ADAMTS13 and hyperinsulinemic hypoglycemia, familial, 4: Advanced diagnostic tools for TMA include ADAMTS13 activity assays, which are used to document severe ADAMTS13 deficiency typical of immune TTP, and complement testing (C3 and C4 levels and, when available, functional assays), which can support the diagnosis of complement-mediated TMAs such as aHUS [3,5].