Prolactin levels during short- and long-term cross-sex hormone treatment: an observational study in transgender persons

N. M. Nota, M. J.H.J. Dekker, M. Klaver, C. M. Wiepjes, M. A. van Trotsenburg, A. C. Heijboer, M. den Heijer

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The cause of prolactin alterations in transgender persons is often assigned to oestrogens, but the precise cause and time course during different phases of cross-sex hormone treatment (CHT) remain unclear. In this study, we prospectively examined prolactin levels in 55 female-to-males (FtMs) and 61 male-to-females (MtFs) during the first year of CHT. Because long-term prolactin data were not available in this population, we studied these levels in a retrospective population of 25 FtMs and 38 MtFs who underwent gonadectomy. FtMs were treated with testosterone and MtFs with estradiol, with or without the anti-androgen cyproterone acetate (CPA) (after gonadectomy CPA is cessated). During the first year of CHT, prolactin decreased with 25% (95CI: −33%, −12%) in FtMs and increased with 193% (95CI: 156%, 219%) in MtFs. Eighteen MtFs developed hyperprolactinemia (≥0.6 IU L−1). In the retrospective population, post-gonadectomy levels in FtMs were lower than baseline levels (−39%; 95CI: −51%, −20%) while in MtFs post-gonadectomy levels and baseline levels were comparable (−6%; 95CI: −24%, 15%). No hyperprolactinemia was found after gonadectomy. In conclusion, in FtMs, prolactin decreased consistently during CHT and in MtFs, prolactin increased during pre-surgical CHT but normalised after gonadectomy. It is likely that CPA induces increasing prolactin levels in MtFs.

Original languageEnglish
Article numbere12666
Pages (from-to)e12666
Issue number6
Early online date2017
Publication statusPublished - 1 Aug 2017


  • cyproterone acetate
  • gender dysphoria
  • oestrogens
  • prolactin

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