IM Board Review

Renal failure in HCV cirrhosis

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A 54-year-old man with a history of cirrhosis secondary to hepatitis C virus (HCV) infection has had a progressive decline in kidney function. He was diagnosed with hepatitis C 15 years ago; he tried interferon treatment, but this failed. He received a transjugular intrahepatic shunt 10 years ago after an episode of esophageal variceal bleeding. He has since been taking furosemide and spironolactone as maintenance treatment for ascites, and he has no other medical concerns such as hypertension or diabetes.

Two weeks ago, routine laboratory tests in the clinic showed that his serum creatinine level had increased from baseline. He was asked to stop his diuretics and increase his fluid intake. Nevertheless, his kidney function continued to decline (Table 1), and he was admitted to the hospital for further evaluation.

On admission, he appeared comfortable. He denied recent use of any medications, including nonsteroidal anti-inflammatory drugs, antibiotics, and diuretics, and he had no genitourinary symptoms. His temperature was normal, blood pressure 170/90 mm Hg, pulse rate 72 per minute, and respiratory rate 16. His skin and sclerae were not jaundiced; his abdomen was not tender, but it was grossly distended with ascites. He also had +3 pedal edema (on a scale of 4) extending to both knees. The rest of his physical examination was unremarkable. Results of further laboratory tests are shown in in Table 2.

Ultrasonography of the liver demonstrated cirrhosis with patent flow through the shunt, and ultrasonography of the kidneys showed that both were slightly enlarged with increased cortical echogenicity but no hydronephrosis or obstruction.

EXPLORING THE CAUSE OF RENAL FAILURE

1. Given this information, what is the likely cause of our patient’s renal failure?

  • Volume depletion
  • Acute tubular necrosis
  • Hepatorenal syndrome
  • HCV glomerulopathy

Renal failure is a common complication in cirrhosis and portends a higher risk of death.1 The differential diagnosis is broad, but a systematic approach incorporating data from the history, physical examination, and laboratory tests can help identify the cause and is essential in determining the prognosis and proper treatment.

Volume depletion

Volume depletion is a common cause of renal failure in cirrhotic patients. Common precipitants are excessive diuresis and gastrointestinal fluid loss from bleeding, vomiting, and diarrhea. Despite having ascites and edema, patients may have low fluid volume in the vascular space. Therefore, the first step in a patient with acute kidney injury is to withhold diuretics and give fluids. The renal failure usually rapidly reverses if the patient does not have renal parenchymal disease.2

Our patient did not present with any fluid losses, and his high blood pressure and normal heart rate did not suggest volume depletion. And most importantly, withholding his diuretics and giving fluids did not reverse his renal failure. Thus, volume depletion was an unlikely cause.

Acute tubular necrosis

The altered hemodynamics caused by cirrhosis predispose patients to acute tubular necrosis. Classically, this presents as muddy brown casts and renal tubular epithelial cells on urinalysis and as a fractional excretion of sodium greater than 2%.1 However, these microscopic findings lack sensitivity, and patients with cirrhosis may have marked sodium avidity and low urine sodium excretion despite tubular injury.3

This diagnosis must still be considered in patients with renal failure, especially after an insult such as hemorrhagic or septic shock or intake of nephrotoxins. However, because our patient did not have a history of any of these and because his renal failure had been progressing over weeks, acute tubular necrosis was considered unlikely.

Hepatorenal syndrome

Figure 1. Pathophysiology of hepatorenal syndrome and other common associated clinical findings.

Hepatorenal syndrome is characterized by progressive renal failure in the absence of renal parenchymal disease. It is a functional disorder, ie, the decreased glomerular filtration rate results from renal vasoconstriction, which in turn is due to decreased systemic vascular resistance and increased compensatory activity of the renin-angiotensin-aldosterone axis and of antiduretic hormone release (Figure 1).

Hepatorenal syndrome often occurs in patients with advanced liver disease. These patients typically have a hyperdynamic circulation (systemic vasodilation, low blood pressure, and increased blood volume) with a low mean arterial pressure and increased renin and norepinephrine levels. Other frequent findings include hyponatremia, low urinary sodium excretion (< 2 mmol/day), and low free water clearance,4 all of which mark the high systemic levels of antidiuretic hormone and aldosterone.

Importantly, while hepatorenal syndrome is always considered in the differential diagnosis because of its unique prognosis and therapy, it remains a diagnosis of exclusion. The International Ascites Club5 has provided diagnostic criteria for hepatorenal syndrome:

  • Cirrhosis and ascites
  • Serum creatinine greater than 1.5 mg/dL
  • Failure of serum creatinine to fall to less than 1.5 mg/dL after at least 48 hours of diuretic withdrawal and volume expansion with albumin (recommended dose 1 g/kg body weight per day up to a maximum of 100 g per day)
  • Absence of shock
  • No current or recent treatment with nephrotoxic drugs
  • No signs of parenchymal kidney disease such as proteinuria (protein excretion > 500 mg/day), microhematuria (> 50 red blood cells per high-power field), or abnormalities on renal ultrasonography.

While these criteria are not perfect,6 they remind clinicians that there are other important causes of renal insufficiency in cirrhosis.

Clinically, our patient had no evidence of a hyperdynamic circulation and was instead hypertensive. He was eunatremic and did not have marked renal sodium avidity. His pyuria, proteinuria (his protein excretion was approximately 1.9 g/day as determined by urine spot protein-to-creatinine ratio), and results of ultrasonography also suggested underlying renal parenchymal disease. Therefore, hepatorenal syndrome was not the likely diagnosis.

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