Which laboratory findings are typically associated with hypocomplementemic urticarial vasculitis (HUVS)?

Hypocomplementemic urticarial vasculitis (HUVS) is associated with specific laboratory findings that reflect the underlying complement system dysregulation. In HUVS, the complement levels are affected, leading to decreased levels of complement components. The presence of increased erythrocyte sedimentation rate (ESR) indicates an inflammatory process, which is consistent with the vascular inflammation seen in HUVS.

Among the complement components, C3 and C4 are particularly relevant. In HUVS, it is common to see low levels of both C3 and C4, as well as low total hemolytic complement (CH50). This pattern indicates that the complement pathway is being consumed or depleted during the process of vasculitis, making their decreased levels a hallmark finding for this condition.

The observed laboratory findings—elevated ESR coupled with low C3, C4, and CH50 levels—help in confirming the diagnosis of HUVS and distinguishing it from other conditions that may present with urticarial lesions but have different immunological profiles.