Can we use plasma fibronectin levels as a marker for early diabetic nephropathy.

Although increased plasma fibronectin (PF) levels have been found in diabetic patients with microalbuminuria, there is still controversy about its clinical implication for detecting early diabetic nephropathy. To evaluate the PF concentration as a possible marker for early diabetic nephropathy, three groups of sex-and age-matched patients were studied I) 22 insulin dependent diabetic (IDDM) patients with microalbuminuria (mean age +/- SEM: 23.3 +/- 3.6 years, mean urinary albumin excretion rate (AER) +/- SEM: 47.1 +/- 39.5 micrograms/min); II) 17 IDDM patients with normoalbuminuria (mean age: 23.4 +/- 4.4 years, mean AER: 7.8 +/- 2.1 micrograms/min) and III) 20 healthy control subjects (mean age: 22.6 +/- 4.1 years, mean AER: 6.7 +/- 2.1 micrograms/min). PF and urinary excretion of albumin were measured by an immunoturbidimetric method using commercially available kits (Boehringer Mannheim GMBH FRG, and Miles Lab., UK). The mean PF was significantly higher in the group with microalbuminuria (406.5 +/- 122.9 micrograms/ml) than in the group with normoalbuminuria (295.6 +/- 96.9 micrograms/ml, P < 0.01) or in the control group (299.54 +/- 105.5 micrograms/ml, P < 0.01). A weak positive correlation was found between PF and urinary albumin values (r = 0.35, P < 0.05). There were no significant correlations between PF and the other variables such as age, duration of diabetes, body mass index, arterial blood pressure, fasting blood glucose, fructosamine and HbA1 in the diabetic patients or in the control group. Our results suggest that the PF concentration could be a weak marker for early diabetic nephropathy. We cannot therefore use PF instead of microalbuminuria because there is only a weak correlation between PF and microalbuminuria.