Analysis of urinary sediment by transmission electron microscopy. An innovative approach to diagnosis and prognosis in renal disease.

Urinary sediment TEM is capable of unequivocally demonstrating renal tubule cells and distinguishing them from urinary tract epithelial cells. The renal tubule cells and the accompaniments including myeloid bodies, inflammatory cells, or fibrin permit, in a particular clinical setting, synthesis of a meaningful renal diagnosis. Sequential TEM sediment studies can clarify ambiguities in diagnosis. Precisely, when much difficulty is experienced in distinguishing ATN from aminoglycoside nephrotoxicity in a patient with sepsis who has received aminoglycoside, urinary sediment TEM can facilitate the differential diagnosis with confidence. In another clinical setting, such as hypersensitivity acute interstitial nephritis, TEM urinary sediment has an irrevocable place by exhibiting the characteristic eosinophil granules that will confirm the above diagnosis, or deny it when they are absent. The morphologic features in the renal tubule cells in the sediment reflect similar changes in the tubular cells in renal tissue. Therefore, the severity of tubular changes are commensurate with the clinical outcome in terms of renal function recovery, need of dialysis, and mortality. The degree of correlation is significant. Thus, slight or no TEM sediment tubular changes signifies a good prospect for renal function recovery and low or no mortality. Conversely, severe tubular changes in the TEM sediment denote persistent renal failure accompanied by high mortality. Furthermore, the most severe tubular changes, found in hepatorenal syndrome, are consistent with its dismal prognosis.