Urinary angiotensinogen level and its risk factors in patients with " subclinical" diabetic nephropathy

Abstract

Objective To evaluate the level and related factors of urinary angiotensinogen in patients with subclinical diabetic nephropathy. Methods (1)A total of 80 type 2 diabetic patients without angiotensin-converting enzyme inhibitor (ACEI) or angiotensin Ⅱ receptor blocker(ARB) treatment and hypertension were divided into 3 groups according to 24-hour urinary albuminuria and estimated glomerular filtration rate(eGFR): normoalbuminuria with normal glomerular filtration rate group[urinary microalbuminuria(UMA) <30 mg/24 h, 90≤eGFR <120 ml·min-1·(1.73 m2)-1, NC group, n=28], normoalbuminuria with glomerular hyperfiltration group[UMA<30 mg/24 h, eGFR≥120 ml·min-1·(1.73 m2)-1, SDN group, n=36], microalbuminuria group[30 h≤UMA<300 mg/24 h, 90≤eGFR<120 ml·min-1·(1.73 m2)-1, EDN group, n=16]. The levels of urinary angiotensinogen among various groups were compared.(2)The levels of urine retinol binding protein(RBP), N-acetyl-β-D-glucosaminadase, α-galactosidase, and β2-microglobubin were used to evaluate the renal tubular function. Then all the patients were divided into 4 groups according to the degree of renal tubular injury; the urinary angiotensinogen was compared and the independent related factors were analyzed. (3)20 type 2 diabetic patients with microalbuminuria and ACEI or ARB treatment were also enrolled in this study. The level of urinary angiotensinogen was compared between patients with and without ACEI or ARB treatment. Results Compared with NC group, the level of urinary angiotensinogen in the SDN group was lowered[(1.47±0.11 vs 1.59±0.11)ng/ml, P<0.05], but was raised in the EDN group[(1.62±0.15)ng/ml, P<0.05]. With the aggravation of renal tubular injury, the level of urinary angiotensinogen was increased. Multiple regression analysis showed that urinary angiotensinogen was positively correlated with RBP(P<0.05)and negatively correlated with eGFR(P<0.05). Compared with the patients without ACEI or ARB treatment, the level of urinary angiotensinogen was decreased in patients with ACEI or ARB treatment [(1.43±0.16 vs 1.62±0.15)ng/ml, P<0.05]. Conclusion The level of urinary angiotensinogen in patients with subclinical diabetic nephropathy is lowered, but is then raised in patients with microalbuminuria, which may participate in the progression of renal glomerular and tubular injury in diabetic nephropathy. The renin-angiotensin system inhibitors may delay the progression of diabetic nephropathy via decreasing urinary angiotensinogen level. (Chin J Endocrinol Metab, 2015, 31: 395-399) Key words: Subclinical; Diabetic nephropathy; Urinary angiotensinogen; Renal tubular injury