How is biological assessment of purpura?

• The following laboratory tests may be used to evaluate patient with suspected vasculitis: Urinalysis with micro (helps detect renal involvement) • CBC with platelets • ANA (a positive antinuclear antibody test suggests the presence of an underlying connective tissue disorder) • ANCA (helps diagnose an ANCA-associated or drug-induced vasculitis) • Complement (low serum complement levels may be present in mixed cryoglobulinemia, urticarial vasculitis and lupus) • ESR (systemic vasculitides may have elevated sedimentation rates • Also consider ordering RF (elevated in cryo vasculitis), cryoglobulins, an HIV test, HBV and HCV serology, occult stool samples, an ASO titer and streptococcal throat culture)