Transmission Electron Microscopy of Urinary Sediment in Aminoglycoside Nephrotoxicity

Abstract

Urinary sediment from 20 patients treated with aminoglycosides (AG) was studied using transmission electron microscopy. For the purpose of comparison, urinary sediment was also studied (control) from an additional 9 patients who had acute renal failure (ARF) but who did not receive AG (5 posttransplant, 4postsurgical). Urinary myeloid bodies and renal tubule cells were analyzed semiquantitatively. The diagnosis of AG nephrotoxicity (or ARF) was made on the basis of a rise in serum creatinine ≥ 0.5 mg/dL from the baseline levels. Among 20 patients, 12 developed AG-ARF, and 11 of these 12 showed myeloid bodies and necrotic renal tubule cells in their urinary sediment. Of the 8 patients that did not develop AG-ARF, 5 showed myeloid bodies and 2 of these also showed renal tubule cells in their urinary sediment. This incidence of necrotic renal tubule cells in the nephrotoxic group is significantly higher than in the nonnephrotoxic group (p < 0.01). Although no statistical difference was found in the incidence of myeloid bodies between the two groups, the number of myeloid bodies was significantly (p < 0.05) greater in the nephrotoxic group than in the nonnephrotoxic group. Furthermore, consecutive sediment studies revealed that the appearance of necrotic renal tubule cells (and not of myeloid bodies) coincided with the increase in serum creatinine. All control patients showed necrotic renal tubule cells but no myeloid bodies in their urinary sediment. Thus this study suggests that the presence of necrotic renal tubule cells signifies ARF, and when preceded or accompanied by large numbers of myeloid bodies that it indicates AG-ARF.