Patients and sample collection
This study randomly recruited 482 participants considered as controls and 292 women with PCOS from the Center for Reproductive Medicine at the Shengjing Hospital of China Medical University between May and October 2020. PCOS was diagnosed based on the new guidelines for the diagnosis and treatment of PCOS,10 which specify that two of the following three conditions should be satisfied: menstrual disturbance (oligomenorrhea, amenorrhea, or anovulation), clinical or biochemical signs of hyperandrogenism, and polycystic ovarian manifestations after exclusion of other etiologies. The control group consisted of healthy women and those with clinical infertility due to the involvement of the fallopian tube.
The exclusion criteria were in accordance with our previous publications.11 These involved excluding participants with less than 3 years of menarche; smokers; pregnant women; breastfeeding women; and those having hyperprolactinemia or any other disease such as thyroid disease, diabetes, adrenal disease, or a history of any known neoplastic, infectious, or inflammatory diseases. During the 6 months prior to enrollment, none of the participants consumed drugs that would affect reproductive or metabolic functions. The characteristics of the study participants are listed in Table 1.
The basic information of the participants, including age and body mass index (BMI), was recorded using the electronic health care record databases of Shengjing Hospital, China Medical University. BMI was calculated as body weight in kilograms divided by body height in meters squared.12 Venous blood samples were collected from the participants after 10 hours fasting between days 3 and 5 of spontaneous menstruation or progesterone withdrawal bleeding. The blood samples were centrifuged and divided into the following two parts: one part was used as the basal blood sample for testing various biochemical indicators at the laboratory of Shengjing Hospital, including the levels of serum uric acid, luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, total testosterone (TT), progesterone, prolactin, thyroid-stimulating hormone (TSH), fasting plasma glucose (FPG), fasting serum insulin (FSI), and lipids; the other part was stored at -80 °C for further determination of serum fructose, free testosterone, and dehydroepiandrosterone sulfate (DHEAS) levels. Freezing and thawing was avoided for all the samples.