Are the serum 25-hydroxyvitamin D concentrations in winter associated with forearm bone mineral density in healthy elderly Japanese women?

The objective of this study was to investigate whether the serum 25-hydroxyvitamin D (25[OH]D) concentrations in winter are associated with the BMD in elderly Japanese women. The subjects were 117 healthy elderly Japanese women. Serum 25(OH)D concentrations were determined by high-performance liquid chromatography. Forearm BMD in the non-dominant arm was measured by dual-energy X-ray absorptiometry (DXA) using a DTX-200 Osteometer. The mean age of the subjects was 66.1 (SD 6.5) years (range: 46-80). The average 25(OH)D concentration was 59.1 nmol/L (SD 16.1), and five of the subjects had low 25(OH)D concentrations (< 30 nmol/L). Forearm BMD decreased linearly with age (r2 = 0.275). There was no linear association between the serum 25(OH)D concentrations and the forearm BMD (p = 0.9483). Multiple regression analysis did not reveal any association between the two (p = 0.5318) when age (p < 0.0001, r2 = 0.271) and weight (p < 0.0001, r2 = 0.153) were taken into account. Our cross-sectional study failed to reveal any association between the serum 25(OH)D concentrations and the forearm BMD in elderly Japanese women, suggesting that 25(OH)D does not play an important role in the determination of BMD. A follow-up study should be conducted to confirm the results of our cross-sectional study.