Extremely high levels of vancomycin can cause severe renal toxicity Jaime Barceló-Vidal,1 Eva Rodríguez-García,2 Santiago Grau3 1Department of Pharmacy, Hospital del Mar, Parc de Salut Mar, Barcelona, Spain; 2Department of Nephrology, Hospital del Mar, Parc de Salut Mar, Barcelona, Spain; 3Department of Pharmacy, Hospital del Mar, Parc de Salut Mar, Universitat Autònoma de Barcelona, Barcelona, Spain Abstract: Vancomycin has usually been associated with nephrotoxicity. Generally, this ­toxicity is presented as proximal tubular cells injury with or without necrosis and as acute interstitial nephritis. However, development of both lesions is uncommonly described in literature. We present a case of vancomycin-induced nephrotoxicity resulting in both acute interstitial nephritis and tubular cells damage confirmed by renal biopsy. Peak and trough levels of 77.11 and 63.60 μg /mL, respectively, were obtained at the first plasma determination. After 8 more plasma determinations and several hemodialysis sessions, vancomycin levels were undetectable 1 month after therapy was stopped. To our knowledge, this is the case report with the highest vancomycin trough levels developing both lesions and describing total vancomycin washout after a biopsy-proven vancomycin toxicity. In conclusion, early vancomycin therapeutic drug monitoring should be performed in order to avoid toxicities where, as seen in our patient, antibiotic exposure could last around 1 month after last dose administration. Keywords: vancomycin, therapeutic drug monitoring, nephrotoxicity