Endocrine Abstracts

Objectives

The European Network for Investigation of Gender Incongruence (ENIGI) is a multicenter prospective cohort study. All participants receive a standardized gender affirming treatment (GAHT) protocol including regular follow-up. The current study compared changes in androgens upon starting GAHT and during follow-up in transgender women (TW) with or without gonadectomy by investigating serum total testosterone (TT), calculated free testosterone (cFT), DHEA, DHEAS, androstenedione and SHBG.

Methods

This research was part of the ENIGI study. Sex steroids were assessed at baseline and 12 and 24 months of follow-up using immuno-assay (SHBG, DHEAS) and LC-MS/MS (TT, DHEA, androstenedione). FT was calculated. GAHT was initiated at baseline: estrogens (oral or transdermal) and anti-androgens (cyproterone acetate 25–50 mg/day). After orchiectomy the anti-androgen therapy was stopped and the estrogens were continued unchanged. Data from 113 TW with ≥2 years of follow-up at Ghent, Belgium were analyzed prospectively. Subgroup analyses were performed in TW who underwent orchiectomy (group A, n = 59) vs TW who did not (group B, n = 54), at baseline, pre-operatively vs at month 12, and post-operatively vs at month 24.

Results

In group A, serum TT levels decreased from 572.69 ± 11.76 ng/dl to 18.71 ± 11.91 ng/dl (baseline vs pre-gonadectomy, P < 0.001) and cFT decreased from 11.34 ± 0.35 ng/dl to 0.26 ± 0.35 ng/dl (baseline vs pre-gonadectomy, P < 0.001). No further effect of gonadectomy on serum TT and cFT levels was assessed, although a trend towards decrease was observed. SHBG increased post-gonadectomy (P < 0.001). Androstenedione, DHEA, DHEAS decreased from baseline to pre-gonadectomy (P < 0, 001), but remained stable afterwards. Similarly in group B, serum TT, cFT, androstenedione, DHEA and DHEAS decreased between baseline vs 12 months (P < 0.001), while SHBG increased (P < 0.001); all variables remained stable afterwards. Comparing groups after 24 months, no differences in serum TT levels were found. However, SHBG was higher in group A vs group B (73.2 ± 39.6 nmol/l vs 57.2 ± 37.2 nmol/l respectively, P = 0.004), whereas cFT (0, 18 ± 0.12 ng/dl vs 0, 26 ± 0.26 ng/dl, P = 0, 016), androstenedione (71.0 ± 32.4 ng/dl vs 85.3 ± 37.2 ng/dl, P = 0.042) and DHEA (4.99 ± 3.61 µg/l vs 7.34 ± 4.62 µg/l, P = 0.002) were lower.

Conclusion

Serum TT and cFT levels remained unchanged post-orchiectomy compared to before, if low TT was confirmed when on GAHT (including anti-androgens) reflecting patient compliance. At 24 months, TW who underwent orchiectomy had lower cFT, androstenedione and DHEA and higher SHBG, compared to those with a continued stable dose of anti-androgens.