Dx studies of Cryoglobulinemic vasculitis
✓ Cryoglobulins (keep blood warmed to 37°C en route to lab to avoid false ⊖, loss of RF and ↓↓ C3, C4). Cryocrit quantifies cryoprotein but not always indicative of disease activity. May see false ↑ in WBC or plt on automated CBC due to precipitation.
Type I
✓ serum viscosity, symptomatic if ≥4.0 centipoise; complement normal.
Type II
↓ C4, variable C3, ↑ ESR, ⊕ RF. ✓ HCV, HBV, HIV in mixed cryoglobulinemia. Bx: hyaline thrombi; small vessel leukocytoclastic vasculitis w/ mononuclear infiltrate.