Christchurch Kidney Research Group, Department of Medicine, University of Otago, Christchurch, New Zealand.
J Am Soc Nephrol. 2012 Feb;23(2):322-33. doi: 10.1681/ASN.2011040325. Epub 2011 Nov 17.
The concentration of urine influences the concentration of urinary biomarkers of AKI. Whether normalization to urinary creatinine concentration, as commonly performed to quantitate albuminuria, is the best method to account for variations in urinary biomarker concentration among patients in the intensive care unit is unknown. Here, we compared the diagnostic and prognostic performance of three methods of biomarker quantitation: absolute concentration, biomarker normalized to urinary creatinine concentration, and biomarker excretion rate. We measured urinary concentrations of alkaline phosphatase, γ-glutamyl transpeptidase, cystatin C, neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, and IL-18 in 528 patients on admission and after 12 and 24 hours. Absolute concentration best diagnosed AKI on admission, but normalized concentrations best predicted death, dialysis, or subsequent development of AKI. Excretion rate on admission did not diagnose or predict outcomes better than either absolute or normalized concentration. Estimated 24-hour biomarker excretion associated with AKI severity, and for neutrophil gelatinase-associated lipocalin and cystatin C, with poorer survival. In summary, normalization to urinary creatinine concentration improves the prediction of incipient AKI and outcome but provides no advantage in diagnosing established AKI. The ideal method for quantitating biomarkers of urinary AKI depends on the outcome of interest.
尿液浓度会影响急性肾损伤（AKI）尿液生物标志物的浓度。在重症监护病房中，是否将生物标志物浓度标准化为尿肌酐浓度（通常用于定量白蛋白尿）以解释患者之间尿液生物标志物浓度的变化，目前尚不清楚。在这里，我们比较了三种生物标志物定量方法的诊断和预后性能：绝对浓度、以尿肌酐浓度标准化的生物标志物和生物标志物排泄率。我们在 528 名入院患者以及入院后 12 小时和 24 小时测量了碱性磷酸酶、γ-谷氨酰转肽酶、胱抑素 C、中性粒细胞明胶酶相关脂质运载蛋白、肾损伤分子-1 和白细胞介素-18 的尿液浓度。入院时的绝对浓度最能诊断 AKI，但标准化浓度最能预测死亡、透析或随后发生 AKI。入院时的排泄率在诊断或预测结果方面并不优于绝对浓度或标准化浓度。估计 24 小时生物标志物排泄与 AKI 严重程度相关，与中性粒细胞明胶酶相关脂质运载蛋白和胱抑素 C 相关，与较差的生存率相关。总之，标准化为尿肌酐浓度可改善新发 AKI 及预后的预测，但在诊断已确诊 AKI 方面没有优势。用于定量尿液 AKI 生物标志物的理想方法取决于感兴趣的结果。
