Dataset Information

Higher serum 25-hydroxyvitamin D levels in school-age children are inconsistently associated with increased calcium absorption.

ABSTRACT:

Context

Increasing serum 25-hydroxyvitamin D (25-OHD) in adults may enhance calcium absorption (Ca-abs). There are few similar pediatric data leading to uncertainty about the optimal target for 25-OHD to maximize Ca-abs.

Objective

Our objective was to evaluate the relationship between 25-OHD and Ca-abs in a large cohort of school-age children and adolescents.

Design

We evaluated data from 439 Ca-abs measurements performed using dual-tracer stable isotope techniques conducted at our center over a 15-yr period in 251 healthy children, 4.9-16.7 yr of age.

Results

Serum 25-OHD ranged from 28 to 197 nmol/liter (mean 85 +/- 2 nmol/liter) (sem). Total Ca-abs (intake times fractional absorption) were significantly correlated to 25-OHD in the whole population (r = 0.16, P = 0.001). This relationship was closer in the 197 studies in early puberty (Tanner 2 or 3, r = 0.35, P < 0.001) and not significant in pre- or late pubertal subjects. For the whole population, fractional Ca-abs adjusted for calcium intake were slightly but significantly higher at 25-OHD of 28-50 nmol/liter (0.344 +/- 0.019) compared with 25-OHD of 50-80 nmol/liter (0.280 +/- 0.014) or 25-OHD greater than 80 nmol/liter (0.297 +/- 0.015, P < 0.01 for each), suggesting adaptation to moderately low 25-OHD values.

Conclusion

There is no consistent pattern of relationship between 25-OHD and either fractional or total calcium absorption in school-age children. However, there appears to be a modest calcium absorptive response to higher 25-OHD during early puberty.

SUBMITTER: Abrams SA

PROVIDER: S-EPMC2708956 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:ContextDisturbances in 25-hydroxyvitamin D, calcium, and phosphorus concentrations have been associated with increased risks of total and cardiovascular mortality. It is possible that changes in electrocardiographic QT interval duration may mediate these effects, but the association of 25-hydroxyvitamin D, phosphorus, and calcium concentrations with QT interval duration has not been evaluated in general population samples.ObjectiveThe objective of the study was to evaluate the association of 25-hydroxyvitamin D, phosphorus, and calcium concentrations with QT interval duration in two large samples of the U.S. general population.DesignThis study included cross-sectional analyses the Third National Health and Nutrition Survey (NHANES III) and the Atherosclerosis Risk in Communities (ARIC) study.SettingThe study was conducted in the general community.Patients or other participantsPatients included 7,312 men and women from NHANES III and 14,825 men and women from the ARIC study.InterventionsSerum 25-hydroxyvitamin D, total and ionized calcium, and inorganic phosphorus were measured in NHANES III, and serum total calcium and inorganic phosphorus were measured in ARIC.Main outcome measureQT interval duration was obtained from standard 12-lead electrocardiograms.ResultsIn NHANES III, the multivariate adjusted differences in average QT interval duration comparing the highest vs. the lowest quartiles of serum total calcium, ionized calcium, and phosphorus were -3.6 msec (-5.8 to -1.3; P for trend = 0.005), -5.4 msec (-7.4 to -3.5; P for trend <0.001), and 3.9 msec (2.0-5.9; P for trend <0.001), respectively. The corresponding differences in ARIC were -3.1 msec (-4.3 to -2.0; P for trend <0.001), -2.9 msec (-3.8 to -1.9; P for trend <0.001), and 2.3 msec (1.3-3.3; P for trend <0.001). No association was found between 25-hydroxyvitamin D concentrations and QT interval duration.ConclusionsIn two large samples of the general population, QT interval duration was inversely associated with the serum total and ionized calcium and positively associated with serum phosphorus.

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