Elsevier

Journal of Clinical Densitometry

Volume 22, Issue 4, October–December 2019, Pages 544-553
Journal of Clinical Densitometry

2019 ISCD Official Position
Bone Densitometry in Transgender and Gender Non-Conforming (TGNC) Individuals: 2019 ISCD Official Position

https://doi.org/10.1016/j.jocd.2019.07.004Get rights and content

Abstract

The indications for initial and follow-up bone mineral density (BMD) in transgender and gender nonconforming (TGNC) individuals are poorly defined, and the choice of which gender database to use to calculate Z-scores is unclear. Herein, the findings of the Task Force are presented after a detailed review of the literature. As long as a TGNC individual is on standard gender-affirming hormone treatment, BMD should remain stable to increasing, so there is no indication to monitor for bone loss or osteoporosis strictly on the basis of TGNC status. TGNC individuals who experience substantial periods of hypogonadism (>1 yr) might experience bone loss or failure of bone accrual during that time, and should be considered for baseline measurement of BMD. To the extent that this hypogonadism continues over time, follow-up measurements can be appropriate. TGNC individuals who have adequate levels of endogenous or exogenous sex steroids can, of course, suffer from other illnesses that can cause osteoporosis and bone loss, such as hyperparathyroidism and steroid use; they should have measurement of BMD as would be done in the cisgender population. There are no data that TGNC individuals have a fracture risk different from that of cisgender individuals, nor any data to suggest that BMD predicts their fracture risk less well than in the cisgender population. The Z-score in transgender individuals should be calculated using the reference data (mean and standard deviation) of the gender conforming with the individual's gender identity. In gender nonconforming individuals, the reference data for the sex recorded at birth should be used. If the referring provider or the individual requests, a set of “male” and “female” Z-scores can be provided, calculating the Z-score against male and female reference data, respectively.

Introduction

Transgender/gender nonconforming (TGNC) individuals experience many changes that have the potential to affect their bone mineral density (BMD). This fact raises the question of whether TGNC individuals should have routine densitometry at a younger age than cisgender patients, and whether a transgender woman or man should have the Z-score calculated according to a male or female reference database. The ISCD charged this Task Force with addressing the following questions regarding bone densitometry in the TGNC population:

  • 1.

    What are the indications for performing a baseline dual-energy X-ray absorptiometry (DXA) in TGNC individuals?

  • 2.

    In which TGNC individuals should DXA measurements be repeated, and at what interval?

  • 3.

    Which databases can be used for diagnosis?

  • 4.

    What parameters need to be included in the DXA report for TGNC individuals?

Before these questions are addressed in turn, some comments about terminology relevant to TGNC individuals are in order. An attempt was made to use terms surrounding the management of TGNC individuals that are clear, consistent with current scientific usage, and acceptable to TGNC individuals (1). This manuscript was vetted with experts in the management of TGNC individuals and with representatives of the TGNC community. Please understand that no agenda motivated the members of the Task Force other than to support the most compassionate and scientifically valid care for TGNC individuals.

The following is a brief glossary of the terms used in this manuscript:

  • 1.

    TGNC: this refers to individuals whose gender identity does not correspond to the recorded sex at birth. The gender identity may fall within the typical gender binary of male or female, or may not conform to the gender binary.

  • 2.

    Transgender man: an individual who was recorded female at birth, who has a masculine gender identity.

  • 3.

    Transgender woman: an individual who was recorded male at birth, who has a feminine gender identity.

  • 4.

    Cisgender: a patient whose gender identity conforms with the sex recorded at birth.

  • 5.

    Gender-affirming hormone treatment: for transgender women, this includes GnRH analogs or androgen blockers, and estrogen. For transgender men, this includes testosterone.

  • 6.

    Gender nonbinary individuals: individuals who do not experience gender identity in a binary fashion, as a man or a woman. This term encompasses a concept similar to “gender non-conforming.”

  • 7.

    Male Z-score: a Z-score that is calculated by comparing the BMD of the individual to the mean of age- and ethnicity-matched men.

  • 8.

    Female Z-score: a Z-score that is calculated by comparing the BMD of the individual to the mean of age- and ethnicity-matched women.

Section snippets

Methodology and Data Sources

To determine whether TGNC individuals have a BMD different from that of cisgender individuals, and to determine the effect of gender-affirming hormonal treatment on bone metabolism and bone density status in TGNC individuals, a search of the literature using Medline, Pubmed, and Google Scholar was done in November 2018. The search terms that were used were “transgender” and “bone,” “transsexual” and “bone,” and “gender dysphoria” and “bone.” The reference lists of these articles were also

Position 1

Baseline BMD testing is indicated for TGNC individuals if they have any of the following conditions:

  • a.

    History of gonadectomy or therapy that lowers endogenous gonadal steroid levels prior to initiation of hormone therapy.

  • b.

    Hypogonadism with no plan to take gender-affirming hormone therapy.

  • c.

    Existing ISCD indications for BMD testing, such as glucocorticoid use and hyperparathyroidism, apply.

Grade for transgender men and women: Good, A, W.

Grade for gender nonconforming individuals: Poor, C, W.

Discussion/Summary

TGNC individuals experience profound changes that can affect many aspects of their health. Because BMD is dependent on hormones and other factors, it is widely thought that TGNC individuals start off with BMD typical for the sex recorded at birth and that the BMD gradually becomes more similar to that of the gender corresponding with gender identity with gender-affirming hormone treatment. The literature supports the opposite view; there are abundant data to suggest that transgender women start

Acknowledgments

We thank William Leslie and Tom Kelly for the data showing the difference in Z-score when calculated according to male vs female reference data for GE-Lunar and Hologic, respectively. We thank Amy Sholiton for assistance with editing.

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