The Clinical Significance Of Glomerular Hyperfiltration, Urinary NAG/Cr In Early Renal Damage Assessment Of Type 1 Diabetes

Objective:To investgate the screening value of glomerular hyprfiltration、urinary N-acetyl-D-glucosaminidase creatinine ratio(NAG/Cr)in early renal damage of type 1diabetes.Methods:100 cases of type 1 diabetes in Children’s hospital of Soochow university were recruited from February 2015 to December 2016,and male 49 cases,female 51 cases,average 9.99±2.23 years old,periods 0.5-13 years.Healthy control group is 34 normal physical examination personnel,male 17 cases,female 17 cases,average 9.29±2.26 years old.According to urinary albumin creatinine ratio(UACR),the diabetes were divided into two experimental groups:normoalbuminuria group(UACR<30mg/g),81 cases;albuminuria group(UACR≥30mg/g),19 cases.Another group was the healthy control group,34 cases.Renal tubular damage indexs were detected in each group,including urinary NAG/Cr,urinaryα1 microglobulin creatinine ratio(α1-MG/Cr)and serum neutrophil gelatinase-associated lipocal(NGAL).The estimated glomerular filtration(eGFR)was estimated using the Macisaac’s equation(eGFR=(86.7/Cys C)-4.2).According to eGFR’s level,the diabetes were divide into three groups:A group(60ml/min·1.73m~2≤eGFR<90ml/min·1.73m~2),24 cases;B group(90ml/min·1.73m~2≤eGFR<130ml/min·1.73m~2),33 cases;C group(Hyperfiltration group,eGFR≥130ml/min·1.73m~2),43 cases.The age、course of disease、glycosylated hemoglobin(Hb A1c)、triacylglycerol(TG)and renal glomerular damage indexs(UACR)、renal tubular damage indexs(urinary NAG/Cr、urinaryα1-MG/Cr、serum NGAL)of each group were observed.Results:1.The values of urinary NAG/Cr in the normoalbuminuria group was significantly higher than those in the healthy control group,but the UACR、BUN and SCr values between the two groups were not significant differernt.The values of urinary NAG/Cr in the albuminuria group was significantly higher than those in the normoalbuminuria group.2.The urinary NAG/Cr values in diabetes duration of 0-2 years、2-5 years、and greater than 5 years groups were significant higher than those in the healthy control group.In the0-2 years、2-5years、and greater than 5 years groups,the urinary NAG/Cr values was gradually increased,but the difference did not reach statistically significant.3.The urinary NAG/Cr values in the poor glycemic control(HbA1c>6.5%)group was significantly higher than those in the good glycemic control(HbA1c≤6.5%)group.4.Correlation analysis showed that in all diabetes patients the levels of urinary NAG/Cr was positive correlated with the levels of HbA1c and urinary Lgα1-MG/Cr,the difference was statistically significant.Multiple regression analysis showed that Lg(TG*10)、urinary Lgα1-MG/Cr、HbA1c were important influencing factors of urinary NAG/Cr.5.ROC analysis revealed that the optimal cut-off value of urinary NAG/Cr to predict diabetic kidney damage was 20.66U/g,for this cut-off value,specificity was 80.2%,sensitivity was 57.9%.Under the curve was 0.725.6.The TG values in the C group(Hyperfiltration group,eGFR≥130ml/min·1.73m~2)was significantly higher than those in the A group、B group and healthy control group,but the TG values betweens the A group、B group and healthy control group were not significant difference.The HbA1c values in the C group was significantly higher than those in the A group and B group,but the Hb A1c values betweens the A group and B group were not significant difference.The values of serum NGAL was significantly lower than those in the A group and healthy control group.7.Logistic regression analysis showed that in diabetes patients shorter diabetes duration and higher HbA1c levels were important influence factors of whether diabetes patients had hyperfiltration.Conclusions:1.The urinary NAG/Cr values was higher in the nonalbuminuric groups than in the healthy controls,indicated that tubular damage do not followed by glomerular damage or might even occur earlier than glomerular damage.2.Diabetic kidney tubular damage possibly begins in a very early phase of T1DM,the degree of kidney tubular damage was positive correlates with glycemic control.3.Urinary NAG/Cr may be a specificity indicator for detecting kidney damage in clinical,which help to early detection and early intervention.4.Glomerular hyperfiltration may be detected at the early stage of the type 1 diabetes,reflected abnormal glucose and lipid metabolism,but whether it independent correlates with diabetic kidney damage need further research.5.Serum NAGL values was lower in the diabetes group than in the healthy control group,and decreased with the hyperfiltration occored、course being longer、HbA1c level increased,which may be related to the hyperfiltration occur and tubular reabsorption injury.