OBJECTIVE: This study, we examined the relationship between bone mineral density (BMD) and the menstrual cycle and vitamin D receptor (VDR) gene Bsm1 polymorphism in female athletes.
METHODS: Subjects were 100 female athletes belonging to eight types of competitive sports (age 19.9±0.7 year). Subjects were monitored for menstrual cycles over 6 months. From the obtained data, the subjects with the longest cycle of 39 days or more were classified into menstrual cycle abnormal group (MA), and those with menstrual cycle of 25 to 38 days were regarded as menstrual cycle normal group (MN). BMD measures whole body, lumbar spine L2–4 and femoral neck by double X-ray absorption measurement method (DXA). VDR gene Bsm1 polymorphism (rs 1544410) was analyzed by PCRRFLP method.
RESULTS: In lumbar spine BMD, MA showed significantly lower value than MN. In body composition, MA showed significantly lower values of body weight, BMI, %fat, fat mass, and nonfat mass than in the MN. Body composition was associated with factors of the menstrual cycle, but it was not related to the vitamin D receptor gene Bsm1 polymorphism. Regarding the lumbar spine BMD, in the MN, the Bb type of VDR gene Bsm1 polymorphism was significantly higher than that of the bb type, and among the Bb type, the MA was significantly lower than the MN.
CONCLUSION: It is considered that prolonging the menstrual cycle in female athlete may adversely affect maintenance of bone mass. In particular, in the case of female athlete who had expression of Bb type of VDR gene Bsm1 polymorphism, it was suggested that menstrual cycle abnormality might have a high risk of adverse effect on lumbar spine BMD.
