I’ve been asked about this question at the end of the Growth Session Notes several times:
- A 7 year old child is given a drug that alters the action of growth hormone on the liver. Late studies reveal that the child’s rate of growth increased significantly as a result of the drug. Which of the following describes the changes in the concentrations of growth hormone (GH) and somatomedin (SM) produced by the drug:
[GH] [SM]
a. incr incr
b. decr incr
c. incr decr
d. decr decr
The answer is “b”.
This question addresses Figure 5 from your notes.
The action is upon the liver and increased growth results leading us to the conclusion that IGF-1 (i.e. somatomedin) has likely increased.
However, IGF-1 has a negative feedback effect upon the hypothalamus and the pituitary such that growth hormone secretion is reduced.
This is a very typical type of problem that you’ll see in endocrinology as you progress through the year. You should understand how to make predictions based upon figures like this one.