In the current study, we measured urinary angiotensinogen (AGT) through 
enzyme-linked immunoadsordent assay (ELISA) and analyzed its correlation with 
intrarenal renin-angiotensin system (RAS) activity in 128 chronic kidney disease 
(CKD) patients. Urinary and plasma renin activity, AGT, angiotensin II (Ang II) 
and aldosterone levels were also measured by radioimmunoassay (RIA) or ELISA in 
these participants. Further, the expression level of intrarenal renin, AGT, Ang 
II and Ang II receptors were examined by immunohistochemistry staining (IHCS) in 
72 CKD patients. Their correlations with urinary AGT were also analyzed. We 
found that the urinary AGT level was positively correlated with hypertension (ρ 
= 0.28, P < 0.01), urinary protein (r = 0.38, P < 0.01), urinary Ang II (r = 
0.29, P < 0.05), urinary type IV collagen (Col IV) (r = 0.56, P < 0.01), and was 
negatively correlated with estimated glomerular filtration rate (eGFR) (r = 
-0.28, P < 0.01), urinary sodium (r = -0.22, P < 0.05) and serum AGT (r = -0.27, 
P < 0.01). Multiple regression analysis indicated low serum AGT (P < 0.01), high 
urinary protein (P < 0.01), high urinary Ang II (P < 0.05) and high urinary Col 
IV (P < 0.01) were correlated significantly with high urinary AGT. Urinary AGT 
level was positively correlated with intrarenal expression level of AGT (ρ = 
0.46, P < 0.01), Ang II (ρ = 0.56, P < 0.01) and Ang II type 1 receptor (ρ = 
0.32, P < 0.01), as detected by IHCS. Together, these data suggest that urinary 
AGT might be a potential biomarker of intrarenal RAS and Ang II activities in 
CKD patients.