Identifying Urine Biomarkers for Kidney Injury in Patients with IgAN

Renal pathology is critical in clinical management and prognosis in patients with immunoglobulin A nephropathy (IgAN), a primary glomerular disease commonly leading to chronic kidney disease, creating a need for reliable biomarkers for noninvasive evaluation of the kidney. Researchers at Ohio State University, Columbus, conducted a study designed to identify potential biomarkers of severity of kidney injury in patients with IgAN.

The study included 45 patients with IgAN and 29 healthy volunteers (control group). Spot urine samples were collected at the time of diagnostic kidney biopsy from the IgAN patients. Results of the spot urine tests were classified by the Oxford system and the renal pathologist recorded the degree of activity and chronic damage blindly as none, mild, moderate, or severe.

The potential biomarkers of kidney injury assessed were adiponectin, CD163, epidermal growth factor (EGF), neutrophil gelatinase-associated lipocalin (NGAL), ICAM-1, VCAM-1, and complement component C5a.

There were significant differences in urine adiponectin, CD163, C5a, and VCAM-1 in patients with IgAN compared with the controls, with fold-increases of 7, 399, 28, and 7, respectively (all P<0.0001). EGF decreased ~1.4-fold compared with controls (P=0.0015). There was an inverse correlation between EGF and interstitial fibrosis and tubular atrophy (IFTA) and overall chronicity. There was a positive correlation between C5a and IFTA. There were positive correlations between adiponectin and C5a and overall activity. Using receiver operating characteristic analysis, the area under the curve for EGF to differentiate between mild and moderate-severe chronic injury is 0.91 (P<0.0001). The area under the curve for adiponectin to detect the presence of active lesions is 0.96 (P=0.0011).

In summary, the researchers said, “Urine EGF could serve as a biomarker for chronic kidney lesions in IgAN while adiponectin and complement 5a may be biomarkers for active kidney lesions. These biomarkers could be helpful in noninvasively evaluating the efficacy of therapies for IgAN.”

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Source: Zhang L, Zhang X, Birmingham DJ, Satoskar AA, Rovin BH. Urine biomarkers for kidney injury in IgA nephropathy. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2019, November 8, 2019 (Abstract FR-PO837), Washington, DC.