Failure to achieve castrate levels of testosterone during luteinizing hormone releasing hormone agonist therapy: the case for monitoring serum testosterone and a treatment decision algorithm.

PURPOSE: We report the failure to achieve a castrate level of testosterone associated with 3-month depot luteinizing hormone releasing hormone (LH-RH) agonist therapy, which to our knowledge is a previously unrecognized outcome.
MATERIALS AND METHODS: We prospectively enrolled in our study 38 men with prostate cancer on 3-month depot LH-RH agonist therapy. We monitored total serum testosterone and prostate specific antigen every 28 days beginning 90 days after the last depot LH-RH agonist injection. Data were analyzed with castrate testosterone defined as less than 50 and 20 ng./dl. or less.
RESULTS: Using the 50 and 20 ng./dl. definitions of castrate testosterone 2 (5%) and 5 (13%) of the 38 men, respectively, failed to achieve castrate testosterone. A patient with a nadir testosterone of 70 ng./dl. subsequently underwent orchiectomy and testosterone decreased to 10 ng./dl. thereafter.
CONCLUSIONS: A small but potentially important subgroup of men on depot LH-RH agonist therapy fail to achieve a castrate level of testosterone. Our findings support monitoring testicular response when LH-RH agonist therapy is initiated.