Etiology and Pathogenesis

PCOS is thought to result from an interaction involving multiple genetic loci and environmental factors that disrupt several metabolic pathways. Resulting androgen excess can present as hyperandrogenism (Figure 84-1). One androgen pathway involved in PCOS is altered luteinizing hormone (LH) function, which can lead to increased androgen production by ovarian theca cells. This finding is especially common in thin or normal weight women with PCOS. Another potential pathway that leads to elevated androgens involves insulin resistance and compensatory hyperinsulinemia. Elevated insulin levels can also stimulate androgen production by ovarian theca cells while simultaneously inhibiting liver synthesis of sex hormone–binding globulin (SHBG), which in turn results in an increased fraction of bioavailable or free testosterone.

Figure 84-1 Polycystic ovarian disease.

Clinical Presentation

PCOS typically presents during adolescence with one or more of these symptoms: menstrual irregularities, androgen excess including hirsutism, acne that is resistant to treatment, male pattern hair loss, and obesity. Menstrual dysfunction may present as primary amenorrhea, oligomenorrhea, secondary amenorrhea, or dysfunctional uterine bleeding. Eighty percent of women with PCOS present with menstrual irregularity; however, 20% experience “regular” anovulatory vaginal bleeding. One of the factors that can delay diagnosis of PCOS during early adolescence is the high frequency of developmental anovulation (≈50% of cycles) during the 2 years after menarche. Although irregular menses is common during this stage of development, this is not accompanied by clinical or biochemical evidence of androgen excess.

Clinical signs of hyperandrogenism may include hirsutism, acne and androgenic alopecia (thinning of the crown hair with preservation of the anterior hairline). Hirsutism affects approximately 70% of women with PCOS. Significant virilization, such as severe hirsutism, clitoromegaly, or bitemporal hair recession, is rarely seen with PCOS. Obesity is present in approximately 50% of women with PCOS. Insulin resistance and dyslipidemia are also very common. One center noted that 25% of their adolescent females with PCOS had metabolic syndrome.