Correlation between urinary angiotensinogen and intrarenal renin-angiotensin system activity in chronic kidney disease patients / 中华肾脏病杂志

ABSTRACT

Objective To analyze the correlation of urinary angiotensinogen (AGT) with clinical index of kidney injury and intrarenal renin-angiotensin system (RAS) activity in chronic kidney disease (CKD) patients. Methods Urinary or plasma renin activity, AGT, angiotensin Ⅱ (Ang Ⅱ ), aldosterone were measured by RIA or ELISA in 129 CKD patients. Expression of intrarenal renin, AGT, Ang Ⅱ and angiotensinⅡ receptor was examined by immunohistochemistry staining (IHCS) in 73 CKD patients undergoing renal biopsy. Correlation of urinary AGT with other indexes was performed. Results Average urinary AGT in 129 CKD patients was (159.08 ± 125.18) μg/g Cr, Scr was (113.20± 105.05)μmol/L, and urinary AGT was positively correlated with Scr (r=0.51, P<0.01). Average estimated glomerular filtration rate (eGFR) was (58.52±27.15) ml·min-1·(1.73 m2)-1, which was negatively correlated with urinary AGT (r=-0.55, P<0.01). Average urinary protein was (2.03±2.65) g/24 h, which was positively correlated with urinary AGT (r=0.30, P<0.01). Average urinary Ang Ⅱ was (164.71 ±139.25) ng/g Cr, which was positively correlated with urinary AGT (r=0.20, P<0.05). Average urinary type Ⅳ collagen was (447.60± 800.66) μg/g Cr, which was positively correlated with urinary AGT (r=0.47, P<0.01). Average urinary soduim was (162.17±81.61) mmol/24 h, which was negatively correlated with urinary AGT (r=-0.20, P<0.05). Multiple regression analysis indicated that low eGFR (P<0.01), high Scr (P< 0.01), high urinary protein (P<0.05), high urinary Ang Ⅱ (P<0.05) and high urinary type Ⅲ collagen (P<0.01) were significantly correlated with high urinary AGT. In renal tissues of CKD patients, there was positive correlation of urinary AGT with positive IHCS area of AGT (r=0.45, P< 0.01), Ang Ⅱ (r=0.52, P<0.01) and angiotensin Ⅱ type 1 receptor (r =0.28, P <0.05). Conclusions Urinary AGT level may indicate the kidney injury severity, especially in chronic kidney injury, and may be used as a non-invasive marker of intrarenal Ang Ⅱ activity in CKD patients.