The true renal function of preterm infants is difficult to evaluate. Serum creatinine (Cr) levels in infants are unreliable as a detector of renal function in the first few days of life because they may continue to reflect maternal levels. Although few candidates appear to be a useful biomarker for kidney injury, scant reference data on these biomarker in preterm infants exist, and studies have yielded conflicting results. Therefore, we aimed to determine the reliable urinary biomarkers to detect kidney injuries in preterm infants.

Inclusion Criteria:

• premature infants born before 37 weeks of gestational age

Exclusion Criteria:

• cardiac or renal anomalies
• transferred in 2 days after birth from other hospitals

below gestational age 37 weeks