| STEC-HUS |
| Infection with Shiga toxin–producing Escherichia coli or less frequently with Shigella dysenteriae. The most common cause of HUS in children. |
| TTP |
| Deficiency of ADAMTS13 hereditary (Upshaw-Shulman syndrome) or acquired that causes by ADAMTS13 inhibitor. |
| aHUS, complement regulation abnormality |
| Congenital |
| Genetic mutations of complement proteins |
| Acquired |
| Autoantibodies against complement proteins, such as anti-factor H antibody |
| Secondary TMA |
| Cobalamin metabolism disorder |
| Drug-induced |
| Chemotherapeutic agents (e.g., gemcitabine, mitomycin) |
| Immunosuppressive agents (e.g., cyclosporine, tacrolimus) |
| Antiplatelet agents (e.g., ticlopidine) |
| Infection |
| Pneumococcus, human immunodeficiency virus, pertussis, influenza, varicella |
| Pregnancy-related |
| Preeclampsia/eclampsia, hemolysis, elevated liver HELLP |
| Auto-immune disease, collagen disease |
| Systemic lupus erythematosus, systemic sclerosis, polymyositis/dermatomyositis |
| Bone marrow transplant, organ transplant-related |
