Urinary N-Acetyl-β-D-Glucosaminidase Excretion in Type – II Diabetes Mellitus

Abstract

Renal complications develop in about 40% of all type II diabetic patients, characterized by persistent albuminuria, leading towards end stage renal disease. N-acetyl-β-D-Glucosaminidase (NAG) a large protein is released in the tubular lumen after proximaltubular damage thus considered as a tubular injury marker. Its raised levels were observed even in normoalbuminu-rics as the onset of microalbuminuria was considered a late finding. With the objective of comparing urinary NAG between normoalbuminuric and microalbuminuric type II Diabetes Mellitus patients, this study was planned.

Methods:  This comparative cross-sectional study was conducted from January to June 2014 at Shaikh Zayed Hospital Lahore on 86 type-II diabetic patients. Out of known type-II diabetic patients from both genders coming to diabetic clinic for routine checkup, those having duration of diabetes for less than 10 years since its diagnosis made and aged 45 – 65 years, were selected through convenient sampling except those with any comorbidity involving kidneys, pregnancy or history of nephrotoxic drug intake. After taking consent, their spot urine samples were collected. Those having urinary ACR (albumin creatinine ratio in mg/g creatinine) > 300 on dipstick termed ‘macroalbumi-nuria’ were also excluded. The albumin, creatinine and NAG assays were performed in the selected spot urine samples. On the basis of urinary ACR, patients were divided into normoalbuminurics (ACR < 30) as group 1 (n = 42) and microalbuminuric (ACR 30 – 300) as group 2 (n = 44). Urinary NAG level was measured in U/L and also expressed as NAG to creatinine ratio (U/ gram creatinine). Data were analyzed through SPSS (v: 21.0) and described as tables and graphs for age, gender, duration of diabetes and urinary NAG. Five point pictorial comparison of NAG to creatinine ratio in both groups was presented through box plot.

Results:  Out of 86 subjects, mean age was 50.79 years in group 1 while it was 51.89 years in group 2. Majority subjects presented with disease history of 5 – 8 years, with male predominance (64% n = 55). Mean urinary NAG level was 18.69 U/L in group 1 and 42.36 U/L in group 2 and difference was significant
(p = 0.01). Similarly NAG to creatinine ratio values revealed small sized box-plot in group 1 with lower minimum, maximum, median and interquartile range values as compared to group 2.

Conclusion:  Among uncomplicated type-II diabetic patients in the first decade of their illness, the excretion of the urinary enzyme, ‘N-acetyl-β-D-Glucosami-nidase’ was observed. Its levels were lower in normo-albuminurics with less variation as compared to micro-albuminurics.