Acute Liver Failure Workup

Updated: Jun 13, 2017
  • Author: Gagan K Sood, MD; Chief Editor: BS Anand, MD  more...
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Workup

Approach Considerations

The most important step in patients with acute liver failure is to identify the cause. [36, 37] Prognosis in acute liver failure is dependent on the etiology. Acute liver failure from certain causes demands immediate and specific treatment. It is also critical to identify those patients who will be candidates for liver transplantation. [36, 37]

All patients with clinical or laboratory evidence of moderate or severe acute hepatitis should have immediate measurement of prothrombin time (PT) and careful evaluation of mental status. Prolongation of the PT, an international normalized ratio (INR) above 1.5, or alteration in mental sensorium is grounds for hospital admission or transfer to a specialized unit. [37]

A complete blood cell (CBC) count in patients with liver failure may reveal thrombocytopenia.

Consider electroencephalography in the evaluation of a patient with encephalopathy if seizures must be excluded.

American College of Gastroenterology guidelines for drug-induced liver injury

In 2014, the American College of Gastroenterology released new guidelines for the diagnosis and management of drug-induced liver injury. [36, 38] Key points include the following [36] :

  • Drug-induced liver injury is a diagnosis of exclusion; a thorough history-taking and workup should be performed to rule out other possible etiologies

  • Liver biopsy should be considered to help confirm the presence of drug-induced liver injury, if autoimmune hepatitis may be associated with the condition, and when immunosuppressive agents are being considered

  • The widely used Roussel Uclaf Causality Assessment Method (RUCAM) scale may underestimate the risk of liver injury associated with herbal and dietary supplements

These guidelines also include an algorithm for the diagnosis of patients with suspected drug-induced liver injury and provide separate diagnostic pathways based on the type of liver damage (hepatocellular, mixed, or cholestatic) present.

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Laboratory Studies

Prothrombin time (PT)

The PT and/or the international normalized ratio (INR) are used to determine the presence and severity of coagulopathy. These are sensitive markers of hepatic synthetic failure and are usually abnormal in the setting of fulminant hepatic failure. Results may be worsened because of extrahepatic causes (eg, vitamin K deficiency, disseminated intravascular coagulation [DIC], consumptive coagulopathy).

Hepatic enzymes

The levels of the transaminases (aspartate aminotransferase [AST]/serum glutamic-oxaloacetic transaminase [SGOT], and alanine aminotransferase [ALT]/serum glutamic-pyruvic transaminase [SGPT]) are often elevated dramatically as a result of severe hepatocellular necrosis.

In instances of acetaminophen toxicity (especially alcohol-enhanced), the AST and ALT levels may be well over 10,000 U/L. The alkaline phosphatase (ALP) level may be normal or elevated.

Serum bilirubin

By definition, the serum bilirubin level should be elevated in fulminant hepatic failure. It climbs as hepatic dysfunction worsens. A serum bilirubin level that is elevated to greater than 4 mg/dL suggests a poor prognosis in the setting of acetaminophen poisoning.

Serum ammonia

The serum ammonia level may be elevated dramatically in patients with fulminant hepatic failure. The arterial serum ammonia level is the most accurate measurement, but venous ammonia levels are generally acceptable. An elevated serum ammonia level does not exclude the possibility of another cause for mental status changes (notably, increased intracranial pressure and seizures).

Serum glucose

Serum glucose levels may be dangerously low. This decrease results from impairments in glycogen production and gluconeogenesis.

Serum lactate

Arterial blood lactate levels, either at 4 hours (>3.5 mmol/L) or at 12 hours (>3.0 mmol/L), are early predictors of outcome in acetaminophen-induced acute liver failure. Blood lactate levels are often elevated as a result of both impaired tissue perfusion, which increases production, and decreased clearance by the liver.

Patients with elevated lactate levels may have an associated metabolic acidosis due to an increased anion gap. Alternatively, this condition may be accompanied by a respiratory alkalosis as a result of hyperventilation.

Arterial blood gases

Like pulse oximetry, arterial blood gas evaluation is valuable for identifying acid-base imbalances. However, because of significant disturbances in the acid-base balance, which are usually progressive, arterial blood gas evaluation is required, rather than only monitoring pulse oximetry. Placement of an arterial line is recommended.

Additionally, arterial blood gases may reveal hypoxemia, which is a significant concern as a result of adult respiratory distress syndrome (ARDS) or other causes (eg, pneumonia).

Serum creatinine

Serum creatinine levels may be elevated, signifying the development of hepatorenal syndrome or some other cause of acute renal failure.

Serum free copper

Patients with Wilson disease have low ceruloplasmin and total serum copper levels. However, ceruloplasmin acts as an acute-phase reactant as well as a copper transporter, and levels may be increased (eg, from active inflammation, pregnancy, or estrogen treatment) or depressed in a nonspecific fashion as a result of hepatic failure. Thus, determination of serum free copper (ie, non-ceruloplasmin–bound copper) is important when Wilson disease must be excluded or confirmed. Fulminant hepatic failure from Wilson disease appears to be uniformly fatal without transplantation.

The free copper level is determined by subtracting 3 times the ceruloplasmin level (mg/dL) from the total serum copper level (µg/dL). Normal free copper levels range from 1.3 to 1.9 µmol/L (8-12 µg/dl); in Wilson disease, levels exceed 3.9 µmol/L (>25 µg/dL).

Serum phosphate

Levels of serum phosphate may be low. It has been hypothesized that hypophosphatemia develops in people whose livers regenerate rapidly. Elevated phosphate levels suggest impaired regeneration.

Autoimmune markers

Antinuclear antibody (ANA), anti-smooth muscle antibody (ASMA), and immunoglobulin levels are important markers for the diagnosis of autoimmune hepatitis.

Acetaminophen studies

In patients with liver failure from acetaminophen toxicity, the acetaminophen level may have decreased by the time a patient presents with fulminant hepatic failure. Nevertheless, this assay may be helpful for documentation purposes.

Acetaminophen-protein adducts are specific biomarkers of acetaminophen-related toxicity. These can be measured in blood. Measurement of acetaminophen-protein adducts is particularly useful for diagnosis in cases lacking historical data or other clinical information. [18]  Serum acetaminophen-protein adducts decrease in parallel to aminotransferases and can be detected up to 7 days.

Drug screen

Consider a drug screen in a patient who is an intravenous drug abuser.

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Blood Cultures

Most patients with acute liver failure develop infection during or before hospitalization. Patients are at risk of catheter sepsis and complications from all other invasive procedures. Fungal infections are common, most likely as a result of decreased host resistance and antibiotic treatment. [39]

Infection may be associated with bacteremia. Early identification and treatment of bacteremia is important because the mortality from fulminant hepatic failure increases significantly with the development of this serious complication.

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Viral Serologies

Hepatitis A virus (HAV) immunoglobulin M (IgM), hepatitis B surface antigen (HBsAg), and hepatitis B virus (HBV) anticore IgM serologies help identify acute infection with HAV or HBV.

Hepatitis C virus (HCV) antibody test results may remain negative for several weeks or months. Repeat testing may be necessary, but acute HCV infection as a cause of fulminant hepatic failure appears to be exceedingly uncommon. If a strong clinical suspicion exists, obtain hepatitis C viral load testing.

If the HBsAg assay is positive, consider testing for hepatitis D virus (HDV) IgM. This test is particularly advisable if the patient is a known intravenous (IV) drug abuser.

Other viral studies may be helpful in the posttransplantation setting or when patients are otherwise heavily immunosuppressed. Such studies include cytomegalovirus viremia and cytomegalovirus antigenemia. Also consider herpes simplex virus (HSV).

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Liver Ultrasonography

A Doppler ultrasonography scan of the liver establishes the presence of ascites and may establish the patency and flow in the hepatic veins (allowing exclusion of Budd-Chiari syndrome), hepatic artery, and the portal vein.

Liver ultrasonography may not be necessary if an obvious explanation exists for the hepatic failure. However, it may assist the clinician in excluding the presence of a hepatocellular carcinoma or intrahepatic metastases (see the image below).

Ultrasonogram shows a hyperechoic mass representin Ultrasonogram shows a hyperechoic mass representing hepatocellular carcinoma.
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Computed Tomography Scanning

Computed tomography (CT) scanning (or magnetic resonance imaging [MRI]) of the abdomen may be required for further definition of hepatic anatomy and to help the clinician exclude other intra-abdominal processes, particularly if the patient has developed massive ascites, if the patient is obese, or if transplantation is being planned.

Intravenous contrast media may compromise renal function. Consider performing a contrast-free study.

CT scanning of the head may help identify cerebral edema, although CT scans do not reliably demonstrate evidence of edema, especially at early stages. Head imaging with CT scanning is also used to exclude other causes of decline in mental status, such as intracranial mass lesions (especially hematomas) that may mimic edema from fulminant hepatic failure. It can also exclude subdural hematomas (see the image below).

Subacute subdural hematoma with extension into the Subacute subdural hematoma with extension into the anterior interhemispheric cistern. Note that the sulci do not contain the spread of these hemorrhages.
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Liver Biopsy and Histologic Findings

A percutaneous liver biopsy is contraindicated in the setting of coagulopathy. However, a transjugular biopsy is helpful for diagnosis if autoimmune hepatitis, metastatic liver disease, lymphoma, or herpes simplex hepatitis is suspected. Liver biopsy findings may be nonspecific, but in general, the findings depend on the underlying etiology of the acute liver failure.

Liver biopsy specimens in patients with idiosyncratic medication-induced hepatitis leading to fulminant hepatic failure generally shows panlobular necrosis. In patients with acetaminophen-induced fulminant hepatic failure, centrilobular necrosis is typical but panlobular injury may also be observed.

Viral hepatitis typically produces a panlobular injury and may be difficult to distinguish from medication-induced hepatitis. The presence of microvesicular steatosis suggests certain medications (eg, valproic acid, salicylates in Reye syndrome) as a cause for fulminant hepatic failure, but this finding is also observed in acute fatty liver of pregnancy.

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Intracranial Pressure Monitoring

When establishing a diagnosis of intracranial hypertension or cerebral edema, intracranial pressure monitoring is frequently necessary. Monitoring also has value in guiding management.

Typically, extradural catheters are safer than intradural catheters. However, intradural catheters are somewhat more accurate and, in the hands of a neurosurgeon experienced with their use, may be equally safe.

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