Bingham S A, Cummings J H
Am J Clin Nutr. 1985 Dec;42(6):1276-89. doi: 10.1093/ajcn/42.6.1276.
In order to determine the value of 24 h urine nitrogen (N) excretion as a way of validating dietary methods of measuring protein intake in individuals, daily N intake and excretion has been measured in eight healthy subjects while consuming their usual, varying, diets for 28 days. Daily duplicates of all food eaten were obtained and consecutive 24 h collections of urine and feces were made throughout and analyzed for N by the Kjeldahl method. The completeness of the 24 h urine collections was verified by the use of PABA and of feces by radiopaque pellets. N losses in blood and from the skin were measured. The within person variation in dietary intake ranged from 14 to 26% (coefficient of variation, CV) while urine N was more constant, varying from 11 to 18% (CV) within individuals. In these subjects eight 24 h urine collections, verified for their completeness, were sufficient to estimate dietary N intake to within 81 +/- 5% (SD) as assessed by 18 day dietary records.
为了确定24小时尿氮（N）排泄量作为验证个体蛋白质摄入量膳食测量方法的一种价值，在8名健康受试者按照其日常不同饮食进食28天的过程中，对其每日氮摄入量和排泄量进行了测量。获取了所有所吃食物的每日双份样本，并在整个期间连续收集24小时尿液和粪便，采用凯氏定氮法对其中的氮进行分析。通过使用对氨基苯甲酸验证24小时尿液收集的完整性，通过不透射线的药丸验证粪便收集的完整性。测量了血液和皮肤中的氮损失。个体膳食摄入量的个体内变异范围为14%至26%（变异系数，CV），而尿氮更为稳定，个体内变异范围为11%至18%（CV）。在这些受试者中，经完整性验证的8次24小时尿液收集足以将膳食氮摄入量估计在18天膳食记录所评估的81±5%（标准差）范围内。
