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Thrombocytopenia: ITP, TTP, HIT and DIC

Before any treatment, pseudothrombocytopenia is excluded on a blood film; then the question is whether the patient is "bleeding" (ITP, DIC) or "clotting" (TTP, HIT) — because in the latter two a platelet transfusion is dangerous and treatment is urgent.

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Why it matters in the exam

Questions present a low platelet count and ask the candidate to identify the syndrome from the setting. ITP is isolated thrombocytopenia (the rest of the count and the film are normal) in a well person, and it is a diagnosis of exclusion — HIV, hepatitis C and H. pylori are checked. Treatment is given when platelets are below 30 thousand or there is bleeding: steroids (prednisone or dexamethasone 40 mg for 4 days), and IVIG when a rapid rise is needed. HIT appears 5–10 days after starting heparin, with a fall of more than 50% in platelets and sometimes new thrombosis; the right step is to stop all heparin and start a non-heparin anticoagulant, even before the laboratory result.

TTP is an emergency: haemolytic anaemia with schistocytes on the film, low platelets, and sometimes fever, neurological signs and kidney injury; ADAMTS13 activity below 10% confirms it. Treatment is urgent plasma exchange with steroids, caplacizumab and sometimes rituximab — not a platelet transfusion. HUS is similar but with prominent kidney failure, usually after bloody diarrhoea from Shiga toxin-producing E. coli. DIC appears in sepsis, trauma or obstetric complications, with prolonged PT and aPTT, low fibrinogen and high D-dimer — and the cause is treated.

Key points

Film first: exclude clumps and look for schistocytes.
ITP: isolated, a diagnosis of exclusion; treat below 30 thousand or with bleeding.
TTP: schistocytes, ADAMTS13 below 10%, plasma exchange at once, no platelets.
HIT: 5–10 days after heparin, a fall of more than 50%; stop heparin and give an alternative.
DIC: long PT and aPTT, low fibrinogen, high D-dimer; treat the cause.

Summary table

Syndrome	Clues	Confirming test	Treatment
ITP	Isolated thrombocytopenia, well patient	Diagnosis of exclusion; HIV, HCV, H. pylori	Treat if below 30 thousand or bleeding: steroids, IVIG
TTP	Schistocytes, haemolysis, neurological signs	ADAMTS13 below 10%	Urgent plasma exchange, steroids, caplacizumab; no platelets
HUS	Bloody diarrhoea followed by kidney failure	STEC in stool; complement in aHUS	Supportive; eculizumab in aHUS
HIT	5–10 days after heparin, fall of more than 50%, thrombosis	4T score, PF4-heparin antibodies	Stop heparin; argatroban, fondaparinux or a DOAC
DIC	Sepsis, trauma, childbirth	Long PT and aPTT, low fibrinogen, high D-dimer	Treat the cause; blood products for bleeding
Pseudothrombocytopenia	No bleeding	Platelet clumps on the film (EDTA)	Repeat in a citrate tube

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Sources

American Society of Hematology Guidelines for Immune Thrombocytopenia, 2019 — Management of newly diagnosed ITP in adults
International Society on Thrombosis and Haemostasis Guideline for the Treatment of Immune Thrombotic Thrombocytopenic Purpura, 2020 — Treatment of iTTP
American Society of Hematology Guidelines for Heparin-Induced Thrombocytopenia, 2018 — Diagnosis and management of acute HIT

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.