question 11

How is acromegaly diagnosed? [3]

Answer 11

Random GH >0.4mcg/L and increased IGF-1 / then proceed to OGTT / if lowest GH value <1mcg/L then acromegaly diagnosis

Question 12

What is the 1st line of treatment? [3]

Answer 12

trans-sphenoidal surgery / to remove tumour / and correct tumour compression of surrounding structures

Question 13

What is the 2nd line of treatment? [4]

Answer 13

if surgery fails to correct GH/IGF-1 hypersecretion / somatostatin analogues (SSA) / e.g. IM octreotide / to inhibit GH release

Question 14

What is the 3rd line of treatment? [4]

Answer 14

if resistant or intolerant to SSA / GH receptor antagonists / e.g. SC pegvisomant / suppress IGF-1