Q: Which equation best represents the relationship between hormone secretion and negative feedback in the HPA axis?

$$GnRH \rightarrow LH \rightarrow Testosterone \rightarrow \text{Negative Feedback}$$

Question 1

Which hormone is released from the hypothalamus to initiate the HPA axis for testosterone production?

Accepted Answer

Gonadotropin-releasing hormone (GnRH)

Question 2

During exogenous testosterone supplementation, what happens to the levels of LH and GnRH due to long-loop negative feedback?

Accepted Answer

Both LH and GnRH levels decrease

Question 3

A patient with testicular cancer undergoes treatment resulting in low testosterone levels. What is the expected effect on GnRH and LH levels?

Accepted Answer

GnRH increases, LH increases

Question 4

Which of the following best describes the change in testosterone receptors after years of exogenous testosterone supplementation?

Accepted Answer

Testosterone receptors are downregulated

Question 5

Given the following blood testosterone levels: cycling career (20.2 nmol/L), testicular cancer treatment (5.4 nmol/L), exogenous supplementation (60.8 nmol/L), and post-supplementation (7.2 nmol/L), which scenario represents hypersecretion?

Accepted Answer

Exogenous supplementation

Question 6

Which equation best represents the relationship between hormone secretion and negative feedback in the HPA axis?

Accepted Answer

$$GnRH ightarrow LH ightarrow Testosterone ightarrow 	ext{Negative Feedback}$$

Question 7

A patient presents with high testosterone, low LH, and low GnRH. What is the most likely cause?

Accepted Answer

Exogenous testosterone supplementation

Question 8

Which of the following is a consequence of long-loop negative feedback in the HPA axis?

Accepted Answer

Decreased secretion of GnRH and LH

Question 9

If the anterior pituitary is the source of dysfunction and both LH and testosterone levels are low, what type of dysfunction is this?

Accepted Answer

Secondary dysfunction

Question 10

Which hormone acts directly on the testes to stimulate testosterone production?

Accepted Answer

LH

Question 11

A patient with secondary hypertestosteronemia would have which combination of hormone levels?

Accepted Answer

High GnRH, high LH, high testosterone

Question 12

Which of the following is NOT a plausible effect of exogenous testosterone supplementation?

Accepted Answer

Upregulation of testosterone receptors

Question 13

What is the expected effect on the strength of long-loop negative feedback after stopping exogenous testosterone supplementation?

Accepted Answer

Weak negative feedback

Question 14

Which stage of the HPA axis involves the release of LH into the blood?

Accepted Answer

Stage 2

Question 15

If a patient has low testosterone and high LH, what is the most likely site of dysfunction?

Accepted Answer

Testes (primary dysfunction)

Question 16

Which of the following best describes the feedback mechanism when testosterone levels are low?

Accepted Answer

Long-loop negative feedback is weak, increasing GnRH and LH

Question 17

Which hormone is measured to determine primary vs. secondary dysfunction in the HPA axis?

Accepted Answer

LH

Question 18

What is the normal adult male range for blood testosterone levels?

Accepted Answer

10-35 nmol/L

Question 19

Which of the following is a real-world consequence of long-term exogenous testosterone use?

Accepted Answer

Suppressed endogenous testosterone production

Question 20

Which hormone is released into the portal blood from the hypothalamus in the HPA axis?

Accepted Answer

GnRH

Endocrine Physiology: Regulation of Testosterone and Clinical Case Study

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