Vitamin D Status and Bone Health in Healthy Thai Elderly Women

Objective: The prevalence of hypovitaminosis D varies in different countries. Therefore, the current study was designed to assess vitamin D status and bone health in elderly women in Thailand, which is situated near the equator.

Methods: This cross-sectional study was performed in 446 healthy women aged 60-97 y.

Results: Serum 25-hydroxyvitamin D (25(OH)D) was 67.6 ± 15.7 (mean ± SD) nmol/L. Daily calcium intake was 309.5 ± 147.2 mg/d. Serum 25(OH)D levels tended to decline with bone mineral density (BMD) status. Based on functional health-based reference values, plasma-intact parathyroid hormone began to rise below serum 25(OH)D level 70 nmol/L and increase significantly when serum 25(OH)D was ≤ 60 nmol/L. Thirty-two percent of elderly women had 25(OH)D insufficiency (≤ 60 nmol/L). There was no trend toward a decrease in the concentration of serum 25(OH)D with age (r = -0.078, P = 0.10) and no significant inverse relationship with plasma intact parathyroid hormone values (r = -0.079, P = 0.097). However, a positive relationship was observed between serum 25(OH)D level and femoral neck BMD (r = 0.156, P = 0.001) but not lumbar spine L(2)-L(4) BMD (r = 0.093, P = 0.050). In addition, BMD at the femoral neck but not lumbar spine of the vitamin D insufficiency group was significantly lower than that of the vitamin D sufficiency group.

Conclusion: The optimum level of serum 25(OH) value in Thai elderly women should be higher than 70 nmol/L. Vitamin D insufficiency is observed in one-third of elderly women in Bangkok.