Eculizumab withdrawal. Reasons for restarting eculizumab in patients with functioning kidneys in whom it was stopped but restarted. Individuals who entered the SETS clinical trial are excluded. For 49 individuals with CaHUS who stopped eculizumab because of patient or clinician choice, the median time to relapse following eculizumab withdrawal was 244 days (range, 104-1095 days). ∞Two patients with CFH pathogenic mutations were noncompliant with eculizumab and died because of refusal to undergo dialysis. ^¥One patient with CD46 VUS who moved overseas. ^¤Three patients with no mutation detected were lost to the follow-up. ^ˆOne individual with pancreatitis and a pathogenic CD46 mutation had no renal involvement but no hematological improvement. Nmd, no mutation detected.