Objective:To investigate the association between serum complement C3(C3)and metabolic syndrome(MS)and its components in women with polycystic ovary syndrome(PCOS).Methods:91 women with PCOS and 115 age-matched normal women were enrolled in this study.Anthropometric measurements and biochemical parameters were evaluated to find the relationship between C3 and other parameters.Results:The concentration of C3 was significantly higher in women with PCOS compared with control subjects(1.39± 0.33) g/L vs(1.10±0.22) g/L

P<0.05);it was also higher in subjects with MS or any components of MS in PCOS;and the C3 level rose gradually along with the increase of the number of MS features(P<0.05).Correlation analyses indicated that the C3 was associated positively with BMI

waistline

systolic blood pressure

diastolic blood pressure

fasting plasma glucose

2-h plasma glucose

fasting insulin

triglyceride

total cholesterol

LDL-c and Homa-IR(r=0.65

0.63

0.36

0.29

0.39

0.49

0.56

0.58

0.40

0.32

0.58

P<0.05)

While negatively with M value and HDL-c(r=-0.65

-0.36

P<0.05).Multiple linear regression showed WC and TG(β=0.31

P<0.05)

TG(β=0.23

P<0.05)were significant influential factors for C3.Binary logistic regression analysis showed that subjects in PCOS group were more likely to get MS when C3 increase(P<0.05).Conclusion:High concentration of C3 is a risk factor for MS in women with PCOS.