Pathology of Acute Renal Failure

The pathology of acute renal failure (ARF) as it is encountered in the mid- 1990s reflects the changing character of the patients developing this condition. Increasingly, individuals develop ARF as a part of a multiorgan failure syndrome rather than with a single organ disease presentation (Solez and Racusen 1993). As a consequence, ARF patients are more likely to be in the intensive care unit than on the renal medicine ward, and their primary physician is more likely to be an intensive care physician than a nephrologist. These trends reflect improvement in the general medical care of the critically ill patient. Patients who would not have survived their acute event in the past now live long enough to develop multiorgan failure. The high proportion of (concurrent) heart and liver disease means that many more of the patients present with a “prerenal” picture in which the kidney is still capable of reabsorbing sodium and concentrating the urine and morphologic alterations are minimal. Similarly, the increasing complexity and general poor health of the patients makes it less likely that a renal biopsy will be performed. Thus the renal morphologic alterations that accompany some types of ARF in critically ill patients remain largely unknown.