[Relationship of ionized calcium and 25-(OH) D in serum with obesity]

To investigate the relationship of ionized calcium and 25-(OH) D level in serum with obesity in order to provide theoretical basis for preventing obesity-related diseases.

Base on a cross-sectional study, 169 overweight/obese subjects (92 men: age (37.76 +/- 17.56) years, 77 women: age (38.79 +/- 17.40) years) and 169 normal weight control subjects (92 men: age (36.24 +/- 17.28) years, 77 women: age (32.32 +/- 13.07) years) were selected in a 1:1 case-control matches. 25-(OH) D was assessed by ELISA. Serum ionized calcium was measured by flame atomic absorption spectrophotometry. The relationship of ionized calcium and 25-(OH) D level in serum with obesity was analyzed by using a Logistic regression model.

The average serum ionized calcium in overweight or obese subjects was(46.9 +/- 20.7) mg/L and that in normal control subjects was (63.2 +/- 19.5) mg/L (P < 0.001). Serum 25-(OH) D of overweight or obese was lower than normal control subjects ((48.3 +/- 16.7) nmmol/L vs. (63.8 +/- 35.4) nmmol/L, P < 0.001). Serum ionized calcium and 25-(OH) D was independently associated with body mass index in a logistic regression model [OR = 0.959, 95% CI 0.945-0.973; OR = 0.435, 95% CI 0.329-0.575].

Serum 25-(OH) D levels in obesity group was lower than that in control group. The results suggest that vitamin D might play an important role in the risk of developing obesity.