Urinary excretion of epidermal growth factor and rapid loss of kidney function.

BACKGROUND Lower urinary excretion of the kidney tubule-specific biomarker epidermal growth factor (uEGF) is associated with increased risk of renal function [glomerular filtration rate (GFR)] loss in diabetes and in patients with established chronic kidney disease (CKD). We investigated whether uEGF is associated with rapid GFR decline or incident CKD in the general population. METHODS Subjects without CKD or diabetes were recruited from the general population in Tromso, Norway [Renal Iohexol Clearance Survey (RENIS); N = 1249] and Groningen, the Netherlands [Prevention of REnal and Vascular END-stage disease (PREVEND); N = 4534], with a median follow-up of 5.6 and 7.4 years, respectively. GFR was measured by iohexol clearance in the RENIS and estimated using the CKD Epidemiology Collaboration creatinine-cystatin C equation in the PREVEND study. Rapid GFR decline was defined as an annual GFR loss >3.0 mL/min/1.73 m2 and in sensitivity analyses as subjects with the 10% steepest GFR slope within each cohort. RESULTS Lower baseline uEGF excretion was associated with rapid GFR loss in both cohorts {RENIS, odds ratio [OR] per 1 μg/mmol lower uEGF 1.42 [95% confidence interval (CI) 1.06-1.91], P = 0.02; PREVEND, OR 1.29 [95% CI 1.10-1.53], P < 0.01}, adjusted for baseline GFR, albumin:creatinine ratio and conventional CKD risk factors. Similar results were obtained using the outcome of the 10% steepest GFR slope in each cohort. Lower uEGF levels were associated with incident CKD in the combined analysis of both cohorts. CONCLUSIONS Lower uEGF levels are associated with increased risk of rapid GFR loss and incident CKD in the general population. This finding, together with previous findings in CKD and high-risk populations, supports that uEGF may serve as a broadly applicable biomarker representing the tubular component of the current glomerulus-centric clinical risk assessment system.