Objective      To explore the pathogenesis of hot flashes

and study the correlation of polymorphism of estrogen metabolic enzyme cytochrome P450 (CYP) gene and hot flashes in the perimenopause women.       Methods      Totally 328 perimenopausal women were select

ed randomly for case-control study

including 156 women with hot flashes in the case study group and 172 women without hot flashes in the control group. Follicle stimulating hormone (FSH)

luteinizing hormone (LH)

estradiol (E

2

) and testosterone (T) were detected by radioimmunoassay. Sex hormone binding globulin (SHBG) and dehydroepiandrosterone sulfate (DHEA-S) were detected by enzyme linked immunosorbent assay. The gene polymorphisms of CYP17 MspA1Ⅰ

CYP19 RsaI

CYP1A1MspI and CYP1B1 Eco57I were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).       Results      The level of FSH was statistically higher

but the levels of E

2

and SHBG were statistically lower in the women with hot flashes compared to the women without hot flashes (all P0.05). The CYP1B1 Eco57I genotype was statistically significant between the women with hot flashes and the women without hot flashes (P0.05). The women with CYP1B1 Eco57I polymorphism were 1.25 folds in the hot flashes risk （OR=1.25， 95% CI=1.03~1.82）

1.28 folds in the severity and 1.35 folds in the duration (persisted for a year or longer) compared to the women without hot flashes.       Conclusion      Low E

2

level may be one of the reasons for hot flashes. Women with CYP1B1 Eco57I polymorphism are more likely to have hot flashes with high severity and long duration.