Acromegaly/Gigantism

Question 1

What is acromegaly?

Answer 1

excess in growth hormone in adults (after the epiphyseal growth plates have closed)

Question 2

what is gigantism?

Answer 2

excess in growth hormone in children before epiphyseal growth plates have closed

Question 3

what is pseudoacromegaly (acromegaloidism)?

Answer 3

these are patients that present with acromegaly facial features or tall stature common in gigantism, but the work up is negative and there is no excess GH

Question 4

What is the most common cause of both acromegaly and gigantism?

Answer 4

pituitary adenoma

Question 5

what are 4 potential causes for excess GH?

Answer 5

1. pituitary adenoma
2. ectopic functional tumour secreting GH ➔ pancreatic, lung, adrenal
3. excess GHRH secretion from tumours in the brain or peripheral tumours (lungs)
4. familial genetic syndromes like Multiple endocrine neoplasia 1

Question 6

what are key characteristics of acromegaly?

Answer 6

1. hands and feet getting larger
2. coarsening of facial features ➔ jaw protrusion, macroglossia, increased spaced dentation, prominent forehead

general increase in connective tissue and muscle size

Question 7

what is a key characteristic feature of gigantism?

Answer 7

rapid growth in height, bypassing expected growth by parental calculations

Question 8

how do you work up a suspected acromegaly?

Answer 8

1. serum IGF1 levels ➔ if acro, would be elevated
2. would completed an OGTT ➔ glucose inhibits GH secretion ➔ normally should decrease GH secretion
   - blood GH ➔ glucose ➔ blood GH
   - if acro, GH would stay up/levels similar to before glucose
   - if not acro, GH should decrease
3. find underlying etiology ➔ consider pituitary MRI bc most common cause is pituitary adenoma

Question 9

when working up a potential pituitary adenoma, what other hormone tests would you run?

Answer 9

you could test for all pituitary hormones

Growth hormone
Thyroid-stimulating hormone
Luteinizing hormone and follicular stimulating hormone
Prolactin
Antidiuretic hormone
Adrenocorticotropin stimulating hormone

Question 10

how would you treat acromegaly?

Answer 10

depends on the etiology
1. if tumour ➔ resect the tumour; can give radiation for benign and malignant masses, can consider chemo for malignant masses
2. somatostatin analogue
3. +/- dopamine agonist and GH receptor agonist
4. control complications

Question 11

what potential complications can you get from acromegaly?

Answer 11

1. OSA ➔ increased connective tissue in the larynx area
2. carpal tunnel syndrome ➔ increased connective tissue pressing on the nerves
3. dilated cardiomyopathy ➔ CHF, arrhythmias, valvular dysfunction
4. HTN
5. increased risk of developing cancer
6. hyperglycemia

Question 12

why is bilateral hemianopia common in acromegaly?

Answer 12

because if there is a pituitary adenoma, can put pressure on the optic chiasm and impact visual field