- 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)
- 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).
- Reduced intravascular volume
- Indomethacin use
- Adrenergic drugs
- Birth asphyxia
- Congenital abnormalities
- Renal agenesis
- Renal dysplasia
- Polycystic disease
- Thromboembolic disease
- Radiographic contrast
- Maternal ACE inhibitor or indomethacin use
- Urethral obstruction (eg, posterior urethral valves)
- Ureteropelvic obstruction
- Ureterovesicular obstruction
- Extrinsic compression of ureters
- Neurogenic bladder
- Megacystis or megaureter syndrome
- 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)
- Imaging: US examination of kidneys and urinary system
Urine osmolality (mOsm)
Urine sodium (mEq/L)
31 ± 19
63 ± 35
29 ± 16
10 ± 4
Fractional excretion of sodium (%)
Oliguric Acute Kidney Injury
- 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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