Acute Liver Failure

Meet the patient

A 23-year-old woman is brought to the emergency department 48 hours after a deliberate paracetamol overdose. She is drowsy and confused, her asterixis is marked, her INR is 9.4, her arterial pH is 7.25, her lactate is 6, and her creatinine is climbing. There is no chronic liver disease on collateral history.[1][2]

Three questions are now live and they are all time-critical: is this acute liver failure? (the triad says yes — INR at least 1.5, encephalopathy, no cirrhosis, within 26 weeks); does she meet King's College Criteria for transplant? (arterial pH below 7.3 alone meets the paracetamol criteria); and what must be started in the next 15 minutes? (N-acetylcysteine empirically, ICU admission, cerebral-oedema protection, and an early call to the transplant centre).[2][5]

The defining triad — and the two accepted exceptions

The triad is the diagnosis. Severe acute liver injury plus coagulopathy (INR at least 1.5) plus any degree of hepatic encephalopathy, all within 26 weeks, in a patient without pre-existing cirrhosis.[1][3]

Encephalopathy is the cardinal feature that separates ALF from severe acute hepatitis. A raised INR alone with a normal conscious level is not ALF — it is severe acute injury, and it becomes ALF only when the brain is involved. Examiners test this distinction because it gates the urgency and the transplant pathway.[1]

Two conditions are the accepted exceptions to the "no chronic disease" rule, because they can present as ALF on a chronic substrate: Wilson's disease and reactivation of chronic hepatitis B. Recognising them matters because their treatment and transplant listing differ — Wilson's ALF uses its own prognostic score (the Wilson index), not the King's College Criteria.[1]

The lineage examiners test: the original 1970 Trey and Davidson description coined "fulminant hepatic failure" for encephalopathy within eight weeks; the Paris group split fulminant (within two weeks of jaundice) from subfulminant (two weeks to three months); the modern AASLD consensus collapses these into "acute liver failure", timed from symptom onset to encephalopathy up to 26 weeks, divided by tempo into hyperacute, acute and subacute.[4]

Classification — by time and by cause, both prognostic

ALF is classified two ways — by time (O'Grady's syndromic classification) and by cause — and both carry prognostic weight.[1]

By the interval from jaundice to encephalopathy (O'Grady, 1993):[4]

• Hyperacute — encephalopathy within 7 days of jaundice. Typical of paracetamol and ischaemic injury. It carries the highest risk of cerebral oedema and severe coagulopathy, yet paradoxically the best transplant-free survival: if the patient survives the acute insult, hepatocyte regeneration restores function.
• Acute — encephalopathy at 8 to 28 days. Typical of many viral and drug-induced cases.
• Subacute — encephalopathy at 29 days to 26 weeks. Typical of indeterminate, idiosyncratic drug and some Wilson's cases; prominent jaundice and ascites, and a poor prognosis without transplant.[1]

[1]

How common, and the aetiological mix is strongly regional

ALF is rare — incidence roughly 1 to 8 per million per year in the developed world (an estimated 2000 cases a year in the United States, around 400 in the UK) — but it strikes previously well, often young, people and carries a high short-term mortality. The aetiological mix is strongly regional:[1][6]

• Developed world (US, UK, Europe, Australasia): paracetamol (acetaminophen) is the single commonest cause (around 40 to 50 percent of cases in the UK), followed by idiosyncratic drug-induced liver injury and viral hepatitis; a substantial minority (around 10 to 20 percent) remain indeterminate.
• Developing world (India, South-East Asia, Africa): viral hepatitis predominates — hepatitis A, B and especially E (HEV is notorious for causing ALF and a high case-fatality in pregnancy, where mortality can approach 20 to 25 percent). Paracetamol overdose is far less common.[1]

The complete aetiological list, with the exam clue:[1][3]

[1]

Risk factors for severe paracetamol hepatotoxicity — the exam-tested modifiers that deplete glutathione or induce CYP2E1, lowering the toxic threshold: chronic alcohol misuse, malnutrition, fasting or anorexia, chronic liver disease, AIDS, and concomitant enzyme-inducing drugs (rifampicin, phenytoin, carbamazepine, isoniazid). These patients develop toxicity at doses nearer the therapeutic range — the rationale for treating any of them with NAC at lower thresholds.[1]

[1]

Why patients die — the mechanism cascade

The liver performs three jobs that ALF destroys: synthesis (clotting factors, albumin, glucose), detoxification (ammonia, drugs), and excretion (bilirubin). The mechanism cascade below explains every clinical feature — and, critically, why the patient dies.[1][3]

1. Massive hepatocyte necrosis. Whatever the cause — paracetamol's NAPQI, a virus, ischaemia, immune attack — the dominant lesion is loss of functioning hepatocytes, classically centrilobular (zone 3) in paracetamol and ischaemic injury, because zone 3 is farthest from the oxygenated portal triad and richest in CYP2E1. The wholesale loss of functional hepatocyte mass drives every downstream event.[1]

2. Loss of synthetic function. The liver stops making clotting factors (II, V, VII, IX, X, fibrinogen); factor VII has the shortest half-life, so the INR or PT rises first. The INR is therefore the best single marker of hepatic synthetic function and prognosis, and the cornerstone of the King's College Criteria. Gluconeogenesis fails (hypoglycaemia — dangerous because it worsens encephalopathy and mimics cerebral oedema; check glucose hourly). Albumin falls.[2]

The "rebalanced haemostasis" concept. Although the INR is markedly prolonged, ALF patients bleed far less than the number suggests — the liver also synthesises the natural anticoagulants (protein C, protein S, antithrombin) and both fall together. The system is "rebalanced" rather than auto-anticoagulated, so the INR overstates bleeding risk. Thromboelastography (TEG or ROTEM) is preferred for functional bleeding risk, and prophylactic FFP is not given.[1]

3. Loss of detoxification — and how the patient dies. Ammonia and other neurotoxins are no longer cleared, cross a blood-brain barrier made leaky by circulating cytokines, and enter astrocytes, where glutamine synthetase converts ammonia to glutamine. The accumulating glutamine is osmotically active, drawing in water — astrocyte swelling (cytotoxic oedema). Two further mechanisms amplify this: loss of cerebral autoregulation (blood flow passively follows arterial pressure, so hypotension causes cerebral hypoperfusion and hypertension risks hyperaemia), and synergistic neurotoxicity between ammonia and lactate. The cascade progresses to intracranial hypertension and brainstem herniation — the leading cause of death.[1]

4. The systemic inflammatory and haemodynamic phenotype. Like sepsis, ALF produces a vasoplegic, hyperdynamic circulation: low systemic vascular resistance, high cardiac output, hypotension, microcirculatory shunting, tissue hypoxia. The degree of the systemic inflammatory response syndrome (SIRS) independently predicts encephalopathy progression and death. The result is acute kidney injury (ATN or functional hepatorenal physiology), lactic acidosis and progression to multi-organ failure.[1]

5. Immune dysfunction. The acutely failing liver cannot clear gut-derived endotoxin and bacteria from portal blood, and Kupffer-cell function collapses. Patients are therefore functionally immunocompromised — vulnerable to bacterial and fungal sepsis, the second leading cause of death. Fever and leucocytosis are often absent, so surveillance cultures are mandatory.[3]

[1]

Paracetamol toxicity — the molecular mechanism

Paracetamol is mostly glucuronidated and sulphated; a small fraction (5 to 10 percent) is oxidised by CYP2E1 to the reactive intermediate NAPQI. At therapeutic doses NAPQI is immediately detoxified by conjugation with glutathione. After overdose, glutathione is depleted, NAPQI binds covalently to hepatocyte proteins, mitochondrial injury releases apoptosis-inducing factors, and zone-3 (centrilobular) necrosis follows. This is why N-acetylcysteine (NAC) works: it is a glutathione precursor (a cysteine donor) that repletes stores and detoxifies NAPQI. The toxic threshold is lowered by anything that depletes glutathione or induces CYP2E1 — chronic alcohol, malnutrition, fasting, enzyme-inducing drugs.[1]

Clinical presentation — and the cause-specific fingerprints

The presentation reflects speed of onset and the underlying cause, but the common features are:[1]

• Encephalopathy — the cardinal feature. West Haven grading: I mild confusion, euphoria or anxiety, asterixis, sleep reversal; II lethargy, disorientation, marked asterixis; III somnolent but rousable, severe confusion, aggressive; IV coma. Cerebral oedema becomes common from grade III to IV.[3]
• Jaundice — usually present, though in hyperacute (paracetamol) jaundice can be mild or lag behind encephalopathy.
• Coagulopathy — bleeding (gum, nasal, GI, puncture sites), bruising; the INR rises early.
• Right-upper-quadrant discomfort or tender hepatomegaly, nausea, vomiting, anorexia.
• Ascites — especially in subacute disease.
• Hypoglycaemia, metabolic acidosis, hypokalaemia, hypophosphataemia, infection (fever may be absent).[1]

[1]

Asterixis (liver flap): with the arms outstretched and wrists hyperextended, a flapping, irregular flexion-extension at the wrist and metacarpophalangeal joints — a sign of grade I to II encephalopathy (metabolic brain dysfunction), lost as the patient progresses to deeper coma.[1]

Cause-specific clues (high-yield stems):[1]

• Paracetamol — deliberate overdose; the four phases (0 to 24 h nausea and pallor; 24 to 72 h RUQ pain with rising INR and AST; 72 to 96 h peak hepatotoxicity with renal failure; over 5 d recovery or progression to ALF).
• Wilson's ALF — young patient, Coombs-negative intravascular haemolysis (low haemoglobin, high bilirubin), Kayser-Fleischer rings, low urate, low ceruloplasmin; ALP much lower than expected for the bilirubin.
• Amanita phalloides — mushroom foraging; a biphasic course: GI phase (nausea, vomiting, diarrhoea) 6 to 24 h after ingestion, an apparent recovery, then hepatorenal failure at 2 to 4 days.
• Ischaemic hepatitis — context of cardiopulmonary arrest, severe shock or heart failure; very high AST or ALT (often over 10 000) that falls rapidly once perfusion is restored.
• Pregnancy (AFLP or HELLP) — third trimester, malaise, nausea, epigastric pain, hypoglycaemia, high ammonia, thrombocytopenia, haemolysis.
• HSV hepatitis — immunosuppressed or pregnant; often anicteric (jaundice may be absent); high mortality — treat empirically with aciclovir while awaiting PCR.[1]

[1]

The atypical presentations examiners test deliberately. The elderly patient may have a blunted confusional state attributed to infection when it is early encephalopathy. The diabetic patient with paracetamol toxicity can collapse first from hypoglycaemia. The pregnant patient in the third trimester with AFLP presents with vomiting and abdominal pain that can masquerade as HELLP or even gastritis. The immunocompromised patient with HSV hepatitis is often anicteric with a flu-like prodrome, and the diagnosis is missed until the AST exceeds 5000. The alcoholic patient with malnutrition develops paracetamol toxicity at doses closer to therapeutic than to a true overdose — the so-called "therapeutic misadventure".[1]

The differential — and the patterns of a very high AST

An acutely jaundiced, encephalopathic patient is not always ALF. Distinguish carefully:[1][3]

• Acute-on-chronic liver failure or decompensated cirrhosis — the key exclusion. Look for stigmata of chronic disease, low platelets, splenomegaly, imaging or elastography showing a shrunken nodular liver, and previous LFTs. These patients do not meet ALF criteria (pre-existing cirrhosis) and are not listed under the same transplant pathway.
• Severe sepsis with cholestatic jaundice and septic encephalopathy — sepsis causes jaundice and confusion but, in the absence of shock liver, does not cause INR over 1.5 with encephalopathy. Look for the source, cultures, lactate.
• Ischaemic hepatitis (shock liver) — profound hypotension or cardiogenic shock; AST or ALT often over 1000 to 10 000 U/L with a rapid fall on reperfusion; the INR rises but encephalopathy is usually from the underlying insult rather than the liver.
• Intracranial event or metabolic encephalopathy — a stroke, subdural, uraemia, drug intoxication, Wernicke's, or hypoglycaemia can mimic ALF encephalopathy; the liver function and INR will be near-normal (unless coexistent liver disease).
• Severe acute viral hepatitis without encephalopathy — by definition not ALF until encephalopathy appears.
• Acute biliary obstruction with cholangitis — fever, RUQ pain, jaundice (Charcot triad); AST, ALT and INR usually only mildly abnormal; ultrasound or MRCP shows dilated ducts.[1]

Patterns that help distinguish the cause of a very high AST or ALT (over 1000 U/L):[1]

| Pattern | Most likely cause |[1] |---|---| | AST or ALT over 1000 to 10 000 U/L, rapid rise and fall, context of hypotension | Ischaemic hepatitis | | AST or ALT over 10 000 U/L after a known overdose | Paracetamol toxicity | | AST or ALT 400 to 2000 U/L, prodromal illness, viral risk | Acute viral hepatitis | | AST or ALT modestly raised with very high bilirubin, young, haemolysis | Wilson's ALF | | Anicteric transaminitis in the immunosuppressed or pregnant | HSV hepatitis |

[1]

Bedside assessment — airway, brain, and collateral

ABCDE first. The priority in grade III to IV encephalopathy is airway protection and intracranial-pressure control — these patients need early intubation and mechanical ventilation.[3]

Focused assessment:[1]

• Conscious level and encephalopathy grade — orientation, simple arithmetic, day and date; asterixis; then assign the West Haven grade I to IV.
• Cerebral oedema signs — the preterminal picture is Cushing's triad: hypertension plus bradycardia plus irregular (Cheyne-Stokes) respiration, with pupillary changes, decerebrate posturing and loss of brainstem reflexes as herniation progresses.
• Stigmata of chronic liver disease — palmar erythema, spider naevi, caput, gynaecomastia, Dupuytren contracture — to look for (but not rule out) underlying cirrhosis. Their absence does not exclude chronic disease.
• Kayser-Fleischer rings (slit-lamp) — Wilson's.
• Haemodynamic monitoring — hypotension, tachycardia; assess perfusion (capillary refill, lactate, urine output), not pressure alone.[1]

Collateral history (the single most useful bedside act): timing and dose of any paracetamol or drug ingestion (single versus staggered, co-ingestants), mushroom foraging, viral risk (travel, contacts, IV drug use, sexual exposure), pregnancy status, and available previous LFTs and imaging.[1]

Investigations — prognostic and aetiological, sent in parallel

ALF investigations serve two purposes at once — prognostic monitoring (is the liver failing further, does the patient meet transplant criteria?) and aetiological diagnosis (is there a treatable antidote?). Send both panels on admission and repeat the prognostic markers (INR, lactate, glucose, pH, creatinine, phosphate) serially.[1][6]

First-line (every ALF patient):[1]

• Coagulation — INR or PT (the prognostic and transplant-trigger marker), APTT, fibrinogen.
• Biochemistry — LFTs (AST, ALT, bilirubin, ALP, GGT, albumin), glucose hourly, lactate, ammonia (arterial preferred), arterial blood gas (arterial pH), U&E, creatinine, phosphate, magnesium, calcium, CRP.
• Haematology — full blood count, blood film, group and save.
• Microbiology — blood, urine and (if ascites) peritoneal cultures; surveillance cultures on admission and then daily.
• Pregnancy test in any woman of childbearing potential.
• Imaging — abdominal ultrasound with Doppler (hepatic and portal vein patency — Budd-Chiari, portal vein thrombosis; liver texture; biliary dilatation); CT or MRI brain for cerebral oedema, herniation or an alternative intracranial cause. Transient elastography to detect occult cirrhosis.[1]

Diagnostic work-up to identify the cause:[1]

• Paracetamol level (and salicylate, ethanol, toxicology screen).
• Viral serology — HAV IgM, HBsAg, anti-HBc IgM, anti-HCV, anti-HEV IgM or HEV RNA; HSV, EBV, CMV PCR in the immunosuppressed or pregnant.
• Autoimmune markers — ANA, anti-smooth muscle antibody (ASMA), anti-LKM1, immunoglobulins.
• Wilson's — serum ceruloplasmin, 24-hour urinary copper, slit-lamp for Kayser-Fleischer rings; the ALP-to-bilirubin ratio below 2 is characteristic.
• Pregnancy — AFLP or HELLP panel (platelets, haemolysis markers, glucose, ammonia, urate).
• Liver biopsy — rarely needed and hazardous (coagulopathy); considered for autoimmune, malignancy, or indeterminate disease, usually via the transjugular route.[1]

Serial lactate kinetics — the dynamic prognostic marker. A single lactate is informative, but the trajectory is more powerful. Bernal and colleagues (Lancet 2002) showed that arterial lactate measured early and again after fluid resuscitation outperformed the static King's College Criteria in paracetamol ALF: a lactate above 3.5 mmol/L early (before fluids) or above 3.0 mmol/L after 12 hours of resuscitation predicts poor outcome (death or transplant) with high sensitivity. Measure arterial lactate on admission, at 4 hours and again at 12 hours.[7]

Phosphate. Persistent hypophosphataemia in paracetamol ALF reflects hepatic regeneration (regenerating hepatocytes consume phosphate) and is paradoxically a favourable sign; replace it to keep serum phosphate above 0.6 mmol/L.[1]

King's College Criteria — reproduced verbatim

The King's College Criteria (O'Grady, 1989) are the standard tool to decide emergency liver transplantation in ALF, and must be reproduced exactly. They were derived from the King's College Hospital cohort and remain the global default because they use bedside-available variables.[2]

For paracetamol-induced ALF — transplant if EITHER:[1]

• Arterial pH below 7.3 after adequate fluid resuscitation (the single most powerful predictor), OR
• ALL THREE of: INR over 6.5 (the original 1989 paper expressed this as prothrombin time over 100 seconds), serum creatinine over 300 micromol/L (3.4 mg/dL), and grade III to IV encephalopathy.

For non-paracetamol ALF — transplant if EITHER:[1]

• INR over 6.5 alone, OR
• ANY THREE of: age under 10 or over 40; an unfavourable cause (non-A non-B hepatitis, drug-induced or halothane); interval from jaundice to encephalopathy over 7 days; INR over 3.5; bilirubin over 300 micromol/L (17.5 mg/dL).

[1]

The lactate modifier and other prognostic models. Because King's criteria prioritise specificity over sensitivity (they miss some who will die), the arterial lactate modifier (Bernal, 2002) is added in paracetamol ALF: an early lactate over 3.5 mmol/L, or a post-resuscitation lactate over 3.0 mmol/L, independently predicts poor outcome.[7] In France the Clichy criteria (from HBV-related ALF) trigger transplant for factor V below 20 percent in patients under 30 (with encephalopathy), or below 30 percent in those over 30. The dynamic model of Bernal (2016) tracks the trajectory of lactate, INR and encephalopathy over time and is more accurate than a single static assessment.[3][9]

Additional prognostic markers:[1][3]

• Arterial ammonia — over 100 to 150 mcg/dL predicts cerebral oedema and raised ICP; a falling ammonia suggests improvement.
• Factor V — low factor V (under 20 percent) is a poor prognostic marker (used in the Clichy criteria).
• Phosphate — persistent hypophosphataemia paradoxically favours regeneration.
• Cause, age, interval jaundice-to-encephalopathy, and number of organ failures all carry independent prognostic weight.[1]

Management — resuscitation and the five priorities

[1]

ALF is managed in intensive care, with early discussion and transfer to a liver transplant centre — do not wait for every King's criterion to be met before calling. The resuscitation priorities, done in parallel, are:[1][3][6]

ABCDE and organ support.[1]

• Airway and breathing — intubate and ventilate for grade III to IV encephalopathy (airway protection plus ICP control); oxygen to maintain normoxia; target normocapnia (PaCO2 around 4.5 to 5.0 kPa; avoid hypercapnia, which raises ICP).
• Circulation — two large-bore cannulae; arterial line; resuscitate with albumin and balanced crystalloid; use noradrenaline (norepinephrine) as the first-line vasopressor for vasoplegic hypotension, with vasopressin as an adjunct; avoid over-resuscitation (worsens cerebral oedema).
• Disability — check and correct glucose; maintain glucose over 7 mmol/L; assess encephalopathy grade.
• Exposure — full examination, source control, surveillance cultures.[1]

Time-critical antidotes — give early and empirically.[5]

• N-acetylcysteine (NAC) — give to all patients in whom paracetamol cannot be confidently excluded, and continue in paracetamol-induced ALF regardless of timing. NAC is safe and inexpensive, and the randomised trial by Lee et al (2009) showed IV NAC improves transplant-free survival in non-paracetamol ALF too.[5]
• Targeted antidotes once the cause is clear — see the cause-directed table below.

Sepsis bundle. Patients with ALF are functionally immunocompromised and at high risk of infection. Send surveillance cultures, and start broad-spectrum prophylactic antibiotics plus an antifungal per local protocol; treat any infection promptly.[3]

Renal replacement therapy. Indicated for the standard AKI criteria (acidosis, fluid overload, hyperkalaemia, uraemia) and to help lower ammonia and control cerebral oedema. Prefer continuous modes (CVVHDF) over intermittent haemodialysis in cerebral oedema, to avoid rapid solute shifts that worsen ICP.[3]

Definitive management — the five priorities in detail

Once resuscitated, management follows the five priorities, with cause-specific therapy layered on.[1]

[1]

Priority 2 — encephalopathy and cerebral oedema. The goal is to keep cerebral perfusion pressure above 60 mmHg and ICP below 20 mmHg.[3]

• Head of bed elevated 30 degrees, midline (optimises venous drainage).
• Maintain the five norms: normoxia, normocapnia, normotension, normoglycaemia, normothermia. Avoid hyponatraemia (it worsens cerebral oedema).
• Hypertonic saline (a 30 percent bolus, e.g. 20 to 30 mL of 30 percent NaCl, or a 5 percent infusion) to a target sodium of 145 to 155 mmol/L — the cornerstone of ICP control in ALF.
• Mannitol 0.5 g/kg IV bolus (20 percent) for rising ICP, repeated if serum osmolality is under 320 mOsm/L and urine output is adequate; use continuous RRT to clear the mannitol and control ammonia.
• Continuous renal replacement therapy to control ammonia, fluid and acid-base.
• Rescue therapies for refractory ICP: induced hypothermia (33 to 34 degrees C), indomethacin (reduces cerebral blood flow), barbiturates (thiopentone) to suppress cerebral metabolism.
• ICP monitoring — considered in selected centres for grade III to IV patients, weighing the bleeding risk (which is lower than the INR suggests) against the benefit of an ICP-targeted approach.[3]

Priority 3 — coagulopathy, hypoglycaemia and metabolic.[1]

• Correct glucose and keep it over 7 mmol/L (10 percent dextrose infusion at 50 to 100 mL per hour).
• Vitamin K 10 mg IV slow (in case of vitamin-K deficiency from cholestasis, antibiotics or poor intake).
• Give fresh frozen plasma, cryoprecipitate, platelets — only if bleeding or before a procedure (e.g. line insertion). Do not correct the INR prophylactically — it is the key prognostic marker and transplant trigger, and routine FFP erases it. Thromboelastography (TEG or ROTEM) better reflects functional bleeding risk.
• Stress-ulcer prophylaxis (PPI) and DVT prophylaxis (LMWH once bleeding risk acceptable).
• Replace phosphate to keep it above 0.6 mmol/L; correct potassium and magnesium.[1]

Priority 4 — circulation, infection and renal. Noradrenaline, albumin, surveillance cultures plus antimicrobials, continuous renal replacement therapy. Enteral nutrition is started early (the gut is functional); avoid overfeeding protein unless encephalopathy worsens.[1]

Priority 5 — early transplant referral. Apply the King's College Criteria; refer the moment criteria are met, not when multi-organ failure develops. The transplant assessment evaluates aetiology, grade of encephalopathy, comorbidity, age, psychosocial suitability and contraindications. Where available, super-urgent national listing (UK) activates within hours.[2]

Specific antidotes and cause-directed therapy

[1]

N-acetylcysteine — the regimen, reproduced

[5]

The standard IV NAC regimen for ALF is 150 mg/kg over 1 hour (loading), then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours — a total of 300 mg/kg over 21 hours.[5] In paracetamol ALF, continue until the INR is improving and the paracetamol level is undetectable. Adverse effects (nausea, flushing, bronchospasm, urticarial rash — histamine-mediated) are managed by slowing or pausing the infusion, antihistamines, and rarely switching to oral NAC. Give NAC early and empirically whenever the diagnosis of ALF is entertained — late NAC still helps.[5]

High-volume plasma exchange (HELP)

The HELP trial (Larsen et al, J Hepatol 2016) randomised ALF patients to high-volume plasma exchange (8 to 12 litres of plasma exchange over three sessions) plus standard medical therapy. It improved transplant-free survival — partly by removing inflammatory mediators and improving haemodynamics — and is a useful bridge to transplant or to spontaneous recovery, though it is not a substitute for transplant in those who meet King's criteria.[8]

The special causes and scenarios

• Paracetamol ALF — the prototypical cause; mechanism (NAPQI, glutathione, zone-3 necrosis), the Rumack-Matthew nomogram (a treatment line on a plot of paracetamol level against time since ingestion; give NAC if the level is above the line, within 24 h of a single ingestion), the four phases, and the King's College paracetamol criteria. Staggered overdoses are riskier than a single ingestion — the nomogram cannot be used, so give NAC on history alone.[1]
• Drug-induced liver injury (DILI) — idiosyncratic. Classic exam offenders: isoniazid (add pyridoxine; baseline and monthly LFT monitoring on anti-TB therapy), valproate, halothane ("halothane hepatitis", now largely retired), phenytoin, nitrofurantoin, amiodarone, statins, carbamazepine, sulphonamides, and herbal or AYUSH preparations. Stop the offending drug; consider steroids for autoimmune or hypersensitivity (DRESS) overlap; supportive care; transplant if progressive.[1]
• Viral ALF. HAV, HBV, HEV dominate in the developing world (HEV worst in pregnancy). HSV hepatitis is easily missed — often anicteric, high mortality, treat empirically with aciclovir in the immunosuppressed or pregnant. Prevention: HAV and HBV vaccination; post-exposure HBIG plus vaccine for HBV contacts.[1]
• Wilson's ALF. The classic stem — young, Coombs-negative haemolysis, Kayser-Fleischer rings, ALP-to-bilirubin ratio below 2, low ceruloplasmin, high urinary copper, low urate. King's College Criteria do NOT apply — use the Wilson index and refer for urgent transplant; chelation is only a bridge.[1]
• Pregnancy-related ALF (AFLP or HELLP). Third trimester; hypoglycaemia, high ammonia, coagulopathy, thrombocytopenia, haemolysis. Definitive treatment is urgent delivery; supportive ICU care; transplant if liver failure does not recover postpartum.[1]
• Amanita phalloides. Biphasic (GI then hepatorenal); silibinin IV plus high-dose benzylpenicillin plus NAC; early transplant referral.[1]
• Ischaemic hepatitis (shock liver). Profound hypotension, cardiac failure or arrest; very high AST or ALT with rapid fall on reperfusion; manage the underlying cardiac or haemodynamic cause. The "shock" transaminitis typically resolves in 3 to 7 days once perfusion is restored.[1]
• Budd-Chiari syndrome. Hepatic vein thrombosis; painful hepatomegaly, ascites; anticoagulation, TIPS, transplant if fulminant.[1]
• Indeterminate ALF. No cause after full work-up; poor prognosis; transplant pathway.[1]

Complications and the classic pitfalls

[1]

The full complication set:[1][3]

• Cerebral oedema with raised ICP and brainstem herniation — the leading cause of death.
• Infection or sepsis — bacterial (chest, catheter, urinary, spontaneous bacteraemia) and fungal; often clinically silent (no fever); worsens encephalopathy and multi-organ failure.
• Renal failure — ATN or functional hepatorenal physiology; contributes to fluid overload and acidosis.
• Coagulopathy or bleeding — GI, intracranial, puncture-site; balanced by a paradoxically low rate of spontaneous major bleeding (rebalanced haemostasis).
• Metabolic — hypoglycaemia, lactic and metabolic acidosis, electrolyte disturbance (hypokalaemia, hypophosphataemia, hyponatraemia — which worsens cerebral oedema).
• Cardiorespiratory — arrhythmias, ARDS, aspiration (reduced conscious level).
• Pancreatitis — particularly after paracetamol overdose.
• Multi-organ failure — the final common pathway.[1]

The classic management pitfalls (exam favourites):[1][6]

1. Not giving NAC early and empirically — NAC is safe, inexpensive, and works in paracetamol and non-paracetamol ALF.
2. Prophylactically correcting the INR with FFP — this erases the key prognostic and transplant marker; correct only if bleeding or before procedures.
3. Late transplant referral — refer the moment King's College Criteria are met.
4. Missing treatable causes — HSV, autoimmune, Wilson's, Budd-Chiari, pregnancy.
5. Fluid overload, hypotension, hypoxia, hypoglycaemia, or hyponatraemia — each directly worsens cerebral oedema and outcome.
6. Delayed intubation in grade III to IV encephalopathy — airway and ICP control require it.
7. Using intermittent haemodialysis in cerebral oedema — rapid solute shifts raise ICP; use continuous RRT.[1]

How ALF patients come to harm — the preventable list

• Death from unrecognised cerebral oedema because the Cushing triad was missed until herniation.[1]
• A patient denied NAC because "the paracetamol level was not back yet" or the overdose was staggered.[5]
• An INR corrected with FFP that then no longer meets King's College Criteria — the transplant trigger erased.[2]
• A late transplant referral, made only after multi-organ failure had set in.[2]
• A young patient with Wilson's ALF assessed with King's Criteria (which do not apply) instead of the Wilson index.[1]
• Intermittent haemodialysis raising ICP in cerebral oedema.[3]
• HSV hepatitis in the immunosuppressed, missed because the patient was anicteric and aciclovir was withheld pending PCR.[1]

Prognosis and disposition

Prognosis depends on cause, age and speed of onset.[1][3]

• Best outcomes: paracetamol and hepatitis A — transplant-free survival 50 to 70 percent in specialist centres (hyperacute regeneration).
• Worst outcomes without transplant: indeterminate, idiosyncratic DILI, Wilson's and subacute ALF.
• Overall survival with modern ICU care and transplantation now exceeds 70 percent; post-transplant survival is over 80 percent at one year. Without transplant, mortality ranges from 30 to over 50 percent depending on cause and grade, and approaches 80 to 90 percent in grade IV coma with cerebral oedema.[1]

Prognostic markers reproduced: the King's College Criteria, arterial pH, arterial lactate (admission, 4 h and 12 h), phosphate, encephalopathy grade, cause, age, interval jaundice-to-encephalopathy, and the number of organ failures. The dynamic paracetamol model (Bernal, 2016) — tracking the trajectory of lactate, INR and encephalopathy — outperforms static thresholds.[3][9]

Disposition: all ALF patients are managed in intensive care; the principle is to discuss with, and transfer early to, a liver transplant centre — do not wait for every King's criterion to be met before referring. Living-donor transplantation may be needed where deceased donors are scarce.[1]

Prevention — public health meets the bedside

Prevention is cause-specific and heavily examined because it is where public health meets the bedside.[1]

• Paracetamol pack-size restrictions. The UK introduced legislation in 1998 limiting paracetamol pack sizes sold without prescription to 16 tablets (32 in pharmacies). This measurably reduced both fatal and non-fatal paracetamol overdoses and the number of liver unit admissions — a public-health success.
• Hepatitis B vaccination. Universal infant HBV vaccination (and catch-up programmes) and post-exposure prophylaxis with HBIG plus vaccine after needle-stick, sexual or vertical exposure prevents HBV-related ALF.
• Hepatitis A and E prevention. HAV vaccination for travellers and high-risk groups; safe water, safe food and sanitation are the foundation of HEV prevention (a licensed HEV vaccine exists in China but is not widely available elsewhere).
• Drug-monitoring programmes. Baseline and regular LFT monitoring on anti-tubercular therapy and other high-risk idiosyncratic drugs, with prompt cessation at the first sign of hepatotoxicity.
• Antidote availability. Timely access to NAC in emergency departments, and to silibinin or benzylpenicillin in mushroom-endemic regions.
• Reye's syndrome avoidance. Avoid aspirin in children under 16 with viral illness.[1]

Special populations

• Pregnancy (AFLP or HELLP). Diagnose early, deliver (often the cure), correct coagulation for delivery or anaesthesia, supportive ICU care, transplant if liver failure persists postpartum.[1]
• Children. Different aetiological spectrum (metabolic — tyrosinaemia, galactosaemia; viral; drug); weight-based NAC dosing (same mg/kg); lower threshold for transplant; paediatric transplant criteria (Paediatric End-stage Liver Disease, PELD).
• The elderly. Poorer prognosis, higher paracetamol or DILI risk, comorbidity limits transplant candidacy, atypical or blunted presentation.
• The immunocompromised. Broader differential (HSV, adenovirus, EBV, CMV, drug); empiric aciclovir if HSV suspected; lower threshold for biopsy.
• The anticoagulated patient. Complex coagulopathy; use thromboelastography (TEG or ROTEM) over the INR for functional bleeding risk; reverse anticoagulation only if bleeding or before procedures.
• Wilson's ALF in the young. A true emergency — King's does not apply; urgent transplant referral; bridging chelation.[1]

The evidence — the three landmark studies

The evidence base that shapes modern ALF practice rests on three landmark studies.[2][5][8]

[2] [5] [8]

Guidelines: the AASLD position paper (Polson and Lee, 2005) and the 2023 AASLD guidance update (US practice); the EASL Clinical Practice Guidelines (European practice, King's College transplant listing); NICE and the UK liver transplant guidelines use King's as the default for super-urgent listing.[6]

Controversies: routine prophylactic antibiotics or antifungals; the risk-to-benefit ratio of ICP monitor placement (bleeding risk vs benefit — but the bleeding risk is lower than the INR suggests); high-volume plasma exchange as routine; induced hypothermia and indomethacin for refractory ICP; living-donor versus deceased-donor transplantation; the utility of ammonia targets; the futility of transplant in established severe cerebral oedema with fixed pupils; the role of MARS (molecular adsorbent recirculating system) and other liver-support devices, which have not shown a survival benefit but may bridge to transplant.[1]

The mantra — three decisions in parallel

The mantra: give NAC early and empirically, do not correct the INR, and refer for transplant the moment King's College Criteria are met.[1][2][5]

Ward-round test — three stems

Stem 1 — the woman from the top of the topic (answer)

A 23-year-old woman 48 hours after a deliberate paracetamol overdose: drowsy and confused, marked asterixis, INR 9.4, arterial pH 7.25, lactate 6, rising creatinine, no chronic liver disease. What do you do in the first 15 minutes, and what is the referral decision? Model: This is acute liver failure — the triad of acute liver injury, INR at least 1.5, and encephalopathy within 26 weeks, no cirrhosis. She meets King's College paracetamol criteria (arterial pH below 7.3 alone is sufficient). In the first 15 minutes: give N-acetylcysteine empirically (150 mg/kg over 1 hour, then 50 mg/kg over 4 hours, then 100 mg/kg over 16 hours), admit to ICU, intubate for airway and ICP protection given grade III encephalopathy, head of bed 30 degrees with hypertonic saline to Na 145 to 155, maintain glucose over 7, send the aetiological panel, and call the transplant centre now — do not wait for more criteria. Do not correct the INR with FFP (it is the transplant trigger). Start surveillance cultures and prophylactic antimicrobials; arrange continuous renal replacement therapy for the AKI and to lower ammonia.[2][5]

Stem 2 — the young patient with haemolysis and a low ALP (answer)

An 18-year-old presents with jaundice, anaemia, confusion and INR 4. Blood film shows fragmented red cells; bilirubin is very high, ALP is oddly low, ceruloplasmin is low, and slit-lamp shows Kayser-Fleischer rings. Do the King's College Criteria apply? Model: This is Wilson's ALF — young, Coombs-negative haemolysis, Kayser-Fleischer rings, ALP-to-bilirubin ratio below 2, low ceruloplasmin. King's College Criteria do NOT apply to Wilson's ALF — use the Wilson index and refer for urgent transplant; chelation with penicillamine is only a bridge. The haemolysis is from copper released by the necrotic liver; the low ALP is a classic biochemical clue. Delaying transplant assessment while waiting for King's criteria to be met is a preventable error in this disease.[1]

Stem 3 — the INR you must not correct (answer)

An examiner asks: "A patient with paracetamol ALF has an INR of 8 and is being prepared for central line insertion. The registrar plans to give FFP to bring the INR under 1.5 before the procedure. Is that the right call?" Model: This is the classic trap. The INR is the single best marker of hepatic synthetic function and prognosis, and the cornerstone of the King's College Criteria — prophylactic FFP erases it. Correct the INR only if bleeding or immediately before a procedure, and use thromboelastography (TEG or ROTEM) to assess functional bleeding risk, because ALF is a state of "rebalanced haemostasis" in which both procoagulants and anticoagulants fall together and the INR overstates bleeding. For a line, give a targeted correction (FFP, cryoprecipitate, platelets as TEG directs) and proceed — then resume tracking the uncorrected INR for the transplant decision. Continue NAC throughout.[1][2]

References

1. [1]Stravitz RT, Lee WM. Acute liver failure Lancet, 2019.PMID 31498101
2. [2]O'Grady JG, Alexander GJ, Hayllar KM, et al. Early indicators of prognosis in fulminant hepatic failure Gastroenterology, 1989.PMID 2490426
3. [3]Bernal W, Wendon J. Acute liver failure N Engl J Med, 2013.PMID 24369077
4. [4]O'Grady JG, Schalm SW, Williams R. Acute liver failure: redefining the syndromes Lancet, 1993.PMID 8101303
5. [5]Lee WM, Hynan LS, Rossaro L, et al. Intravenous N-acetylcysteine improves transplant-free survival in early stage non-acetaminophen acute liver failure Gastroenterology, 2009.PMID 19524577
6. [6]Polson J, Lee WM; American Association for the Study of Liver Diseases. AASLD position paper: the management of acute liver failure Hepatology, 2005.PMID 15841455
7. [7]Bernal W, Donaldson N, Wyncoll D, Wendon J. Blood lactate as an early predictor of outcome in paracetamol-induced acute liver failure: a cohort study Lancet, 2002.PMID 11867109
8. [8]Larsen FS, Schmidt LE, Bernsmeier C, et al. High-volume plasma exchange in patients with acute liver failure: An open randomised controlled trial J Hepatol, 2016.PMID 26325537
9. [9]Craig DG, Ford AC, Hayes PC, Simpson KJ. Systematic review: prognostic tests of paracetamol-induced acute liver failure Aliment Pharmacol Ther, 2010.PMID 20180786