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Definition

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  • Oliguric: Anuria or oliguria (<0.5 mL/kg/h in children; <1 mL/kg/h in infants) with an associated increase in serum creatinine
  • Non-oliguric: Increased serum creatinine with normal or increased urine output (usually seen with nephrotoxic medications)

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Etiology

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  • It should be understood that the following classifications of etiology are somewhat artificial because there can be a great deal of overlap (eg, sepsis can cause both prerenal and intrinsic renal disease; obstructive uropathy, if severe enough, can also cause intrinsic renal disease).

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Prerenal

Intrinsic Renal

Postrenal

  • Reduced intravascular volume
  • Hemorrhage
  • Dehydration
  • CHD
  • Polycythemia
  • Indomethacin use
  • Adrenergic drugs
  • Birth asphyxia
  • Sepsis
  • ATN
  • Congenital abnormalities
    • Renal agenesis
    • Renal dysplasia
    • Polycystic disease
  • Thromboembolic disease
  • Nephrotoxins
    • Medications
    • Radiographic contrast
    • Maternal ACE inhibitor or indomethacin use
  • Urethral obstruction (eg, posterior urethral valves)
  • Ureterocele
  • Ureteropelvic obstruction
  • Ureterovesicular obstruction
  • Extrinsic compression of ureters
  • Neurogenic bladder
  • Megacystis or megaureter syndrome
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Diagnosis

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  • Perform history to elicit predisposing factors listed above and physical exam to palpate for abdominal masses and other congenital urogenital abnormalities.
  • Bladder catheterization to confirm inadequate urine output and r/o obstruction.
  • If prerenal failure is suspected on the basis of history or physical exam and there is no evidence of heart failure or volume overload, a fluid challenge of 10–20 mL/kg of normal saline can be administered over 30–60 min. Lack of response suggests intrinsic renal or postrenal failure.
  • Laboratory studies
    • Serum electrolytes, BUN, creatinine
    • CBC, platelet count
    • Urinalysis with microscopic analysis
    • Urinary sodium and creatinine with simultaneous serum sodium and creatinine to calculate FENa (these studies are not valid if diuretic is used)

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  • Imaging: US examination of kidneys and urinary system

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Prerenal

Intrinsic Renal

Urine osmolality (mOsm)

>400

<400

Urine sodium (mEq/L)

31 ± 19

63 ± 35

Urine/plasma creatinine

29 ± 16

10 ± 4

Fractional excretion of sodium (%)

<1.5

>2.5

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Management

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Oliguric Acute Kidney Injury

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  • Discontinue or minimize all fluids that contain potassium and phosphorus.
  • Please see chapter 34 for management of hyperkalemia in neonates.
  • Fluid management should be strict, with administration of fluids equal to insensible fluid losses plus urine and other fluid output (eg, chest tubes).
  • Monitor serum sodium, potassium, calcium, and phosphorus levels.
  • Treat hypocalcemia as required (see Chapter 34 [Endocrinology] for treatment of hypocalcemia in neonates).
  • Protein intake may need to be restricted.
  • Monitor for metabolic acidosis and correct as appropriate with intermittent administration of sodium bicarbonate or sodium acetate infusions.
  • Monitor BP and treat hypertension as indicated (See “Hypertension” section in this chapter).
  • Serum levels of all medications that are excreted by the kidney must be monitored carefully to avoid further nephrotoxic injury. Limit all nephrotoxic agents when clinically feasible.
  • Dialysis is indicated when conservative measures fail to prevent severe fluid overload, hyperkalemia, and metabolic acidosis.
    • Hemodialysis vs peritoneal dialysis vs continuous renal ...

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