Authors: C J Bacon J Woo E M C Lau C W K Lam G D Gamble I R Reid
Publish Date: 2010/02/13
Volume: 21, Issue: 11, Pages: 1935-1941
Abstract
Optimal levels of 25hydroxyvitamin D 25OHD were investigated in premenopausal Chinese women Parathyroid hormone PTH change at 3 months was associated with change in 25OHD but not with baseline levels and PTH fell even when starting levels of 25OHD were 40 nmol/L consistent with optimal values for 25OHD of ≥40 nmol/lThe upper level of 25hydroxyvitamin D 25OHD which constitutes a longterm bone health risk by causing elevated PTH levels is uncertain Although many studies have addressed this question using crosssectional data the present study is one of few employing a prospective approach to determine 25OHD levels required to minimize PTHBaseline 25OHD was 34 ± 11 nmol/L and was inversely related to baseline PTH r = −018 P = 0007 with a plateau in PTH levels when 25OHD was 40 nmol/L After 3 months intervention PTH fell 11 and neither Δ25OHD nor ΔPTH differed between treatment and control groups ΔPTH was inversely related to Δ25OHD P 0001 but not to baseline 25OHD Similarly ΔPTH differed between quartiles of Δ25OHD P 0001 but not between quartiles of baseline 25OHD and no interaction was observed between quartiles of baseline 25OHD and Δ25OHD Even in the highest quartile of baseline 25OHD 40 nmol/L PTH fell 04 ± 01 pmol/L mean ± SEM P = 0008We conclude that vitamin D deficiency is common in young women in Hong Kong The crosssectional analysis indicates that optimal 25OHD is 40 nmol/L and the longitudinal data is consistent with a higher optimal value which is not defined in this study’s results
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