Bedside interpretation: ECG, CXR, CT and labs

Liver tests, coagulation and cardiac biomarkers

Reviewed Nov 2026·6 references
New· views rounded down, updated weekly

Patterns of LFT derangement, ischaemic hepatitis, interpreting PT/INR, fibrinogen and DIC scores, natriuretic peptides, lactate and procalcitonin.

Definition
ICU labs are best interpreted as patterns and trends. LFT patterns are classified by the R ratio [(ALT/ULN)/(ALP/ULN)]: ≥ 5 hepatocellular, ≤ 2 cholestatic, 2-5 mixed.

At the bedside

  1. 1

    LFT pattern

    Calculate R ratio; ALT > 1,000 units/L suggests ischaemic hepatitis, paracetamol or acute viral hepatitis; cholestasis in ICU is often sepsis, drugs or PN.

  2. 2

    Ischaemic hepatitis

    Very high ALT/AST with high LDH (ALT/LDH < 1.5) after shock, peaking at 1-3 days and falling rapidly.

  3. 3

    Synthetic function

    INR, albumin and bilirubin reflect liver function; INR in cirrhosis does not predict bleeding (see liver-coagulopathy topic).

  4. 4

    Coagulation

    Prolonged PT/APTT: dilution, consumption (DIC), liver failure, vitamin K deficiency, anticoagulants, heparin contamination of samples; check fibrinogen and platelets; viscoelastic tests where available.

  5. 5

    DIC score (ISTH)

    Calculate in a patient with a disorder associated with DIC; ≥ 5 = overt DIC; repeat daily.

  6. 6

    Natriuretic peptides

    Acute heart failure unlikely if NT-proBNP < 300 pg/mL or BNP < 100 pg/mL; values rise with AKI, age, sepsis and PE; lower in obesity.

  7. 7

    Lactate

    Elevated lactate (> 2 mmol/L) marks hypoperfusion or impaired clearance; follow trends to guide resuscitation.

  8. 8

    Procalcitonin

    Do not use PCT to decide whether to start antibiotics in suspected sepsis; use PCT with clinical review to support stopping antibiotics.

ISTH overt DIC score

Parameter0123
Platelets (× 10⁹/L)> 10050-100< 50-
D-dimer / fibrin markersNo increase-Moderate increaseStrong increase
PT prolongation (s)< 33-6> 6-
Fibrinogen (g/L)> 1.0< 1.0--

Score ≥ 5 compatible with overt DIC.

LFT patterns

PatternR ratioICU causes
Hepatocellular≥ 5Ischaemic hepatitis, paracetamol, viral (hepatitis A/E, dengue), drugs
Cholestatic≤ 2Sepsis cholestasis, biliary obstruction, PN, drugs (co-amoxiclav, ceftriaxone sludge)
Mixed2-5Drug-induced liver injury, infiltrative disease
Red flag · call your senior now
Rising INR with encephalopathy in a patient without cirrhosis: acute liver failure - contact a liver centre (liver-failure module).
Pitfall
Treating an abnormal INR with FFP in a non-bleeding patient before a low-risk procedure.
Pitfall
Starting or continuing antibiotics because of a single PCT value.
Pearl
Isolated high unconjugated bilirubin in ICU: consider haemolysis (LDH, haptoglobin, smear) and large haematoma resorption.

References

  1. 1

    Kwo PY, Cohen SM, Lim JK. ACG clinical guideline: evaluation of abnormal liver chemistries. Am J Gastroenterol 2017;112:18-35.

  2. 2

    Taylor FB Jr, Toh CH, Hoots WK, Wada H, Levi M. Towards definition, clinical and laboratory criteria, and a scoring system for disseminated intravascular coagulation. Thromb Haemost 2001;86:1327-30.

  3. 3

    McDonagh TA, Metra M, Adamo M, et al. 2021 ESC guidelines for the diagnosis and treatment of acute and chronic heart failure. Eur Heart J 2021;42:3599-726.

  4. 4

    Prescott HC, Antonelli M, Alhazzani W, et al. Surviving Sepsis Campaign: international guidelines for management of sepsis and septic shock 2026. Intensive Care Med. 2026;52(5):863-936. Co-published in Crit Care Med. 2026 (doi:10.1097/CCM.0000000000007075)

  5. 5

    de Jong E, van Oers JA, Beishuizen A, et al. Efficacy and safety of procalcitonin guidance in reducing the duration of antibiotic treatment in critically ill patients (SAPS). Lancet Infect Dis 2016;16:819-27.

  6. 6

    Farkas J. The Internet Book of Critical Care (IBCC). EMCrit Project; continuously updated.

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