Wen L, et al. - In order to gain clarity regarding the clinical implication of abnormal complement protein levels in serum and urine in immunoglobulin A nephropathy (IgAN) cases, researchers focused on the correlation between disease activity and complement proteins in serum and urine from IgAN patients. The findings were compared to patients with other types of chronic kidney disease (CKD) as well as healthy controls. Participants included Chinese patients with IgAN (n=85), patients with non-proliferative CKD (n=23), and healthy subjects (n=20). Both IgAN and CKD patients had increased urinary complement factor H (CFH), membrane attack complex and serum CFH, compared with healthy controls. Findings revealed an association of increased urinary excretion of complement proteins in IgAN, with chronic injury and tubular dysfunction. The use of urinary complement proteins as markers of disease activity warrants caution.