24th July 2024

Thrombotic thrombocytopenic purpura

TTP is defined by reduced activity of the vWF-inactivating protein ADAMTS13. This leads to platelet aggregation within vessels, microangiopathic haemolytic anaemia and organ damage.

Clinical features of TTP

Traditionally, TTP has been thought of as a pentad consisting of:

• Thrombocytopenia
• Microangiopathic haemolytic anaemia
• AKI
• Fever
• Neurological symptoms

However, due to earlier treatment, the complete pentad is much rarer nowadays. Symptoms can vary and typically affect the neurological system (confusion, headache, weakness and stroke), gastrointestinal tract (pain, nausea, vomiting and diarrhoea), kidneys (this may manifest as rises in creatinine that are not necessarily diagnostic for AKI; anuria is rare) and cardiac (arrhythmias, MI). Patients can vary from ambulant to moribund.

Investigations are similar to those in HUS. ADAMTS13 levels should be checked, however results may take some time.

TTP can be secondary to HIV, medications such as clopidogrel and pregnancy.

Management of TTP

Due to the potential rapid deterioration with TTP it is a medical emergency. Plasma exchange is the first line treatment along with steroids, followed by monoclonal antibody infusions such as rituximab.