Acute postrenal azotemia: etiology, clinicopathology, and pathophysiology.

When rupture or obstruction of the urinary tract prevents the normal collection and expulsion of urine from the body, the resulting azotemia is termed postrenal. Postrenal azotemia can coexist with prerenal and/or renal azotemia. Detection of postrenal azotemia requires attentiveness to the history and physical examination findings and to the results of specifically directed diagnostic tests. Prompt correction of postrenal causes of azotemia limits the potential for intrinsic renal damage and can contribute to a positive clinical outcome; therefore, postrenal azotemia should be investigated in all azotemic patients.