Acute hepatic failure

(Redirected from Acute liver failure)

Definitions[1]

  • Hyperacute liver failure: encephalopathy occurs within 7 days of the onset of jaundice; this subset is likely to survive with medical management despite the high incidence of cerebral edema
  • Acute liver failure: interval of 8-28 days from jaundice to encephalopathy; this subset has a high incidence of cerebral edema and a poorer prognosis without liver transplant
  • Subacute liver failure: interval of 5-12 weeks from the onset of jaundice to the onset of encephalopathy; this subset has a lower incidence of cerebral edema, but a poor prognosis

Causes

Acetaminophen Toxicity

  • Now the most common cause of acute liver failure in the US[2]
  • Small amount of acetaminophen is metabolized by CytochromeP450 into NAPQI, which is a toxic metabolite
  • In therapeutic doses, NAPQI combines rapidly with glutathione to form nontoxic metabolites that are excreted in the urine
  • In overdose, glutathione stores are used up and NAPQI binds to cell proteins in the liver which leads to cell death
  • See Acetaminophen toxicity

Viral Hepatitis

  • Hepatocellular pattern of injury, where AST and ALT are higher than Tbili and Alk Phos; likely to have significantly elevated ALT and AST (20x normal or higher)
  • Of note, transmission of Hepatitis B and Hepatitis C through donated blood, blood products, and organs is rare in the US since blood screening became available in 1992
  • Hepatitis A
    • Fecal-oral transmission
    • Associated with epidemics linked to a common source (water)
    • Most common risk factor is travel outside of the US [3]
    • Not associated with chronic carrier state; incubation period is approximately 30 days, and infectivity usually resolved prior to symptom onset
  • Hepatitis B
    • Transmitted parenterally, blood contact, and unprotected sex
    • 90% of exposed infants progress to chronic hepatitis; 10% of exposed adults progress to chronic hepatitis
    • Serology[4]
Clinical Scenario HBsAg anti-HBc anti-HBs
Susceptible to infection negative negative negative
Immune due to natural infection negative positive positive
Immune due to Hep B infection negative negative positive
Acutely infected positive anti-HBc- positive; IgM anti-HBc- positive negative
Chronically infected positive anti-HBc- positive; IgM anti-HBc- negative negative
  • Hepatitis C
    • Blood-borne, in US, most commonly transmitted through IV drug use. Infrequently transmitted through sexual contact
    • 90% of HCV infections progress to chronic hepatitis[5]
  • Hepatitis D
    • Transmission similar to Hepatitis B
    • Can only co-infect patients with Hepatitis B (actively producing HBsAg)
    • Presentation can range from acute self-limited disease to fulminant hepatitis or chronic infection
  • Hepatitis E
    • Fecal-oral transmission
    • Usually results in mild illness, but can cause fulminant hepatitis in pregnant women[6]

Alcohol-related Liver Disease and Alcoholic hepatitis

  • Presentation can range from mild abdominal pain, nausea and vomiting to acute liver failure
  • May have large palpable liver from fatty infiltration, or may have small nonpalpable liver secondary to cirrhosis from chronic disease
  • Will have moderate elevations in AST and ALT (levels >10x normal are unusual)
    • AST:ALT ration >2 is typical
  • May also have electrolyte abnormalities from malnutrition or alcoholic ketoacidosis

Drug or Toxin Related Liver Disease

Other Rare Causes of Acute Liver Failure

Clinical Features

Differential Diagnosis

Encephalopathy (altered mental status)

Jaundice

Ascites

Evaluation

Labs

  • LFTs
    • AST and ALT
      • Enzymes found mainly in hepatic cells, though ALT is more specific to the liver than AST
      • Extreme elevation in AST (>3000U/L, or >40x upper limit of normal) is consistent with acetaminophen toxicity or ischemic injury
      • Moderate elevations (10-40x upper limit of normal) is consistent with viral hepatitis
      • Mild elevations (<10x upper limit of normal) is consistent with alcoholic hepatitis
    • Alkaline Phosphatase
      • Found in bile canaliculi (but also in placenta, ileal mucosa, bone, and kidney)
      • Elevated in diseases of cholestasis
      • Rare for levels to be >3x normal limit in acute liver failure
    • Bilirubin
      • Elevated in diseases of cholestasis
      • In obstructive diseases, the direct bilirubin will usually be about 50% of the total bilirubin; if indirect bilirubin is higher, more suggestive of hemolysis or problem with conjugation
  • Coagulation Studies
    • Reflects the liver’s ability to synthesize clotting factors
    • INR >6.5 or PT >20 seconds indicates patients at high risk for death
  • Albumin
    • Reflects synthetic function of the liver
    • Has a long half-life (20 days) and may not be decreased early in disease
  • Ammonia
    • Elevated as a result of impaired clearance
    • Poor correlation between degree of elevation and severity of encephalopathy symptoms
  • Chemistry Panel
    • Electrolyte abnormalities may indicate malnutrition or dehydration
    • Creatinine is used as a prognostic indicator
    • Need to check a glucose because patients with liver failure are prone to hypoglycemia
  • CBC
  • Viral hepatitis Serologies
    • Consider for all patients with undifferentiated liver failure
    • IgM anti-HBc may be the only positive marker in acute Hepatitis B infection
    • Anti-HCV and HCV RNA are present in both chronic and acute Hepatitis C infections, so it is difficult to differentiate based on serologies, but presence of HCV RNA in the absence of anti-HCV is more suggestive of acute infection[8]
    • Only need to test for IgM anti-HEV in patients who are symptomatic and have just travelled from areas where Hepatitis E is endemic

Imaging

  • Consider RUQ US or CT in patients with jaundice to evaluate for a mechanical obstruction
  • Otherwise, tailor imaging towards specific complaints

Management

  • Treatment is mostly supportive and tailored towards the specific etiology
  • Early consideration regarding transporting patient to a transplant center given potential for rapid deterioration
  • Symptom specific supportive treatment options

Disposition

  • Admission to ICU with early consideration for transportation to transplant center

See Also

References

  1. O’Grady, JG, Schalm SW, Williams R. Acute liver failure: redefining the syndromes. Lancet. July 1993, Volume 342, Issue 8866, Page 273-275
  2. Ostapowicz G, Fontana RJ, Schiodt FV, et al. Results of a prospective study of acute liver failure at 17 tertiary care centers in the United States. Ann Intern Med. 2002 Dec 17; 137(12): 947-54.
  3. Oyama, LC: Disorders of the Liver and Biliary Tractin Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2014, (Ch) 107: p 1186-1204.
  4. www.cdc.gov/hepatitis
  5. Oyama, LC: Disorders of the Liver and Biliary Tractin Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2014, (Ch) 107: p 1186-1204
  6. Rein DB, Stevens GA, Theaker J, Wittenborn JS, Wiersma ST. The Global Burden of Hepatitis E Virus Genotypes 1 and 2 in 2005. Hepatology, Vol. 55, No. 4, 2012: 988-997
  7. Oyama, LC: Disorders of the Liver and Biliary Tractin Marx JA, Hockberger RS, Walls RM, et al (eds): Rosen’s Emergency Medicine: Concepts and Clinical Practice, ed 8. St. Louis, Mosby, Inc., 2014, (Ch) 107: p 1186-1204
  8. Bailey, C, Hern HG. Hepatic Failure: An Evidence-Based Approach In The Emergency Department. Emergency Medicine Practice. Vol. 12, No. 4, 2014.

Authors:

Ross Donaldson