Researchers from Columbia University in New York City have identified the new biomarker urinary neutrophil gelatinase-associated lipocalin (uNGAL) that has a substantial accuracy to identify febrile infants and young children with and without urinary tract infections (UTIs). The study was reported in the journal Pediatrics.

Dr Tamar Lubell and his associates conducted a prospective cross-sectional study of 84 infants younger than three months old with a fever of at least 38.0 degrees Celsius and 176 children 3 to 24 months old with a fever of at least 39.0 degrees Celsius.

The team evaluated the participants for UTIs. The researchers obtained uNGAL levels, urinalysis, Gram-stain and culture. Median uNGAL levels were successively higher in children with no UTI (negative urine culture), possible UTI and definite UTI.

The median uNGAL level was 215.1 ng/mL in the UTI group compared with 4.4 ng/mL in the culture-negative group. The differences were seen in boys and girls. The uNGAL area under the receiver-operating characteristic curve for diagnosis of UTI was 0.978.

At a threshold of 39.l ng/mL, uNGAL testing had 97.1% sensitivity and 95.6% specificity for UTI, with slightly higher sensitivity and specificity in infants 0 to 3 months (100% and 97.2%) compared to older children (95.5% and 94.8%), although with wide confidence intervals.

The research team noted that uNGAL had higher sensitivity than Gram-stain and urinalysis for leukocyte esterase and nitrite, with similar specificity. Prior studies in animals and humans have uniformly found that uNGAL levels increase significantly in response to UTI.

Previous studies have also revealed that the expression of uNGAL temporally correlates with the inciting stimulus (e.g., bacteria), that it responds in a quantitative fashion to the bacterial load, and that it quickly reverses with a resolution of infection.

The study findings suggested that urinary neutrophil gelatinase-associated lipocalin (uNGAL) has a role in the diagnosis of urinary tract infections (UTIs), the researchers said. Further studies are required to confirm the study findings and determine if uNGAL is a more cost-effective test than standard screening tests, they concluded.