Subdermal levonorgestrel implants: serum androgens.

Serum levels of androstenedione, dihydrotestosterone, and testosterone were determined by radioimmunoassay procedures in 25 female volunteers using subdermal levonorgestrel implants as a contraceptive. Mean serum androstenedione levels were increased after 1 and 6 months in comparison with preimplantation levels, the increase being significant only after 1 month. This could be attributed to increased production from the adrenal or ovaries and/or changes in clearance rate. Testosterone levels showed approximately 24% increase above basal values after 6 months' use of levonorgestrel implants, which was attributed to concomitant increases in androstenedione levels. The implication of these results is discussed.