Figure 4.

Approach to thrombotic microangiopathy (TMA) management according to evidence of complement involvement. ∗Evidence of complement activation, if available: (i) genetics: pathogenic/likely pathogenic variant or risk haplotype in alternative complement pathway genes; (ii) antibody: autoantibodies to complement factors (mainly anti–factor H and anti–factor B), (iii) functional assays: soluble C5b-9, tissue deposition of C5b-9, others; (iv) biopsy: staining for C4d, C5b-9. aHUS, atypical hemolytic uremic syndrome; STEC-HUS, Shiga toxin hemolytic uremic syndrome; TTP, thrombotic thrombocytopenic purpura.