Deranged Liver Function
at the bedside
- vitals → septic, encephalopathic, or bleeding?
- assess jaundice, asterixis, conscious level, abdominal tenderness
- review drug chart (paracetamol, anti-TB, statins, co-amoxiclav, flucloxacillin, antiepileptics), alcohol, recent procedures
- confirm pattern, compare with previous LFTs
escalate now if
- INR >1.5 or rising → acute liver failure → N-acetylcysteine, hepatology now
- encephalopathy / asterixis → decompensation
- hypoglycaemia → hypoglycemia
- severe jaundice · hypotension
- Charcot’s triad (fever + jaundice + RUQ pain) → cholangitis
interpret the pattern
- ALT / AST up → hepatocellular · ALP / GGT up → cholestatic · INR up, albumin down → synthetic failure
- R factor = (ALT/ULN) / (ALP/ULN): >5 hepatocellular, <2 cholestatic, 2–5 mixed · R factor · MDCalc ↗︎
hepatocellular: let the number narrow the cause
- 1000s → paracetamol / toxins, ischemic (shock liver), acute viral A B D E, acute stone passage (< 24 h), autoimmune, Budd-Chiari
- 100s → viral B C CMV EBV, congestive hepatopathy, alcohol (AST > ALT)
- < 100 → MASLD, celiac, hemochromatosis, Wilson’s, A1AT deficiency, hypothyroidism
cholestatic: ultrasound decides
- ducts dilated → painful → stones; painless → stricture (PSC), IgG4 / AIP, malignancy
- no dilatation → drugs (antibiotics, TPN, estrogens, methotrexate), PBC, sepsis, pregnancy, infiltration (sarcoid, mets), congestion
- ERCP treats, it does not diagnose: MRCP or EUS first
- mixed → any of the above, drugs and sepsis most often
- isolated bilirubin → unconjugated = Gilbert’s / haemolysis; conjugated = biliary
focused check
- viral risk, alcohol, drugs (paracetamol, statins, antibiotics, herbals, antiepileptics), autoimmune
- RUQ pain, pale stools, dark urine, pruritus → cholestatic picture
- chronic liver disease → spider naevi, palmar erythema, ascites, splenomegaly, encephalopathy, GI bleeding
- abdomen → hepatomegaly, RUQ tenderness, Murphy’s sign
send now
- INR, albumin, glucose: these define severity
- viral hepatitis serology, paracetamol level (+ timed level if overdose)
- USS abdomen → biliary dilatation, liver texture, portal flow; MRCP if obstruction suspected
- if cause unclear → autoimmune screen, ferritin, ceruloplasmin (selected)
if abdominal pain, add lipase
- pancreatitis if >3× ULN with consistent pain; lipase cleaner than amylase (also rises in bowel ischemia, perforation, DKA, renal failure)
treat
- stop the hepatotoxic drug; treat the cause
- hepatocellular → INR rising or encephalopathy → hepatology + ICU now
- cholestatic → USS; obstruction → GI for ERCP
- cholangitis (fever + jaundice + RUQ pain): IV antibiotics now + urgent biliary drainage
- known liver disease, new ascites or confusion → tap the ascites (SBP), think encephalopathy
acute liver failure
- rising INR + encephalopathy + hypoglycaemia → hepatology + ICU now
- N-acetylcysteine if paracetamol-related (start before the level if staggered or late):
- bag 1: 150 mg/kg in 200 mL glucose 5% IV over 1 h
- bag 2: 50 mg/kg in 500 mL glucose 5% IV over 4 h
- bag 3: 100 mg/kg in 1000 mL glucose 5% IV over 16 h
- flushing / urticaria / wheeze are common: slow the infusion, antihistamine, continue unless true anaphylaxis
- obesity dosing and beyond 21 h: local toxicology protocol
calculator MELD-Na · MDCalc ↗︎
- severity = INR, albumin, glucose: trend these, not the transaminases; repeat LFTs for the trend
- hand over → INR / encephalopathy trend, escalation trigger for acute liver failure
evidence
| source | type |
|---|---|
| R-factor (R-ratio) pattern classification | common practice |
| IV N-acetylcysteine 3-bag (Prescott) protocol for paracetamol toxicity | established protocol / BNF |
Verify indication, dose, allergies, interactions, renal/hepatic function and local protocols before prescribing.
go deeper MOC+ Vol 4 · Acute GI & Hepatology covers this in the full reference, or the complete set.
free the on-call checklist covers the whole shift on one printable page.
More clinical resources in the MOC+ Library →
updated Oct 2026file lab/lft-liver-function