Endoxifen-induced ovarian hyperstimulation and galactorrhea in an adolescent with severe personality disorder

Dear Sir, Endoxifen is gaining recognition as a novel treatment for managing manic episodes in bipolar disorders and impulsivity in borderline personality disorder (BPD).[1,2] Endoxifen exhibits an inhibitory impact on protein kinase C that is four times more potent than that of its predecessor, tamoxifen. While endoxifen’s psychiatric applications have been increasingly documented, its reproductive endocrine effects remain largely unexplored. Here, we document a report of endoxifen-induced ovarian hyperstimulation in psychiatric practice. A 17-years old female, diagnosed with severe personality disorder (borderline pattern) according to ICD-11, showed minimal response to initial psychopharmacology with sequential trials of mood stabilizers (mainly lithium carbonates up to 600 mg/day or lamotrigine 50 mg/day) along with antipsychotics (aripiprazole up to 10 mg/day or cariprazine 3 mg/day) and dialectical behavior therapy conducted biweekly. However, when endoxifen up to 16 mg/day was administered along with lithium 600 mg/day and escitalopram 20 mg/day, her impulsivity and self-harming behavior reduced significantly. Within a month of this regimen, she developed galactorrhea, secondary amenorrhea, and bloody discharge from the left breast nipple despite normal serum prolactin levels. Hence, consultation liaison with gynecologist and general surgeon was made and she was evaluated further. Her hormonal evaluation revealed markedly elevated estradiol (>1000 pg/mL), elevated testosterone (183 ng/dL), elevated FSH (23.56 mIU/mL), elevated LH (19.62 mIU/L), normal progesterone (2.80 ng/mL), negative beta-hCG (