Potential of intestinal fatty acid-binding protein in assessing enteral tolerance in neonates of different gestational ages: A cross-sectional cohort study
Authors: Bavykina I. A. , Berdnikov A. A. , Zvyagin A. A. , Kubyshkina A. V. , Barannikov S. V. 
Published: February 2025

Background. Functional gastrointestinal disorders are highly prevalent among young children and pose a significant burden on outpatient healthcare services. Functional disorders of the gastrointestinal tract may be caused by increased intestinal permeability. Markers characterizing the transcellular pathway are currently being studied. Intestinal fatty acid-binding protein (I-FABP) serves as a marker of intestinal mucosal integrity, represents a cytosolic protein that plays a crucial role in intracellular transport and metabolism of fatty acids in enterocytes, and is released upon their death.

Objectives. To evaluate the diagnostic value of the intestinal fatty acid-binding protein as a marker for enteral tolerance in neonates with gestational ages ranging from 33 to 41 weeks.

Methods. A cross-sectional cohort study involved 115 newborns admitted to the second-stage care units of Voronezh Regional Children’s Clinical Hospital No. 1 from maternity facilities in Voronezh Oblast between March 2023 and May 2024. The cohort included boys n = 72, 62.6%; girls n = 43, 37.4%. The participants were divided into two groups: Group 1 consisted of term neonates (gestational age 37–41 weeks, n = 80), while Group 2 included preterm neonates (gestational age 33–36 weeks, n = 35). The age of term patients accounted for 5.0 [4.0; 7.0] days, while the age of preterm neonates was 7.0 [4.0; 8.0] days. I-FABP concentration was measured once using the Human IFABP/FABP2 ELISA kit on a Multiskan Go analyzer. Based on the presence of symptoms indicating impaired enteral tolerance during the neonatal period, the groups were further subdivided into Subgroups 1A (n = 39) and 2A (n = 10) without symptoms of reduced enteral tolerance, 1B (n = 41) and 2B (n = 25) with symptoms of reduced enteral tolerance. Statistical analysis was performed using StatTech v. 4.3.2 (Stattech, Russia). The differences were considered statistically significant at p <0.05.

Results. The circulating intestinal fatty acid-binding protein level in term neonates accounted for 1.130 [0.796–1.911] ng/ml, while in preterm neonates, it was 1.134 [1.050–1.614] ng/ml, showing no dependence on the type of feeding (p > 0.05). In term newborns without gastroenterological symptoms in the neonatal period, the concentration of I-FABP amounted to 0.920 [0.695–1.160] ng/ml, compared to 1.900 [0.965–2.564] ng/ml in those with gastrointestinal symptoms, (p < 0.001). A similar  tendency was observed in preterm neonates: those without clinical signs of reduced enteral tolerance had an I-FABP concentration of 1.002 [0.867 to 1.073] ng/mL versus 1.312 [1.102 to 1.972] ng/mL in neonates with gastroenterological symptoms (p = 0.002). The level of intestinal fatty acid-binding protein was associated with the degree of enteral tolerance: the highest values were noted in newborns with all three symptoms, measuring 2.802 [1,641–3.402] ng/ml.

Conclusion. Circulating intestinal fatty acid-binding protein during the neonatal period is independent of gestational age and feeding type but increases in neonates with gastrointestinal symptoms, suggesting that intestinal fatty acid-binding protein may serve as a biomarker for assessing enteral tolerance in neonates. Further investigation of intestinal fatty acid-binding protein may contribute to the development of decision-making tools for complex clinical situations, including the initiation and expansion of enteral nutrition in extremely preterm neonates or following an enteral pause, as well as in the differential diagnosis of early stages of surgical gastrointestinal pathology in newborns.