Malignant hypertension as a presentation of complement-mediated thrombotic microangiopathy: case series report.

Complement-mediated thrombotic microangiopathy (TMA) presenting as malignant hypertension (mHTN) is frequently misdiagnosed as mHTN-associated TMA, particularly when their clinical presentations overlap. The diagnostic challenge is further compounded when patients have normal serum levels of complement factor H (CFH) and test negative for anti-CFH. We presented two patients of complement-mediated TMA exhibiting clinical features consistent with mHTN-associated TMA, yet their renal function did not improve following the achievement of target blood pressure (BP) levels. Notably, both patients demonstrated elevated serum soluble C5b-9 levels. Based on these findings, we hypothesized the presence of complement-mediated TMA and initiated treatment with eculizumab. Consequently, one patient was successfully weaned off dialysis, and the other experienced substantial improvement in renal function, highlighting that in patients with mHTN-associated TMA where antihypertensive treatment fails to ameliorate renal function, consideration should be given to the possibility of complement-mediated TMA.