Serum Fetuin-A concentration in PCOS and healthy women
Table 1 summarizes the demographic, anthropometric and metabolic parameters of all women in the current study. In PCOS women, BMI, WHR, blood pressure (BP), TG, TC, LDL-C, FBG, FIns and HOMA-IR were significantly increased compared to healthy women (Table 1). Furthermore, sex hormone levels, including LH, LH/FSH, TEST and DHEA-S, were also markedly increased in PCOS women relative to those in healthy women (Table 1). The distribution of Fetuin-A concentrations in healthy women were showed in Figure 1A. We found that circulating Fetuin-A concentration ranged from 196.6 to 418.2 µg/L for most normal women (95 %). Importantly, as shown in Figure 1B, PCOS patients have higher circulating Fetuin-A levels than healthy women. Even after adjusting for weight and age, the difference was significant (Table 1). According to BMI < 25kg/m2 or ≥ 25kg/m2, PCOS patients were divided into obese/overweight (ob/ow) and non-obese/overweight groups (non-ob/ow). We found that the level of Fetuin-A in obese/overweight group was significantly higher than that in non-obese/overweight group (Figure 1C). In addition, serum Fetuin-A was divided into three tertiles (tertile 1, < 322.6 µg/L; tertile 2, 322.6-419.6 µg/L; tertile 3, >419.6 µg/L). The odds of developing PCOS were calculated by logistic regression analysis. In the tertile 2 and 3 of blood Fetuin-A, the odds ratios of developing PCOS were higher than tertile 1 (95% CI 1.28 - 5.14 for tertile 2 and 95% CI 11.8 – 113.5 for tertile 3; vs. tertile 1, both p < 0.01; Figure 1D).
Serum Fetuin-A level and its association with other parameters in the study population
We next investigated the relationship between the levels of circulating Fetuin-A and various other parameters. Serum Fetuin-A was positively correlated with WC, TG, LDL-C, FIns, HOMA-IR, TEST and DHEA-S (Table 2). We also performed multiple stepwise regression to determine variables that had independent associations with serum Fetuin-A. The results showed that only HOMA-IR and TEST were independent predictors of the levels of circulating Fetuin-A (Table 2). The multiple regression equation was YFetuin-A = 38.9 + 10.7 XHOMA-IR +317.4XWHR + 46.7XTETS.
With the increase of serum Fetuin-A levels, the risk of PCOS increased linearly. When analyzed by means test and Cheran-Armitage trend test, the concentration of fetoglobulin A was independently associated with polycystic ovary syndrome, and Fetuin-A was independently associated with PCOS when analyzed by a Row Mean Scores test and a Cochran-Armitage trend test (Table 3). Additionally, logistic regression analysis revealed that Fetuin-A was significantly related to PCOS, even after controlling for anthropometric variables, blood lipid and so on (Table 4).
ROC curve analysis
In order to explore the prediction of PCOS and IR by blood Fetuin-A, we performed receiver operating characteristic (ROC) curve analysis. The data analyzed by ROC showed that the area under the ROC curves for PCOS (AUCPCOS) was 0.81 with a specificity of 83 %, and sensitivity of 0.70 % (p < 0.01, Figure 2A), and AUCIR was 0.82 with a specificity of 72%, and sensitivity of 81 %. The best cut-off values for Fetuin-A to detect PCOS and IR were 366.3 µg/L for PCOS and 412. 6µg/L for IR.