Background: Serum creatinine (SCr)- or urine output-based definitions of acute kidney injury (AKI) have important limitations in neonates. This study evaluates the diagnostic value of urinary biomarkers in very low-birth-weight (VLBW) infants receiving indomethacin for closure of a patent ductus arteriosus (PDA).
Methods: Prospective cohort study in 14 indomethacin-treated VLBW infants and 18 VLBW infants without indomethacin as controls. Urinary biomarkers were measured before, during, and after indomethacin administration.
Results: Indomethacin therapy was associated with significantly higher SCr concentrations at 36, 84, and 120 h compared to controls. At 36 h, three indomethacin-treated patients met the criteria for neonatal modified Kidney Disease: Improving Global Outcomes (KDIGO) AKI. The product of urinary tissue inhibitor of metalloproteinase-2 and insulin-like growth factor-binding protein 7 ([TIMP-2]•[IGFBP7]) was significantly elevated in the AKI subgroup at 12 h (P < 0.05), hence 24 h earlier than the increase in SCr. Urinary neutrophil gelatinase-associated lipocalin (NGAL) and calprotectin were significantly increased in the indomethacin group at 12 h (P < 0.05), irrespective of fulfillment of the AKI criteria. Urinary kidney injury molecule-1 (KIM-1) was not significantly altered.
Conclusion: While urinary [TIMP-2]•[IGFBP7] proves valuable for the early diagnosis of neonatal modified KDIGO-defined AKI, elevated urinary NGAL and calprotectin concentrations in indomethacin-treated VLBW infants not fulfilling the AKI criteria may indicate subclinical kidney injury.