Study of Urinary Level of Vitamin D Binding Protein in Diabetic Nephropathy

Background: Diabetic nephropathy is usually a clinical diagnosis made based on the presence of albuminuria and or reduced estimated glomerular filtration rate in the absence of signs or symptoms of other primary causes of kidney damage. The aim of this work was to study urinary level of vitamin D binding protein as an early predictor for DN and its role in early diagnosis of diabetic nephropathy.

Methods: This prospective cohort observational study was carried out on 60 subjects. All subjects were divided into 3 equal groups: Group I: Patient with type 2 DM. with UACR<30 mg\gm. Group II: Patient with type 2 DM. with UACR 30-300mg\gm. Group III: Healthy Controls (matched with other groups as regard the age, gender and body mass index). All patients were subjected to routine laboratory investigation and specific laboratory investigation (Urinary Vitamin D Binding Protein by ELISA).

Results: The area under the ROC curve of urine VDBP levels for the diagnosis of DN was 90%. The analysis rendered an optimum cut-off value of 125µg/ml/mg corresponding to 77.50% sensitivity and 85.00% specificity. There was significant positive correlation between Urinary VDBP level and FBS serum level (P value<0.001). There was significant positive correlation between Urinary VDBP level and HA1C serum level (P value<0.001)

Conclusions: Our findings indicate that UVDBP levels may be a potential biomarker for early detection of DN. In the present study, urine samples were collected from patients with DN only but not from patients with additional nephropathies. This may have caused an overestimation of the specificity of VDBP as a biomarker for the detection of DN.