Diagnostic significance of urinary fibronectin in diabetic nephropathy

We evaluated the diagnostic utility of urinary fibronectin (FN) in patients with diabetic nephropathy by comparing the findings with those of renal biopsy specimens. A total of 46 diabetic patients were divided into four groups, D0, DI, DII and DIII-IV, according to the severity of diffuse glomerular lesions using Gellman's criteria. Using 24-hour urine specimens, FN was measured by a solid phase enzyme-linked immunosorbent assay. The urinary excretion of FN was significantly higher in the overt proteinuric group than in the normo- and micro-albuminuric groups. Urinary FN level showed a significant increase with respect to the progress of glomerular diffuse lesions. There was a weak correlation between the urinary level of FN and serum creatinine level and a weak inverse correlation between the urinary level of FN and creatinine clearance. When patients with overt proteinuria were excluded from the analysis, there was no correlation between the urinary level of FN and serum creatinine level, creatinine clearance, or that of beta 2-microglobulin and NAG. The findings indicate that urinary FN may be useful in estimating pathologic conditions, especially the early stage of diabetic nephropathy.