Reassessment of the definition of castrate levels of testosterone: Implications for clinical decision making

Objectives. Based on methods introduced in the late 1960s and no longer use d, serum testosterone level in men after surgical castration was reported t o be 50 ng/dL or less. Radioimmunoassay and, subsequently, chemiluminescent methods have supplanted the early analytic methods because of their improv ed accuracy and ease of testing. The purpose of this study was to define th e castrate testosterone level in the era of chemiluminescent testing. Methods. After bilateral orchiectomy, serum testosterone (total) levels wer e measured prospectively in 35 prostate cancer patients. Results. The median testosterone value in this patient cohort was 15 ng/dL (0.5 nmol/L; 95% confidence interval 12 to 17 ng/dL). Conclusions. In a contemporary series, castrate testosterone should be defi ned as less than 20 ng/dL (0.7 nmol/L). The important biologic and economic implications are discussed. UROLOGY 56: 1021-1024, 2000. (C) 2000, Elsevie r Science Inc.