Gamma-glutamyltransferase and immunoglobulin G in intestinal maturation: Pilot study in preterm and term infants and the influence of breast milk.

Gamma-glutamyltransferase (γGT), a key enzyme in glutathione metabolism, is abundant in colostrum and may indicate neonatal gastrointestinal maturation, although normative serum values and associations with breast milk intake remain unclear, particularly in preterm infants. In this prospective study, serum γGT was measured in 84 neonates, including 36 born before 32 weeks' gestation and 48 born at or after 32 weeks, across the first 4 postnatal weeks. Breast milk γGT was analyzed in samples from 107 mothers, and correlations with colostrum intake were assessed in 66 neonates. Serum γGT remained relatively stable (110-130 U/L). Preterm infants receiving colostrum had higher γGT in Week 1 than non-exposed infants, although not conventionally significant, and lower values by Week 4 (138.7 vs. 91.7 U/L, p = 0.056; Week 4, p = 0.027). Week-1 breast milk intake correlated with serum γGT across all 4 weeks in preterm infants (p = 0.007, 0.001, 0.003, 0.022).