Сlinical significance of nephrin and podocin urinary excretion in patients with diabetes mellitu

Aim

To evaluate the clinical significance of nephrin and podocin urinary excretion for early diagnosis of diabetic nephropathy in patients with type 1 and type 2 diabetes.

Material and methods

We studied 74 diabetic patients (type 1 in 30 patients and type 2 in 44 patients). They were distributed into three groups: 41 patients with albuminuria <30 mg/g Cr (AU1), 13 patients with albuminuria 30-300 mg/g Cr (AU2) and 20 patients with proteinuria. Estimated glomerular filtration rate (GFR) was reduced to 60-90 and <60 ml/min/1.73 m2 in 25 and 8 patients, respectively. Arterial hypertension was found in 52 patients (70%), mainly with type 2 diabetes. Ten healthy subjects were studied as a control group. Urinary levels of nephrin and podocin were measured by ELISA.

Results

High nephrinuria (>5.84 ng/ml/g) was found in 63%, 77% and 80% of patients with AU1, AU2, and proteinuria, respectively. The median urinary nephrin levels in patients with AU1 and AU2 did not differ in type 1 and type 2 diabetes. In patients with proteinuria, the median urinary nephrin level was significantly higher compared with that in patients with AU1 and AU2 (p<0.05). Podocinuria was increased (>1,73 ng/ml/g) in 78%, 54% and 83% patients with AU1, AU2, and proteinuria, respectively. There was a direct correlation between nephrinuria and albuminuria, particularly in patients with AU2 (r=0.947, p<0.05). In type 1 diabetes, nephrinuria and podocinuria correlated directly with serum creatinine (r=0.489, p<0,05, and r=0.468, p<0.05) and indirectly with GFR (r=-0.461, p<0.05). In patients with GFR<60 ml/min/1.73 m2, there was a direct relationship between nephrinuria and diabetes duration, that was independent on diabetes type. In patients with diabetes of a shorter duration (<5 years), nephrinuria correlated directly with НbА1с level (r=0.84, р<0,01), and in type 2 diabetes it correlated with systolic blood pressure (r=0.73, р<0.05).

Conclusion

Nephrinuria and podocinuria can be useful markers for early diagnosis and monitoring of DN.

Key words

Diabetes mellitus, diabetic nephropathy, albuminuria, proteinuria, podocytes damage, nephrinuria, podocinuria.