Pubertal suppression with gonadotropin-releasing hormone (GnRH) agonists in transgender and gender non-conforming (TGNC) youth may affect acquisition of peak bone mass. Bone marrow adipose tissue (BMAT) has an inverse relationship with bone mineral density (BMD). To evaluate the effect of pubertal suppression on BMAT, in this pilot study we prospectively studied TGNC youth undergoing pubertal suppression and cisgender control participants with similar pubertal status over a 12-month period. BMD was measured by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography. Magnetic Resonance T1 relaxometry (T1-R) and spectroscopy (MRS) were performed to quantify BMAT at the distal femur. We compared the change in BMD, T1-R values, and MRS lipid indices between the two groups. Six TGNC (two assigned female and four assigned male at birth) and three female control participants (mean age 10.9 and 11.7 years, respectively) were enrolled. The mean lumbar spine BMD Z-score declined by 0.29 in the TGNC group, but increased by 0.48 in controls (between-group difference 0.77, 95% CI: 0.05, 1.45). Similar findings were observed with the change in trabecular volumetric BMD at the 3% tibia site (-4.1% in TGNC, +3.2% in controls, between-group difference 7.3%, 95% CI: 0.5%-14%). Distal femur T1 values declined (indicative of increased BMAT) by 7.9% in the TGNC group, but increased by 2.1% in controls (between-group difference 10%, 95% CI: -12.7%, 32.6%). Marrow lipid fraction by MRS increased by 8.4% in the TGNC group, but declined by 0.1% in controls (between-group difference 8.5%, 95% CI: -50.2%, 33.0%). In conclusion, we observed lower bone mass acquisition and greater increases in BMAT indices by MRI and MRS in TGNC youth after 12 months of GnRH agonists compared with control participants. Early changes in BMAT may underlie an alteration in bone mass acquisition with pubertal suppression, including alterations in mesenchymal stem cells within marrow.

使用促性腺激素释放激素 (GnRH) 激动剂抑制跨性别和性别不合格 (TGNC) 青少年的青春期可能会影响峰值骨量的获得。骨髓脂肪组织（BMAT）与骨矿物质密度（BMD）呈反比关系。为了评估青春期抑制对 BMAT 的影响，在这项试点研究中，我们前瞻性研究了 12 个月内接受青春期抑制的 TGNC 青少年和具有相似青春期状态的顺性别对照参与者。通过双能X射线吸收法和外周定量计算机断层扫描测量BMD 。进行磁共振 T1 松弛测量(T1-R) 和光谱 (MRS) 来量化股骨远端的 BMAT 。我们比较了两组之间的 BMD、T1-R 值和 MRS 血脂指数的变化。纳入了 6 名 TGNC（出生时指定的两名女性和四名男性）和三名女性对照参与者（平均年龄分别为 10.9 岁和 11.7 岁）。TGNC 组的平均腰椎 BMD Z 值下降了 0.29，但对照组增加了 0.48（组间差异 0.77，95% CI：0.05，1.45）。3% 胫骨部位的小梁体积 BMD 变化也观察到类似的结果（TGNC 为-4.1%，对照组为+3.2%，组间差异为 7.3%，95% CI：0.5%-14%）。TGNC 组股骨远端 T1 值下降（表明 BMAT 增加）7.9%，但对照组增加 2.1%（组间差异 10%，95% CI：-12.7%、32.6%）。TGNC 组的 MRS 骨髓脂质分数增加了 8.4%，但对照组下降了 0.1%（组间差异 8.5%，95% CI：-50.2%，33.0%）。总之，与对照参与者相比，在使用 GnRH 激动剂 12 个月后，TGNC 青年的 MRI 和 MRS 观察到骨量获得较低，BMAT 指数增加较多。BMAT 的早期变化可能是青春期抑制引起的骨量获取变化的基础，包括骨髓内间充质干细胞的变化。