Relation of 25-hydroxyvitamin D and parathyroid hormone levels with metabolic syndrome among US adults

Objective: Previous research on the combined association of 25-hydroxyvitamin D (25(OH)D) and parathyroid hormone (PTH) with metabolic syndrome may have been limited by restricted age variability and a lack of representation of the general population. This study examined the combined association of 25(OH)D and PTH with Adult Treatment Panel III-defined MetSyn among a nationally representative sample of US adults. Design and methods: This population-based cross-sectional study included 834 men and 820 women aged ≥20 years without diagnosed diabetes who completed a physical examination as part of the 2003-2004 US National Health and Nutrition Examination Survey. Results: After adjusting for age, sex, race/ethnicity, income, lifestyle factors, total calcium, and energy intake, the odds ratio (OR) for MetSyn in the highest quintile of 25(OH)D (median 88.0 nmol/l) compared with the lowest quintile (median 26.8 nmol/l) was 0.27 (0.15, 0.46; P_trend < 0.001). This relation was unchanged after additional adjustment for PTH level (OR, 0.26; 0.15, 0.44; P_trend < 0.001) and did not differ by sex (P interaction 0.6) or age ( < or ≥ 50 years; P interaction 0.2). In contrast, the multivariable-adjusted odds for MetSyn increased with increasing PTH among older men (P_trend 0.004), but not younger men (P _trend 0.4) or women regardless of age (P_trend 0.4 in younger and older women). Conclusions: These data suggest an inverse association of 25(OH)D with MetSyn, independent of potential confounding factors, calcium intake, and PTH, and a positive association of PTH with MetSyn among older men.