The main finding in our study is that FAI values were similar between adolescents with PCOS and non-PCOS cases with hyperinsulinemia and obesity, indicating using the FAI (Free Androgen Index) for diagnosing PCOS may be unreliable. Additionally, SHBG levels were found to be lower than adolescents with PCOS than hyperinsulinemic obese adolescents with oligomenorrhea, suggesting that FAI and SHBG should not be used as a diagnostic criterion, particularly in the presence of hyperinsulinism.
In healthy adolescents, the average age of menarche is around 12–13 years. In Zuchelo et al.'s meta-analysis, it is stated that the age of menarche in adolescents with PCOS is similar to that of non-PCOS adolescents (21). In our study, the similar average age of menarche in adolescents with oligomenorrhea suggests that oligomenorrhea is unrelated to the age of menarche. Adolescents' awareness of menstrual cycles and menstrual disorders can vary depending on social and educational factors which can delay adolescents from seeking medical help (22). The persistence of complaints for a considerable amount of time as in our patients may be related to factors like lack of knowledge, feelings of shame, and etc. Particularly menarche can be the first indication of an underlying bleeding disorder. As coagulopathy is reported to occur in up to 20% of patients presenting with heavy uterine bleeding, it is crucial to rule out underlying bleeding disorders. The frequency of coagulopathy among our patients with menorrhagia was consistent with the literature (23). While anovulatory cycles are the most common cause of oligomenorrhea, Polycystic Ovary Syndrome (PCOS) has been reported to have a prevalence ranging from 4–19.6% among adolescents in numerous studies, which is consistent with our findings (5, 7, 8). Increased androgen levels due to Functional Ovarian Hyperandrogenism lead to increased activity of the GnRH pulse generator and result in elevated levels of LH in PCOS. This rise in LH level and LH/FSH ratio have been investigated as a diagnostic criterion for PCOS in various studies(8). Le et al.'s research, which included 441 PCOS patients and 442 non-PCOS patients, reported a mean LH/FSH ratio of 2.08. Their study also identified an LH/FSH cutoff greater than 1.33, which exhibited a sensitivity of 65.76% and specificity of 95.24% for diagnosing PCOS in ROC analysis (24). In a study conducted in China involving 111 PCOS patients, a mean LH/FSH ratio of 1.87 ± 0.76 was observed (25). Additionally, Khashchenko et al. investigated 130 adolescents with PCOS and 30 healthy controls, proposing an LH/FSH ratio cutoff greater than 1.23, which has a sensitivity of over 75.0% and specificity of over 83.0% (26). Although the LH/FSH means were higher in our patients with PCOS than in these studies, there was no statistical difference in terms of the LH/FSH ratio between the anovulatory patients. Unlike the control groups of Khashchenko et al. and Le et al., our study was conducted on adolescents presenting with complaints of oligomenorrhea. While oligomenorrhea is the common complaint for both PCOS and anovulation, attempting to make a diagnostic aproach between these groups as in our study may be more specific for adolescent PCOS. Additionally, there are varying reports concerning the upper limit of total testosterone used in the diagnosis of PCOS. And hirsutizm can vary among populations, for instance in Middle Eastern populations, a modified Ferriman-Gallwey (m-FG) score up to 9–10 is considered within the normal range(27). In a recent review/meta-analysis, Zuchelo et al. accepted patients who have serum testosterone levels between 48 to 82 ng/dl as having biochemical hyperandrogenism (21). In previosuly mentioned Le et al.'s study, the average total testosterone in PCOS patients was 36.9 ng/dL ± 25. Khashchenko et al. applied the Rotterdam criteria to adolescent patients and found that the mean total testosterone in PCOS patients was 54 ng/dL (34.6–72 ng/dL; as median 25–75 percentiles), indicating that up to one-third of the patients had testosterone levels below 50 ng/dL, which was the cutoff we used as a biochemical criterion. Particularly, in our anovulatory group, 59 oligomenorrheic patients were in the “grey zone” who had a total testosterone level between 40–50 ng/dL and/or a m-FG score between 8–16. The value obtained in the ROC analysis for LH/FSH exhibited good specificity but had low sensitivity for our PCOS group. The reduced sensitivity of the LH/FSH ratio may be tied to the parameters set during patient selection, specifically the acceptance of a lower limit of 50 ng/dL for hyperandrogenism. Given the wide spectrum of severity from atypical to typical PCOS and the challenges of diagnosing adolescent patients, the long-term follow-up of this high-risk group patients may provide valuable data on determining a testosterone cut-off level in the diagnosis of PCOS.
PCOS, FAI and Hyperinsulinism
Obesity and insulin resistance are health problems frequently associated with menstrual irregularities during adolescence, and PCOS is uniquely accompanied by disruptions in insulin and lipid metabolism. In a study by Green et al., involving 18 non-obese adolescents with PCOS and 20 healthy controls, it was demonstrated that PCOS patients exhibited greater insulin resistance and liver fat accumulation despite they were having lower mean daily caloric intake (1379 kcal/day vs. 1577 kcal/day). They associated the metabolic alterations observed in PCOS with muscle mitochondrial deficiency (28). PCOS also carries an 18-fold increased risk for diabetes, with a prevalence of approximately 16% in non-obese and 50–70% in obese PCOS patients. Similiar to previous reports approximately one-quarter of the patients with PCOS had insuline resistance in our study. We aimed to compare the pivotal clinical and hormonal features of patients with PCOS to those of hyperinsulinemic/obese patients with oligomenorrhea. In a meta-analysis by Li et al., involving 13 studies and 756 patients, it was noted that obese adolescents with PCOS had higher levels of total testosterone, free testosterone, fasting insulin, HOMA-IR, fasting glucose, lipid profile abnormalities, and leptin, as well as lower SHBG levels compared to normal-weight adolescents with PCOS. Also similiar findings were mentioned between obese adolescents with PCOS and obese adolescents without PCOS in their study (29). These findings indicate that obesity exacerbates the clinical presentation of PCOS. Similarly in our study, patients with PCOS had significantly higher total testosterone and DHEA-S levels, and lower BMI and HOMA-IR levels than patients with hyperinsulinism. Although hyperinsulinemia contributes to existing hyperandrogenemia by increasing LH sensitivity in theca cells, the higher LH and LH/FSH levels in our PCOS patients compared to hyperinsulinemic adolescents may suggest that functional ovarian hyperandrogenism (FOH) plays a more pivotal role in the development of PCOS and hyperandrogenism (28, 30, 31). The Free Androgen Index (FAI), a ratio of total testosterone to SHBG, has been widely discussed as a potential diagnostic index for PCOS in adolescents. Sağsak et al. proposed a FAI level above 6.15 in adolescents, demonstrating a sensitivity of 89% and a specificity of 77% (32). In Khashchenko et al.’s study on 130 adolescents with PCOS and 30 healthy controls, significantly higher mean FAI levels were found in PCOS patients (FAI: 5.5 vs. 1.6). For a FAI > 2.75 cut-off, a sensitivity of 75% and a specificity of 93% were found in ROC analyses(26). In a study by Yetim et al. conducted on 53 adolescents with PCOS and 26 healthy controls, the FAI value was significantly higher in PCOS patients (6.7 vs. 3.0) (33). However, the interpretation of FAI values is complex due to the interactions of SHBG with hyperinsulinemia, diabetes, and hypothyroidism. Obesity, characterized by disrupted glucose-insulin metabolism, is associated with decreased SHBG levels (34). Bideci et al. previously reported lower SHBG levels in patients with PCOS and obesity compared to non-obese PCOS patients (30). In Khashchenko et al.’s study the adolescents with PCOS had a significantly higher BMI than healthy controls (p = 0.0002) and despite lack of postprandial glucose and insulin data higher leptin levels. In Yetim et al.'s study, the mean BMI of adolescents with PCOS was higher than that of healthy controls (1.4 vs. 0.8) (33). In our study, to demonstrate the impact of hyperinsulinemia/obesity on FAI and SHBG, we compared patients with PCOS to hyperinsulinemic/obese adolescents. The slightly higher FAI values in hyperinsulinemic/obese adolescents (8.30 vs. 8.0) and the lower SHBG levels (12.2 vs. 29.2 mol/L) suggest that glucose/insulin metabolism has a greater influence on FAI/SHBG levels than androgens. This suggests the need for selective consideration in the use of FAI for diagnosing PCOS.
Ovarian cysts
The use of the Rotterdam criteria for assessing ovarian cyst counts in adolescents is debated due to frequent anovulatory cycles and the physiological presence of up to 24 ovarian cysts in this age group. Additionally this debate is further complicated by the challenges of performing transvaginal ultrasonography (USG) and pelvic Magnetic Resonance Imaging in adolescents. However, ovarian volume, rather than the number of cysts, is considered more diagnostic in this population and previous studies have proposed a significant ovarian volume for PCOS diagnosis in adolescents as 15 cc in one ovary or 12 cc in both (7, 10, 35, 36). Similarly, our study using suprapubic ultrasonography revealed a mean ovarian volume of 11.8 cc in patients with PCOS, indicating use of overian volumes in diagnosis should be reliable.
Eating disorders typically occur during mid-to-late puberty, especially in the 15–19 age group. Oligomenorrhea onset was longer in malnourished patients than those with anovulatory cycles, and they were more likely to experience secondary amenorrhea (37). Malnutrition may have a greater impact on LH pulsatility by affecting the hypothalamic-pituitary-gonadal axis and leading to decreased LH secretion and consequently decreased ovarian function and anovulation. Notably LH secretion is more affected than FSH and E2 secretion in our patients affected by malnutrition.
Retrospective planing of the study limited our ability to control for potential confounding factors and to collect detailed information. Prospective studies with larger population sizes may provide more statistical power and allow for more detailed subgroup analyses. Besides, having a relatively large sample size of 305 patients with various etiologies presenting with oligomenorrhea at a tertiary center and using utilized diagnostic criteria to identify/analyze patients with PCOS were the strengths of the study.