Ver el código de «Acute hepatic failure»

==Background==
[[File:Liver vascular anatomy.png|thumb|Liver vascular anatomy.]]
===Definitions===
*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<ref>O’Grady, JG, Schalm SW, Williams R. Acute liver failure: redefining the syndromes. Lancet. July 1993, Volume 342, Issue 8866, Page 273-275</ref>
*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<ref>O’Grady, JG, Schalm SW, Williams R. Acute liver failure: redefining the syndromes. Lancet. July 1993, Volume 342, Issue 8866, Page 273-275</ref>
*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<ref>O’Grady, JG, Schalm SW, Williams R. Acute liver failure: redefining the syndromes. Lancet. July 1993, Volume 342, Issue 8866, Page 273-275</ref>

{{Acute hepatitis causes}}
{{Drug or Toxin Related Liver Disease}}

===Other Rare Causes of Acute Liver Failure===
*'''[[Wilson's disease]]''': unexplained elevations in LFTs, neuro-psychiatric symptoms, Kayser-Fleischer rings on eye exam
*'''[[Autoimmune hepatitis]]''': more common in women, liver disease without explanation, may have family history of other autoimmune disorders
*'''[[Hemochromatosis]]''': family history of liver disease and cardiac disease
*'''[[Budd-Chiari]]''': history of hypercoagulable disorder, abdominal pain, and ascites

==Clinical Features==
[[File:Jaundice08.jpg|thumb|Jaundice of the skin]]
[[File:SpiderAngioma.jpg|thumb|Spider angioma]]
[[File:Hepaticfailure.jpg|thumb||Ascites secondary to [[cirrhosis]].]]
[[File:Jaundice.jpg|thumb|Pediatric jaundice with icterus of sclera.]]
*Common findings in acute liver failure
**Tender [[hepatomegaly]]
**[[Jaundice]]
**[[Hepatic encephalopathy]]
**Asterixis
*Common findings in chronic liver failure
**[[Ascites]]
**Caput medusae
**Palmar erythema
**Spider angiomata
**Gynecomastia
**Testicular atrophy
**Parotid gland enlargement
**Muscular atrophy
**May also have [[jaundice]], [[hepatic encephalopathy|encephalopathy]], and asterixis as in acute liver failure

==Differential Diagnosis==
===[[Encephalopathy]] (altered mental status)===
*[[Hypoglycemia]]
*[[Hypoxia]]
*[[Intracerebral hemorrhage]] or mass
*[[Meningitis]]/[[encephalitis]]
*[[CVA]]
*[[Alcohol intoxication]]
*[[Myxedema coma]]
*[[Wernicke encephalopathy]]
*[[Sepsis]]
*[[Seizure]]/post-ictal state
*[[Uremia]]
*[[Electrolyte abnormality]]
*[[Acute hepatic failure]]

===[[Jaundice]]===
*[[Hepatic dysfunction]]
*[[Biliary disease]] (e.g. [[Choledocholithiasis|CBD obstruction]])
*[[hemolytic anemia|Hemolysis]]
*[[Pregnancy]]
*Congenital diseases (e.g. [[inborn errors of metabolism]]; (more likely to present in early childhood)

{{Hepatomegaly DDX}}

==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
**Not useful in diagnosing the cause of liver failure, but helpful in determining coexisting [[infection]], [[anemia]], [[thrombocytopenia]]
*[[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<ref>Bailey, C, Hern HG. Hepatic Failure: An Evidence-Based Approach In The Emergency Department. Emergency Medicine Practice. Vol. 12, No. 4, 2014.</ref>
**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

{{Ascites Evaluation}}

==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
**[[Hepatic encephalopathy|Encephalopathy]]: consider [[lactulose]] of [[neomycin]]
**[[Seizures]]: consider [[phenytoin]] over [[benzodiazepines]] (prevent benzodiazepine oversedation secondary to decreased hepatic clearance)
**[[Increased ICP|Intracranial Hypertension]]: elevated head of bed, [[mannitol]], short-term hyperventilation; hypothermia may be a bridge to transplant; no benefit from steroids
**[[liver disease induced coagulopathy|Coagulopathy]]
***Prophylactic normalization of the INR is not necessary unless procedure (such as paracentesis) is planned; then can give [[Vitamin K]]
***Recommend [[platelet transfusion]] to 10K for asymptomatic patients, and to 50-70K for patients undergoing invasive procedures	
**See [[Acetaminophen toxicity]] for specifics regarding treatment of acetaminophen toxicity
**See [[Spontaneous Bacterial Peritonitis]] for specifics regarding diagnosis and treatment of SBP

==Disposition==
*Admission to ICU with early consideration for transportation to transplant center

==See Also==
*[[Jaundice]]
*[[Cirrhosis]]
*[[Acute hepatitis]]
*[[Hepatic encephalopathy]]

==References==
<references/>

[[Category:GI]]