TU is an effective option for androgen replacement in FtM subjects, but long-term physiological effects and the significance of T and its metabolites dihydrotestosterone (DHT) and estradiol (E) on physiological functions are unclear. The aim of our study was to investigate the effects of long-term TU treatment on bone metabolism, body composition and lipid profile in FtM subjects and to evaluate the relationship between the observed effects and circulating levels of T, E and DHT. This was a 1-year, randomised treatment, open label, uncontrolled safety study. Ovariectomized FtM were randomly assigned to receive 1000 mg TU injection at week 0, 6, 18, 30, 42 and 54 alone (TU-alone, n=5) or in combination with letrozole 2.5 mg, orally (TU+L, n=5) or dutasteride 5 mg, orally (TU+D, n=5). The Ethics Committee of the S Orsola Hospital approved the study. Outcome parameters included measurement of reproductive hormones, bone metabolism, body composition and lipid profile. Hormones at baseline and at week 54, in group TU-alone, TU+D and TU+L respectively were:
Total T (nmol/l) 7.9+6.0 and 13.6+2.6; 7.1+6.3 and 18.4+4.6§; 4.8+4.8 and 18.2+4.2§; E (pmol/l) 64.4+43.4 and 89.6+36.3; 41.4+19.4 and 76.0+47.4; 37.8+23.1 and 18.0+0.0*; DHT (nmol/l) 1.3+1.2 and 2.2+0.9; 1.0+0.7 and 0.4+0.1*; 0.9+0.7 and 2.7+1.3; *=P<0.05% change versus TU-alone; §=P<0.05 versus baseline. TU-alone and TU +D treatments were successful in terms of hormone adjustment, did not result in any adverse effects and were well tolerated. BMD decreased by an average of 0.9 g/cm in the TU +L group and the addition of dutasteride resulted in a failure to gain lean mass.
Conclusions: This study confirms that TU is a successful and safe treatment for FtM subjects. Results indicate that E has an important role in bone metabolism and that DHT might play a role in muscle development.
03 - 07 May 2008
European Society of Endocrinology