7019 Persistently Elevated Estradiol Levels in a Transgender Male; An Unexpected Pregnancy

Abstract Disclosure: M. Kanin: None. S. Grock: None. N. Agrawal: None. Background: Testosterone is the backbone of gender-affirming hormone therapy (GAHT) for transmasculine and non-binary individuals assigned female at birth (AFAB). While testosterone can affect fertility, it should not be used as contraception and is contraindicated in pregnancy. It is important to counsel patients on fertility preservation, pregnancy, and contraceptive options prior to testosterone initiation. However, the Endocrine Society Guidelines and World Professional Association for Transgender Health Standards of Care provide minimal guidance on reproductive health and contraceptive options. Case Description: An 18-year-old individual AFAB on GAHT with testosterone was referred to endocrinology for elevated estradiol levels. On presentation, the patient denied vaginal bleeding or breast tenderness. The date of last menstrual period was reported as two years prior. There was no significant past medical or surgical history. Medications included subcutaneous testosterone cypionate 20 mg weekly. Physical exam was notable for elevated BMI 42.6kg/m², mild facial hair and central adiposity. Hormone analysis revealed testosterone of 172 ng/dL (adult male: 200-1000) and estradiol 27,322 pg/mL (mid-cycle Female: 80-400). Estradiol by mass spectrometry obtained due to concern for immunoassay interference resulted at > 10,000 pg/mL. FSH <0.1 mIU/mL, LH<0.1 mIU/mL, DHEA-S 2,460 ng/mL (adult female: 400-3600), androstenedione 1.85 ng/mL (0.260 - 2.140), prolactin 328 ng/mL (3 -23.1). CT abdomen and pelvis and pituitary MRI were ordered to assess for ovarian, adrenal and/or pituitary tumor. Later that day additional laboratory tests revealed alpha fetoprotein 126 ng/mL (0 -6.7), progesterone 100.2 ng/mL (luteal phase: 3.0-25.0), beta-hCG 32,571 mIU/ml, inhibin B<10, inhibin A 500.1pg/ml (luteal phase: 40-80) and CA-125 19 U/mL (0 - 35). Given the elevated beta-hcg the patient was asked if they were having sex in a way that could result in pregnancy to which they answered affirmatively. CT and MRI were cancelled, and abdominal ultrasound was obtained which revealed a single living intrauterine pregnancy with estimated gestational age 35 weeks 2 days. Testosterone was stopped and they subsequently delivered a healthy baby girl. Conclusion: Gender diverse patients on testosterone can experience unplanned pregnancy. As testosterone is contraindicated in pregnancy, counseling on reproductive health and contraception is needed. A pregnancy test should be considered prior to initiating hormones for appropriate individuals. It is important to be aware that Individuals AFAB may not desire estrogen containing birth control and placement of intrauterine devices can be dysphoric. Further investigation into how contraceptive options may affect outcomes for individuals on GAHT is needed to minimize barriers to care and to enable patients to make well informed decisions. Presentation: 6/2/2024