Enhanced coagulation-fibrinolysis in patients on regular hemodialysis treatment

Terminal Phase Components of the Clotting Cascade in Patients with End-Stage Renal Disease Undergoing Hemodiafiltration or Hemodialysis Treatment

Hemostasis disorder in patients with end-stage renal disease (ESRD) is frequently associated with bleeding diathesis but it may also manifest in thrombotic complications. Analysis of individual coagulation and fibrinolytic factors may shed light on the background of this paradox situation. Here we explored components essential for fibrin formation/stabilization in ESRD patients being on maintenance hemodiafiltration (HDF) or hemodialysis (HD). Pre-dialysis fibrinogen, factor XIII (FXIII) antigen concentrations and FXIII activity were elevated, while α₂-plasmin inhibitor (α₂PI) activity decreased. The inflammatory status, as characterized by C-reactive protein (CRP) was a key determinant of fibrinogen concentration, but not of FXIII and α₂PI levels. During a 4-h course of HDF or HD, fibrinogen concentration and FXIII levels gradually elevated. When compensated for the change in plasma water, i.e., normalized for plasma albumin concentration, only FXIII elevation remained significant. There was no difference between HDF and HD treatments. Individual HDF treatment did not influence α₂PI activity, however after normalization it decreased significantly. HD treatment had a different effect, α₂PI activities became elevated but the elevation disappeared after normalization. Elevated fibrinogen and FXIII levels in ESRD patients might contribute to the increased thrombosis risk, while decreased α₂PI activity might be associated with elevated fibrinolytic potential.

Formation of Thrombin-Antithrombin III Complex Using Polyamide and Hemophan Dialyzers

The recently developed ELISA for the thrombin-antithrombin III complex (TAT) is a sensitive, specific, and simplified means of detecting intravascular coagulation. For further evaluation of the thrombogenicity of a polyamide (P) and a Hemophan (H) hollow-fibre dialyzer a cross-over study was done in ten stable patients on maintenance hemodialysis. At the same doses of heparin (mean bolus of 30 U/kg bw and maintenance doses of 86 U/kg bw), thrombin time and partial thromboplastin time were significantly lower using H. At the end of dialysis TAT was significantly higher in H (mean ± SEM before HD 3.57 ± .56, at 240 min 14.9 ± 6.5 ng/ml, p < 0.05, Wilcoxon-test) than in P (before HD 4.36 ± .98, at 240 min 8.95 ± 3.0 ng/ml, p ± 0.05 H 240 vs. P 240, Wilcoxon-test). Visible clotting was more pronounced in the H filter. Among other favourable features of blood compatibility the polyamide/polyvinylpyrrolidone copolymer with a hydrophilic/hydrophobic microdomain structure has less thrombogenicity. The modified cellulosic membrane H has advantages in complement activation and leukocyte depression, but thrombogenicity seems less favourable since the incorporated diethyl-amino-ethyl groups with their positive charge bind and inactivate negatively charged heparin.

Coagulation and Fibrinolysis in Amyloid and Non-amyloid Hemodialysis Patients: Assessment of Local Hemostatic Kinetics Within Arteriovenous Fistulas

This study was designed to determine whether systemic amyloidosis is an additional risk factor for he mostatic abnormalities in hemodialysis patients and to evaluate local alterations of the hemostatic process within the patent-functional native arteriovenous fistula (AVF). Concentrations of in vivo molecular hemostatic markers, including prothrombin fragment1 +2 (PF 1.2), thrombin antithrombin III complex (TAT) and plasmin-α 2 antiplasmin complex (PAP) were determined in plasma samples taken simultaneously from AVFs and contralat eral upper extremity large veins of hemodialysis patients associated with and without systemic amyloidosis. Seven amyloid (2 women, 5 men, aged 34 ± 6 years), and 13 non-amyloid patients (4 women, 9 men, aged 36 ± 7 years) on maintenance hemodialysis and 20 healthy vol unteers (8 women, 12 men, aged 36 ± 9 years) were in cluded in the study. Peripheral vein PF 1.2 and TAT lev els showed no difference between amyloid and non- amyloid patient groups, but both were significantly higher than control group. PF 1.2 and TAT levels were also found to be elevated in fistulas when compared with that of peripheral vein in both amyloid and non-amyloid pa tient groups. Determination of PAP in peripheral veins of each group revealed significantly higher levels in amyloid hemodialysis patients than in non-amyloid patients and controls. PAP levels were significantly higher in fistulas of amyloid patients than in non-amyloid patients. In con clusion, this study confirms enhanced coagulation and fibrinolysis in hemodialysis patients and excessive fibri nolysis in amyloid patients with remarkable contribu tion of AVF on enhanced coagulation and fibrinolysis.

Hemodialysis patients have plasmatic hypercoagulability and decreased fibrinolytic vulnerability: role of carbon monoxide

Chronic hemodialysis is associated with significant thrombophilia. Of interest, hemodialysis patients have increased carboxyhemoglobin (COHb) and exhaled carbon monoxide (CO), signs of upregulated heme oxygenase (Hmox) activity. Given that CO enhances plasmatic coagulation, we determined whether patients requiring chronic hemodialysis had an increase in endogenous CO, plasmatic hypercoagulability and decreased fibrinolytic vulnerability. Carbon monoxide was determined by noninvasive pulse oximetry measurement of COHb. Blood samples were obtained just before hemodialysis. Thrombelastographic methods to assess plasma coagulation kinetics, fibrinolytic kinetics, and formation of carboxyhemefibrinogen (COHF) were used. Hemodialysis patients (n = 45) had abnormally increased COHb concentrations of 2.2 ± 1.9%, indicative of Hmox upregulation. Coagulation and fibrinolytic parameter normal values were determined with normal individual (n = 30) plasma. Thirty-seven patients of the hemodialysis cohort had COHF formation (82.2%, [67.9%-92.0%]; mean, [95% confidence interval]), and many of this group of patients had abnormally great velocity of clot growth (73.3%, [58.1%-85.4%]) and strength (75.6%, [60.5%-87.1%]). Furthermore, over half of COHF positive patients had a hypofibrinolytic state, evidenced by an abnormally prolonged time to maximum rate of lysis (53.3%, [37.9%-68.6%]) and clot lysis time (64.4%, [48.8%-78.1%]). Carbon monoxide enhanced coagulation and diminished fibrinolytic vulnerability in hemodialysis patients. Future investigation of hemodialysis, CO-related thrombophilia is warranted.

Association between vascular access failure and microparticles in hemodialysis patients

Background

Vascular access failure, a major cause of morbidity in hemodialysis (HD) patients, occurs mainly at stenotic endothelium following an acute thrombotic event. Microparticles (MPs) are fragments derived from injured cell membrane and are closely associated with coagulation and vascular inflammatory responses.

Methods

We investigated the relationship between levels of circulating MPs and vascular access patency in HD patients. A total of 82 HD patients and 28 healthy patients were enrolled. We used flow cytometry to measure endothelial MPs (EMPs) identified by CD31+CD42− or CD51+ and platelet-derived MPs (PMPs) identified by CD31+CD42+ in plasma samples of participants. Vascular access patency was defined as an interval from the time of access formation to the time of first access stenosis in each patient. MP counts were compared according to access patent duration.

Results

The levels of EMP (both CD31+CD42− and CD51+) and CD31+CD42+PMP were significantly higher in patients than in healthy participants. Levels of CD31+CD42−EMP and CD31+CD42+PMP showed a positive correlation. In non-diabetic HD patients, CD31+CD42−EMPs and CD31+CD42+PMPs were more elevated in the shorter access survival group (access survival <1 year) than in the longer survival group (access survival ≥ 4 years).

Conclusion

Elevated circulating EMP or PMP counts are influenced by end-stage renal disease and increased levels of EMP and PMP may be associated with vascular access failure in HD patients.

Oral anticoagulant therapy in hemodialysis patients: do the benefits outweigh the risks?

Managing oral anticoagulation may be difficult in hemodialysis patients because the antithrombotic effect can be counterbalanced by an increased risk of hemorrhagic complications. There is insufficient evidence to recommend the routine use of warfarin for thrombosis prophylaxis of the vascular access in all patients. If a decision for anticoagulation is made, dosing warfarin to a "therapeutic" level is suggested, although the most appropriate target INR range remains unclear. Many hemodialysis patients with atrial fibrillation have multiple risk factors for stroke and generally benefit from warfarin, with careful and frequent laboratory monitoring. Treatment with standard dose warfarin is also recommended in patients with venous thromboembolism provided that patients do not have contraindications to anticoagulation. For those with such contraindications, placement of an inferior vena cava filter is suggested. These recommendations are limited by the almost complete lack of data in dialysis patients. Sound randomized evidence of efficacy and harm for anticoagulation in these patients will likely never be available. Knowledge of the risk of bleeding and thrombosis in anticoagulated and nonanticoagulated dialysis patients could be provided by feasible, well-designed cohort studies.

The Role of Intrinsic Fibrinolytic System Activation in Pathogenesis of Hemostasis Disturbances in Hemodialized Patients with Chronic Renal Failure

In the hemodialysis patient, hemostasis changes may occur. The contribution of fibrinolysis in pathogenesis of these disorders is unclear. The aim of the study was to estimate intrinsic fibrinolysis pathway in patients treated with hemodialysis (HD) because of chronic renal failure caused by chronic glomerulonephritis. The study was performed with 43 patients; the control group consisted of 51 healthy volunteers chosen by sex and age. The following parameters were determined: concentration of the urokinase plasminogen activator antigen (uPA:Ag), plasmin--antiplasmin complexes (PAP), fibrin and fibrinogen degradation products (FDP), activity of prekallikrein (PK) and C1-inhibitor (C1-INH) and also euglobulin clot lysis time (ELT). The above parameters were assessed in the patients before and after HD and were compared with the control group. In the HD patients, in comparison with the control group, prolonged statistically ELT [153 (125;215) vs. 105 (75;142) min.; p<0.001], with increase of PAP (508.6 +/- 274.7 vs. 184.7 +/- 69.4 microg/L; p<0.001) and FDP concentrations [5 (5;15) vs. 2.5 (0;0.3) microg/mL; p<0.05] before the procedure were determined. It suggests increased plasmin production and fibrin digestion despite determination of decreased general fibrinolytic activity. The C1-INH activity before HD was also significantly increased as compared with the control group [157 (136;171) vs. 107 (100;124)%; p<0.001], and its significant decreased after the HD is 157.7 +/- 23.9 vs. 122.3 +/- 20.3%; p<0.001, as it seems to be a nondirect proof of intrinsic pathway contribution in fibrinolysis activation in the HD patients. The remaining examined parameters did not change significantly after the dialysis procedure.

Thromboembolism and anticoagulant management in hemodialysis patients: A practical guide to clinical management

The need for anticoagulation in dialysis patients is common and the incidence of venous thromboembolism (VTE) and atrial fibrillation in this population is high. While direct data are lacking on the management of anticoagulation in dialysis patients, careful weighing of risks and benefits on the basis of evidence from other populations is crucial. VTE should be managed with adjusted dose warfarin for most patients. Placement of an inferior vena cava filter is a reasonable option for those patients with unacceptable bleeding risks. Studies are ongoing to assess the safety of some low-molecular-weight heparins (LMWH), which may potentially be useful for long-term anticoagulation in hemodialysis patients. In atrial fibrillation the available data on risk of bleeding, risk of stroke, and patient preferences should all be taken into account when considering long-term anticoagulation. We have constructed an evidence model to help quantitate the risks and benefits for an individual patient. The impact of dialysis on risk of bleeding is such that the risk of bleeding will outweigh the benefit in many patients, and anticoagulation will not be used: in some of these patients aspirin therapy may be an alternative. Finally, in the area of prevention of graft and access thrombosis, some randomized controlled trials are available, but none have to date shown benefit from anticoagulation for primary or secondary prevention of thrombosis, and the risk of bleeding in these studies was high.

Global fibrinolytic capacity in children on dialysis

Disturbances of coagulation and fibrinolysis have been reported in patients with chronic uremia. Studies of different coagulation and fibrinolysis parameters in regularly dialyzed patients have yielded conflicting results. Global fibrinolytic capacity (GFC) examines the function of the entire fibrinolytic system. This assay is a sensitive and reliable method for evaluating the fibrinolytic function of plasma in vitro. In this study, GFC was used as a screening test to investigate the effects of two different dialysis modalities on the fibrinolytic system on children on long-term dialysis.

MATERIALS AND METHODS

The study included 12 children (age range, 11-20 years; mean age, 15.9+/-3.3 years) who were undergoing regular hemodialysis (HD) and 12 children (age range, 10-15 years; mean age, 13.1+/-1.7 years) who were undergoing continuous ambulatory peritoneal dialysis (CAPD). Thirteen healthy age- and sex-matched subjects served as controls. Each sample was investigated for complete blood count and serum levels of C-reactive protein, serum electrolytes, total cholesterol, triglyceride, fibrinogen, total protein and albumin. A GFC assay was also done in each case.

RESULTS

The mean GFC in the CAPD group was lower than that in the HD and control groups (p<0.05). There was no significant difference between the mean GFC values of HD patients and controls. The mean serum albumin level was lower in CAPD patients than in HD patients (p<0.05), and there was also a positive correlation between serum albumin level and GFC in patient groups(r=0.52, p<0.05). Global fibrinolytic capacity was positively correlated with hemoglobin level and negatively correlated with weekly erythropoietin dose per kg body weight (r=0.56 and r=-0.49, respectively; p<0.05).

CONCLUSION

The results suggest that CAPD patients have decreased fibrinolytic capacity compared to HD patients. Hypoalbuminemia and erythropoietin treatment may contribute to suppression of fibrinolytic function CAPD patients.

Red blood cells may contribute to hypercoagulability in uraemia via enhanced surface exposure of phosphatidylserine

BACKGROUND

The exposure of phosphatidylserine (PS) on the outer leaflet of the erythrocyte membrane may have several pathophysiological consequences, including the development of a procoagulant phenotype, a finding that seems relevant to the thrombotic risk seen in many disorders.

METHODS

Because PS externalization increases in erythrocytes from patients suffering from chronic uraemia, which is frequently associated with a prothrombotic state, the possible relationship between erythrocyte PS exposure, erythrocyte procoagulant activity and plasma levels of several haemostatic markers was studied in a group of haemodialysed patients.

RESULTS

Uraemic erythrocytes displayed increased procoagulant activity, which proved to be correlated directly with erythrocyte PS exposure. Pre-incubation of uraemic erythrocytes with annexin V, a protein with high affinity and specificity for PS, strongly inhibited in vitro thrombin generation induced by erythrocytes as compared with untreated red cells. Thrombin generation and activation of fibrinolysis were found to occur in uraemic patients, as substantiated by increased plasma levels of markers for thrombin generation (prothrombin fragment F1.2 and thrombin-antithrombin complex) and fibrinolysis (D-dimer and plasmin-antiplasmin complex), respectively. Significant correlations between prothrombin fragment F1.2 and D-dimer suggested that hyperfibrinolysis was secondary to thrombin generation. Correlations were also found between erythrocyte PS levels and plasma levels of haemostatic markers, including prothrombin fragment F1.2 (P = 0.007), thrombin-antithrombin complex (P = 0.00009), plasmin-antiplasmin complex (P = 0.0009) and D-dimer (P = 0.005).

CONCLUSIONS

Our study suggests that increased PS exposure may cause a pathological erythrocyte procoagulant phenotype, which may be a factor inducing a hypercoagulable state in uraemia.

Carbonyl stress induced by intravenous iron during haemodialysis

BACKGROUND

Anaemic haemodialysis (HD) patients are treated with erythropoietin and intravenous iron for effective erythropoiesis. Since iron is a potent inducer and aggravator of pre-existing oxidative processes in HD patients, this study was aimed to evaluate the acute in vivo effect of two recommended iron doses on protein oxidation during the HD session.

METHODS

Iron gluconate was intravenously administered to HD patients in doses of 62.5 or 125 mg per session. A dialysis session without iron administration served as a control for each patient. Carbonylated fibrinogen and iron profile parameters were monitored before and after each session. Plasma carbonylated fibrinogen levels from healthy subjects and HD patients before dialysis were compared. Protein associated carbonyls were identified in plasma by derivatization with 2,4-dinitrophenylhydrazine followed by western analysis and were quantified by densitometry.

RESULTS

HD patients on maintenance iron showed elevated carbonylated fibrinogen compared with healthy subjects. During a HD session, carbonyls on fibrinogen further increased when 125 mg iron gluconate was administered, but no changes were detected with 62.5 mg iron gluconate or in the absence of iron. The changes in carbonylated fibrinogen during dialysis showed a significant linear correlation with the calculated values of transferrin saturation and free transferrin.

CONCLUSIONS

The significant acute increase in carbonylated fibrinogen with 125 mg iron gluconate suggests that this iron dose should be used with caution. As fibrinogen is highly susceptible to iron-induced oxidation in vivo, it may serve as a marker reflecting acute iron oxidative damage and as a tool in refinement of the existing clinical dose guidelines for intravenous iron therapy.

Circulating platelet-derived microparticles with procoagulant activity may be a potential cause of thrombosis in uremic patients

BACKGROUND

Clinical experience indicates that bleeding and thrombotic tendencies co-exist in uremic patients. Numerous studies have shown that platelet functional defects contribute to the bleeding tendency in uremic patients. In contrast, there are no solid studies clarifying the pathogenesis of the prothrombotic state in uremic patients. Platelet-derived microparticles (PMPs), which are small vesicles with procoagulant activity released from activated platelets, are thought to be involved in clinical thrombogenesis. This study addressed the question of why uremic patients are thrombophilic even though they have a bleeding tendency, focusing on the clinical significance of PMPs.

METHODS

The subjects were pre-dialyzed patients, patients under hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) therapy, and age-matched healthy controls. Analyses of PMPs were performed using a flow cytometer. Annexin V was used to probe procoagulant activity of PMPs. The impacts of the HD procedure, arteriovenous (AV) fistula, and recombinant human erythropoietin (rHuEPO) treatment on the release of PMPs were additionally assessed.

RESULTS

Major results are: (1) PMP counts were significantly greater in each uremic group than in controls. The PMP counts were not different among three types of uremic groups; (2) PMP counts were significantly higher in uremic patients with thrombotic events than in those without thrombotic events; and (3) the HD procedure and existence of AV fistula did not affect PMP counts, but rHuEPO treatment possibly enhanced the PMP release in these patients.

CONCLUSIONS

Elevated PMP counts may trigger thrombosis in uremic patients. The primary cause of PMP elevation in uremia was not clarified in this study.

Circulating levels of plasminogen activator inhibitor type-1, tissue plasminogen activator, and thrombomodulin in hemodialysis patients: biochemical correlations and role as independent predictors of coronary artery stenosis

This study investigated the relationship between the circulating levels of the endothelial cell glycoproteins plasminogen activator inhibitor type 1 (PAI-1), tissue plasminogen activator (TPA), and thrombomodulin (TM) and the major vascular risk factors described in dialysis patients. In addition, the role of these endothelial cell products as independent predictors of coronary artery disease (CAD) was analyzed. Levels of TM, TPA antigen (Ag), TPA activity, PAI-1 Ag, PAI-1 activity, TPA/PAI complexes, thrombin-antithrombin complexes, fibrinopeptide A, C-reactive protein (CRP), interleukin-1beta and tumor necrosis factor-alpha, lipids, apoproteins A1 and B, and albumin were measured in a group of 200 nondiabetic dialysis patients and 100 healthy matched volunteers. When compared with healthy controls, dialysis patients showed increased levels of CRP, TM, TPA, and PAI-1 and evidence of increased thrombin-dependent fibrin formation. Increased levels of active PAI-1 were associated to a great extent with major classic vascular risk factors and to a lesser extent with CRP and serum triglycerides. Forty-six patients (23%) had evidence of CAD. Variables associated with CAD in the univariate analysis included age, time on dialysis, male gender, number of packs of cigarettes per year, high BP, fibrinogen, apolipoprotein B, albumin, PAI-1 activity, CRP, thrombin-antithrombin complexes, and fibrinopeptide A. Logistic regression analysis found age, high-density lipoprotein cholesterol, gender, high BP, CRP, time on dialysis, and PAI-1 activity to be independent predictors of CAD. This model classified correctly 85% of patients as having CAD and showed adequate goodness of fit for all risk categories. Our data support a pathogenic link among activated inflammatory response, endothelial injury, and CAD in hemodialysis patients and suggest that assessment of circulating PAI-1 levels could be an additional tool to identify dialysis patients who are at risk for developing atheromatous cardiovascular disease.

Increased activation of protein C, but lower plasma levels of free, activated protein C in uraemic patients: relationship with systemic inflammation and haemostatic activation

Chronic renal failure (CRF) courses with both systemic inflammatory reaction and haemostatic activation. We explored the relationship of these processes with plasma levels of free, activated protein C (APC) and complexes of APC with its inhibitors in patients with CRF under conservative treatment. Plasma concentrations of inflammatory cytokines [tumour necrosis factor alpha (TNFalpha) and interleukin 8], acute-phase proteins (C-reactive protein, fibrinogen, alpha1-anti-trypsin and von Willebrand factor), and markers of haemostatic activation (thrombin-anti-thrombin complexes, plasmin-anti-plasmin complexes, and fibrin and fibrinogen degradation products) were higher in patients than in controls. Inflammatory and haemostatic markers were significantly and positively correlated. Total plasma APC and APC:alpha1-anti-trypsin (alpha1AT) complexes were 44% and 75% higher in patients than in controls (P = 0.0001), whereas free APC was 20% lower (P < 0.015). No significant difference was observed in APC:protein C inhibitor (PCI) complexes between both groups. The free/total APC ratio was significantly lower in patients than in controls (P < 0.0001). Total plasma APC and APC:alpha1AT were positively correlated with activation markers of haemostasis and acute-phase proteins, whereas free APC was inversely correlated with plasma levels of creatinine, acute-phase proteins and fibrin degradation products (FnDP). Systemic inflammation and activation of haemostasis are interrelated processes in CRF. APC generation was increased in response to elevated thrombin production, but the inflammatory reaction, associated with increased synthesis of alpha1AT, reduced its anticoagulant effect. Lower free plasma APC in CRF may be pathogenically associated with atherothrombosis, a major cause of death in this disease.

Increased albumin and fibrinogen synthesis in hemodialysis patients with normal nutritional status

This study compared the rates of whole-body proteolysis and of albumin and fibrinogen synthesis of seven hemodialysis patients (HD) with those of seven normal matched control subjects (C). HD patients had a normal nutritional and inflammatory status and serum albumin levels >3.5 g/dl. Endogenous leucine flux, albumin and fibrinogen fractional synthesis rate (FSR), and absolute intravascular synthesis rate (ASR) of albumin and fibrinogen all were evaluated by a primed/continuous infusion of 5,5,5-D3-L-leucine. Plasma volume was determined by the Evans blue dye dilution method. Endogenous leucine flux was significantly increased in HD (2.64 +/- 0.08 micromol/kg per min) compared with C (2.17 +/- 0.07 micromol/kg per min, P: < 0.05). Serum albumin concentrations were similar in HD and C. Plasma fibrinogen levels were significantly increased in HD compared with C (P: < 0.05). Plasma volume was greater in HD than in C (P: < 0.05). As a result, total intravascular pool of both albumin (141 +/- 7 versus 114 +/- 3 g/1.73 m(2), P: < 0.05) and fibrinogen (11.7 +/- 1 versus 6.7 +/- 0.5 g/1.73 m(2), P: < 0.05) were greater in HD than in C. Albumin FSR was not statistically different in HD and C. However, albumin ASR was significantly increased in HD than in C (13.7 +/- 2 versus 10.3 +/- 1 g/1.73 m(2) per d, P: < 0.05). Similarly, FSR of fibrinogen did not differ in HD and C groups, whereas ASR of fibrinogen was significantly higher in HD than in C (3.31 +/- 0.6 versus 1.94 +/- 0.3 g/1.73 m(2) per d, P: < 0.05). In summary, normoalbuminemic HD patients have an increased intravascular pool with a greater absolute synthesis rate of both albumin and fibrinogen and an increased rate of whole-body leucine flux.

Monocyte expression of tissue factor and adhesion molecules: the link with accelerated coronary artery disease in patients with chronic renal failure

OBJECTIVE

To investigate the expression of monocyte tissue factor (MTF) and adhesion molecules in patients with chronic renal failure (CRF) and to look for any correlation with thrombin generation and Lp(a) lipoprotein.

DESIGN

A study of MTF expression and adhesion molecules, prothrombin fragments 1+2 (PTf1+2), an index of thrombin generation, and lipoproteins in patients with CRF and in normal control subjects.

BACKGROUND

Patients with end stage renal failure have an increased risk of coronary artery disease despite advances in therapy. Stimulated monocytes are potent activators of blood coagulation through the generation of MTF, which was recently implicated in the aetiology of acute coronary ischaemic syndromes.

METHODS

MTF expression and adhesion molecules were measured in whole blood using immunofluorescence of monocytes labelled with anti-tissue factor antibody and CD11b and c by flow cytometry. PTf1+2 and Lp(a) lipoprotein in plasma were measured by enzyme linked immunosorbent assay (ELISA).

PATIENTS

70 patients with CRF without documented coronary artery disease (30 patients with CRF undialysed, 20 patients undergoing chronic ambulatory peritoneal dialysis (CAPD), and 20 undergoing haemodialysis (HD)), together with 20 normal controls, were studied.

RESULTS

The (mean (SD)) increased MTF of CRF (48.0 (29) v 33.3 (7.2) mesf unit/100 monocytes in controls, p = 0.04) was more pronounced in patients undergoing dialysis (HD 73.1 (32.8) (p < 0.003) and CAPD 62.8 (28.9) mesf unit/100 monocytes, p < 0.04). MTF activity showed a positive correlation with both PTf1+2 and serum creatinine (p < 0.003) but not with Lp(a) lipoprotein. Lp(a) lipoprotein was significantly increased in both dialysis groups compared with controls (p < 0.005) and non-dialysis CRF groups (p < 0.02). Monocyte adhesion molecule (CD11b) was significantly higher in all three CRF groups than in the controls (p = 0.006).

CONCLUSION

This study has demonstrated a hypercoagulable state in patients with CRF. This was especially pronounced in the dialysis patients. These findings provide a possible explanation for the increased cardiovascular and cerebrovascular morbidity and mortality in these patients.

Endothelial cell markers in chronic uremia: relationship with hemostatic defects and severity of renal failure

Plasma von Willebrand factor antigen, soluble thrombomodulin, and tissue factor were increased in 31 patients with severe chronic renal failure (creatinine clearance <20 ml/min) under conservative treatment, whereas plasminogen activator inhibitor antigen did not differ significantly from healthy controls. No correlation among plasma levels of these proteins was found. Three patterns of relationship between endothelial cell markers and hemostatic defects were identified: 1) Plasma thrombomodulin, a marker of endothelium damage, was found an independent predictor of bleeding time and platelet aggregation, and secretion defects, and was also related to the severity of renal failure; 2) von Willebrand factor antigen, an index of endothelial cell activation and secretion, was significantly correlated with intravascular markers of thrombin and plasmin generation and with platelet adenosine triphosphate content, but not with plasma creatinine levels; and 3) tissue factor and plasminogen activator inhibitor antigen levels were not statistically correlated with the diverse hemostatic defects. Activation of coagulation and fibrinolysis, secondary to endothelial cell activation, appearing early during the evolution of chronic renal failure, is pathogenically related to the platelet dysfunction, and probably to development of atherosclerosis and thrombotic events in this disease. The progression of chronic renal failure, through endothelial cell damage, would lead to aggravation of the platelet functional defect potentiating the hemorrhagic risk.

Coagulation inhibitors and fibrinolytic parameters in patients on peritoneal dialysis and haemodialysis

Coagulation inhibitors and fibrinolytic parameters were studied in twelve patients on continuous ambulatory peritoneal dialysis (CAPD) and ten patients on haemodialysis (HD). Patients on CAPD exhibited higher levels of ATIII and proteins C and S than those on HD. No significant differences were noted in tPA and PAI levels. Both groups of patients showed higher levels of tPA than controls. Besides, patients on HD had significantly lower levels of ATIII and protein C than controls. PAI levels in both patient groups were similar to those of the controls, but tPA levels were higher in patients than in controls. These results indicate that HD is associated with marked diminution in the circulating levels of coagulation inhibitors. This is in contrast to CAPD patients who showed elevated levels of these inhibitors, despite their significant loss in the dialysate. The finding of enhanced fibrinolysis in both patient groups may be a natural protective mechanism against the development of a thrombotic tendency.

Increased cardiovascular risk factors and features of endothelial activation and dysfunction in dialyzed uremic patients

Due to the incidence of symptomatic atherosclerosis in uremic patients, hemostasis-derived cardiovascular risk factors, basal plasma concentrations of some endothelial-derived glycoproteins and desmopressin-induced variations of endothelial-derived proteins were studied in 22 uremic patients on prolonged maintenance hemodialysis with no cardiovascular antecedent. Compared to control subjects, patients had increased predialysis hemostasis-related cardiovascular risk factors: high fibrinogen, proconvertin, and type 1 plasminogen activator inhibitor plasma concentrations; low albumin values; generally low antithrombin III values but sometimes high. They had high predialysis plasma concentrations of endothelium-derived glycoproteins: von Willebrand factor, tissue-type plasminogen activator and urokinase-type plasminogen activator, which are secreted by endothelial cells, but also soluble thrombomodulin, a marker of endothelial cell injury. The desmopressin-induced release of tissue-type plasminogen activator and of von Willebrand factor were lower than in controls. High fibrinogen, type 1 plasminogen activator inhibitor and low albumin plasma concentrations may be linked to repeated acute phase reactions associated with hemodialysis. Data concerning endothelium-related proteins are concordant with the co-existence of a chronic in vivo endothelial activation and endothelial injury in uremia. This could be linked to the initiation and progression of atherosclerosis.

Blood coagulation, fibrinolytic, and inhibitory proteins in end-stage renal disease: effect of hemodialysis

Patients with end-stage renal disease (ESRD) are at risk of ischemic cardiovascular complications and vascular thrombosis. These observations prompted the present survey of the blood coagulation, fibrinolytic, and inhibitory proteins in a group of 31 ESRD patients and 32 normal controls. Immunologic and functional assays were used to quantitate plasma antigen concentrations and/or functional activities of factors XII, XI, IX, VIII, VII, X, II, and XIII, von Willebrand factor, fibrinogen, fibronectin, high molecular weight kininogen, D-dimer, antithrombin III, protein C, protein S, plasminogen, tissue-type plasminogen activator, plasminogen activator inhibitor, alpha 2-antiplasmin, alpha 1-antitrypsin, and alpha 2-macroglobulin as well as antiplasmin activity. The coagulant activities of factors XII, IX, X, and II were significantly reduced in ESRD patients despite their normal or increased plasma antigen concentrations. In addition, the ESRD patients showed hyperfibrinogenemia and significant elevations of plasma concentrations of D-dimer, von Willebrand factor, factor VII, and factor XIII antigens. They also exhibited significant reductions of antithrombin III, free protein S, plasminogen, and tissue-type plasminogen activator concentrations. Despite ultrafiltration, plasma factor IX activity and von Willebrand factor and fibrinogen concentrations decreased after hemodialysis with little or slight changes in other measured parameters. The ESRD patients studied here exhibited numerous abnormalities of coagulation, fibrinolytic, and inhibitory proteins at multiple levels. These abnormalities may be involved in the pathogenesis of cardiovascular complications and vascular thrombosis in this population. The precise mechanism(s) and clinical significance of the observed abnormalities are unknown and await further investigation.

Thrombin generation and factor VIII:C levels in patients with type 1 diabetes complicated by nephropathy

The association between plasma coagulant activity and the presence of diabetic nephropathy was investigated in 31 patients with Type 1 diabetes, 12 with and 19 without nephropathy, and in 11 healthy subjects. Thrombin generation was assessed by computer assisted chromogenic method and expressed as time (in seconds) to 50% maximal thrombin activity (T50). Factor VIII:C levels related to thrombin activity, glycaemic control, and renal function. Median (IQ) FVIII:C concentration was increased in patients with nephropathy (1590 (1130-1900) IU l-1) compared to those without renal disease and with controls (960 (750-1090); 1020 (810-1100) IU l-1, p < 0.01, respectively). There were no significant differences in T50 values between the groups. FVIII:C correlated with age in all subjects and in the diabetic group (r = 0.33, p = 0.036; r = 0.39, p = 0.031) and inversely with T50 in all subjects and in controls (r = -0.35, p = 0.02; r = -0.62, p = 0.04). In all subjects and in patients, FVIII:C was related to urinary albumin excretion and creatinine clearance. FVIII:C and T50 were not related to HbA1c. The results show that FVIII:C levels are increased in Type 1 diabetes complicated by nephropathy and are related to degree of renal impairment but not levels of glycaemia. No associated enhancement of plasma procoagulant activity was detected.

Factor VII hyperactivity in chronic dialysis patients

To study factor VII (F VII) hyperactivity in chronic dialysis patients, we measured the plasma levels of F VII activity (F VII c) and antigen (F VII Ag), prothrombin activation fragments 1 + 2 (F1 + 2), thrombin-antithrombin III complexes (TAT), and thrombomodulin in 28 patients on hemodialysis. Marked elevation of F VII c was found in long-term dialysis patients (185 +/- 30%). This hyperactivity was accompanied by both elevation of the F VII Ag level (153 +/- 28%) and enhanced activation of F VII zymogen, expressed as the F VII c/F VII Ag ratio (1.23 +/- 0.23), but pseudocholinesterase activity was decreased. The 6 patients with ischemic heart disease had slightly higher F VII c (200 +/- 25%) than those without ischemic heart disease (181 +/- 30%), although the difference was not significant. Increased F VII c was accompanied by factor Xa hyperactivity (a high plasma F1 + 2 level) in the long-term dialysis patients, but there was no significant elevation of plasma TAT levels when compared with controls matched for age, sex, and the presence or absence of diabetes mellitus. Plasma TAT levels were significantly correlated with plasma thrombomodulin levels, suggesting that thrombin generation in blood as a result of hemodialysis could induce systemic endothelial cell injury.

Coagulation and fibrinolysis in patients with chronic renal failure undergoing conservative treatment

Eighteen patients with chronic renal failure due to primary glomerular disease undergoing conservative treatment (CRF patients) were studied to evaluate whether coagulation and fibrinolytic activity in plasma are enhanced in the patients. We measured plasma levels of coagulation-fibrinolysis parameters including thrombin-antithrombin III complex (TAT) (an index of thrombin formation), alpha 2-plasmin inhibitor (alpha 2 PI)-plasmin complex (alpha 2 PIC) (an indicator of plasmin production) and cross-linked fibrin degradation products (XL-FDP) (an index of fibrinolysis secondary to coagulation). There was no correlation between plasma levels of TAT, alpha 2PIC and XL-FDP and serum creatinine levels in CRF patients. Both fibrinogen and TAT were found to be significantly higher in CRF patients than in normal controls. TAT was negatively correlated with serum albumin or total protein. Antithrombin III (ATIII) activity was significantly lower in CRF patients than in normal controls. CRF patients showed significantly but slightly higher alpha 2 PIC and XL-FDP when compared to normal controls. These results suggest that TAT, alpha 2PIC and XL-FDP are good indicators of coagulation-fibrinolysis even in patients with decreased renal function. Coagulation activity is significantly increased in CRF patients but fibrinolysis secondary to coagulation is only slightly enhanced.