ICU · Haematology / coagulation
Thrombocytopenia in the ICU — HIT, TTP/HUS, ITP & Septic
Also known as Thrombocytopenia · Heparin-induced thrombocytopenia · HIT · 4T score · Thrombotic thrombocytopenic purpura · TTP · Haemolytic uraemic syndrome · HUS · ADAMTS13 · Immune thrombocytopenia · ITP · Argatroban · Bivalirudin · Plasmapheresis · Caplacizumab
The ICU thrombocytopenia differential: the HIT (heparin-induced — the PF4-heparin antibodies; thrombocytopenia AND thrombosis; 4T score; STOP ALL HEPARIN; switch to argatroban or bivalirudin; NO platelets), the TTP (ADAMTS13 deficiency; MAHA plus neuro; plasmapheresis plus steroids plus caplacizumab; NO platelets), the HUS (Shiga toxin E coli; renal; eculizumab), the ITP (isolated; steroids or IVIG), the septic (the commonest — treat sepsis), the drug-induced, the DIC, the dilutional, the marrow failure. The key: HIT and TTP have thrombocytopenia with THROMBOSIS (paradoxical) — and NO platelets in either (worsens the microvascular thrombosis). The TTP and HUS have the MAHA (schistocytes, raised LDH, low haptoglobin). The 4T score for the HIT; the ADAMTS13 for the TTP; the plasmapheresis is the definitive for the TTP.
Checked against its sources on 14 Oct 2026
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Overview & definition
Thrombocytopenia is common in ICU patients, and the two diagnoses that will hurt your patient if missed are HIT and TTP. Both present as thrombocytopenia with paradoxical thrombosis, and in both, platelet transfusion is contraindicated — it fuels the microvascular occlusion.[1]
Thrombocytopenia is a platelet count below the reference range; prophylactic transfusion thresholds run at 10 × 10⁹ cells/L for hypoproliferative patients and under 50 × 10⁹ for major elective nonneuraxial surgery. Sepsis is the commonest cause, but the count you must not dismiss is the one falling on day 8 of heparin or the one ringed by schistocytes.[1][23]
Frame every case through D-I-S-C — Destruction, Inadequate production, Sequestration, Consumption and dilution. The mantra: thrombocytopenia with thrombosis — HIT or TTP — and neither gets platelets.[1]
References26ShowHide
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