Increased urinary neutrophil gelatinase associated lipocalin in urinary tract infections and leukocyturia.

Abstract

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: An-Sofie C Decavele, Lien Dhondt, Marc L De Buyzere, Joris R Delanghe
• Journal: Clinical chemistry and laboratory medicine (Clin Chem Lab Med) Vol. 49 Issue 6 Pg. 999-1003 (Jun 2011) ISSN: 1437-4331 [Electronic] Germany
• PMID: 21391867 (Publication Type: Journal Article)

Chemical References

• Acute-Phase Proteins
• LCN2 protein, human
• Lipocalin-2
• Lipocalins
• Proto-Oncogene Proteins

Topics

• Acute-Phase Proteins (urine)
• Adult
• Aged
• Culture Techniques
• False Positive Reactions
• Female
• Humans
• Leukocytes (metabolism)
• Lipocalin-2
• Lipocalins (urine)
• Male
• Middle Aged
• Proteinuria (urine)
• Proto-Oncogene Proteins (urine)
• Urinary Tract Infections (blood, microbiology, urine)