MON-048 Proactive on Prolactin: Hyperprolactinemia Management in Transgender Patients

Abstract Disclosure: B. Chow: None. A. Rajpal: None. Introduction: Gender affirming hormone therapy (GAHT) is an essential part of male to female transgender care. In 2022, prevalence of self-reported transgender individuals increased by 0.5% in adults. Consequently, one study estimated that 44 per 100,000 people had an underling prolactinoma, but the prevalence in transgender patients is unknown. Prior to initiation of GAHT, baseline hormone labs are not routinely obtained to assess for pre-existing prolactinomas which can have significant clinical implications. We report a case of macroprolactinoma in a transgender female several years after initiation of high dose GAHT. Case Description: 48-year-old transgender female with a history of depression on high dose estradiol (8 mg/day), progesterone (200 mg/day), and spironolactone (400 mg/day) for the last 10 years was found to have an elevated prolactin (PRL) levels on routine evaluation. The patient was asymptomatic but given an elevated PRL level of 370 ng/ml, she underwent MRI Sella which showed a 1.1 cm pituitary adenoma abutting the right cavernous sinus. Her estradiol and progesterone supplementation were discontinued, resulting in a decline in her psychological well-being. Over next 6 months her PRL level trended down to 163 ng/ml. She was evaluated by neurosurgery and surgical intervention was deferred. Cabergoline was initiated (gradually up titrated to 0.25 mg three times weekly) and her repeat MRI 6 months after initial presentation showed interval decrease of the prolactinoma to 0.6 cm. Repeat PRL levels 2 months after cabergoline therapy were undetectable. Thereafter the patient was restarted on estradiol 2 mg daily with plans to closely monitor her PRL levels and possible repeat MRI 6-9 months afterwards. Discussion: Prolactinomas in transgender women on GAHT can often be masked as symptoms are commonly attributed to reduced testosterone levels. This case highlights the importance of timely biochemical monitoring prior to initiation of GAHT, as elevated PRL levels may indicate an underlying pituitary pathology. The mainstay of prolactinoma treatment involves cessation of hormone supplementation and medical management with dopamine agonists, which reduces tumor size in 80% of patients. However, this response may differ for transgender women on GAHT, particularly with estrogen therapy. As high doses of estrogen have shown to cause stimulation in prolactin secretion and possible growth induction of prolactinomas, the management becomes further challenging in transgender individuals. Additionally, discontinuation of hormone supplementation in transgender women may exacerbate underlying mood disorders; optimization of non-pharmacologic treatments should be pursued after discontinuation of hormone therapy. With the growing transgender population, further discussions on early identification and management of prolactinomas in this group are essential. Presentation: Monday, July 14, 2025