Loder P B, Kee A J, Horsburgh R, Jones M, Smith R C
University Department of Surgery, Royal North Shore Hospital, Sydney, Australia.
Crit Care Med. 1989 Apr;17(4):309-12. doi: 10.1097/00003246-198904000-00002.
The validity of the urinary urea nitrogen (UUN) estimate of total urinary nitrogen (TUN) was tested in patients who required iv nutrition. UUN and TUN were determined in 120 urine collections from ten preoperative, 13 postoperative, and 11 stressed patients. The relationship between TUN and UUN was examined by linear regression, and analysis of covariance was used on log-transformed data to assess differences between the patient groups. Although there was a close relationship between UUN and TUN for the preoperative patients (r2 = .94, total range of differences = 3.85 g N), this was not as accurate in postoperative and stressed patients (r2 = .69 and .76, respectively, total range of differences = 16.8 and 10.7 g N, respectively). There was no significant difference between the slopes of the regression lines for the relationship between UUN and TUN for three groups (f = 1.1, df = 2114, p less than .3), but the intercepts of the regression lines differed between the preoperative and stressed patient groups (t = 3.47, v = 114, p less than .001). The relationship between TUN and UUN for the whole group was improved by the inclusion of the independent variables of both the patient's clinical state and the urinary creatinine excretion. Arm muscle circumference, which is an estimate of muscle mass, may replace creatinine excretion with little loss in prediction accuracy.
在需要静脉营养的患者中测试了用尿尿素氮（UUN）估算总尿氮（TUN）的有效性。对10例术前患者、13例术后患者和11例应激患者的120份尿液样本进行了UUN和TUN测定。通过线性回归研究TUN与UUN之间的关系，并对对数转换数据进行协方差分析以评估患者组之间的差异。虽然术前患者的UUN与TUN之间存在密切关系（r2 = 0.94，差异总范围 = 3.85 g氮），但在术后和应激患者中这种关系并不那么准确（r2分别为0.69和0.76，差异总范围分别为16.8和10.7 g氮）。三组UUN与TUN关系的回归线斜率之间无显著差异（F = 1.1，自由度 = 2 114，P < 0.3），但术前和应激患者组的回归线截距不同（t = 3.47，v = 114，P < 0.001）。纳入患者临床状态和尿肌酐排泄这两个自变量后，全组TUN与UUN之间的关系得到改善。作为肌肉量估算指标的上臂肌肉周长，在预测准确性损失很小的情况下可替代肌酐排泄。
