The relationship between plasma homocysteine levels and bone mineral density in post-menopausal women

Whether or not mild hyperhomocysteinemia and low serum levels of folates or vitamin B12 are risk factors for osteoporosis in the elderly is controversial.

To investigate whether or not plasma levels of total homocysteine (tHcy) and serum levels of folates and vitamin B12 are associated with bone mineral density (BMD), we carried out a cross-sectional study on 446 post-menopausal women (mean age: 65.1+/-9.4 years), consecutively seen at the Siena Unit (Tuscany region, Central Italy) for BMD evaluation over a two-year period. BMD of the total femur, femoral neck and lumbar spine was detected by dual-energy X-ray absorptiometry.

The age-adjusted geometric mean of plasma tHcy levels (micromol/L) was 9.96+/-1.29 in women with normal BMD, 11.06+/-1.32 in those with osteopenia and 11.88+/-1.35 in those with osteoporosis (p<0.0001). On multiple linear regression analysis, adjusting for age, body mass index, folates, vitamin B12, creatinine clearance, smoking habit and alcohol intake, tHcy was negatively related to BMD of the total femur [beta estimate for log-homocysteine: -0.050 (95% CI: -0.100 to -0.001, p=0.048; R(2)=0.02)], but not of femoral neck or lumbar spine. There was no significant association between BMD and serum levels of folates and vitamin B12.

tHcy is negatively associated with BMD of the total femur. The contribution of tHcy to explain the variance of BMD is small (2% of the total variance) but clinically relevant, considering the high prevalence of osteoporosis among post-menopausal women and the possibility to lower tHcy by vitamin supplementation.