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# Thrombotic thrombocytopenic purpura

TTP is a rare emergency in which tiny platelet clots block small vessels, using up platelets and breaking red cells; urgent plasma exchange saves lives.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Kidneys](https://durgical.com/en/anatomy/kidney/)
- [Vessels inside the kidney](https://durgical.com/en/anatomy/intrarenal-arteries-and-veins/)
- [Spleen](https://durgical.com/en/anatomy/spleen/)

## In the clinical exam

- [Bleeding syndromes: platelet vs coagulation pattern](https://durgical.com/en/clinical-exam/bleeding-syndromes-platelet-vs-coagulation-pattern/)

## Why it happens

- [Thrombosis and Virchow's triad](https://durgical.com/en/general-pathology/thrombosis-and-virchow-s-triad/)
- [Hemorrhage: petechiae, purpura, ecchymosis, hematoma, and what blood loss does](https://durgical.com/en/general-pathology/hemorrhage-petechiae-purpura-ecchymosis-hematoma-and-what-blood-loss-does/)
- [Primary hemostasis and platelets](https://durgical.com/en/physiology/primary-hemostasis-and-platelets/)
- [The red cell life cycle and the spleen](https://durgical.com/en/physiology/the-red-cell-life-cycle-and-the-spleen/)

## What it is

A thrombotic microangiopathy caused by severe deficiency of ADAMTS13, the enzyme that cuts von Willebrand factor multimers. Platelet-rich microthrombi form in small vessels, producing thrombocytopenia, microangiopathic haemolytic anaemia and ischaemia of the brain, heart, kidneys and gut.

## Who gets it

Rare, with a few new cases per million people per year; most are acquired (autoimmune) in adults, more often in women. Congenital TTP (Upshaw-Schulman syndrome) can appear in childhood or first during pregnancy.

## Causes

- Acquired: autoantibodies that inhibit ADAMTS13 (most cases)
- Congenital: biallelic ADAMTS13 gene mutations
- Triggers: pregnancy, autoimmune disease such as lupus, HIV infection, some drugs (for example ticlopidine, clopidogrel, quinine, calcineurin inhibitors), cancer and stem cell transplant

## Risk factors

- Female sex and adult age (30–50 years)
- Pregnancy and the postpartum period
- Systemic lupus erythematosus and other autoimmune diseases
- HIV infection
- Previous episode of TTP (relapse risk)

## Pathophysiology

Without ADAMTS13, ultra-large von Willebrand factor multimers stay on the endothelium and catch platelets under high shear, forming microthrombi. Platelets are consumed (thrombocytopenia) and red cells are sheared as they pass the clots, producing schistocytes (microangiopathic haemolysis). The coagulation cascade is not primarily activated, so PT and aPTT are usually normal, unlike DIC.

## Classification

- Immune (acquired) TTP
- Congenital (hereditary) TTP
- Related thrombotic microangiopathies: haemolytic uraemic syndrome (Shiga toxin or complement-mediated), DIC, HELLP syndrome

## Symptoms and signs

- Petechiae, purpura and mucosal bleeding
- Fatigue, pallor and jaundice from haemolysis
- Fluctuating neurological signs: headache, confusion, focal deficits, seizures
- Fever
- Abdominal pain, nausea and vomiting
- Reduced urine or haematuria (kidney involvement usually milder than in HUS)

## Red flags

- Thrombocytopenia plus schistocytes on the smear: treat as TTP until proven otherwise
- Altered consciousness, stroke-like signs or seizures
- [Chest](https://durgical.com/en/anatomy/region/chest/) pain or raised troponin (myocardial ischaemia)
- Abdominal pain with bloody diarrhoea or falling urine output (intestinal or renal ischaemia)

## Diagnosis

**Clinical**
The classic pentad (thrombocytopenia, microangiopathic haemolytic anaemia, neurological signs, [kidney](https://durgical.com/en/anatomy/kidney/) involvement and fever) is complete in only a minority; the first two are enough to suspect it. Clinical scores such as PLASMIC estimate the probability of severe ADAMTS13 deficiency.

**Tests**
Low platelets; anaemia with schistocytes on the peripheral smear; raised LDH and indirect bilirubin, low haptoglobin, high reticulocytes; negative direct Coombs test; normal PT and aPTT; creatinine and troponin. ADAMTS13 activity below 10% confirms the diagnosis, with an inhibitor assay for the immune form; blood should be drawn before plasma therapy.

**Imaging**
Brain CT or MRI when neurological signs appear; not needed for diagnosis.

## Differential diagnosis

- Haemolytic uraemic syndrome (more severe kidney failure, often after bloody diarrhoea in children)
- Disseminated intravascular coagulation (prolonged PT/aPTT, low fibrinogen)
- HELLP syndrome and severe preeclampsia
- Immune thrombocytopenia or Evans syndrome
- Heparin-induced thrombocytopenia
- Malignant hypertension

## Goal of treatment

Start plasma exchange immediately when TTP is suspected, stop microthrombus formation, suppress the antibody against ADAMTS13 and prevent organ damage and relapse.

## Treatment

**Acute**
Urgent daily therapeutic plasma exchange, which removes the autoantibody and replaces ADAMTS13; plasma infusion if exchange is delayed and for congenital TTP.

**Medical**
Glucocorticoids and anti-CD20 monoclonal antibody (rituximab) to suppress the autoimmune response; an anti-von Willebrand factor nanobody (caplacizumab) blocks platelet adhesion.

**Medical**
Recombinant ADAMTS13 or regular plasma infusions for congenital TTP.

**Follow-up**
Daily platelet count, LDH and neurological checks; ADAMTS13 activity during remission to anticipate relapse. Platelet transfusion is avoided unless there is life-threatening bleeding.

**Surgical**
Splenectomy is reserved for rare refractory or relapsing cases.

## Complications

- Stroke, seizures and coma
- Myocardial infarction and arrhythmias
- Acute kidney injury
- Relapse months or years later
- Death, high without treatment

## Prognosis

Untreated TTP is fatal in most cases; with prompt plasma exchange and immunosuppression, most patients survive. Relapses are common, and survivors may have long-term cognitive problems or depression.

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme is deficient in thrombotic thrombocytopenic purpura?

ADAMTS13, the protease that cleaves von Willebrand factor multimers.

## What peripheral smear finding supports microangiopathic haemolytic anaemia?

Schistocytes (fragmented red cells).

## How do PT and aPTT help distinguish TTP from DIC?

They are usually normal in TTP and prolonged in DIC.

## What is the first-line emergency treatment of acquired TTP?

Therapeutic plasma exchange, with glucocorticoids, started as soon as TTP is suspected.

## Why are platelet transfusions generally avoided in TTP?

They may feed new microthrombi and worsen organ ischaemia.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/conditions/thrombotic-thrombocytopenic-purpura/)

## Related conditions

- [Heparin-induced thrombocytopenia](https://durgical.com/en/conditions/heparin-induced-thrombocytopenia/)
- [Acute kidney injury](https://durgical.com/en/conditions/acute-kidney-injury/)
- [Ischaemic stroke](https://durgical.com/en/conditions/ischaemic-stroke/)
- [Systemic lupus erythematosus](https://durgical.com/en/conditions/systemic-lupus-erythematosus/)
- [HIV infection and AIDS](https://durgical.com/en/conditions/hiv-infection-and-aids/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Thrombotic Thrombocytopenic Purpura (TTP)](https://www.nhlbi.nih.gov/health/thrombotic-thrombocytopenic-purpura) (National Heart, Lung, and Blood Institute (NHLBI), 2024); [Thrombotic thrombocytopenic purpura](https://medlineplus.gov/ency/article/000552.htm) (MedlinePlus (U.S. National Library of Medicine), 2024).

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Source: https://durgical.com/en/conditions/thrombotic-thrombocytopenic-purpura/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/thrombotic-thrombocytopenic-purpura/