ABSTRACT
PURPOSE: The renin-angiotensin-aldosterone system activation has been suggested as a potential risk factor for renal progression in autosomal dominant polycystic kidney disease (ADPKD). This study was performed to evaluate urinary angiotensinogen as a biomarker of renal progression in ADPKD. METHODS: Patients with estimated glomerular filtration rate (eGFR) > or =30 mL/min/1.73m2 were enrolled in the study. Specimens (blood and urine) and computed tomography (CT) were taken from each subject. The eGFR was calculated by 4-variable MDRD equation and total kidney volume (TKV) was measured from CT images by modified ellipsoid method. Urinary angiotensinogen (AGT) and neutrophil gelatinaseassociated lipocalin (NGAL) were measured by ELISA. The concentration of AGT was adjusted with random urine creatinine (Cr). The association between urinary biomarkers, TKV and eGFR were evaluated. RESULTS: A total of 59 (M:F=31:28) subjects were enrolled in the study and their mean age was 46 years. The eGFR and TKV at the enrollment were 77.3+/-15.6 mL/min/1.73m2 and 1389.8+/-925.1 mL, respectively. Log AGT/Cr was associated with TKV (r2=0.117, p=0.01) in the earlier stage of disease (TKV<3,000 mL). However, it did not show significant correlation with eGFR. Log NGAL was not associated with either TKV or eGFR. Urinary AGT/Cr was closely related to the number of anti-hypertensive medication, TKV, and the presence of albuminuria, although there was no correlation with plasma renin activity or aldosterone level. CONCLUSION: Urinary angiotensinogen may be a useful biomarker of disease progression in ADPKD patients.