An 18-year-old male complains about continuous growth, lack of facial hair, small genitalia and lack of muscle development. Laboratory values include total testosterone 125 ng/dL (normal 300-1100 ng/dL) and luteinizing hormone (LH)

Question

An 18-year-old male complains about continuous growth, lack of facial hair, small genitalia and lack of muscle development. Laboratory values include total testosterone 125 ng/dL (normal 300-1100 ng/dL) and luteinizing hormone (LH) < 2 mIU/mL (normal 6-23 mIU/mL). A major causal factor in some cases of hypogonadism is:
A) Increased number of follicle stimulating hormone (FSH) receptors in the testis
B) Hypersecretion of pituitary LH and FSH as the result of increased gonadotropin-releasing hormone (GnRH)
C) Excess secretion of testicular activin by Sertoli cells
D) Failure of the hypothalamus to respond to testosterone
E) Reduced secretion of GnRH

Quizplus · Accepted Answer

The patient's symptoms and lab values indicate hypogonadism with low testosterone and low LH levels, suggesting a central (secondary) cause. Reduced secretion of GnRH by the hypothalamus would lead to decreased stimulation of the pituitary gland, resulting in low levels of LH and subsequently low testosterone production, aligning with the patient's condition.

An 18-Year-Old Male Complains About Continuous Growth, Lack of Facial