Should kidney tubular markers be adjusted for urine creatinine? The example of urinary cystatin C
Should kidney tubular markers be adjusted for urine creatinine? The example of urinary cystatin C
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DOI：
10.1515/cclm.2009.341
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发表时间：
2009-12-01
影响因子：
6.8
通讯作者：
Loric, Sylvain
中科院分区：
文献类型：
--
作者：
Conti, Marc;Moutereau, Stephane;Loric, Sylvain
背景：与尿肌酐（uCreat）相关的特异性尿标志物的评价是常见的。然而，由于uCreat是肾小球滤过和肾小管分泌两者的函数，使用uCreat作为特定的肾小管标记物表明肾小球功能正常，并且没有肾小管分泌。因此，调整值的任何管标记uCreat，特别是在急性或甚至中度慢性肾功能衰竭的患者，可以是missibly.Methods：使用尿胱抑素-C（uCST 3）作为模型以下120个肾移植受体每天的管标记，我们评估的效用，无论是uCST 3单独或uCST 3/uCreat比检测肾小管损伤。所有阳性肾活检总是与uCST 3>0.18 mg/L相关。结果：使用uCST 3/uCreat比率，在9名患者中观察到活检状态的差异（4个假阳性，5个假阴性结果）。在2例患者中，uCreat的变异性似乎是导致uCST 3/uCreat比值不一致的最重要因素。uCST 3/uCreat的阴性预测值（NPV）为85.7%，可能导致临床解读错误。这些错误是可以避免的，当估计肾小管损伤的uCST 3浓度单独的基础上（NPVs100%）。结论：我们建议使用uCST 3值来评估肾小管损伤的程度。事实上，我们对uCST 3/uCreat的相互矛盾的结果可以扩展到每一个肾小管功能的标志物。将对肾小管损伤具有特异性的尿液标记物评价为本身强烈依赖于肾小球或其他肾脏或非肾脏疾病的第二尿液标记物，会损害其临床相关性，并可能导致不正确的解释。当测量肾小球功能的特异性标志物时（即，尿白蛋白）。在所有其他肾脏疾病的情况下，这种矫正是不合适的，应该避免。临床化学实验室医学2009;47：1553-6
Background: Evaluation of specific urinary markers with respect to urine creatinine (uCreat) is common. However, as uCreat is a function of both glomerular filtration and tubular secretion, using uCreat for specific tubular markers, suggests that glomerular function is normal, and there is no tubular secretion. Thus, adjusting values of any tubular marker to uCreat, especially in patients with acute or even moderate chronic renal failure, can be misleading.Methods: Using urine cystatin-C (uCST3) as a model tubular marker for following 120 kidney graft recipients daily, we evaluated the utility of either uCST3 alone or the uCST3/uCreat ratio to detect tubular damage. All positive kidney biopsies were always associated with a uCST3>0.18 mg/L.Results: Using the uCST3/uCreat ratio, discrepancies regarding biopsy status were observed in nine patients (4 false positive, 5 false negative results). In two patients, variability of uCreat appeared to be the most important factor causing inconsistent uCST3/uCreat ratios. With a negative predictive value (NPV) of 85.7%, uCST3/uCreat can lead to errors in clinical interpretation. These errors can be avoided when estimates of tubular damage are based on uCST3 concentrations alone (NPVs100%).Conclusions: We recommend using the uCST3 value to evaluate the extent of renal tubular damage. Indeed, our conflicting results on uCST3/uCreat can be extended to every marker of tubular function. Evaluating a urine marker specific for renal tubular damage to a second urine marker that is itself strongly dependent upon glomerular or other renal or non-renal conditions, impairs its clinical relevance and may lead to incorrect interpretations. Correction with uCreat can be performed only in pure glomerulopathy, when specific markers of glomerular function are measured (i.e., urinary albumin). In all other cases of renal diseases, such correction is inappropriate and should be avoided. Clin Chem Lab Med 2009;47:1553-6