acute liver failure (alf) profile

definition

Acute Liver Failure (ALF): Severe acute liver injury with encephalopathy and INR $\ge$ 1.5 in a patient without pre-existing cirrhosis / chronic liver disease (illness duration < 26 weeks).

the “alf screen”

1. etiology (the “why”)

test	target pathology	sensitivity / specificity
Acetaminophen Level	Acetaminophen Toxicity	Sens: High (if <24h). Spec: High. Note: Low/undetectable levels do not rule out delayed presentation.
Viral Hepatitis Serology	Hep A (IgM), Hep B (HBsAg, IgM anti-HBc), Hep E (IgM), HSV/VZV (PCR).	Sens: >95% for acute viral hepatitis.
Ceruloplasmin	Wilson’s Disease	Sens: Low in ALF (acute phase reactant). Better: Alk Phos / Bili Ratio < 4.0 + AST/ALT > 2.2.
Autoimmune Panel	ANA, ASMA, IgG Levels	Sens: Variable. Biopsy often needed for confirmation.
Toxicology Screen	Cocaine, Amphetamines, Ecstasy	Variable. History is key.
Pregnancy Test	Acute Fatty Liver of Pregnancy / HELLP	Sens: 100% for pregnancy status.
Doppler U/S Liver	Budd-Chiari, Ischaemic Hepatitis	Sens: >85% for vascular flow abnormalities.

2. severity & prognosis (the “how bad”)

test	utility	reference
INR / PT	Diagnostic Criterion. Defines ALF vs. ALI.	King’s College Criteria
Lactate	Prognostic. Early marker of graft failure/death.	arterial lactate > 3.0 mmol/L
Creatinine	Prognostic. HRS-AKI worsens mortality.	King’s College Criteria
Phosphate	Prognostic. Hyperphosphatemia (>1.2 mmol/L) suggests inability to regenerate liver.	At 48-72h post-overdose.
Ammonia	Risk Stratification. Correlation with cerebral edema risk.	> 150 $\mu$mol/L = High Risk.

diagnostic algorithm

graph TD
    A[Patient with Acute Liver Injury\nALT/AST > 1000] --> B{Encephalopathy Present?}
    B -- No --> C[Acute Liver Injury (ALI)\nMonitor Closely]
    B -- Yes --> D{INR >= 1.5?}
    D -- No --> C
    D -- Yes --> E[**Acute Liver Failure (ALF)**]
    E --> F[Admit to ICU]
    F --> G[Order ALF Profile]
    G --> H[Check Transplant Criteria]

king’s college criteria (transplant selection)

acetaminophen induced

• Arterial pH < 7.30 (after fluid resuscitation)
• OR all three of:
  1. INR > 6.5
  2. Creatinine > 300 $\mu$mol/L
  3. Encephalopathy Grade III/IV

non-acetaminophen

• INR > 6.5
• OR three of five:
  1. Age < 10 or > 40
  2. Etiology: Drug/Toxin (non-APAP), Wilson’s, Indeterminate
  3. Jaundice to Encephalopathy interval > 7 days
  4. INR > 3.5
  5. Bilirubin > 300 $\mu$mol/L

calculator

Embed React Calculator Component Here (e.g., <KingsCollegeCalculator />)

pearls & pitfalls

• Ammonia: Venous ammonia is often sufficient for trend and screening, though arterial is gold standard. Do not use ammonia to stage encephalopathy (clinical diagnosis).
• Coagulopathy: Do not correct INR with plasma unless active bleeding or invasive procedure planned (masks the trajectory of recovery/failure).
• Hypoglycemia: The liver makes glucose. Refractory hypoglycemia is a sign of massive necrosis.