• Oliguria is decreased urine output.
  • Infants: < 0.5 mL/kg per hour for 24 hours
  • Older children: < 500 mL/1.73 m² body surface area per day
• Anuria is absence of any urine output.
  • Normal, healthy newborns may have no urine output for 24 hours after birth.
• Oliguria is much more common than anuria but can lead to anuria, resulting in serious renal damage that requires specialized care.

• Incidence of oliguria or anuria is unknown in previously healthy children.
• In hospitalized patients
  • Oliguric acute renal failure (ARF) occurs in:
    • 10% of newborns in the intensive care unit
    • 2–3% of older children requiring intensive care
    • 8% of patients undergoing cardiac surgery
• Prevalence of ARF in newborns
  • Prerenal: 85%
  • Renal: 11%
  • Postrenal: 3%
• Prevalence of ARF in older children
  
  • Prerenal: 66%
  • Renal: 33%,
  • Postrenal: < 1%

Causes of oliguria, anuria, and ARF

• Common causes of oliguria, anuria, or ARF are best defined in relation to the patient’s age.
• Prerenal ARF caused by dehydration is the most common cause of oliguria/anuria (70% of community-acquired cases of ARF and up to 60% of hospital-acquired cases).
• Renal ARF caused by intrinsic renal damage can be categorized into 3 types.
  • Acute tubular necrosis (ATN) result form prolonged ischemia or drug- or toxin-mediated renal tubular injury (reversible).
  • Glomerular lesions may occur with postinfectious glomerulonephritis.
  • Vascular lesions may occur with hemolytic-uremic syndrome or Henoch-Schönlein purpura.
• Postrenal ARF
  • Mechanical or functional obstruction to urine flow
    • May be in lower urinary tract, e.g., posterior urethral valves
    • May be bilaterally in the upper tract, e.g., bilateral ureteropelvic junction obstruction (rare)
  • Unilateral obstruction can cause ARF in patients with only 1 functioning kidney.
  • More common in newborns than in older infants

Most common causes of oliguria and anuria in neonates and children

• Neonates
  • Prerenal
    • Perinatal asphyxia
    • Respiratory distress syndrome
    • Hemorrhage
    • Sepsis or shock
    • Congenital heart disease
    • Dehydration
    • Drugs (indomethacin, maternal use of ACE inhibitors or nonsteroidal antiinflammatory drugs)
  • Renal
    • Acute tubular necrosis
    • Exogenous toxins (aminoglycosides, amphotericin B)
    • Endogenous toxins (hemoglobin, myoglobin, uric acid)
    • Congenital kidney diseases
    • Vascular (renal vein thrombosis, renal artery thrombosis)
  • Postrenal
    • Posterior urethral valves
    • Meatal stenosis
    • Bilateral ureteral obstruction
    • Neurogenic bladder
• Children
  • Prerenal
    • Dehydration
    • Hemorrhage
    • Burns
    • Third-space loss (surgery, trauma, nephrotic syndrome)
    • Renal loss (diabetes mellitus, diabetes insipidus, diuretics)
    • Shock
    • Decreased cardiac output
  • Renal
    • Acute tubular necrosis
    • Glomerulonephritis
    • Exogenous toxins (aminoglycosides, amphotericin B)
    • Endogenous toxins (hemoglobin, myoglobin, uric acid)
    • Vascular (hemolytic-uremic syndrome, vasculitis)
  • Postrenal
    • Posterior urethral valves
    • Meatal stenosis
    • Bilateral ureteral obstruction
    • Neurogenic bladder

• Common underlying comorbid conditions
  • Neurologic conditions
    • Compromised thirst mechanism
    • Serious disability and total dependence on others for nutrition and hydration, eg, patients with severe cerebral palsy
  • Renal diseases that impair ability to concentrate the urine, eg, salt-losing nephropathy or chronic renal failure
  • Gastrointestinal conditions that cause hypoalbuminemia and decreased intravascular volume, eg, celiac disease or hepatic failure
  • Endocrine disease, such as:
    • Diabetes insipidus, associated with increased hypotonic urine output
    • Diabetes mellitus, associated with osmolar diuresis
  • Hematologic conditions that impair urine concentration mechanism
• Oncologic emergencies, eg tumor lysis syndrome (causes renal failure, particularly if patient is not well hydrated)
• Therapy that may predispose to renal failure because they impair renal autoregulation in the presence of mild renal insufficiency or dehydration
  • Nonsteroidal antiinflammatory drugs
  • Angiotensin-converting enzyme inhibitors
  • Aminoglycosides
  • Radiologic contrast media