After 3 months on leuprolide for metastatic prostate cancer, how have serum LH and testosterone concentrations changed?

Leuprolide is a gonadotropin-releasing hormone (GnRH) analog that works by initially stimulating and then downregulating the pituitary gland's production of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In the initial phase of administration, leuprolide causes a surge in LH and FSH, which consequently leads to an increase in testosterone levels due to stimulation of the testes. However, with continued use, leuprolide suppresses pituitary function, leading to decreased secretion of LH and FSH. This results in lower testosterone production by the testes.

After three months of consistent administration, the feedback mechanism leads to decreased levels of both LH and testosterone in the serum. This is due to the downregulation of the body's own hormonal response as a result of prolonged exposure to the GnRH analog. Therefore, at this stage of treatment, both LH and testosterone concentrations in the serum are decreased.

This therapeutic approach is primarily used in managing conditions such as metastatic prostate cancer, where reducing testosterone levels is beneficial for slowing the progression of the disease.