Urinary intestinal fatty acid-binding protein concentration predicts extent of disease in necrotizing enterocolitis

Urinary intestinal fatty acid-binding protein (i-FABP), a marker of intestinal mucosal cell damage, has recently been proposed as a clinically useful measure in the early detection of necrotizing enterocolitis (NEC). However, there are no data on urinary i-FABP in more advanced (Bell stage II /III) NEC. The aim of this study was to test the use of urinary i-FABP in surgical NEC.

Urine was collected every 24 hours from infants with Bell stage II/III NEC admitted to a surgical Neonatal Intensive Care Unit. Clinical, laboratory, and surgical data were collected concurrently. Urinary i-FABP was quantified by enzyme-linked immunosorbent assay and expressed as picograms per nanomole creatinine (median [range]). Results are presented as median (range) and compared by Mann-Whitney test and by linear regression.

There was a trend toward an increase in i-FABP:Cr in infants with NEC (controls, 1.0 [0.4-1.3], vs NEC, 2.1 [0.39-35.1], P = .055). Urinary i-FABP:Cr was significantly higher in infants with extensive disease (7.4 pg/mmol [2.1-35.0 pg/mmol]) than in those with focal disease (1.1 pg/mmol [0.3-1.7 pg/mmol]), P = .002. In addition, i-FABP:Cr was less than the previously suggested 2 pg/mmol cutoff in 6 of 16 infants with NEC, 5 of whom had focal disease. Urinary i-FABP:Cr decreased during both successful nonoperative management (P < .0001) and after surgery in the operated group.

In this pilot study, urinary i-FABP was associated with extensive disease in infants with NEC requiring surgery. Further work, in a larger number of patients, is required to investigate the applicability of urinary i-FABP as a marker of intestinal damage and as an adjunct to current indications for surgical intervention in infants with NEC.