Send to

Choose Destination
J Clin Endocrinol Metab. 2013 Mar;98(3):1198-206. doi: 10.1210/jc.2012-3527. Epub 2013 Jan 24.

Androgen synthesis in the gonadotropin-suppressed human testes can be markedly suppressed by ketoconazole.

Author information

Departments of Internal Medicine, University of Washington, 1959 NE Pacific Street, Box 357138, Seattle, Washington 98195, USA.



The concentration of intratesticular testosterone (IT-T) required for human spermatogenesis is unknown because spermatogenesis can persist despite the markedly reduced IT-T concentrations observed with LH suppression. Methods to lower IT-T further are needed to determine the relationship between IT-T and spermatogenesis.


The objective of the study was to determine the effect of inhibiting the synthesis and metabolism of testosterone (T) on IT-T in gonadotropin-suppressed human testes.


Forty normal men participated in a blinded, placebo-controlled, randomized trial at an academic center. INTERVENTION/OUTCOME MEASURES: All men were first administered the GnRH antagonist acyline to suppress LH. Forty-eight hours after acyline administration, subjects were randomly assigned to placebo, ketoconazole (to inhibit T synthesis) at 400 or 800 mg, dutasteride (to inhibit T metabolism) 2.5 mg, or anastrazole (to inhibit T metabolism) 1 mg, daily for 7 days (n = 8/group). Intratesticular steroid concentrations were measured 48 hours after acyline administration alone and again after 7 days of combination treatment.


After 7 days of combination treatment, the median IT-T (25th, 75th percentile) in the placebo group was 14 (8.0, 21.2) ng/mL. IT-T was reduced to 3.7 (2.5, 7.1) ng/mL in the ketoconazole 400 mg group and 1.7 (0.8, 4.0) ng/mL in the ketoconazole 800 mg group (P < .001 vs placebo for both comparisons). IT-T concentrations in the dutasteride and anastrazole groups were similar to placebo.


Combining inhibition of steroidogenesis with gonadotropin suppression lowers IT-T more than gonadotropin suppression alone. This combination might be useful to determine the minimum IT-T concentration necessary for human spermatogenesis, information essential for developing male hormonal contraceptives.

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for PubMed Central
Loading ...
Support Center