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Postrenal Acute Renal Failure

  • Postrenal Acute Renal Failure (ARF) is a subcategorization of pathogenic mechanisms by which ARF may develop. It is defined by the development of Acute Renal Failure due to dysregulation of processes after the kidney, that is, within the urinary tract. Thus, the kidneys themselves are not dysfunctional and may exhibit no pathology in cases of postrenal ARF.
  • The basic pathogenesis of postrenal ARF begins with significant urinary tract obstruction which in severe or long-standing cases can yield to backup of urine into the kidneys. Backup of fluid into nephrons and potentially up to the level of the kidney will reduce the rate of glomerular filtration, thus precipitating ARF. Importantly, the obstruction must anatomically occur in such a position that urine flow from both kidneys is compromised, as a single kidney usually has enough functional reserve to secrete sufficient byproducts of metabolism to avoid ARF.
  • Any cause of urinary tract obstruction (see page) which compromises urine flow out of both kidneys can be a cause of Postrenal ARF. Common etiologies include neurogenic bladder or narrowing of the urethra as might occur due to BPH or prostate adenocarcinoma.