Renal replacement therapy

Heparin vs citrate anticoagulation

Reviewed Nov 2026·2 references
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Regional citrate as first choice for CRRT, heparin when citrate is unsuitable, and options in bleeding or HIT.

Definition
KDIGO suggests regional citrate anticoagulation (RCA) rather than heparin for CRRT in patients without contraindications, and heparin (UFH or LMWH) when citrate cannot be used. RICH (2020): citrate prolonged filter life with fewer bleeding complications.

At the bedside

  1. 1

    Assess bleeding and liver function

    Active bleeding, recent surgery, platelets < 50 x10^9/L, coagulopathy: avoid systemic heparin. Severe liver failure or lactate > 4 mmol/L with shock: caution with citrate (accumulation).

  2. 2

    Citrate (first choice)

    Pre-filter citrate to post-filter iCa 0.25-0.35 mmol/L; calcium infusion to systemic iCa 1.0-1.2 mmol/L. Check iCa at 1 h and 6-hourly.

  3. 3

    Detect citrate accumulation

    Total Ca/ionised Ca ratio > 2.5, rising anion gap acidosis, falling systemic iCa despite increasing Ca infusion: reduce citrate/blood flow, increase dialysate, or switch method.

  4. 4

    Heparin (if citrate unsuitable)

    UFH pre-filter 5-10 units/kg/h, aPTT target 45-60 s (or per protocol); avoid in HIT.

  5. 5

    No anticoagulation

    In high bleeding risk: pre-dilution, higher blood flow (200-250 mL/min), low FF, minimise interruptions; accept shorter filter life.

  6. 6

    HIT

    Stop all heparin; use citrate or argatroban (or no anticoagulation).

Regional anticoagulation

Trisodium citrate (regional citrate anticoagulation)

Pre-filter infusion
Dose
Titrate to post-filter iCa 0.25-0.35 mmol/L
Target
Systemic iCa 1.0-1.2 mmol/L; total/iCa ratio < 2.5

Systemic heparin for circuit

Unfractionated heparin (CRRT circuit)

Pre-filter IV infusion
Dose
5-10 units/kg/h (typically 300-1,000 units/h)
Preparation
5,000 units in 50 mL NS = 100 units/mL
Target
aPTT 45-60 s
Worked example
70 kg at 7 units/kg/h = 490 units/h = 4.9 mL/h of 100 units/mL
Open infusion calculator
Red flag · call your senior now
Rising anion gap, falling iCa and total/iCa > 2.5 on citrate = citrate accumulation: act now (risk of severe hypocalcaemia and acidosis).
Pitfall
Measuring 'systemic' iCa from the post-filter port.
Pitfall
Running citrate in a patient with acute liver failure and lactate 8 mmol/L without close monitoring.
Pearl
Citrate also supplies bicarbonate (metabolised to bicarbonate in liver/muscle): watch for metabolic alkalosis and reduce bicarbonate in fluids.

Calculators for this topic

Infusion rate from per-kg-per-hour dose

Pump rate for drugs dosed per kg per hour (insulin U/kg/h, midazolam mg/kg/h, propofol mg/kg/h, fentanyl mcg/kg/h, dexmedetomidine mcg/kg/h).

Albumin-corrected calcium

Ca (mg/dL) + 0.8 × (4.0 − albumin g/dL). Prefer ionised calcium in ICU.

References

  1. 1

    Kidney Disease: Improving Global Outcomes (KDIGO) AKI Work Group. KDIGO Clinical Practice Guideline for Acute Kidney Injury. Kidney Int Suppl 2012;2:1-138 (summary: Nephron Clin Pract 2012;120:c179-84).

  2. 2

    Zarbock A, Kullmar M, Kindgen-Milles D, et al. Effect of regional citrate anticoagulation vs systemic heparin anticoagulation during continuous kidney replacement therapy on dialysis filter life span and mortality (RICH). JAMA 2020;324:1629-39.

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