Plasma and platelet von Willebrand factor abnormalities in patients with uremia: lack of correlation with uremic bleeding.

Chronic renal failure often is associated with abnormal bleeding that may represent an important complication of this disorder. The hemorrhagic tendency currently is attributed to altered primary hemostasis, mainly platelet dysfunction. However, von Willebrand factor (vWF) also seems to be involved, even though the nature of its abnormalities is still controversial. To gain insight into the role of vWF in determining uremic bleeding, we studied 11 patients with stable, chronic renal failure. We found a significant increase in plasma factor VIII (FVIII), vWF:antigen (Ag), and vWF:ristocetin cofactor (Rco) levels, associated with a mean decrease in platelet vWF:Ag. Plasma vWF multimer pattern was characterized by increased representation of all oligomers in all patients, but five patients also showed a slight decrease in large vWF multimers. In addition, platelet vWF multimer pattern displayed a decrease in all components, especially those with high molecular weight. Despite normal bleeding time, collagen-induced platelet aggregation was defective in almost all patients, whereas vWF collagen binding capacity was normal. The levels of glycocalicin, the circulating fragment of glycoprotein Ib-IX, the major platelet vWF receptor, were also normal. In six patients who also were studied after initiation of dialysis, collagen-induced platelet aggregation was impaired further. Moreover, plasma vWF, and especially FVIII levels, were increased additionally, in association with a normalized platelet vWF content and an improved vWF multimer pattern. The results suggest that vWF abnormalities are present in uremia. Moreover, thrombopathy caused by impaired collagen-induced platelet aggregation is constantly present and apparently not improved by dialytic treatment.

Atypical hypergammaglobulinaemia D syndrome with amyloidosis: an overlap with familial Mediterranean fever?

A case of hypergammaglobulinaemia D and periodic fever syndrome, developing an amyloidosis-related nephrotic syndrome, is reported. Since such a complication represents a typical feature of another disease characterized by recurrent febrile attacks, i.e., familial Mediterranean fever, an overlap syndrome between these two rare clinical disorders can be suggested.

Tissue factor pathway inhibitor (TFPI) activity in uremic patients during hemodialysis.

We studied tissue factor pathway inhibitor (TFPI) activity during hemodialysis in 10 uremic patients who were not receiving anticoagulant for at least 120 minutes. TFPI activity before dialysis was normal (patients 107 +/- 5.8%, controls 104 +/- 4.5%). During extracorporeal circuit it rose progressively with a statistically significant difference, reaching a plateau between 60 and 120 minutes. Since thrombin induces a marked redistribution and release of TFPI from stimulated endothelial cells and platelets contain about 10% of TFPI activity that is secreted following activation it is possible that thrombin-induced release of TFPI by endothelium and platelets could account for the increased TFPI we found during hemodialysis. To investigate this possibility we measured during dialysis beta-thromboglobulin (beta-TG), thrombin-antithrombin complex (TAT) and prothrombin fragment 1.2 (F 1.2). The increased levels of beta-TG, TAT and F1.2 we noted during extracorporeal circuit are in keeping with this concept. One hundred eighty minutes after initiation of dialysis, by which time all patients were receiving heparin there was a further increase in TFPI (to more than 200% of baseline), due to the presence of the glycosaminoglycan. This was due the previously reported displacement by heparin of the major intravascular pool of TFPI, from endothelial cell surfaces.

Biofiltration vs. bicarbonate dialysis: influence on plasma volume changes and extravascular fluid mobilization.

The present study compares the effects of bicarbonate hemodialysis (Bic. HD) and biofiltration (BF), a new hemodiafiltration technique, on plasma volume (PV) changes and extravascular fluid mobilization (Vfm). Ten uremic patients underwent one experimental session of Bic. HD and, one week later, one of BF, both on the second dialysis of the week. Net ultrafiltration rate was limited to 700 ml/min. At the start of each session, whole blood volume (WBV), PV and red cell volume (RCV) were determined using 5 mu Ci of radioiodinated serum albumin (RISA). PV and Vfm were calculated at hourly intervals using a serial hematocrit method. On Bic. HD, PV increased at 60 min. then decreased at 120 and 180 min., with efficient Vfm only during the first hour. On BF, PV increased throughout treatment, with greater Vfm. It would appear that PV is better preserved in BF, on account of more efficient Vfm.

Bleeding in cirrhotic patients: a precipitating factor due to intravascular coagulation or to hepatic failure?

In 24 cirrhotic patients at different stages of hepatic failure, factor VIII:C (F VIII:C), factor VIIIR:AG (F VIIIR:AG), factor VIII AG/C ratio (F VIII AG/C), and serum fibrin-fibrinogen degradation products (FDP) were investigated. In 11 of the 24 patients, several instances of gastrointestinal bleeding due to esophageal varices rupture were documented and 5 patients died of unarrestable bleeding. In our study, we evaluated whether the cause of bleeding was the development of intravascular coagulation or the severity of hepatic failure. A statistically significant difference between F VIII:C, F VIIIR:AG/C ratio, and serum FDP was found in bleeding in comparison with non-bleeding patients. An inverse correlation between the F VIII:C plasma level and serum FDP as well as a direct correlation between F VIII AG/C ratio and serum FDP in the group of bleeding patients were also found. These data seem to suggest a hypercoagulable state which was more significant in the 5 patients who died owing to bleeding. Furthermore, only 1 of these patients had severe hepatic failure. From this study it appears that, in cirrhotic patients, bleeding is related more to the appearance of disseminated intravascular coagulation, as a consequence of both hemodynamic and endothelial changes, than to the degree of hepatic failure itself.