Disorders of GH (Paulson, Exam 3)

Question 1

What is the most common cause of GH deficiency in adults?

Answer 1

Pituitary tumor

Question 2

If you are concerned about a GH deficiency, what is the 1st lab test you should order?

Answer 2

IGF-1

Question 3

You are concerned your pt might have GH deficiency, so you decide to order an IGF-1 test and it comes back as low. Is this sufficient for your diagnosis of GH deficiency?

Answer 3

Nope. If IGF-1 comes back low, you need to confirm with 2 provocative stimulation tests that there’s an inadequate rise of GH. Examples of stimuli include insulin, deep sleep, glucagon, L-DOPA, vigorous exercise, and arginine.

You could also get an MRI of the hypothalamic-pituitary region.

Question 4

How do you treat children with GH deficiency?

Answer 4

• GH SQ daily
• Start ASAP for best results
• Adjust based upon IGF-1 levels and growth response
• S/E: HA most common
• If tumor: cut that sh*t out!

Question 5

What are the risks involved with untreated GH deficiency?

Answer 5

• Increased mortality
• Decreased lean body mass
• Decreased bone density
• Increased fractures
• Increased HTN
• Increased HLD

Question 6

What’s the difference between gigantism and acromegaly?

Answer 6

• Gigantism: occurs in children before closure of epiphyses, so there is excess growth of long bones
• Acromegaly: occurs in adults after closure of epiphyses, so there isn’t long bone involvement → hands, feet, jaw, internal organs affected

*Both are cause by excessive GH

Question 7

What is the most common cause of GH excess?

Answer 7

Pituitary adenoma

Question 8

People with acromegaly are at increased risk of…..

Answer 8

HTN, DM, cardiomegaly, and CHF

Question 9

Mixed cell tumors in the pituitary can often secrete __________ in addition to excess GH.

Answer 9

Mixed cell tumors in the pituitary can often secrete prolactin in addition to excess GH.

Question 10

Brosef Brad comes into your office and you immediately notice his jaw is huge! He tells you his wedding ring no longer fits and he had to buy 3 new pairs of golf shoes over the past couple years because his feet started growing. Being the genius PA that you are, you immediately think, ah yes, acromegaly! How do you go about confirming BB’s suspected diagnosis?

Answer 10

• 1st: check IGF-1
• Next (fasting for 8 hrs):
  
  • Serum IGF-1, prolactin, glucose, LFTs, BUN/Cr, TSH
  • 1 hour glucose tolerance test (gold standard)
    
    • Shows failure of GH to suppress
• Finally: pituitary MRI to identify lesion

Question 11

The results came back on Brosef Brad and you were right, he has acromegaly! How are you going to treat him?

Answer 11

• Transsphenoidal resection if possible
• Somatostatin analogs: octreotide or lanreotide
  
  • can shrink the pituitary adenoma
  • used if surgery is unsuccessful
• Dopamine agonists: cabergoline or bromocriptine (you tx broseph brad with bromocriptine because he’s a bro, duh)
  
  • May inhibit GH secretion
• Pegvisomant:
  
  • GH receptor antagonist
  • Blocks production of IGF-1

Question 12

Brosef Brad asks you what the prognosis is for his new diagnosis of acromegaly. What do you tell the poor guy?

Answer 12

• Lifespan decreased 10-15 yrs
• Mortality rate 2-3x higher than general population
  
  • most due to CV disease
  • also increased cancer
• BB needs to go see endocrinology