LABORATORY MONITORING OF ANDROGENIC ACTIVITY IN BENIGN PROSTATE HYPERTROPHY TREATED WITH A 5-ALPHA-REDUCTASE INHIBITOR

Testosterone and androstenedione are metabolized by 5-alpha- and 5-beta-reductases to androsterone (A) and etiocholanolone (E), respectively. These are excreted in the urine as conjugates, and the A/E ratio in normal men is usually greater-than-or-equal-to 1.5 (as opposed to 1 in women) because of the high 5-alpha-reductase activity in the prostate. The A/E ratio can be determined simply by gas chromatography after acid hydrolysis of a urine sample, extraction of steroids, and formation of trimethylsilyl derivatives. A timed collection of urine is unnecessary because the ratio of A/E is used rather than absolute values. In men suffering from benign prostate hypertrophy who are treated with Finasteride (a 5-alpha-reductase inhibitor), the A/E ratio decreases to <0.5. The A/E ratio decrease can be detected long before there is clinical improvement.