Curriculum · Hematology
Thrombotic thrombocytopenic purpura
What it is
Thrombotic thrombocytopenic purpura (TTP) is one of the causes of microangiopathic hemolytic anemia (MAHA): fragmentation of red cells and formation of microthrombi leading to non-immune hemolytic anemia and thrombocytopenia.
The pathophysiology is a low ADAMTS13 level, which leaves uncleaved vWF multimers and leads to platelet trapping and activation. It may be acquired, through an autoantibody, or hereditary.
Causes and risk
The other causes of MAHA are worth holding beside TTP:
- Hemolytic uremic syndrome (HUS) or atypical HUS
- Eclampsia, HELLP syndrome
- Malignant hypertension
- Malfunctioning heart valves
- Metastatic carcinoma
- Drugs: calcineurin inhibitors, quinine, simvastatin
How it presents
The pentad may be remembered as FAT RN: Fever, Anemia (MAHA), Thrombocytopenia, Renal symptoms and Neurologic symptoms.
The findings that are always there are hemolytic anemia with a raised LDH and a low haptoglobin and schistocytes on the film, and thrombocytopenia with a raised bleeding time and a normal PT and PTT. Renal failure, neurologic manifestations and fever come sometimes rather than always.