Iyengar A K, Narasinga Rao B S
Am J Clin Nutr. 1982 Apr;35(4):733-40. doi: 10.1093/ajcn/35.4.733.
Three biochemical parameters of protein metabolism, i.e., urea index, urinary 3-methyl histidine, and urinary hydroxyproline, were studied in preschool children fed varying levels of protein and energy. The effect of varying protein and energy intakes on urinary 3-methyl histidine was also studied in adults. Varying protein and energy intakes had no significant effect on urea index and urinary 3-methyl histidine excretion as long as positive nitrogen balance was maintained. However, these two parameters decreased only when intakes of protein and energy were below maintenance levels, which resulted in a negative nitrogen balance. Urea index and urinary 3-methyl histidine excretion can be used therefore as an index to identify those malnourished children whose protein and/or energy intakes are grossly inadequate, resulting in negative nitrogen balance. Hydroxyproline excretion was responsive to alterations in protein intakes rather than to changes in energy intakes and the alteration in its excretion was small for large changes in protein intakes.
对摄入不同水平蛋白质和能量的学龄前儿童，研究了蛋白质代谢的三个生化参数，即尿素指数、尿3-甲基组氨酸和尿羟脯氨酸。还在成年人中研究了不同蛋白质和能量摄入量对尿3-甲基组氨酸的影响。只要维持正氮平衡，不同的蛋白质和能量摄入量对尿素指数和尿3-甲基组氨酸排泄没有显著影响。然而，只有当蛋白质和能量摄入量低于维持水平，导致负氮平衡时，这两个参数才会降低。因此，尿素指数和尿3-甲基组氨酸排泄可用作指标，以识别那些蛋白质和/或能量摄入严重不足、导致负氮平衡的营养不良儿童。羟脯氨酸排泄对蛋白质摄入量的变化有反应，而不是对能量摄入量的变化有反应，并且蛋白质摄入量的大幅变化对其排泄的影响很小。
