Dienogest (DNG) is widely used to treat dysmenorrhea associated with estrogen-dependent diseases such as endometriosis and adenomyosis. DNG becomes unnecessary after menopause when estrogen secretion declines drastically. However, there are no clear criteria for when to halt DNG in perimenopausal patients. Menstruation and dysmenorrhea often resume after discontinuation due to approaching menopause. This case-control study used serum estradiol and follicle-stimulating hormone (FSH) levels to predict whether menstruation would resume in perimenopausal women after discontinuation of DNG. The study enrolled patients aged ≥40 years with endometriosis and/or adenomyosis and who had either completed oral DNG therapy (DNG group) or had spontaneous menopause without hormone therapy (control group). We assessed estradiol and FSH values before DNG termination or the final menstrual period. DNG group members that resumed menstruation after DNG termination (D (+) group, n = 17) had significantly higher estradiol and lower FSH levels than those who did not (D (-) group, n = 22) up to four months before DNG termination but not from four to 12 months. Estradiol and FSH levels were not significantly different between the D (-) and control groups. Receiver operating characteristic curves created from the estradiol and FSH values indicated that menstruation resumed when levels were ≥17 pg/mL and <100 mIU/mL, respectively. In contrast, menstruation did not resume in cases of estradiol ≤20 pg/mL and FSH >80 mIU/mL. The study results provide useful criteria for deciding when to terminate DNG in perimenopausal patients that consider their tolerance for resuming menstruation. Applications to menopause-inducing therapy for uterine fibroids and other conditions are anticipated. Further large-scale studies are needed.
Keywords: Dienogest; Endometriosis; Estrogen; Follicle-stimulating hormone; Perimenopause.