59. Tamoxifen for Puberty Induction and Bone Mineral Density Protection in a Gender Non Binary Patient With 46, XY Complete Gonadal Dysgenesis: A Case Report

Abstract

<h3>Background</h3> 46XY complete gonadal dysgenesis patients present with primary amenorrhea and delayed puberty. There is an increased risk of gonadoblastoma and often undergo surgical resection. Following diagnosis, sex hormone replacement therapy is started for puberty induction. Tamoxifen prevents loss of bone mineral density in postmenopausal women and has been used to treat gynecomastia in prepubertal males. We present a case of a nonbinary patient with 46XY complete gonadal dysgenesis where typical sex hormone replacement therapy would be incongruent with the patient's gender identity and instead, tamoxifen was used for puberty induction and bone health protection. <h3>Case</h3> A 15 year old patient with autism and ADHD presented with primary amenorrhea. Breast development occurred 1.5 years prior without development of pubic or axillary hair. They had previously identified as gender neutral. They had an elevated FSH (51mIU/mL), elevated LH (16mIU/mL), low estradiol (<2.5pg/mL), low testosterone (10ng/dL), and karyotype 46XY SRY+ of unknown molecular etiology. Sonography showed a prepubertal uterus (4.5 × 0.5 × 2.5cm) and intraabdominal gonads. The workup was suggestive of 46XY complete gonadal dysgenesis. DEXA scan showed decreased bone mineral density for chronologic age (Z score -2.3, whole body BMD:0.71 g/cm2). They were counseled regarding the risk of gonadoblastoma in intraabdominal gonads and elected to undergo a laparoscopic gonadectomy. They expressed concerns about sex hormone replacement and did not wish to develop secondary sex characteristics that would be incongruent with their nonbinary identity. A selective estrogen receptor modulator (tamoxifen) was started for bone health protection without the development of secondary sex characteristics. At 4 months, their height had increased 2cm and had a reduction in breast tissue. At 1 year, their height had increased 5cm and the increase in growth velocity showed pubertal induction. Repeat ultrasound demonstrated a uterus size of 6 × 1.3 × 2.2 cm and a non-visualized endometrial stripe. DEXA showed improvement (Z score -2.2, whole body BMD:0.81 g/cm2). Tamoxifen was titrated up to a goal dose of 15-20mg daily. Mental health and psychosocial adaptation was regularly screened following the DSD-TRN protocol. The patient has not had any menstrual bleeding, continues on the tamoxifen, and plans to undergo a hysterectomy at the age of 18. <h3>Comments</h3> Following gonadectomy in patients with 46XY complete gonadal dysgenesis, hormone replacement therapy is imperative for overall heath, puberty induction, and bone health. In patients who require sex hormone replacement but whose gender is not consistent with a male or female gender identity, a selective estrogen receptor modulator can be used.