BACKGROUND: 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. METHODS: NGAL was assayed using an immunoassay (ARCHITECT). Urine flowcytometry was performed with the UF-1000i (Sysmex). RESULTS: 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. CONCLUSIONS: 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).
BACKGROUND: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. METHODS:NGAL was assayed using an immunoassay (ARCHITECT). Urine flowcytometry was performed with the UF-1000i (Sysmex). RESULTS: 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. CONCLUSIONS: 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).
Authors: Magnus Steigedal; Anne Marstad; Markus Haug; Jan K Damås; Roland K Strong; Pacita L Roberts; Stephanie D Himpsl; Ann Stapleton; Thomas M Hooton; Harry L T Mobley; Thomas R Hawn; Trude H Flo Journal: J Immunol Date: 2014-11-14 Impact factor: 5.422
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Authors: Adriano César Carneiro Loureiro; Gabriella Fontenele Nocrato; André Luis Lima Correia; Robson Salviano de Matos; Júlio César Chaves Nunes Filho; Elisabeth De Francesco Daher; Flávio Henrique Macedo Pinto; Ariclécio Cunha de Oliveira; Vania Marilande Ceccatto; Rodrigo Soares Fortunato; Denise Pires de Carvalho Journal: Front Physiol Date: 2022-03-17 Impact factor: 4.566
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