A 40-Year-Old Woman Is Being Evaluated Due to Absence of Menstrual

A 40-year-old woman is being evaluated due to absence of menstrual cycle for 4 months. Previously, her periods occurred at regular 28-day intervals and lasted 4-5 days with moderate flow. She has also noticed breast tenderness and scant nipple discharge. She has type 2 diabetes mellitus and refractory bipolar I disorder. Current medications include metformin, glipizide, lithium, and risperidone. Physical examination shows no abnormalities. A urine pregnancy test is negative. Which of the following is the most likely explanation for this patient's amenorrhea?

A) 21-hydroxylase deficiency
B) Asherman syndrome
C) Drug-induced amenorrhea
D) Polycystic ovary syndrome
E) Primary ovarian insufficiency
F) Weight loss