Sex differences in the metabolic syndrome and the associated cardiovascular risk profile are attributed to sex-specific sex steroid profiles, but the effects of sex steroid treatment remain incompletely understood.
We evaluated the impact of low doses of sex-steroids on cardiovascular risk parameters in 41 young (age range 1946 years), healthy, nonobese (BMI <29), transsexual subjects. 30 male-to-female (MF) transsexuals received transdermal 17Betaestradiol (50 ug/day) + cyproterone acetate (up to 50 mg/day) and 11 female-to-male (FM) transsexuals received testosterone-undecanoate (1000 mg i.m./12 weeks). We analized waist circumference, BMI, serum LH, FSH, testosterone, oestradiol, SHBG, lipid spectrum, glucose, insulin and HOMA index at baseline and after 1-year cross-sex hormone administration. The protocol was approved by the local Ethical Committee.
No changes in the anthropometric variables were detected in both groups. In MF transsexuals, oestrogens+antiandrogens increased serum HDL-Cholesterol (P<0.02) without changes in LDL-Cholesterol or triglycerides but the ratio Chol/HDL-Chol and the HOMA index decreased significantly (P<0.02 and P<0.03, respectively). By contrast, testosterone in MF transsexuals, reduced serum HDL-Cholesterol (P<0.03) and increased the Chol/HDL-Chol ratio, insuline and HOMA index (P<0.02, P<0.04 and P<0.05, respectively). No major adverse effects were detected.
The cross-sex hormone treatment -with the low-doses regimen used here showed that oestrogens in genetically men induced beneficial effects on cardiovascular parameters. On the other hand, epidemiological studies indicate an association between male hypogonadism and metabolic syndrome, while the androgen replacement reverse that profile. However, in our study, testosterone was detrimental on cardiovascular risk in genetically women.
These results seems to support the hypothesis that oestrogens have beneficial effects in men and women but the dual action of testosterone (in genetically men and women) seems to be associated to a gender-specific effect.
Nevertheless, studies of long-term follow-up are needed to establish the real prevalence of morbi-mortalitity with these treatments.
Prague, Czech Republic
24 - 28 Apr 2010
European Society of Endocrinology