Barltrop D, Mole R H, Sutton A
Arch Dis Child. 1977 Jan;52(1):41-9. doi: 10.1136/adc.52.1.41.
Low birthweight infants aged 4-41 days were given from birth one of three experimental milk formulae varying widely in content of calcium and phosphate. Ca and P in feed, urine, and faeces were measured between carmine markers corresponding to a metabolic period of 48 hours. Calcium enriched in 46Ca to provide a marker for the dietary Ca was added to one feed and 46Ca measured in urine and faeces. True absorption of Ca and endogenous excretion into the bowel could then be inferred. True absorption of Ca was proportional to Ca intake and independent of P intake. Endogenous faecal excretion seemed to be independent of both Ca P intakes, and varied widely between different infants in the range 4-150 mg/day. Urine Ca was low and retention was essentially the difference between true absorption and endogenous faecal excretion. Retention of Ca tended to be much greater on a high Ca intake, but the variability in retention between infants on a given intake was large, paralleling the variability in endogenous faecal excretion. The variability in plasma Ca concentrations in newborn infants may in part be a consequence of wide individual variability in endogenous faecal excretion. The 46Ca marker technique provides a means of investigating the factors determining this variability.
对年龄在4至41天的低体重婴儿从出生起就喂食三种实验性奶粉中的一种，这三种奶粉的钙和磷含量差异很大。在对应48小时代谢期的胭脂红标记物之间测量饲料、尿液和粪便中的钙和磷。向一种饲料中添加用46Ca富集的钙作为膳食钙的标记物，并测量尿液和粪便中的46Ca。然后可以推断出钙的真实吸收率和肠道内的内源性排泄量。钙的真实吸收率与钙摄入量成正比，与磷摄入量无关。内源性粪便排泄似乎与钙和磷的摄入量均无关，且在不同婴儿之间差异很大，范围在4至150毫克/天。尿钙含量低，钙潴留基本上是真实吸收率与内源性粪便排泄量之间的差值。高钙摄入量时钙潴留往往要大得多，但给定摄入量的婴儿之间钙潴留的变异性很大，这与内源性粪便排泄的变异性相似。新生儿血浆钙浓度的变异性部分可能是内源性粪便排泄个体差异较大的结果。46Ca标记技术提供了一种研究决定这种变异性的因素的方法。
