Hepatorenal Syndrome Workup

Updated: Oct 16, 2017
  • Author: Deepika Devuni, MBBS; Chief Editor: BS Anand, MD  more...
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Workup

Laboratory Studies

Guidelines by the the British Society of Gastroenterology, the European Association for the Study of the Liver (EASL) and the American Association for the Study of Liver Diseases (AASLD) recommend the use of abdominal ultrasonography, diagnostic paracentesis, and ascitic fluid cultures in the workup of patients with suspected hepatorenal syndrome (HRS). [18]  

The diagnosis of HRS is one of exclusion [13] and depends mainly on serum creatinine level, as no specific tests establish the diagnosis of HRS. Although serum creatinine level is a poor marker of renal function in patients with cirrhosis, no other validated and reliable noninvasive markers exist for monitoring renal function in these patients. [19]

Diagnosis of HRS is based on the presence of a reduced glomerular filtration rate (GFR) in the absence of other causes of renal failure in patients with chronic liver disease. The following criteria, as proposed by the International Ascites Club in 1996, help diagnose HRS:

Major criteria include the following (All major criteria are required to diagnose HRS.):

  • Low GFR, indicated by a serum creatinine level higher than 1.5 mg/dL or 24-hour creatinine clearance lower than 40 mL/min
  • Absence of shock, ongoing bacterial infection and fluid losses, and current treatment with nephrotoxic medications
  • No sustained improvement in renal function (decrease in serum creatinine to <1.5 mg/dL or increase in creatinine clearance to >40 mL/min) after diuretic withdrawal and expansion of plasma volume with 1.5 L of plasma expander
  • Proteinuria less than 500 mg/d and no ultrasonographic evidence of obstructive uropathy or intrinsic parenchymal disease

Additional criteria include the following (Additional criteria are not necessary for the diagnosis but provide supportive evidence.):

  • Urine volume less than 500 mL/d
  • Urine sodium level less than 10 mEq/L
  • Urine osmolality greater than plasma osmolality
  • Urine red blood cell count of less than 50 per high-power field
  • Serum sodium concentration less than 130 mEq/L

Urinary indices are not considered major criteria because a subset of patients with HRS may have high urine sodium levels and low urine osmolality (similar to acute tubular necrosis [ATN]), while other patients with cirrhosis and ATN may have low urine sodium levels and high urine osmolality.

Complete blood cell count with differential

This may indicate the presence of underlying infection such as spontaneous bacterial peritonitis (SBP) if leukocytosis or bands are present, a condition known to present with reversible impairment in renal function. However, many patients with SBP do not have serum leukocytosis. Because shock from gastrointestinal bleeding may cause acute tubular necrosis, checking the hematocrit level and platelet count is helpful.

Serum electrolytes and renal function

These are essential investigations to obtain data for diagnosing HRS.

Liver function tests with prothrombin time

Although the degree of liver failure does not correlate with the development of HRS, these investigations are necessary to assess patients' Child-Pugh scores. [16]

Alpha-fetoprotein levels

Although few studies demonstrate a relationship between hepatoma and the development of HRS, this test should be performed when patients with cirrhosis decompensate.

Blood cultures

Infections place patients at an increased risk for decompensation, and looking for bacteremia, particularly if no precipitant is identified, is prudent. Occasionally, patients may present with culture-negative SBP (20%), and performing blood cultures is wise under these circumstances.

Cryoglobulins

Measuring these may be helpful in patients with hepatitis B and/or C, who can develop renal failure from cryoglobulinemia. Treatment and eradication of the underlying disease, if performed early in the course of the disease process, can reverse renal failure.

Urinalysis and urine electrolytes

Significant proteinuria or hematuria may provide a clue that an organic cause may be responsible for patients' renal failure. Similarly, urinary tract infection may be detected, and this usually is readily treatable.

Measuring urine sodium and creatinine levels is used as a screening test to assess the degree of sodium retention. Patients with low urine sodium excretion (<5 mEq/L) are at a greater risk of developing HRS. Urine sodium and creatinine levels are also used to calculate the fractional excretion of sodium, which is helpful in differentiating HRS and prerenal azotemia from intrinsic renal disease.

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Imaging Studies

Abdominal ultrasonography

This is a useful noninvasive test to help exclude hydronephrosis and intrinsic renal disease, which may be characterized by bilateral small kidneys. When combined with Doppler studies, valuable information may be provided on renal vascular flow.

Echocardiography

This study may be helpful for evaluating the right ventricular preload, ventricular filling pressures, and cardiac performance in response to fluid replacement.

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Procedures

Paracentesis

Spontaneous bacterial peritonitis (SBP) can present with reversible impairment of renal function, and performing diagnostic paracentesis is strongly recommended in all patients. The role of therapeutic paracentesis/large-volume paracentesis (LVP) in hepatorenal syndrome (HRS) is more controversial in the absence of tense ascites. Concerns exist that further volume depletion may aggravate renal function, due to third spacing in a patient with a known underlying systemic circulatory disturbance. Albumin replacement is recommended in these patients when LVP is performed. Ten grams of albumin is administered for every liter of ascites drained, to a maximum of 50 g of albumin.

Bladder catheterization

Catheterization may be helpful to exclude urinary retention as a potential cause of acute renal failure in these patients. However, long-term indwelling urinary catheters are not recommended (because of the risk of acquiring urinary tract infection) unless patients are incontinent and are at risk of developing skin breakdown or unless strict recording of urinary output is mandatory.

Central line and Swan-Ganz line placement

Measurement of central venous pressure and pulmonary capillary wedge pressure may be helpful in patients who do not respond to an adequate trial of plasma expansion. Hemodynamic findings in HRS include increased cardiac output, reduced mean arterial pressure (range of 60-80 mm Hg), and reduced total systemic vascular resistance. These findings, although characteristic of patients with cirrhosis, can also be observed in other conditions, such as anaphylaxis and sepsis. Invasive hemodynamic monitoring, aside from the risk of procedure-related complications, also has limitations for assessing volume status in patients. For example, a study by Kumar showed that, in healthy volunteers, neither central venous pressure nor pulmonary artery occlusion pressure was useful for predicting ventricular preload with respect to optimizing cardiac performance. [20]

Histologic findings

The kidneys are histologically normal because HRS is a functional disorder.

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