Acute Renal Failure

Overview
  • Acute Renal Failure (ARF) refers to a reduction in Glomerular Filtration Rate (GFR) over the course of hours to days. Because GFR is normally assessed by measurement of plasma creatinine, reductions in GFR are typically detected by a spike in the plasma creatinine concentration. Although many etiopathogenic processes can yield ARF, sudden reductions in GFR are always of concerning and can manifest with a characteristic clinical picture that is a direct result of deficient GFR and attendant renal function.
Etiology and Pathogenesis
  • The etiopathogenic processes that result in ARF can be split into three basic categories based on the geographic location of the initial injury. Each of these etiopathogenic categories is discussed in more detail on its own page.
  • Prerenal ARF: Occurs due to reduced perfusion of the kidneys in the absence of any actual renal pathology
  • Intrinsic ARF: Occurs due to a primary pathology within the kidneys themselves
  • Postrenal ARF: Occurs due to a primary pathology within the urinary tract
Clinical Consequences
  • Overview
    • Regardless of the primary insult causing ARF, sudden reductions in GFR can result in a similar clinical picture on top of symptoms which are unique to the particular etiology resulting in ARF. These symptoms are all direct consequences of reduced GFR and thus an inability of kidneys to properly control resorption and secretion of key physiological electrolytes or metabolic products. The pathogenesis of each of these symptoms is fairly similar to those of Uremia so refer to the uremia page for a fuller discussion of how these symptoms arise.
  • Symptomology
    • Azotemia: A generic term referring to build up of metabolites such as creatinine and BUN due to reduced GFR
    • Generalized Edema: Due to insufficient excretion of sodium and water
    • Hyperkalemia: Insufficient excretion of potassium
    • Metabolic Acidosis: Insufficient excretion of metabolic acids
    • Hyperphosphatemia: Insufficient excretion of plasma phosphate
    • Normocytic Anemia: Multifactorial pathogenesis but may be due to reduced renal secretion of erythropoietin
    • Oliguria: Reduced glomerular filtration and processing lead to less urine production
  • Complications
    • Uremia: May occur if ARF is not treated.
Subtopics