Vascular endothelial markers, von Willebrand factor and thrombomodulin index, are specifically elevated in type 2 diabetic patients with nephropathy: comparison of primary renal disease.

To elucidate the hypothesis that albuminuria in diabetic subjects reflects widespread vascular damage, plasma markers for vascular endothelial damage was measured in diabetic subjects with various degrees of albuminuria and compared to results in patients with primary renal disease. The groups consisted of 31 non-diabetic patient controls with normoalbuminuria, 109 type 2 diabetic patients with normo- micro- and macro-albuminuria, and 16 proteinuric patients with primary renal disease. Endothelial markers, plasma von Willebrand factor (vWF) and thrombomodulin (TM), were measured by enzyme-linked immunosolvent assay and enzyme immunoassay (EIA) methods, respectively. Plasma vWF levels were similar in controls (119+/-7%, mean+/-S.E.M.) and diabetic patients with normoalbuminuria (139+/-6), but significantly elevated in diabetic patients with microalbuminuria (174+/-11) and macroalbuminuria (204+/-17), while the level was not increased in patients with primary renal disease (124+/-11). Because plasma TM level was strongly affected by kidney function, TM index (TM (FU/ml)/serum creatinine (mg %)) was used as an endothelial marker. The TM index was substantially increased in diabetic patients with overt nephropathy compared with controls (5.29+/-2.98 vs. 2.35+/-0.85), whereas this was not observed in patients with primary renal disease (3.25+/-0.29). Both vWF and TM index were significantly higher in diabetic patients with retinopathy than in the patients without retinopathy. These results suggest that generalized vascular endothelial damage occurs in diabetic nephropathy including the microalbuminuric stage, which is not attributed to kidney damage per se.