The Difference in Vitamin D Status between Urban and Rural Elderly Women of Khon Kaen Province, Thailand

Abstract

Background Our study in the year 2000 concluded that the level of calcidiol at £ 35 ng/ml indicated a vitamin D deficiency, making the deficiency prevalence among the elderly in Khon Kaen municipality to be about 66.3%

Objectives To compare 104 urban elderlies with 130 rural elderlies in:  1) Verified calcidiol and PTH levels; 2) Re-determine the level associated with vitamin D deficiency; and, 3) Compare the bone mineral density (BMD) of femoral neck, lumbar vertebrae and distal radius.

Design Cross-sectional, descriptive study.

Setting Urban and rural Khon Kaen, Thailand.

Measures Serum calcidiol and PTH levels, and the proximal femur, lumbar spine and distal radius BMD.

Results The rural elderly were older (p < 0.004), but their weight, BMI and alkaline phosphatase were lower (p = 0.007, p < 0.001 and p < 0.001, respectively) than their urban counterparts.  The correlation coefficient for calcidiol and PTH of the pooled data (n = 234) was -0.35 (p < 0.001).  The quantity of calcidiol at £ 35 ng/ml was associated with a significant increase in PTH (one-way ANOVA, Tamhane post hoc test p £ 0.007).  The prevalence of vitamin D deficiency, and the mean (SD) calcidiol and PTH levels in the rural vs. urban elderly were 17 vs. 65% (p<0.001), 45 (11) ng/ml vs. 33 (7) ng/ml and 18 (15) pg/ml vs. 32 (18) pg/ml (p < 0.001), respectively.  The BMD of the ultradiatal  and distal one-third of the radius (not the femoral neck or lumbar spine) were significantly higher in the rural vs. urban elderly (p < 0.001).

Conclusion The higher calcidiol levels and bone strength in the rural population suggest that lifestyle and activity levels are important factors.  Further study is needed to confirm this.

Keywords vitamin D status, calcidiol, rural, urban, elderly