LAUSR

Luteinizing hormone–releasing hormone (LH-RH) agonists are the standard for androgen deprivation therapy (ADT) in patients with prostate cancer (PCa). The European Urology Association guideline on PCa [1] recommends serum testosterone measurement during ADT to assess its efficacy and diagnose castration resistance. The castrate level of serum testosterone remains at 50 ng/dl, although recent studies have suggested better outcomes for patients who reach lower levels. We would like to point out that the castrate level of serum testosterone was established during the early 1980s using patients who had undergone surgical castration and the lowest sensitivity limit of the radioimmunoassays used so far. We also would like to highlight that all the recent studies seeking to identify the optimal level of serum testosterone during medical castration have been carried out using chemiluminescent assays (CLIAs) [2]. CLIAs have been used in clinical laboratories worldwide since the late 1990s given that they are very sensitive, fast, and inexpensive and can be automated, despite a disturbing lack of accuracy and reproducibility especially, when low levels of testosterone are measured. This was the reason why in 2007 the American Endocrine Society and the Centre for Disease Control and Diagnosis recommended only methods using chromatography and mass spectrometry to measure testosterone, especially in children and women [3]. We are therefore facing a PCa guideline recommendation to measure serum testosterone during ADT, but without any specification regarding the appropriate method that should be used. We recently confirmed the lack of accuracy of CLIAs compared to liquid chromatography and tandem mass spectrometry (LC-MSMS) in measuring serum testosterone levels in PCa patients undergoing LH-RH agonist therapy. We found that the proportion of patients with serum testosterone >50 ng/dl was up to 16% when a widely