A patient Complains of hematuria. Renal biopsy demonstrates a focal necrotizing glomerulonephritis with crescent formation. He also complains of decreased sensation in hand and feet .What next best investigation should be done to diagnose the condition?

Patient is suffering from vasculitis due to which he is manifesting symptoms of haematuria , periphral neuropathy and glomerulopnephritis ,and next investigation should be ANCA to narrow down specific cause. Antineutrophil cytoplasmic antibodies (ANCA) The antibodies are of two types, anti-proteinase 3 (PR3) or anti-myeloperoxidase (MPO) ANCA are produced with the help of T cells and activate leukocytes and monocytes, which together damage the walls of small vessels. ANCA antibodies are directed against cell constituents because of which circulating immune complexes are not present. c - ANCA p- ANCA Anti-proteinase 3 Anti-myeloperoxidase Granulomatosis with polyangiitis (Wegener granulomatosis) Microscopic polyangiitis and Churg-Strauss syndrome Cytoplasmic staining Perinuclear staining FIG: 1. C-ANCA, 2. P-ANCA-staining patterns on alcohol-fixed human neutrophils.