Evaluation of Neutrophil Gelatinase-Associated Lipocalin as a Predictor of Glomerular Filtration Rate and Amikacin Clearance During Early Rat Endotoxemia: Comparison with Traditional Endogenous and Exogenous Biomarkers.

Background and Objectives: Renal elimination of amikacin and other aminoglycosides is slowed down in sepsis-induced acute kidney injury increasing the risk of adverse effects. Since neutrophil gelatinase-associated lipocalin (NGAL) and aminoglycosides share the mechanisms for renal excretion, the predictive power of NGAL was examined towards the changes in amikacin pharmacokinetics during early endotoxemia in anesthetized Wistar rats.
Methods: Endogenous biomarkers of inflammation and acute kidney injury were assessed including NGAL in saline-injected controls and two groups of rats challenged with an intravenous injection of bacterial lipopolysaccharide (5 mg/kg)-a fluid-resuscitated group (LPS) and a fluid-resuscitated group infused intravenously with 8 μg/kg/h terlipressin (LPS-T). Sinistrin and amikacin were infused to measure glomerular filtration rate (GFR) and amikacin clearance (CL _am ). The investigations included blood gas analysis, chemistry and hematology tests and assessment of urine output, creatinine clearance (CL _cr ) and sinistrin clearance (CL _sini ).
Results: Within 3 h of injection, systemic and renal inflammatory responses were induced by lipopolysaccharide. Gene and protein expression of NGAL was increased in the kidneys and the concentrations of NGAL in the plasma (pNGAL) and urine rose 4- to 38-fold (P < 0.01). The decreases in CL _am and the GFR markers (CL _cr , CL _sini ) were proportional, reflecting the extent to which endotoxemia impaired the major elimination mechanism for the drug. Terlipressin attenuated lipopolysaccharide-induced renal dysfunction (urine output, CL _cr , CL _sini ) and accelerated CL _am . The pNGAL showed a strong association with the CL _sini (rs = - 0.77, P < 0.0005). Concerning prediction of CL _am , pNGAL was comparable to CL _cr (mean error - 24%) and inferior to CL _sini (mean error - 6.4%), while the measurement of NGAL in urine gave unsatisfactory results.
Conclusions: During early endotoxemia in the rat, pNGAL has a moderate predictive ability towards CL _am . Clinical studies should verify whether pNGAL can support individualized dosing of aminoglycosides to septic patients.