Intestinal fatty acid-binding protein as a diagnostic marker for complicated and uncomplicated necrotizing enterocolitis: a prospective cohort study.

BACKGROUND: Early NEC symptoms are non-specific and diagnostic tests lack discriminative power. Intestinal fatty acid-binding protein (I-FABP), mainly located in small bowel enterocytes, is released into the blood following NEC-associated enterocyte disruption. Aim of this prospective cohort trial was to determine the diagnostic value of I-FABP measured in plasma (I-FABPp) and urine (I-FABPu) for the presence of NEC, to evaluate I-FABP levels during NEC development, and to assess its prognostic value for the progression from suspected to complicated disease. METHODS: Between 2010 and 2012 we prospectively enrolled neonates with suspected NEC. We measured I-FABP levels eight-hourly from onset of suspected NEC for at least 48 hours, or until surgery. NEC diagnosis was confirmed radiologically or during operation. We defined NEC as complicated if it resulted in surgery and/or death. We determined disease course and diagnostic I-FABP cut-off points. RESULTS: The study comprised 37 neonates (24M, 13F), gestational age 28 (24-36) weeks, birth weight 1190 (570-2,400) grams. We found significantly higher I-FABPp and I-FABPu levels in NEC patients (n = 22) than in patients with other diagnoses (n = 15). Cut-off values for diagnosing NEC were 9 ng/mL I-FABPp and 218 ng/mL I-FABPu, with corresponding likelihood ratios (LRs) of 5.6 (95% CI 0.89-35) and 5.1 (95% CI 0.73-36), respectively. I-FABP levels were highest in the first eight hours after symptom onset and gradually decreased over time. Cut-off values for complicated disease were 19 ng/mL I-FABPp and 232 ng/mL I-FABPu, with LRs of 10 (95% CI 1.6-70) and 11 (95% CI 1.6-81), respectively. CONCLUSIONS: Both plasma and urinary I-FABP levels specifically identify NEC in preterm infants prior to appearance of diagnostic radiological signs suggestive for NEC. Moreover, serial I-FABP measurements accurately predict development of complicated disease.

Intestinal fatty acid-binding protein in neonates with imminent necrotizing enterocolitis.

BACKGROUND: Intestinal fatty acid-binding protein (I-FABP) is a promising marker for necrotizing enterocolitis (NEC). It can be measured in plasma (I-FABPp) and urine (I-FABPu). Data on the best way to measure I-FABP (in plasma or urine) and the necessity of simultaneous measurement of the urinary creatinine concentration to correct for physiological variations in urine concentration are not available. This holds also true for the reciprocal relation between I-FABPp, I-FABPu and other more conventional laboratory parameters. OBJECTIVES: To evaluate the above-mentioned correlations of I-FABP measurements in neonates with suspected NEC. METHODS: All neonates with suspected NEC were prospectively included. I-FABPp and I-FABPu were analyzed at regular intervals during the first 24 h after onset of symptoms. Correlation and agreement were assessed between these and other parameters (i.e., IL-6, WBC, platelet count, CRP, pH and lactate). RESULTS: Included were 24 boys, 13 girls [median (range) GA 28 weeks (24-36), median birth weight 1,190 g (570-2,400)]. I-FABPu correlated strongly with I-FABPp (r 0.80, p < 0.001) with an adequate agreement. A very strong correlation between I-FABPu and I-FABPu/urine creatinine ratio (r 0.98, p < 0.001) existed. Correlations between I-FABPp/u and conventional parameters were moderate to strong until 8 h after onset of symptoms. CONCLUSION: In neonates with suspected NEC, I-FABPu correlates strongly with I-FABPp, offering an opportunity to choose the most appropriate way of measuring I-FABP. Calculating urinary IFABP/creatinine ratio seems redundant. Moderately strong correlations between I-FABPu and IL-6, WBC and lactate were found.