Clinically Relevant Laboratory Monitoring of Gender-Affirming Hormone Therapy in Transgender People-Experiences from a Teaching Hospital in the Netherlands.

Most used clinical practice guidelines for GAHT provide hormonal target values without recommending a preferred assay method.

• Clinical practice guidelines on GAHT were screened and summarized as part of the study methodology.
• No guideline specified whether immunoassay or mass spectrometry should be used for hormone monitoring.
• This represents an evidence gap in recommendations regarding the assay needed to monitor GAHT.

A comprehensive literature search on agreement between immunoassay and mass spectrometry showed substantial heterogeneity in results.

• Scientific literature on assay methodologies was screened and summarized.
• The heterogeneity in agreement between immunoassay and mass spectrometry results was described as 'substantial.'
• This heterogeneity has significant implications for clinical decision making in GAHT monitoring.

Retrospective analysis of immunoassay data in transgender patients showed hormonal changes during GAHT consistent with expectations from the medication used.

• Laboratory and medical data from 252 patients were retrospectively analyzed.
• Patients visited the transgender outpatient clinic of the Maasstad Hospital between 2020 and 2022.
• The Maasstad Hospital is a nonacademic (teaching) hospital in the Netherlands.
• Hormonal changes observed were described as 'to be expected from the medication used.'

Immunoassay can be used safely for laboratory monitoring of GAHT in a nonacademic hospital in most cases.

• The study evaluated immunoassay estradiol and testosterone concentrations in transgender people.
• More sophisticated methods (mass spectrometry) were deemed necessary only when clinical observation is discordant with hormonal results.
• Transgender care is shifting from academic to nonacademic settings, increasing the use of common immunoassay methods compared to mass spectrometry.
• A best practice model was proposed for transgender care in nonacademic hospitals based on these findings.

A best practice model was proposed for monitoring GAHT in nonacademic hospital settings.

• The model recommends immunoassay as the primary monitoring method for GAHT.
• Mass spectrometry is recommended as a secondary method when clinical observations are discordant with immunoassay hormonal results.
• The model is intended to address the shift of transgender care from academic to nonacademic settings.