Positive correlation between kidney injury molecule-1 and gentamicin trough level in neonates with infection

Background: Gentamicin is a nephrotoxic drug but chosen for neonates with severe infection. Early detection of kidney injury regarding the use of gentamicin is highly needed. Kidney Injury Molecule-1 (KIM-1) is one of the new specific and sensitive biomarker for kidney damage. This study aimed to determine the association between urinary KIM-1 and the trough level of gentamicin in neonates with infection. Method: This observational study is conducted on neonates with infection hospitalized in Perinatology Unit Cipto Mangunkusumo Hospital, Jakarta, Indonesia. Blood samples were taken from the heel pricks for 1 to 3 doses just before gentamicin administration (trough level). Gentamicin plasma concentrations were measured by Liquid Chromatography Tandem Mass Spectrometry while urinary KIM-1 levels were measured using enzyme-linked immunosorbent assay. Results: Twenty-seven neonates treated with gentamicin were included in the study and measured for 34 trough gentamicin levels. There were 18 gentamicin trough levels higher than the safe concentrations (2 mcg/mL). Normalized KIM-1 to creatinine levels in patients with high gentamicin trough concentration was significantly different from those who had safe trough levels (p = 0.015). The mean difference for normalized KIM-1 levels between those two groups was 3.85±1.409 mcg/g creatinine (95% CI: 0.845 to 6.85). There was a moderate correlation between gentamicin trough levels and log normalized KIM-1 level (p = 0.007; r = 0.63; R²= 0.39). Conclusion: Kidney Injury Molecule-1 urinary levels could be an early signal for gentamicin dose adjustment before kidney injury occurs in neonates.