TMA

Entity

Pathophysiology

Typical SHU

Most common variant, more common in childhood. Preceded by infectious symptoms: dysenteric diarrhea caused by Escherichia coli strain O157: H7 and other strains, Shigella dysenteriae type I, more rarely without diarrhea caused by Streptococcus pneumoniae (neuraminidase). These germs produce toxins (shiga toxin) or antigens (Thomsen-Friedenreich) that produce inflammation and apoptosis at the endothelial level, mainly renal, which generates a prothrombotic state with aggregation and platelet consumption accompanied by hemolysis with severe renal deterioration.

SHUa

Like HUS but without a history of infection. Worse prognosis with mortality of 15% and kidney injury in 50% of cases. Genetic defects in the regulation of the alternative complement pathway generate activation of C3 that increases the production of C3b which is deposited in the membranes and induces mainly endothelial injury, platelet and leukocyte activation, with finally microcirculation thrombosis.

Idiopathic TTP

Inhibitory antibodies that reduce the activity of ADAMTS13 < 5% - 10%, responsible for the excision of von Willebrand factor, without this, platelets adhere to the endothelium causing platelet consumption, hemolysis and multiple ischemic areas due to microcirculatory compromise. Classic pentad in 40% of cases: microangiopathic hemolytic anemia, marked thrombocytopenia, neurological deficit, fever and kidney dysfunction. If there is no triggering cause, it is called idiopathic. Secondary when there is an associated factor: medications (quinine, cisplatin, clopidogrel, oral contraceptives, tacrolimus, cyclosporine, penicillin, NSAIDs, among others), SLE, APS, scleroderma, viral infections (HIV, hepatitis C and B, helicobacter pylori), vaccines (measles, mumps, rubella and chickenpox)

Congenital TTP

Genetic alterations of ADAMTS13 without the presence of inhibitory antibodies, it is rare and is expressed early it is also known as Upshaw-Schulman syndrome

HELLP syndrome

Above