Won K. Han, MD
BASICS
DESCRIPTION
• Anuria: No urine output or <50 mL/d
• Oliguria: Urine output of 500 mL/d or <0.5 mL/kg/h
• Often the earliest sign of impaired renal function
• Associated with a severe decrease in the glomerular filtration rate (GFR) compromising kidney’s main functions
– Maintenance of body composition (such as fluid, acid–base, electrolyte content, and concentration)
– Excretion of metabolic end products and foreign substances (urea, toxins, and drugs)
EPIDEMIOLOGY
Incidence
• Frequency depends on various clinical settings:
– 1% at admission
– 2–5% during hospitalization
– 4–15% after cardiopulmonary bypass
Prevalence
N/A
RISK FACTORS
• Chronic kidney disease
• Congestive heart failure
• Diabetes mellitus
• Hypertension
• Myeloma
• Nephrotoxic medications
Genetics
N/A
PATHOPHYSIOLOGY
• Oligoanuria may result from 3 broad pathophysiologic processes: Prerenal, intrarenal, and postrenal causes
• Prerenal:
– Physiologic responses that lead to decreased GFR
– Maintain GFR by afferent arterial dilatation and efferent arteriolar constriction (mediated by angiotensin II)
– Enhanced tubular reabsorption of salt and water
– Prolonged renal hypoperfusion can lead to acute tubular injury
True volume depletion: Hemorrhage, gastrointestinal loss (vomiting, diarrhea, bleeding), renal loss (diuretics, osmotic diuresis), skin or respiratory loss (insensible loses, burns), 3rd spacing (pancreatitis, crush injury, or skelet al fracture)
Decrease in effective circulating blood volume: Sepsis, heart failure, hepatic failure, nephrotic syndrome, anaphylaxis
Drugs affecting glomerular hemodynamics: Afferent arteriolar dilatation (nonsteroidal anti-inflammatory drugs [NSAIDs] or calcineurin inhibitors [CNIs]), efferent arteriolar constriction (angiotensin-converting enzyme inhibitors [ACEIs] or angiotensin II receptor blockers [ARBs])
• Intrarenal:
– Associated with structural renal damage
Vascular (renal infarction, renal artery stenosis, renal vein thrombosis, etc.)
Tubular (ischemia, nephrotoxin)
Glomerular (acute glomerulonephritis, vasculitis, thrombotic microangiopathy)
Interstitium (interstitial nephritis, tumor infiltration)
• Postrenal (obstructive uropathy):
– Mechanical or functional obstruction of the flow of urine
Intraureteral obstruction (stones, crystals, clots, tumor)
Extraureteral obstruction (tumor, retroperitoneal fibrosis)
Prostatic hypertrophy
Neurogenic bladder
ASSOCIATED CONDITIONS
• Chronic kidney disease
• Nephrolithiasis
• Diabetes mellitus
• Peripheral vascular disease
• Bladder outlet obstruction
• Pelvic and abdominal tumors
GENERAL PREVENTION
• Avoid nephrotoxic medications (NSAIDs, ARBs (angiotensin receptor blockers), ACEIs (angiotensin-converting-enzyme inhibitors), radiographic contrast) especially in the setting of impaired renal function
• Avoid hypotension (keep mean arterial pressure [MAP] >60 mmHg)
• Adequate hydration
DIAGNOSIS
HISTORY
• Age, gender
• Duration of symptoms
• Chronic kidney disease
• Diabetes mellitus
• Hypertension
• Cardiac disease
• Liver disease
• Organ transplantation
• Episode of hypotension (MAP <60 mmHg)
• Fluid losses
– Vomiting, diarrhea
– Diuretics
– Burns, trauma, surgery
• Exposure to nephrotoxic medications
– ACEIs, ARBs, NSAIDs
– CNIs (cyclosporine, tacrolimus)
– Aminoglycosides, cephalosporins amphotericin B, radiographic contrast
– Acyclovir, sulfonamides, indinavir (can precipitate within the tubular lumen)
– Anticholinergics
– Chemo agents (cisplatin, methotrexate, 5-fluorouracil, interleukin-2, etc.)
• Symptoms of urinary tract obstruction
– Anuria or oliguria
– Urinary urgency, hesitancy
– Intermittent polyuria
– History of kidney stones
– Gross hematuria
PHYSICAL EXAM
• Signs of intravascular depletion
– Orthostatic hypotension
– Tachycardia
– Decreased skin turgor
– Dry mucous membrane
• Signs of heart failure
– Jugular venous distension
– Rales or crackles in lung exam
– Dyspnea, orthopnea
– Gallop rhythm
• Signs of volume overload
– Generalized edema
– Ascites
– Dyspnea
– Paroxysmal nocturnal dyspnea
• Signs of abdominal compartment syndrome
– Abdominal distension
– Abdominal tenderness
• Signs of postrenal obstruction
– Bladder distention
– Enlarged prostate on rectal exam
– Signs of urethral trauma
– Pelvic mass
– Patients with indwelling catheters should be irrigated to rule out blockage
DIAGNOSTIC TESTS & INTERPRETATION
Lab
• Serum electrolytes
– Acute kidney injury (AKI)
Rise in serum creatinine (SCr) of at least 0.3 mg/dL over a 48-hr period
Over 1.5 times the baseline SCr value within the 7 previous days
– Electrolyte and acid–base disorders
Metabolic acidosis
Hyponatremia
Hyperkalemia
Hyperphosphatemia
• Urinalysis with microscopic exam
– Prerenal: High specific gravity, normal, or hyaline casts
– Intrarenal:
Acute tubular necrosis (ATN): Low specific gravity, granular casts, muddy brown cast, tubular epithelial cells
Glomerulonephritis: Proteinuria, hematuria, red blood cell casts
Interstitial nephritis: White blood cells (WBCs), WBC casts, eosinophils, hematuria
Vascular disorders: Normal or hematuria
– Postrenal: Normal or hematuria. WBCs, occasional granular casts
• Urine indices
– Prerenal: Fractional excretion of sodium (FeNa) <1%, serum Bun/Cr ratio >20:1
– Intrarenal: FeNa >1%, serum Bun/Cr ratio <20:1
– Postrenal: FeNa variable, serum Bun/Cr ratio >20:1
Imaging
• Renal/bladder ultrasonography: 1st line in imaging, noninvasive, no radiation exposure
– Hydronephrosis and hydroureter
– Kidney stones
– Pelvic/retroperitoneal masses
• Duplex Doppler ultrasound: To evaluate the patency of renal artery and vein
• Voiding cystourethrogram: To evaluate vesicoureteral reflux
• Nuclear renal scans (such as technetium 99 m mercaptoacetyltriglycine [MAC3]): To assess the adequacy of renal perfusion and obstructive uropathy
• Intravenous urography or intravascular contrast dye generally does not indicate as it may exacerbate renal injury
Diagnostic Procedures/Surgery
• Foley catheter placement: To rule out lower urinary tract obstruction
• Retrograde pyelography with cystoscopy: To define the site and cause of obstruction
• Urodynamic study: To evaluate functional abnormality of the bladder (neurogenic bladder)
• Renal biopsy: To determine intrarenal etiology
Pathologic Findings
N/A
DIFFERENTIAL DIAGNOSIS
• Prerenal causes of AKI
– Gastrointestinal loss
– Renal loss
– Heart failure
– Hepatic failure
– Nephrotic syndrome
– Medications affecting renal hemodynamics
• Intrarenal causes of AKI
– Renal ischemia
– Nephrotoxins
– Acute glomerulonephritis
– Interstitial nephritis
– Vascular complication
• Postrenal causes of AKI
– Intraureteral obstruction
– Extraureteral obstruction
– Bladder outlet obstruction
TREATMENT
GENERAL MEASURES
• Prompt diagnosis of cause for oliguria/anuria to guide treatment
• All patients with oliguria/anuria should have a Foley catheter placed to monitor accurate urine output and eliminate lower urinary tract obstruction causes
• Appropriate medical managements for acid–base disorder, fluid imbalance, electrolyte imbalance (such as hyperkalemia, hyperphosphatemia, hypocalcemia)
• Renal replacement therapy: If supportive medical managements are not successful
– Refractory hyperkalemia
– Refractory volume overload
– Refractory acidosis
– Uremic pericarditis
MEDICATION
First Line
• Prerenal causes: Usually rapidly reversed following restoring renal perfusion
– Replace fluid with intravenous hydration or blood product transfusion
– Discontinue the nephrotoxic medications (NSAIDs, ARBs, ACEIs)
– Optimize cardiac output and volume status
• Intrarenal causes: ATN is the most common cause
– There is no single or sequence of interventions that will significantly improve renal function after onset of ATN (1)[A]
– Use of diuretics and low-dose dopamine
Increasing urine output does not shorten the duration of renal failure, decrease the requirement for dialysis or improve survival in patients with established oliguric AKI (2,3)[A]
Diuretics may be given for a short length of time for volume control
Low-dose dopamine (1–3 μg/kg/min, intravenously) does not reduce mortality or promote the recovery of renal function (4)[A]
SURGERY/OTHER PROCEDURES
• Obstructive uropathy: Usually responds to release of the obstruction and type of procedure is depending on level of obstruction
– Nephrostomy tube
– Ureteral stent
– Foley catheter
• Thrombotic microangiopathies and dysproteinemias (intrarenal causes)
– Plasmapheresis/or plasma exchange
ONGOING CARE
PROGNOSIS
• Mortality rate depends on the underlying cause and associated medical condition
• In most clinical situations, acute oliguria is reversible and does not result in permanent renal impairment
• Identification and timely treatment of reversible causes are crucial because the therapeutic window may be small
COMPLICATIONS
• Inability to manage electrolytes and fluid balance resulting in various complications
– Cardiovascular
Arrhythmias
Congestive heart failure
– Gastrointestinal
Nausea and vomiting
Ileus
Bleeding
– Neurologic
Confusion
Asterixis
Seizures
– Infection
• Requirement of renal replacement therapy
FOLLOW-UP
Patient Monitoring
• Serial renal function testing for resolution
• Subsequent renal imaging study to confirm the resolution of postrenal obstruction
REFERENCES
1. Han WK. Biomarkers for early detection of acute kidney injury. Current Biomarker Findings. 2012;2:77–85.
2. Metha RL, Pascual MT, Soroko S, et al. Diuretics, mortality, and nonrecovery of renal function in acute renal failure. JAMA. 2002;288:2547–2553.
3. Ho KM, Power BM. Benefits and risks of furosemide in acute kidney injury. Anaesthesia. 2010;65:283–293.
4. Lameire N, Van Biesen W, Vanholder R. Acute renal failure. Lancet. 2005;365:417–430.
ADDITIONAL READING
• Devarajan P. Oliguria. Medscape 2014: http://emedicine.medscape.com/article/983156-overview; Accessed July 28, 2014.
• Klahr S, Miller SB. Acute oliguria. N Engl J Med. 1998;338:671–675.
See Also (Topic, Algorithm, Media)
• Acute Kidney Injury, Adult (Renal Failure, Acute)
• Acute Kidney Injury, Pediatric (Renal Failure, Acute)
• Acute Tubular Necrosis (ATN)
• Anuria or Oliguria Algorithm 
CODES
ICD9
• 593.9 Unspecified disorder of kidney and ureter
• 599.60 Urinary obstruction, unspecified
• 788.5 Oliguria and anuria
ICD10
• N13.9 Obstructive and reflux uropathy, unspecified
• N28.9 Disorder of kidney and ureter, unspecified
• R34 Anuria and oliguria
CLINICAL/SURGICAL PEARLS
• Oliguria is often the earliest sign of impaired renal function.
• Prompt diagnosis and timely treatment of reversible causes are crucial because the therapeutic window may be small.
• Diuretics and low-dose dopamine do not reduce mortality or promote the recovery of renal function.