Circulating androgen levels are not affected by the administration of vaginal micronized progesterone for withdrawal bleeding in patients with polycystic ovary syndrome

BACKGROUND: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age, with hyperandrogenemia as one of its main components. Several medications have been described to properly induce withdrawal, unfortunately, most of them significantly suppress ovarian function and lower circulating androgen levels with a subsequent diagnosis bias. The present study aims to determine whether the use of vaginal micronized progesterone (VMP) to induce withdrawal bleeding in women with PCOS alters circulating androgen parameters.

METHODS: This is a prospective clinical trial, performed at an academic medical center. Fifteen reproductive-aged women with PCOS were studied. Blood samples were collected at baseline (Sample 1) and between the 3rd-5th day of withdrawal after 7 days of VMP (100 mg every 12 h) (Sample 2). Total testosterone (TT), free androgen index (FAI), sex hormone binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), androstenedione (A4) and 17-hydroxyprogesterone (17-OHP) levels were determined in the blood samples.

RESULTS: All 15 patients fulfilled the Rotterdam criteria for PCOS. Two patients presented spontaneous ovulation confirmed in Sample 1 and were not included in the analysis. Mean age was 29.3 ± 4.9 years and mean body mass index was 26.9 ± 6.7 kg/m². The mean values of TT, FAI, SHBG, DHEAS, A4 and 17-OHP did not change after VMP administration.

CONCLUSION: Withdrawal bleeding with VMP in PCOS patients does not significantly alter circulating androgen levels compared to baseline and can thus be used to time blood sampling in these patients.