Abrams S A, Wen J P
USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine and Texas Children's Hospital, Houston 77030-2600, USA.
J Am Coll Nutr. 1999 Feb;18(1):30-5. doi: 10.1080/07315724.1999.10718824.
To provide methodological information regarding the absorption and excretion of dietary magnesium by children and adolescents.
Recently, stable isotope techniques for assessing magnesium absorption and excretion have been developed which allow for these studies to be safely performed in subjects of all ages. In the report, we describe the dosing and sample requirements for such studies.
Our data demonstrate that, after oral and intravenous dosing of isotopes, a complete 72-hour urine collection will allow for determination of fractional magnesium absorption. In our study, urinary, but not endogenous fecal magnesium excretion, was closely correlated with magnesium intake (r = 0.47, p = 0.02 vs r = 0.08, p = 0.69). As endogenous fecal magnesium excretion is small relative to urinary magnesium excretion, measurement of endogenous fecal magnesium excretion is not needed to make a reasonable estimate of net magnesium retention for most studies. Using high-precision analytical techniques, an intravenous dose of 25Mg of approximately 0.2 to 0.3 mg/kg would be adequate for absorption measurements.
The cost and availability of isotopes and their analysis are such that it should be feasible for increasing numbers of investigators to make use of these techniques.
提供有关儿童和青少年膳食镁吸收与排泄的方法学信息。
最近，已开发出用于评估镁吸收和排泄的稳定同位素技术，这使得这些研究能够在所有年龄段的受试者中安全进行。在本报告中，我们描述了此类研究的给药和样本要求。
我们的数据表明，经口服和静脉注射同位素后，完整收集72小时尿液将有助于测定镁的吸收分数。在我们的研究中，尿镁排泄量与镁摄入量密切相关（r = 0.47，p = 0.02），而内源性粪便镁排泄量与镁摄入量无明显相关性（r = 0.08，p = 0.69）。由于相对于尿镁排泄量而言，内源性粪便镁排泄量较少，因此在大多数研究中，无需测量内源性粪便镁排泄量即可合理估算镁的净潴留量。使用高精度分析技术，静脉注射约0.2至0.3 mg/kg的25Mg足以进行吸收测量。
同位素及其分析的成本和可获得性使得越来越多的研究人员使用这些技术应是可行的。
