Specificity of Renal Tubular Damage Criteria for Aminoglycoside Nephrotoxicity in Critically III Patients

Two populations of critical care patients were studied using indices of renal tubular damage (beta 2-microglobulin, enzymes, casts) and indices of glomerular filtration (creatinine, creatinine clearance). The purpose of these studies had been initially to elucidate the type of renal failure typical of the critically ill patient treated with aminoglycoside gentamicin or tobramycin, then to determine its frequency. The second study population included a control group of patients given the nonnephrotoxic cephalosporin moxalactam, in order to assess the specificity of the renal tubular damage criteria for aminoglycoside nephrotoxicity versus other types of renal injury in critical care patients. Creatinine rise occurred in approximately 30 per cent of each tobramycin-treated group and in only 12 per cent in the moxalactam control patients (P less than 0.05). Thus, the data indicate that aminoglycosides are associated with an approximate doubling of the renal damage in those older, critically ill patients. Renal tubular damage criteria appear specific for the aminoglycoside effect, but a substantial percentage of the renal damage in this population is not associated with detectable alterations in renal tubular status.