The nurse in an endocrinology practice is seeing a client with low growth hormone levels. The client's history reveals extensive pituitary damage secondary to a large adenoma. The nurse recognizes that the client's small stature results from:

Question

1. negative feedback from GH receptors.
2. an inability to respond to GH.
3. lack of tissue receptors for GH.
4. high levels of ACTH.

Answer 1

Correct Answer: 2
Rationale 1: GH receptors are not providing negative feedback, because no GH is binding to them.
Rationale 2: Small stature occurs when GH is unavailable to stimulate the growth of bones, muscles, and soft tissues. The hypothalamus stimulates the pituitary to produce GH. In this case, the hypothalamic hormone cannot stimulate the pituitary, because the normal pituitary tissue was destroyed or compressed by a tumor.
Rationale 3: The tissue receptors for GH are normal, but there is no hormone to bind to them.
Rationale 4: ACTH levels would be low, because ACTH is also produced by the pituitary.
Global Rationale: Small stature occurs when GH is unavailable to stimulate the growth of bones, muscles, and soft tissues. The hypothalamus stimulates the pituitary to produce GH. In this case, the hypothalamic hormone cannot stimulate the pituitary, because the normal pituitary tissue was destroyed or compressed by a tumor. GH receptors are not providing negative feedback, because no GH is binding to them. The tissue receptors for GH are normal, but there is no hormone to bind to them. ACTH levels would be low, because ACTH is also produced by the pituitary.