Prevalence and impact of vitamin D insufficiency in southern Chinese adults.

INTRODUCTION

Vitamin D is a vital element for bone health but the problem of vitamin D deficiency is underestimated in Hong Kong.

METHODS

Serum 25(OH)D and parathyroid hormone (PTH) levels were evaluated in 382 community dwelling Chinese adults >50 years for their relation with bone mineral density (BMD) and risks of osteoporotic fractures and falls.

RESULTS

The mean age of the subjects was 69 +/- 9 years. The mean 25(OH)D level was 28.3 +/- 10.8 ng/ml with 62.8% of the subjects having levels <30 ng/ml. 6.3% of the subjects had elevated PTH levels. A curvilinear relation between serum PTH and 25(OH)D was found, with PTH starting to increase when 25(OH)D level fell below 30 ng/ml (r = -0.233, p < 0.05). Although subjects with vitamin D <30 ng/ml had significantly lower BMD, only sex, age and PTH but not 25(OH)D were predictors of BMD at the spine and hip. Subjects with elevated PTH levels had a 2.92-fold increased risk of falls and 2.94-fold increased risk of fractures at the hip and spine.

CONCLUSIONS

Vitamin D insufficiency and its complication of secondary hyperparathyroidism is common even in subtropical region and is an important risk factor for low bone mass, falls and fractures.