The classifier based on 172 peptides reliably differentiated 92 LN cases from the general CKD group (1180 patients) and identified the protein S100-A9 as another specific LN marker, whose increased level was found to be essential for LN differentiation in combination with increased levels of collagen peptides and uromodulin, as well as decreased levels of clusterin, β-2-microglobulin, and α-2-HS-glycoprotein [54]. Here, UMOD is linked to chronic kidney disease.