Vitamin D status and parathyroid hormone in a urban population in Vietnam

Summary In this cross-sectional study in Vietnam, the prevalence of vitamin D insufficiency was 46% in adult women and 20% in adult men. There was a linear inverse relationship between serum 25(OH)D and PTH concentrations, but there was no threshold of 25(OH)D at which PTH levels plateaued. Introduction Vitamin D insufficiency is adversely associated with health outcomes. Vitamin D status in Asian populations is not well documented. This study sought to assess vitamin D status and its relationship to parathyroid hormone in a Vietnamese population. Methods This cross-sectional study involved 205 men and 432 women aged 18–87 years, who were randomly sampled from various districts in Ho Chi Minh City (Vietnam) according to a proportional sampling scheme. Serum concentration of 25(OH)D and PTH were measured by the Electrochemiluminescence immunoassay on the Roche Elecsys 10100/201 system (Roche Diagnosis Elecsys). Vitamin D insufficiency was quantified as serum 25(OH)D levels below 30 ng/ml (75 nmol/L). Results The average age for men and women was 43.8± 18.4 years (mean±SD) and 47.7±17.1 years, respectively. The mean 25(OH)D concentration inmen (36.8±10.2 ng/mL) was significantly higher than in women (30.1±5.9; P< 0.0001). The prevalence of vitamin D insufficiency in men was 20% (41/205) which was significantly lower than in women (46%, 199/432). Age, height and weight were independent predictors of 25(OH)D concentrations, and the three factors explained 15% and 5% of variance in 25(OH)D in men and women, respectively. There was a linear inverse relationship between serum 25(OH)D and PTH concentrations, but there was no threshold of 25(OH)D at which PTH levels plateaued. Conclusions These data show that vitamin D insufficiency is common even in tropical region, and that women had a greater risk of vitamin D insufficiency than men. These data suggest that an elevation in PTH cannot be used as a marker for vitamin D deficiency.