Value of urinary C-terminal agrin fragment in monitoring the progression of early kidney injury in type 2 diabetic patients / 中华检验医学杂志

ABSTRACT

Objective:This study aimed to explore the feasibility and clinical value of monitoring the progression of early kidney injury in type 2 diabetic patients by assessment of the urinary C-terminal agrin fragment (uCAF) with enzymatic chemiluminescence immunoassay.Methods:A total of 251 patients with type 2 diabetes, who attended the Second Affiliated Hospital of Wenzhou Medical University from October 2018 to March 2020, were included in this retrospective analysis. One hundred and fifty-six participants undergoing health check-up at the Second Affiliated Hospital of Zhejiang University School of Medicine in February 2021 served as controls. Basic clinical information, glycosylated hemoglobin type A 1c and serum creatinine values were recorded, and urine specimens were collected for urinary creatinine, urinary α 1 microglobulin(uα 1M), urinary immunoglobulin G (uIgG), urinary albumin, urinary N-Acetyl-B-D-glycosaminidase (uNAG) and uCAF measurements. Based on the estimated glomerular filtration rate (eGFR), 251 patients were classified into G1~G5 stage groups with 116, 22, 28, 55 and 30 patients in each group. One hundred and sixty-six patients with early diabetic kidney disease (stage G1-G3) were divided into subgroups A1 (79), A2 (48) and A3 (39) according to the urinary albumin/creatinine ratio (UACR), the uα1M levels were divided into uα1M subgroup 1 (83 cases), uα1M subgroup 2 (42 cases), and uα1M subgroup 3 (41 cases), and uIgG subgroup 1 (83 cases), uIgG subgroup 2 (42 cases), and uIgG subgroup 3 (41 cases) according to uIgG levels. The Spearman method was used to analyze the correlation between uCAF levels and eGFR, UACR, uα1M and uIgG levels. Results:(1) The linear range of the uCAF detected by enzymatic chemiluminescence immunoassay was 3.97-2 000.00 ng/ml, with a detection limit of 2.28 ng/ml, intra-batch coefficients of variation of 1.15% and 1.57%, inter-batch coefficients of variation of 1.63% and 5.78%, and a biological reference interval of <95.35 μg/g Cr. (2) The uCAF level and positive rate (UACR≥30 mg/g) increased with the decrease of eGFR from G1-G3, uCAF level was negatively correlated with eGFR value ( r=-0.543, P<0.000 1), and the positive rate increased from 24.14% (28/116) to 85.71% (24/28) from G1-G3. The uCAF level and positivity rate decreased with the decrease of eGFR from G4 to G5. uCAF level was positively correlated with eGFR value ( r=0.495, P<0.001), and the positivity rate decreased from 30.91% (17/55) to 23.33% (7/30) from G4 to G5. (3) In patients with early diabetic kidney disease, uCAF levels and positivity rates increased gradually with the increase of UACR. uCAF levels were positively correlated with UACR values ( r=0.602, P<0.001), and the uCAF positivity rate reached 21.52% (17/79) in the A1 subgroup. (4) uCAF level was positively correlated with uα1M and uIgG levels in patients with early diabetic kidney disease ( r=0.757, 0.596, both P<0.001). Conclusion:Analytical performance of enzyme chemiluminescence immunoassay for the detection of CAF is satisfactory and could be used a biomarker for monitoring damage and progression of early diabetic kidney disease in patients with type 2 diabetes.