Department of Clinical Chemistry, Ghent University Hospital, Ghent, Belgium.
Clin Chem Lab Med. 2011 Jun;49(6):999-1003. doi: 10.1515/CCLM.2011.156. Epub 2011 Mar 11.
Neutrophil gelatinase associated lipocalin (NGAL) is a protein present in neutrophils. NGAL is a promising biomarker for acute kidney injury. In urinary tract infections, urinary neutrophils can be a potential source of urinary NGAL. We investigated the effects of urinary tract infection and urinary neutrophil counts on urinary NGAL values.
NGAL was assayed using an immunoassay (ARCHITECT). Urine flowcytometry was performed with the UF-1000i (Sysmex).
A correlation between the urinary white blood cell (WBC) count and NGAL concentrations was observed: log(Y) (NGAL, μg/L)=1.284+0.439 log(X) (urinary WBC, 10(9) cells/L); r=0.518. Similarly, the bacterial count correlated weakly with NGAL: log(Y) (NGAL, μg/L)=1.796+0.124 log(X) (bacterial count, 10(9) cells/L); r=0.243. Albuminuria correlated moderately with NGAL values: log(Y) (NGAL, μg/L)=1.557+0.339 log(X) (albuminuria, mg/L); r=0.368; α(1)-microglobulin (a1M) correlated weakly with NGAL: log(Y) (NGAL, μg/L)=1.631+0.360 log(X) (a1M, mg/L); r=0.381.
Leukocyte contributions to urinary NGAL concentrations can be important. In leukocyturia or tubular damage (e.g., intensive care patients), using a fixed cut-off value for interpreting urinary NGAL data can lead to false positive results. Therefore, we suggest a mathematical correction in cases with pyuria (>100×10(9) cells/L) and urinary NGAL concentration >100 μg/L: corrected NGAL (μg/L)=NGAL-0.12 (urinary WBC, 10(9) cells/L).
中性粒细胞明胶酶相关脂质运载蛋白（NGAL）是存在于中性粒细胞中的一种蛋白质。NGAL 是急性肾损伤的一种很有前途的生物标志物。在尿路感染中，尿中性粒细胞可能是尿 NGAL 的潜在来源。我们研究了尿路感染和尿中性粒细胞计数对尿 NGAL 值的影响。
使用免疫测定法（ARCHITECT）测定 NGAL。使用 UF-1000i（Sysmex）进行尿流式细胞术。
观察到尿白细胞计数（WBC）与 NGAL 浓度之间存在相关性：log(Y)（NGAL，μg/L）=1.284+0.439 log(X)（尿 WBC，10(9) 细胞/L）；r=0.518。同样，细菌计数与 NGAL 呈弱相关：log(Y)（NGAL，μg/L）=1.796+0.124 log(X)（细菌计数，10(9) 细胞/L）；r=0.243。蛋白尿与 NGAL 值中度相关：log(Y)（NGAL，μg/L）=1.557+0.339 log(X)（蛋白尿，mg/L）；r=0.368；α(1)-微球蛋白（a1M）与 NGAL 呈弱相关：log(Y)（NGAL，μg/L）=1.631+0.360 log(X)（a1M，mg/L）；r=0.381。
白细胞对尿 NGAL 浓度的贡献可能很重要。在白细胞尿或肾小管损伤（例如，重症监护患者）中，使用固定的截断值来解释尿 NGAL 数据可能会导致假阳性结果。因此，我们建议在脓尿（>100×10(9) 细胞/L）和尿 NGAL 浓度>100μg/L 时对其进行数学校正：校正后的 NGAL（μg/L）=NGAL-0.12（尿 WBC，10(9) 细胞/L）。
