MPO and glomerulonephritis: Any future study evaluating the role of biospectroscopy in ANCA-associated glomerulonephritis would benefit from assaying and analyzing classical (C-reactive protein (CRP), anti-myeloperoxidase (MPO, p-ANCA)/anti-proteinase-3 titers (PR3, c-ANCA) antibodies) and potential biomarkers (including urinary monocyte chemoattractant protein-1 (uMCP-1), urinary soluble CD163 (sCD163), and complement cascade degradation products) with spectral data [64,65,66,67,68,69,70,71].