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Detection of a hypercoagulable state in nonvalvular atrial fibrillation and the effect of anticoagulant therapy.

The purpose of the study was to evaluate alterations of the hemostatic system and the effect of anticoagulant therapy in nonvalvular atrial fibrillation. A set of molecular hematologic markers was measured prospectively in 69 patients with atrial fibrillation and 28 age-matched patients in sinus rhythm. Significantly elevated levels of thrombin-antithrombin III complex (8.5 +/- 1.6 vs. 2.5 +/- 0.3 micrograms/l; p < 0.001), fibrin monomers (27.1 +/- 3.2 vs. 13.4 +/- 3.7 nM; p < 0.001), D-dimers (788 +/- 76 vs. 405 +/- 46 micrograms/l; p < 0.005), and tissue-type plasminogen activator (9.6 +/- 0.5 vs. 7.2 +/- 0.5 micrograms/l; p < 0.05) were observed in patients with atrial fibrillation compared to those in sinus rhythm. In a subgroup of patients in whom anticoagulant therapy with oral coumadin or standard intravenous heparin was established after the initial study, hemostatic activation decreased significantly. In conclusion, molecular hematologic markers indicate a hypercoagulable state in atrial fibrillation which may characterized a group of patients at elevated risk of thromboembolic disease.

Aged↗

Short heparin thrombin clotting time, increased fibrinogen and platelet aggregates count in coronary disease: a probable hypercoagulable state.

Several indices of plasmatic and platelet coagulability (H.T.C.T., AT III, fibrinogen and Wu-Hoak test) were studied in 82 patients with acute and chronic coronary artery disease. The results were compared with those obtained in a control group. The most interesting result is the consistent shortening of H.T.C.T. as compared to the control group, particularly in patients with acute myocardial infarction. H.T.C.T. was always inversely correlated with the fibrinogen level. Those data suggest an important influence of fibrinogen levels on H.T.C.T., but this observation does not rule out the possibility that the heparin neutralizing activity (PF 4) will also influence the test. No positive correlation between H.T.C.T. and AT III could be observed. The elevated levels of AT III in acute myocardial infarction did not confirm the existence of a consumption of AT III due to chronic intravascular coagulation in these patients. The Wu-Hoak test increased only in patients with acute coronary disease, never in the other groups. In conclusion, H.T.C.T. may be assumed to be a valid test for indicating the existence of a possible hypercoagulability state.

Adult↗

The induction of a hypercoagulable state by medroxyprogesterone acetate in breast cancer patients.

The effects of medroxyprogesterone acetate (MPA) on the mechanism of coagulation in postmenopausal patients were studied and compared with those of tamoxifen by a retrospective analysis. The coagulation test parameters tested included platelet count, bleeding time, clotting time, prothrombin time, activated partial thromboplastin time, and the levels of fibrinogen, fibrin degradation products, factor II, factor V, plasminogen, alpha 2-plasmin inhibitor (alpha 2-PI) and alpha 2-plasmin inhibitor-plasmin complex (alpha 2-PI-P). A shortened APTT was noted and the levels of factors II, V, alpha 2-PI and alpha 2-PI-P were also out of the normal range during treatment in the MPA-treated group. However, these abnormal parameters recovered to within the normal range from 6 months or more after the commencement of treatment without any termination of drug administration. The patients were all asymptomatic. In contrast, a slight prolongation of bleeding time which persisted for more than 6 months was observed in the patients treated with tamoxifen. These data suggest that MPA causes a hypercoagulable state and that any change must be carefully monitored during treatment with either MPA or tamoxifen.

Antineoplastic Agents↗

Activated protein C resistance and thrombosis: molecular mechanisms of hypercoagulable state due to FVR506Q mutation.

Inherited resistance to activated protein C (APC) is the most common genetic risk factor of venous thrombosis. It is caused by a single point mutation in the factor (F)V gene which predicts replacement of Arg506 with a Gln (FVR506Q, FV: Q506 or FV Leiden). This mutation affects the function of the protein C system, a physiologically important natural anticoagulant pathway. APC inhibits coagulation by cleaving a limited number of peptide bonds in both intact and activated forms of factor V (FV/FVa) and factor VIII (FVIII/FVIIIa). Degradation of FVa by APC is stimulated by protein S, whereas inactivation of FVIIIa requires the synergistic cofactor function of protein S and FV proteolytically modified by APC. Thus, FV has the potential to express opposing functions, as a procoagulant after cleavage by thrombin or FXa and as an anticoagulant after cleavage by APC. The FVR506Q mutation not only confers partial resistance of FVa to APC but also impairs the degradation of FVIIIa because APC-mediated cleavage of FV at Arg506 is required for expression of the anticoagulant activity of FV. The impaired degradation of both FVIIIa and FVa yield a hypercoagulable state conferring a lifelong increased risk of thrombosis. The FV mutation is common in Caucasians, whereas it is rarely found among other groups worldwide. In patients with severe thrombophilia having other inherited defects such as deficiencies of protein S, protein C, or antithrombin, APC resistance is often found as a contributing genetic risk factor. Individuals with combined genetic defects have a high risk of thrombosis, and it is now generally accepted that thrombophilia is a multigenetic disease.

Activated Protein C Resistance↗

Hypercoagulable state in patients with Takayasu's arteritis.

Thrombus formation is recognized pathologically in the affected arteries and is supposed to play a major role in the pathogenesis of Takayasu's arteritis; however, hemostatic conditions in this disorder have not been elucidated fully. We determined plasma levels of molecular markers for platelet activity (platelet factor 4; PF4, beta-thromboglobulin; beta TG), thrombotic status (thrombin-antithrombin III complex; TAT, fibrinopeptide A; FPA), fibrinolytic status (plasmin-alpha 2-plasmin inhibitor complex; PIC, D-dimer), and endothelial injury (von Willebrand factor antigen; vWF:Ag, thrombomodulin; TM) in 30 patients with Takayasu's arteritis and 20 age-matched control subjects. Plasma levels of PF4, beta TG, TAT, FPA and D-dimer, but not PIC, in patients with Takayasu's arteritis were substantially higher than those in normal control subjects. The levels of these markers were not different between the active and inactive stages of the disease. Plasma levels of vWF:Ag in patients with Takayasu's arteritis did not differ significantly from those in normal subjects, and plasma levels of TM were significantly lower than those in normal subjects. In patients with Takayasu's arteritis, platelet and coagulation activities are significantly increased, leading to hypercoagulable state and thrombus formation, although there is little, if any, endothelial damage.

Adolescent↗

Diabetes mellitus: a hypercoagulable state.

Eighty percent of patients with diabetes mellitus die a thrombotic death. Seventy-five percent of these deaths is due to cardiovascular complications, and the remainder is due to cerebrovascular events and peripheral vascular complications. Vascular endothelium, the primary defense against thrombosis, is abnormal in diabetes. Endothelial abnormalities undoubtedly play a role in the enhanced activation of platelets and clotting factors seen in diabetes. Coagulation activation markers, such as prothrombin activation fragment 1+2 and thrombin-anti-thrombin complexes, are elevated in diabetes. The plasma levels of many clotting factors including fibrinogen, factor VII, factor VIII, factor XI, factor XII, kallikrein, and von Willebrand factor are elevated in diabetes. Conversely, the level of the anticoagulant protein C (PC) is decreased. The fibrinolytic system, the primary means of removing clots, is relatively inhibited in diabetes due to abnormal clot structures that are more resistant to degradation and an increase in plasminogen activator inhibitor type 1 (PAI-1). Increased circulating platelet aggregates, increased platelet aggregation in response to platelet agonists, increased platelet contractile force (PCF), and the presence of higher plasma levels of platelet release products, such as beta-thromboglobulin, platelet factor 4, and thromboxane B(2), demonstrate platelet hyperactivity in diabetes. This constellation of findings supports the clinical observation that diabetes is a hypercoagulable state. This article briefly reviews the published evidence for this conclusion and the putative roles played by hyperglycemia and hyperinsulinemia in its development.

Anticoagulants↗

Relevance of tissue factor and tissue factor pathway inhibitor for hypercoagulable state in the lungs of patients with idiopathic pulmonary fibrosis.

We investigated the role of tissue factor (TF) and tissue factor pathway inhibitor (TFPI) in the lungs of patients with idiopathic pulmonary fibrosis (IPF). Bronchoalveolar lavage (BAL) fluid was obtained from 22 patients with IPF, and the levels of TF and TFPI antigen were measured by ELISA. The TF and TFPI levels in BAL fluid supernatant were significantly higher in IPF patients than in normal controls. In addition, both levels were significantly higher in advanced cases than in nonadvanced cases. There was a significant correlation between the TF and TFPI levels. Localization of TF and TFPI antigens was investigated by immunohistochemical staining. Both antigens were mainly localized in hyperplastic cuboidal epithelial cells, suggesting that the widespread distribution of these cells contributed to the increase of TF and TFPI antigen levels in the lungs of IPF patients. To assess whether TF activity is counterbalanced by TFPI in the lungs of IPF patients, we examined procoagulant activity and TF activity. It was found, however, that both procoagulant and TF activities were significantly higher in the BAL fluid supernatant of IPF patients than in that of normal controls, which suggested that TFPI was actually increased, but the increase was insufficient to counterbalance TF, leading to the development of a hypercoagulable state in the lungs of IPF patients.

Adult↗

The fibrinolytic potential in patients with Cushing's disease: a clue to their hypercoagulable state.

The aim of our study was to determine the fibrinolytic potential in a large group of patients with Cushing's disease. These patients had a significant shortening of the activated partial thromboplastin time and increase in factor VIII/von Willebrand factor complex compared to normal controls. The mean levels of plasminogen, tissue plasminogen activator (t-PA) antigen and plasminogen activator inhibitor (PAI) activity were significantly higher than in normal subjects, whereas the basal fibrinolytic activity was similar to that seen in the control group. In 17 out of 30 Cushing patients and in 17 normal subjects the fibrinolytic potential was determined with the venous occlusion test. In the Cushing group, the release of t-PA antigen after 20 min of venous occlusion was comparable to that observed in the control group. However, Cushing patients showed a lower fibrinolytic activity than normal subjects, since a lesser shortening of the euglobulin lysis time and a non-significant rise of plasminogen activator activity levels were found. Moreover, in these patients the PAI activity values remained unchanged and significantly increased after venous occlusion test also. In conclusion, the impaired fibrinolytic activation seen in Cushing patients after venous occlusion can be explained by the inhibitory effect of the high PAI levels on plasminogen activators. The defective fibrinolytic potential could further contribute to the hypercoagulable state in Cushing's disease. High PAI levels before surgery may represent an additional risk factor for post-surgical thromboembolic complications in Cushing patients.

Adult↗

Relationship between hypercoagulable state and erythrocyte phosphatidylserine exposure in splenectomized haemoglobin E/beta-thalassaemic patients.

Small pulmonary arterial thromboses can occur following splenectomy of patients with haemoglobin E/beta-thalassaemia (Hb E/beta-thal). We compared plasma markers of coagulation activation in vivo and red blood cell (RBC) markers of procoagulant activity in 15 Hb E/beta-thal patients who were not splenectomized (NS), 15 who had been splenectomized (S), and 15 normal controls (NC). Levels of plasma thrombin-antithrombin III complex (TAT) were significantly higher in the S group than in either the NS or the NC groups, and levels of prothrombin fragment 1.2 (F 1.2) were significantly higher in the S than in the NC group. Diluted Russell's viper venom clotting times were significantly shorter when RBCs from group S patients were added to the assay compared with RBCs from the NC group. Phosphatidylserine (PS) expression (% of annexin V-positive RBCs) on the outer leaflet of RBC membrane of both 'larger'- and 'smaller'-sized RBCs was significantly higher for the S than the NC group. The RBC PS expression of the S and the NS groups, respectively, accounted for 25 x 3% (P = 0 x 174) and 6.3% (P = 0 x 675) of the variation in plasma TAT levels. Our findings indicated that, when compared with NC, splenectomized patients with Hb E/beta-thal were in a chronic low-grade hypercoagulable state associated with increased numbers of circulating PS exposed RBCs. This condition may have a role in the risk of these patients for pulmonary arterial thromboses.

Adult↗

Hypercoagulable states in primary upper-extremity deep vein thrombosis.

BACKGROUND: There are very few data on the prevalence of coagulation abnormalities in primary deep vein thrombosis of the upper limbs. OBJECTIVE: To determine if coagulation abnormalities play a role in effort-related and/or idiopathic (non-effort-related) upper-extremity deep vein thrombosis (UEDVT). METHODS: Fifty-one consecutive patients (21 men and 30 women) who had effort-related (n = 20) or idiopathic (n = 31) UEDVT over an 18-year period (median age at diagnosis, 32 years; age range, 15-86 years) were routinely reexamined. Plasma was screened for antithrombin, protein C, and protein S deficiencies and for antiphospholipid antibodies (lupus anticoagulant and anticardiolipin antibodies). The DNA was screened for factor V Leiden and for prothrombin gene G20210A mutations. RESULTS: The median age (35 vs. 28 years), the proportion of women (81% [25/31] vs. 25% [5/201), the proportion of patients with a personal and/or family history of thromboembolism (42% [13/31] vs. 15% [3/20]), and the proportion of patients with at least 1 coagulation abnormality (42% [13/31] vs. 15% [3/20]) were higher in the idiopathic UEDVT group than in the effort-related UEDVT group. The odds ratio of having a coagulation abnormality was 4.09 (95% confidence interval, 0.99-16.78; P = .06) in the idiopathic UEDVT group compared with the effort-related UEDVT group. CONCLUSION: Hypercoagulable states appear to play a significant role in idiopathic but not in effort-related UEDVT.

Adolescent↗

Hypercoagulable state in hypercholesterolemic subjects assessed by platelet-dependent thrombin generation: in vitro effect of cerivastatin.

BACKGROUND: Hypercholesterolemia is an important risk factor to develop acute thrombotic complications of atherosclerosis like to myocardial infarction and ischemic stroke. Platelets and coagulation factors are strictly involved in the genesis of such thrombotic events and their hyperactivity in hypercholesterolemic patients has been previously reported. Moreover some cholesterol-lowering molecules (statins) seem to be able of reducing platelet activity. METHODS: We performed platelet-dependent thrombin generation (colorimetric method) to assess the coagulative potential of 40 caucasian hypercholesterolemic subjects with respect to normal controls and to the grade of hypercholesterolemia. Moreover we observed the effect of platelets from hypercholesterolemics on thrombin generation in plasma from normal subjects. The effect of Cerivastatin on thrombin generation was evaluated too. RESULTS: Our data show an increased thrombin generation both in mild and high hypercholesterolemic subjects with respect to controls (424.6+/-30.5 vs. 197.1+/-27.4 mIU/ml). No significant difference in the amount of thrombin generation was found between mild and high hypercholesterolemics (399.6+/-20.7 vs. 440.2+/-21.4 mIU/ml). Platelets directly influence thrombin generation and they present an intrinsic hyperactivity that can be modulated by Cerivastatin (223.6+/-24.8 vs. 424.6+/-30.5 mIU/ml). CONCLUSIONS: Mild hypercholesterolemia is associated with an increased thrombinic potential that may be considered an added risk factor to develop thrombotic events. Platelets directly influences this hypercoagulative state and Cerivastatin is able to reduce thrombin generation by way of a direct interaction with platelets.

Blood Coagulation Disorders↗

An abnormal systemic and regional hypercoagulable state in patients with mitral stenosis.

Mitral stenosis still remains a major problem in Southeast Asia including Thailand. It contributes to the morbidity and mortality related to thromboembolism which was associated with the left atrial thrombus. However, the pathogenesis of left atrial thrombus in these patients is not completely understood. Therefore, the objective of this study was to investigate the coagulation and platelet activity including the function of the endocardium in the left atrium and peripheral circulation in patients with mitral stenosis who were free of left atrial thrombus and to compare those hematologic markers activity in the peripheral venous blood between the patients with mitral stenosis and the control. Thirty-six patients with moderate to severe mitral stenosis were included in the study. Most of the patients were in functional class II and 50 per cent had atrial fibrillation. Blood was obtained from the femoral vein, femoral artery, pulmonary artery and left atrium of these patients before heparin was administered to determine the value of various hematologic markers. In the control group, blood for determining the hematologic markers was collected only from the antecubital vein. The results of this study demonstrated that the levels of prothrombin activation fragment 1+2 (F1+2), thrombin-antithrombin III complex (TAT) and Beta-thromboglobulin (beta-TG) in the left atrium of the patients with mitral stenosis were significantly higher than those in the femoral vein and femoral artery, whereas the level of thrombomodulin was significantly lower in the left atrium compared with the femoral artery and vein. When comparing with the control group, the levels of TAT, plasminogen activator inhibitors-1 (PAI-1) from the peripheral vein were significantly higher and the level of thrombomodulin was also significantly lower in the patients with mitral stenosis. In conclusion, the present study demonstrated an abnormal hypercoagulable state of the left atrium and systemic circulation related to the abnormalities of coagulation, platelets and the endocardium which may cause the formation of left atrial thrombus in patients with mitral stenosis.

Adult↗

Factor V Leiden and other hypercoagulable state mutations are not associated with osteonecrosis during or after treatment for pediatric malignancy.

OBJECTIVE: Osteonecrosis (ON) is a debilitating complication of cancer treatment in children and is usually associated with systemic steroid therapy. Defects of coagulation may be important in the pathogenesis of ON. This study evaluated the prevalence of factor V Leiden (FVL, 1691G-->A), the most common inherited thrombophilic state, the prothrombin 20210G-->A polymorphism, and the thermolabile methylene tetrahydrofolate reductase (MTHFR, 677C-->T) variant in a group of children in whom ON developed during or after treatment for cancer. STUDY DESIGN: Children in whom ON developed during cancer treatment at St Jude Children's Research Hospital were studied (n = 24). Genomic DNA was isolated, and polymerase chain reaction was performed to identify the FVL, prothrombin 20210, and thermolabile MTHFR mutations. RESULTS: Sixteen of 24 patients had acute lymphoblastic leukemia. The mean age at ON diagnosis was 14.4 +/- 3. 7 years. The mean interval between cancer diagnosis and ON diagnosis was 27 +/- 21 months. Twenty-two patients had received steroids for a mean duration of 24 +/- 15 weeks before having development of ON. No patient had a history of thrombosis. Five (21%) patients had a family history of thrombosis. Genetic analysis revealed 0 (0%) of 24 FVL, 1 (4.5%) of 22 prothrombin 20210, and 3 (13.6%) of 22 thermolabile MTHFR. None of these mutation frequencies was significantly different from our control frequencies or published values. CONCLUSIONS: Although procoagulant abnormalities in general and FVL in particular have been detected in a significant number of patients with ON of the jaw and Legg-Perthes disease, we did not identify an increased prevalence of FVL or other hypercoagulable state mutations in a cohort of children with ON that developed during or after treatment for a variety of cancers.

Adolescent↗

C-reactive protein contributes to the hypercoagulable state in coronary artery disease.

OBJECTIVES: Elevated plasma C-reactive protein (CRP) levels predict coronary events, but it is unclear whether CRP plays a role in thrombosis associated with these events. We investigated tissue factor (TF) induction by CRP on peripheral blood mononuclear cells (PBMC) from patients with coronary disease. PATIENTS AND METHODS: PBMC from 35 patients with stable angina (SA) in study 1, 10 male patients with SA, 10 with unstable angina (UA) and 10 matched controls in study 2, and 25 patients with inflammatory disorders (ID) and 24 normal controls in study 3 were stimulated with CRP, interferon-gamma (IFN) or lipopolysaccharide (LPS), or their combination. PBMC from additional normal donors were also stimulated with CRP in adherent and non-adherent conditions, and TF activity, antigen and mRNA expression detected. RESULTS: CRP (5-25 microg mL(-1)) dose dependently induced more TF on PBMC from SA patients than 42 contemporary controls (P = 0.001, study 1). Compared with controls, patients with SA or UA had higher basal, and much higher CRP- or CRP/LPS-induced monocyte TF activity although serum CRP levels were similar (study 2). IFN induced monocyte TF activity in patients with angina, but not in controls. Basal or CRP-induced TF levels did not differ between controls and ID, even though ID patients had much higher serum CRP levels (study 3). CRP-induced monocyte TF activity correlated with serum CRP levels in controls (P = 0.005) and ID (P = 0.007) in study 3, but not in patients with angina (P =0.84) in study 2. CRP induced more TF activity, protein and mRNA under adherent than non-adherent conditions implying that it may mainly target macrophages in lymphocyte-rich lesions. CONCLUSIONS: Our results indicate that monocytes from patients with angina are preactivated and express TF but CRP is unlikely to be a major priming factor in vivo. IFN and CRP further increase TF levels that may contribute to the hypercoagulable state in coronary disease.

Adult↗

Coagulation and fibrinolysis changes in normal pregnancy. Increased levels of procoagulants and reduced levels of inhibitors during pregnancy induce a hypercoagulable state, combined with a reactive fibrinolysis.

OBJECTIVE: To establish the physiologic changes in the coagulation and fibrinolytic systems during normal pregnancy and puerperium. STUDY DESIGN: One hundred and seventeen normal pregnant women were investigated in a longitudinal study involving five measurements: blood samples were collected at 10, 20, 30, 36 weeks and on the second day puerperium and were assayed for prothrombin time (PT expressed in INR), activated partial thromboplastin time (PTT), fibrinogen (FBG), antithrombin III activity (AT III), protein C activity (PC), protein S activity (PS), prothrombin fragments 1+2 (F1+2), type 1 plasminogen activator inhibitor activity (PAI) and tissue-plasminogen activator antigen (t-PA). Student t-test, One Way Analysis of Variance (ANOVA) and Bonferroni test were used for statistical analysis. P<0.05 (two tails) was assumed to indicate a significant difference. RESULTS: Fibrinogen concentrations were always increased with respect to controls (P<0.001), while protein S was always decreased, with values averaging 60% of those of controls from the 10th week of pregnancy onwards (P<0.001). Variance analysis showed a statistically significant increase with gestational age for procoagulant factors (INR: P<0.001; FBG: P<0.001), a reduction for anticoagulants (PC: P<0.0001; PS: P<0.0001), and a rise for F1+2 (P<0.0001). With regard to fibrinolysis, there was an increase both for t-PA (P<0.0001) and PAI-1 (P<0.0001) during pregnancy. The t-PA values were always comprised in the normal range. PAI-1 were increased with respect to control values starting from 31st week. The most significant variations in the procoagulants (expressed by PT and FBG) were recorded up to the 20th week (P<0.001); from the 30th week onwards, they remained stable until after the delivery. The same was true for protein S levels (P<0.001), except that the difference between the 10th and the 20th weeks was not statistically significant. The level of F1+2 gradually increased throughout pregnancy (P<0.001), and then fell in the puerperium (P<0.001). CONCLUSIONS: The parameters showing the greatest variation during pregnancy were PT, FBG, PS, F1+2 and PAI-1. The existence of a hypercoagulable state in pregnancy was suggested by the increased levels of F1+2.

Adult↗

[Clinical studies on flow properties of blood in the gynecological patients with potentially hypercoagulable state (author's transl)].

The flow property of blood, the blood viscosity was measured under such gynecological conditions that were potentially hypercoagulable: in the post-operative state for myoma uteri corporis, in the use of oral contraceptives and in the advanced stage of malignant uterine and ovarian tumors. The viscosity was measured at a shear rate of 0.989 sec-1 and at 37 degrees C. Blood viscosity after operation rose to 15.6 +/- 3.7 cp (mean +/- SD), which was significantly higher than that of pre-operative state (12.4 +/- 3.7 cp). This was due to increased hematocrit and fibrinogen levels. The viscosity returned to preoperative level on the 3rd day of post-operation. The blood viscosity of users of oral contraceptives was 15.1 +/- 2.7 cp, not being significantly higher than that of control women (13.4 +/- 2.8 cp). The blood viscosity of patients suffered from malignant tumors was 10.5 +/- 2.0 cp and was significantly lower than that of control. Comparison of viscosity at the same hematocrits revealed, however, that the viscosity of patients of malignant tumors was significantly higher than that of control. Such rheological characteristics in the patients of malignant tumors were due to decreased hematocrit and markedly increased fibrinogen levels. It was suggested that dehydration and infection should be avoided to prevent thrombus formation in the gynecological patients with potentially hypercoagulable state.

Adult↗

The development of hypercoagulability state, as measured by thrombelastography, associated with intraoperative surgical blood loss.

Thrombelastographic evidence of hypercoagulability, including shortening of r-time (P < 0.01); shortening of k-time (P < 0.01); and widening of trace angle (P < 0.01) were observed in a group of 21 Chinese surgical patients when (a) the amount of blood loss was at an estimated 10% of total blood volume and (b) the amount of blood loss was at an estimated 15% of blood volume. The amount of blood loss was documented by haemoglobin measurements. No evidence of hypercoagulability was observed at around one hour into the operation in the absence of bleeding. We conclude that a mild to moderate degree of surgical blood loss with haemodilution is associated with the development of hypercoagulability as measured by thrombelastography. Further studies looking at the thrombebolic outcome in such groups of patients is warranted. It is also suggested that caution should be exercised in the use of intraoperative isovolaemic haemodilution until the phenomenon is further investigated.

Adult↗

Recurrent venous thrombosis and hypercoagulable states.

Patients with recurrent venous thrombosis, or those with thrombosis at a young age (less than 45 years) and a family history of thrombotic disorders, may have an inherited hypercoagulable disorder. The most common disorders are deficiencies of protein S, protein C and antithrombin III, inhibitors of the coagulation cascade. These deficiencies may be found in approximately 10 percent of patients who are under age 45 and have venous thrombosis. Acquired disorders associated with recurrent venous thrombosis include carcinoma and antiphospholipid antibody syndrome. Appropriate anticoagulation can reduce the risk of recurrent thrombosis in patients with inherited and acquired abnormalities.

Adult↗