Thacher Tom D, Obadofin Michael O, O'Brien Kimberly O, Abrams Steven A
Department of Family Medicine, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA.
J Clin Endocrinol Metab. 2009 Sep;94(9):3314-21. doi: 10.1210/jc.2009-0018. Epub 2009 Jun 30.
Children with calcium-deficiency rickets have high 1,25-dihydroxyvitamin D values.
The objective of the study was to determine whether vitamin D increased calcium absorption.
This was an experimental study.
The study was conducted at a teaching hospital.
Participants included 17 children with nutritional rickets.
The participants were randomized to 1.25 mg oral vitamin D(3) (n = 8) or vitamin D(2) (n = 9).
Fractional calcium absorption 3 da after vitamin D administration was measured.
Mean baseline 25-hydroxyvitamin D concentrations were 20 ng/ml (range 5-31 ng/ml). The increase in 25-hydroxyvitamin D was equivalent after vitamin D(3) (29 +/- 10 ng/ml) or vitamin D(2) (29 +/- 17 ng/ml). Mean 1,25-dihydroxyvitamin D values increased from 143 +/- 76 pg/ml to 243 +/- 102 pg/ml (P = 0.001), and the increase in 1,25-dihydroxyvitamin D did not differ between vitamin D(2) and vitamin D(3) (107 +/- 110 and 91 +/- 102 ng/ml, respectively). The increment in 1,25-dihydroxyvitamin D was explained almost entirely by the baseline 25-hydroxyvitamin D concentration (r(2) = 0.72; P < 0.001). Mean fractional calcium absorption did not differ before (52.6 +/- 21.4%) or after (53.2 +/- 23.5%) vitamin D, and effects of vitamin D(2) and vitamin D(3) on calcium absorption were not significantly different. Fractional calcium absorption was not closely related to concentrations of 25-hydroxyvitamin D (r = 0.01, P = 0.93) or 1,25-dihydroxyvitamin D (r = 0.21, P = 0.24). The effect of vitamin D on calcium absorption did not vary with baseline 25-hydroxyvitamin D values or with the absolute increase in 25-hydroxyvitamin D or 1,25-dihydroxyvitamin D values.
Despite similar increases in 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D with vitamin D(2) or vitamin D(3), fractional calcium absorption did not increase, indicating that rickets in Nigerian children is not primarily due to vitamin D-deficient calcium malabsorption.
患有缺钙性佝偻病的儿童1,25 - 二羟维生素D值较高。
本研究的目的是确定维生素D是否能增加钙的吸收。
这是一项实验性研究。
该研究在一家教学医院进行。
参与者包括17名患有营养性佝偻病的儿童。
参与者被随机分为口服1.25毫克维生素D3组（n = 8）或维生素D2组（n = 9）。
测量维生素D给药后3天的钙吸收分数。
25 - 羟维生素D的平均基线浓度为20纳克/毫升（范围为5 - 31纳克/毫升）。维生素D3组（29±10纳克/毫升）和维生素D2组（29±17纳克/毫升）给药后25 - 羟维生素D的升高幅度相当。1,25 - 二羟维生素D的平均值从143±76皮克/毫升增加到243±102皮克/毫升（P = 0.001），维生素D2组和维生素D3组1,25 - 二羟维生素D的升高幅度无差异（分别为107±110和91±102纳克/毫升）。1,25 - 二羟维生素D的增加几乎完全由基线25 - 羟维生素D浓度所解释（r² = 0.72；P < 0.001）。维生素D给药前后的平均钙吸收分数无差异（分别为52.6±21.4%和53.2±23.5%），维生素D2组和维生素D3组对钙吸收的影响无显著差异。钙吸收分数与25 - 羟维生素D浓度（r = 0.01，P = 0.93）或1,25 - 二羟维生素D浓度（r = 0.21，P = 0.24）无密切关系。维生素D对钙吸收的影响不随基线25 - 羟维生素D值、25 - 羟维生素D或1,25 - 二羟维生素D值的绝对增加而变化。
尽管维生素D2或维生素D3使25 - 羟维生素D和1,25 - 二羟维生素D有相似的升高，但钙吸收分数并未增加，这表明尼日利亚儿童的佝偻病并非主要由维生素D缺乏导致的钙吸收不良引起。
