IL18 and acute kidney injury: This study aims to determine the utility of sIL-18 and urine interleukin 18 (uIL-18) as biomarkers of AKI in preterm infants and whether the −137G> C (rs187238), −607C > A (rs1946518) and −656 G > T (rs1946519) polymorphisms are associated with the expression levels of s-/uIL-18 and AKI phenotype in preterm infants.