Very Low Levels of Serum Anti-Müllerian Hormone as a Possible Marker for Follicle Growth in Patients with Primary Ovarian Insufficiency Under Hormone Replacement Therapy

Patients with primary ovarian insufficiency (POI) occasionally present with follicle growth; however, accurately predicting cycles accompanied by follicle growth is challenging. Early-stage follicles produce serum anti-Müllerian hormone (AMH), a useful marker of ovarian reserve. Therefore, serum AMH levels indicate growth of small follicles (which are difficult to detect ultrasonographically) and may predict follicle growth in patients with POI. Using an ultrasensitive enzyme-linked immunosorbent assay (ELISA) kit, we observed very low serum AMH levels in patients with POI. We further evaluated follicle growth in each patient during each cycle to determine the usefulness of measuring serum AMH levels as a predictor of follicle growth in patients with POI who receive hormone replacement therapy (HRT). We investigated 19 patients with POI in whom we analyzed 91 cycles; 14 cycles showed positive and 77 cycles showed negative results on serum AMH testing. The rate of cycles showing follicle growth in AMH-positive cycles was higher than that in AMH-negative cycles (64.3% vs. 6.5%, p = 0.0001). The median serum AMH level (7.7 pg/mL [25th and 75th percentiles 4.6 pg/mL and 22.3 pg/mL, respectively]) in AMH-positive cycles was lower than the lower limit of detection of conventional AMH ELISA kits. The positive predictive value of positive serum AMH levels for follicle growth was higher than that of follicle-stimulating hormone (