Aminoglycoside and glycopeptide renal toxicity in intensive care patients studied by proton magnetic resonance spectroscopy of urine.

Objective: Aminoglycoside and glycopeptide antibiotics are responsible for renal toxicity. In most cases, the nephrotoxicity is limited to a reversible tubular injury, but an acute and sustained renal failure may occur. The aim of our study was to explore the renal function of patients given these antimicrobial agents with proton magnetic resonance spectroscopy of urine. This technique is able to detect, in urine samples, a wide range of metabolites reflecting renal tubular function. The variables assessed by magnetic resonance spectroscopy were compared with the routine markers of renal function: creatinine, urea, and 24-hr urine volume.
Design: Prospective clinical study.
Setting: Intensive care unit.
Patients: All patients in an intensive care unit receiving an aminoglycoside and/or a glycopeptide were included in the study if they presented with signs of renal dysfunction. All experiments were performed on urine samples collected for the routine follow-up of these patients.
Intervention: Proton spectra were acquired with water suppression, and the peak intensity of each metabolite was reported in relationship to the intensity of the creatinine peak.
Measurements and Main Results: The ratio values obtained by magnetic resonance spectroscopy were compared with the values of creatininemia and blood urea obtained routinely by biochemistry and with the value of the 24-hr urine volume by logistic regression and general linear models. This statistical analysis showed that the ratio of dimethylamine to creatinine was highly correlated with creatininemia.
Conclusions: Dimethylamine is an osmolyte released from the medullar region of the kidney. Thus, our study demonstrated that nephrotoxicity from aminoglycosides and glycopeptides is not limited to proximal tubular toxicity but also may involve the medullar region (Henle loop and collecting duct) of the nephron.