C4A and membranoproliferative glomerulonephritis: Furthermore, normal complement (C3, C4) levels and the absence of clinical features suggestive of cryoglobulinemia, such as palpable purpura or membranoproliferative glomerulonephritis, make cryoglobulinemic vasculitis a less likely etiology, although it is acknowledged that cryoglobulin testing itself was not performed due to its limited availability—a recognized limitation in this case.