Urine tests predict early onset NEC

Researchers have found that simple tests for levels of alanine and histidine in newborns’ urine can predict abnormal levels of gut bacteria before the onset of necrotizing enterocolitis (NEC).

In a study of 35 preterm infants born before 29 weeks at Cincinnati Children’s Hospital Medical Center, Ohio, 11 babies developed NEC. Stool samples from those diagnosed with NEC showed a lower diversity of gut organisms between 4 and 9 days after birth. Babies whose NEC started between 7 and 12 days after birth had high levels of Firmicutes (gram positive). Those with NEC that began between 19 and 39 days had high levels of Proteobacteria (gram negative). All babies with NEC lacked the Propionibacterium found in healthy infants compared with only 25% of the controls.

Analysis of urine samples taken from days 4 to 9 found no metabolites associated with all cases of NEC, however alanine was positively associated with NEC cases preceded by Firmicutes and histidine was inversely associated with NEC cases preceded by Proteobacteria. A high urinary alanine-to-histidine ratio had a 78% predictive value for overall NEC.

Necrotizing enterocolitis is an intestinal disease that affects 10% of extremely preterm infants. Nearly a third of these babies will die. Studies have shown that early colonization of gut bacteria shapes infants’ developing immune systems, which could be a factor in the pathobiology leading to onset of NEC.

The researchers say that despite its small sample size, their study identifies noninvasive biomarkers that together are highly predictive of NEC in preterm infants.