TNF and polycystic ovary syndrome: PCOS: polycystic ovary syndrome; SD: standard deviation; BMI: body mass index; TNF-α: tumor necrosis factor-alpha; ELISA: enzyme-linked immunosorbent assay; AES: Androgen Excess Society; HOMA: homeostatic model assessment; IL-6: interkeukin-6; WHR: waist-to-hip ratio