Mackenzie T A, Clark N G, Bistrian B R, Flatt J P, Hallowell E M, Blackburn G L
J Am Coll Nutr. 1985;4(5):575-81. doi: 10.1080/07315724.1985.10720100.
Total urinary nitrogen (TUN) and urinary urea nitrogen (UUN) in a 24-hour urine collection were measured under a variety of clinical and nutritional conditions in 81 patients for 564 study days. The difference between TUN and UUN averaged 1.8 +/- 0.9 g/day (range 0.0-5.8 g/day) and was independent of the absolute value for UUN. Since UUN was found to correlate linearly with TUN (R = 0.98) over a wide range of values, it is possible to estimate an approximate TUN excretion by adding a constant to the nitrogen excreted as urea. On the basis of the measured mean difference, we suggest using an estimate of 2 g of nitrogen per day. We feel this will not seriously under- or overestimate urinary nitrogen excretion in the calculation of nitrogen balance for the clinical management of nutritional support therapies. Since all hospitals can perform this routine test, it provides an effective, simple, and rapid method to follow accurately the protein catabolic response during disease and response to nutritional therapy. This method, without the supporting data presented here, has previously been recommended [Blackburn et al, 1977, JPEN 1:11-22] and has become a widely used technique for nutritional assessment.
在564个研究日里，对81例患者在各种临床和营养状况下进行了24小时尿样收集，测量其中的总尿氮（TUN）和尿尿素氮（UUN）。TUN与UUN的差值平均为1.8±0.9克/天（范围为0.0 - 5.8克/天），且与UUN的绝对值无关。由于发现UUN在很宽的值范围内与TUN呈线性相关（R = 0.98），所以通过给以尿素形式排泄的氮加上一个常数，就有可能估算出大致的TUN排泄量。基于所测得的平均差值，我们建议每天使用2克氮的估算值。我们认为，在计算营养支持疗法临床管理中的氮平衡时，这不会严重低估或高估尿氮排泄量。由于所有医院都能进行这项常规检测，它提供了一种有效、简单且快速的方法，能准确跟踪疾病期间的蛋白质分解代谢反应以及对营养疗法的反应。此前，在没有这里所呈现的支持数据的情况下，这种方法就已被推荐过[布莱克本等人，1977年，《肠外与肠内营养杂志》1:11 - 22]，并且已成为一种广泛用于营养评估的技术。
