Intratesticular testosterone concentrations comparable with serum levels are not sufficient to maintain normal sperm production in men receiving a hormonal contraceptive regimen

Abstract

Intratesticular testosterone (ITT) is thought to play a key role in the control of spermatogenesis in man but is rarely measured. The purposes of this study were 1) to examine the relationship between intratesticular fluid and serum testosterone (T) at baseline and during treatment with a contraceptive regimen known to suppress spermatogenesis and 2) to measure intratesticular fluid androgenic bioactivity. Seven men received 6 months of T enanthate (TE) 100 mg weekly intramuscularly plus levonorgestrel (LNG) 62.5 or 31.25 μg orally daily. Testicular fluid was obtained by percutaneous aspiration at baseline and during month 6. Mean luteinizing hormone (LH) was suppressed 98% from 3.79 ± 0.80 IU/L at baseline to 0.08 ± 0.03 IU/L. Mean follicle stimulating hormone (FSH) was suppressed 97%, from 3.29 ± 0.67 IU/ L to 0.10 ± 0.03 IU/L. Mean serum T levels were similar before (22.8 ± 1.9 nmol/L) and during treatment (28.7 ± 2.0 nmol/L) (P = .12). ITT (822 ± 136 nmol/L) was ∼40x higher than serum T (P