Plasma von Willebrand factor antigen and activity and platelet aggregability in patients with proteinuria

Using a complex stimulating mixture containing ADP, epinephrine and collagen, a significantly (p less than 0.002) enhanced platelet aggregability, expressed as platelet sensitivity factor (PSF) was noted in platelet rich plasma of patients with proteinuria (PSF = 472 +/- 125), as against normal weight normolipidemic control subjects (PSF = 32.76 +/- 2.67). A significantly negative correlation (r. -0.579; p less than 0.001) was found between serum albumin concentration and the logarithmic values of platelet sensitivity factor. Plasma von Willebrand factor activity expressed as a percentage of normal was also significantly (p less than 0.001) higher in proteinuric patients (287% +/- 25.8) than in control subjects (99% +/- 5.02), but this hemostatic variable did not correlate with the logarithm of platelet sensitivity factor. Platelet aggregability was higher in hyperlipidemic nephrotic patients than in proteinuric patients with normal serum lipids, while renal failure led to a decrease of platelet function. The raised plasma levels of von Willebrand factor noted in proteinuric patients were not influenced by either hyperlipidemia or by chronic renal failure. It is concluded that changes affecting platelet function in the nephrotic syndrome are produced by other mechanisms than these leading to an increase of endothelia-derived von Willebrand factor. Both changes may, however, contribute to the thrombotic tendency of nephrotic patients.