Received on January 17, 2006
Accepted on May 31, 2006

Endocrinology and Metabolism

Effect of Testosterone Administration on Serum and Urine Kallikrein Concentrations in Female-to-Male Transsexuals

¹ Department of Endocrinology, VU University Medical Centre, Amsterdam, The Netherlands
² Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Athens, Athens, Greece
³ Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada
⁴ GGZ Delfland, Institute of Mental Health, Delft, The Netherlands
⁵ Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada, and Department of Laboratory Medicine and Pathobiology, University of Toronto, ON, Canada

^* To whom correspondence should be addressed. E-mail: ediamandis{at}mtsinai.on.ca.

Background: Concentrations of human tissue kallikreins (hKs), a group of 15 secreted serine proteases found in many tissues, are modulated by steroid hormones in cancer cell lines. To gain insight into in vivo kallikrein regulation we measured kallikrein concentrations in serum and urinary tissue in female-to-male transsexuals before and after testosterone administration.

Methods: We collected blood and urine samples before treatment and after 4 and 12 months from 28 female-to-male transsexuals who received 250 mg of testosterone esters intramuscularly every 2 weeks. We used ELISA assays to measure multiple kallikreins in serum and urine.

Results: After testosterone administration, serum testosterone concentrations increased by 15-fold. Serum kallikrein concentrations increased dramatically for hK3 (prostate-specific antigen) and increased moderately for hK2, hK5, hK6, hK7, hK8, hK10, and hK11. In urine, we noted major increases for hK3 and hK2 only. For all other kallikrein concentrations, we observed no considerable changes.

Conclusions: We conclude that, in serum and urine of female-to-male transsexuals after testosterone administration, hK3 (prostate-specific antigen) and to a lesser extent hK2 concentrations increase dramatically, but concentration of other kallikreins increase either moderately in serum (hK5, hK6, hK7, hK8, hK10, and hK11) or not at all in either serum (hK4, hK13, hK14) or urine (hK4, hK5, hK6, hK7, hK8, hK10, hK11, hK13, hK14).