Interrelated risk factors for venous thromboembolism

Hypercoagulable States

The hypercoagulable states consist of a group of prothrombotic clinical disorders associated with an increased risk for thromboembolic events. The abnormalities lead to inappropriate thrombus formation. After a review of the coagulation process, inherited disorders (including antithrombin-III deficiency, protein CS system deficiencies, disorders of plasmin generation, dysfibrinogenemias, and homocysteinuria) and acquired disorders (including responses to surgery, cancer, drugs, and the antiphospholipid syndrome) are described. Screening and management methods are discussed. Copyright © 1997 by W. B. Saunders Company.

Increased plasma adiponectin concentrations in poorly controlled patients with phenylketonuria normalize with a strict diet: evidence for catecholamine-mediated adiponectin regulation and a complex effect of phenylketonuria diet on atherogenesis risk factors

Adiponectin (Adpn), an adipose tissue-derived hormone, prevents endothelial inflammation and early atherogenesis. Classic phenylketonuria (PKU), an inborn error of phenylalanine (Phe) metabolism, results in a reduction of catecholamine biosynthesis and requires treatment with lifelong low-Phe diet to prevent mental dysfunction and allow proper intellectual development. In this study, we evaluated the effect of the quality of PKU diet on plasma Adpn concentrations and related biochemical indices of endothelial dysfunction and atherogenesis. Patients with PKU were divided into groups A (n = 18), who were on a strict diet, and B (n = 18), who were on a loose diet, after evaluation of their 30-day dietetic diaries and measurement of Phe blood concentrations. Twenty healthy children of similar ages and body mass indexes served as controls (group C). Group A patients had normal circulating catecholamines and Adpn and decreased tumor necrosis factor alpha concentrations and low-density lipoprotein cholesterol/apolipoprotein B ratio compared with groups B and C. Despite these favorable parameters, however, homocysteine concentration was twice as high in group A compared with groups B and C. Interestingly, group B patients under loose dietary control had significantly elevated Adpn concentrations compared with groups A and C and increased tumor necrosis factor alpha and an unfavorable lipid profile, but normal levels of homocysteine. These data support the hypothesis that catecholamines inhibit Adpn secretion and that the elevated Adpn of the poorly controlled patients might moderate their risk for endothelial dysfunction and atherogenesis. Homocysteine production appears to be unfavorably affected by a strict PKU diet, diverging from the rest of the atherogenesis risk factors, which were improved in the well-controlled patients.

Lumbar Puncture and Dural Sinus Thrombosis – A Causal or Casual Association?

BACKGROUND

A few cases of cerebral venous thrombosis (CVT) were reported after a lumbar puncture (LP), suggesting a causal association. The purpose of our study was to document that LP might predispose to CVT by decreasing blood flow velocities (BFV) in veins or dural sinus.

METHODS

We performed a transcranial Doppler ultrasound study to register the mean BFV of the straight sinus (SS) before, during and after LP.

RESULTS

Thirteen patients were studied. LP induced a decrease of 47% of mean BFV in the SS. The mean decrease of BFV was significant immediately at the end (p = 0.003), 30 min after (p = 0.015) and more than 6 h after LP (p = 0.008).

CONCLUSIONS

LP induced a sustained decrease of mean BFV in the SS. The decrease of venous blood flow is a possible mechanism contributing to the occurrence of CVT.

Association of anticardiolipin antibody and C677T in methylenetetrahydrofolate reductase mutation in women with recurrent spontaneous abortions: a new path to thrombophilia?

CONTEXT

Recurrent spontaneous abortion (RSA) has been associated with venous thrombosis in the mother. Acquired and inherited thrombophilia factors are possible causes.

OBJECTIVE

To evaluate the association between thrombogenic factors and recurrent spontaneous abortion.

TYPE OF STUDY

Case-control study.

SETTING

Centro de Atenção Integral à Saúde da Mulher, Universidade Estadual de Campinas.

METHODS

40 ml of blood was collected from 88 women attending an RSA clinic and 88 fertile women attending a family planning clinic, to evaluate the presence of acquired and inherited thrombophilia factors. Anticardiolipin antibodies (ACA), lupus anticoagulant and deficiencies of proteins C and S and antithrombin III were evaluated by enzyme-linked immunosorbent assay (ELISA), dilute Russell Viper Venom time (dRVVT), coagulometric and chromogenic methods. DNA was amplified by the polymerase chain reaction (PCR) to study factor V Leiden and G20210A mutations in the prothrombin gene and C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene. Data were analyzed using odds ratios and a regression model for age adjustment. Fishers exact test was used to evaluate statistical relationships between associated factors and RSA.

RESULTS

ACA was detected in 11 women with RSA and one fertile woman. Heterozygous C677T was detected in 59 women with RSA and 35 fertile women. Concomitant presence of ACA and C677T was found in eight women with RSA and no fertile women (p < 0.01).

DISCUSSION

The meaning of the association between C677T mutation in the MTHFR gene and ACA is still not clear. It is possible that an inherited factor that alone would not strongly predispose a woman to thrombosis could, when associated with an acquired factor, start the process and increase the likelihood of thrombosis expression.

CONCLUSIONS

ACA and C677T in the MTHFR gene are statistically associated with RSA. The association of these two conditions is a new finding in thrombogenic factors and RSA.

Asymptomatic carriership of factor V Leiden and genotypes of the fibrinogen gene cluster

We investigated the role of frequent fibrinogen polymorphisms in venous thromboembolic disease in conjunction with inherited thrombophilia. Two hundred unrelated subjects, all carriers of the factor V R506Q mutation (FV Leiden), were genotyped at the fibrinogen gene cluster. Among these subjects, 100 had experienced previous venous thromboembolism (VTE) and 100 were still asymptomatic for VTE. Significant differences were observed between the groups for the BclI polymorphism (P = 0.004). Scanning, by sequencing the DNA regions flanking the BclI marker, revealed new polymorphisms, a C to T transition and a G to T transversion at 1520 and 3369 base pairs 3' to the beta gene stop codon respectively. These markers showed less association with the clinical phenotype than BclI itself. A combined genotype including 10 markers was more frequent among the asymptomatic subjects (17%) than among patients (3%), and was associated with a reduction in fibrinogen antigen level (2.42 +/- 0.35 vs 2.69 +/- 0.41 g/l, P = 0.028) among the asymptomatic subjects. Our data suggest that, in the presence of inherited thrombophilia, frequent fibrinogen polymorphisms may interact to modulate the risk of venous thromboembolism.

Thrombophilic genotypes, natural anticoagulants, and plasma homocysteine in myeloproliferative disorders: relationship with splanchnic vein thrombosis and arterial disease

The contribution of pro-thrombotic factors towards the development of arterial disease (AD) and splanchnic vein thrombosis (SVT) was retrospectively evaluated in 79 patients (39M, 40F, mean age 55 +/- 16 years) with myeloproliferative disorders (MPD) (essential thrombocythemia [n = 26], primary proliferative polycythemia [n = 27], and idiopathic myelofibrosis [n = 26]). Of these, 18 had AD and 17 SVT, the remaining 44 were non-thrombotic (NT). Plasma concentrations of natural anticoagulants, plasma homocysteine (HC), IgG anticardiolipin antibodies (aCL), and thrombophilic genotypes (methylenetetrahydrofolate reductase C(677)T, factor V Leiden, prothrombin G(20210)-->A) were determined. Isolated protein C deficiency was found in 23% of patients from the SVT group, in 5% from the AD group, in 6.8% from the NT group, and in 1% of historical controls (P = 0.0001). The prevalence of thrombophilic genotypes and that of the other natural anticoagulants did not differ across the groups. The proportion of patients with elevated plasma HC was 66% in the AD group, 27% in the non-thrombotic group, 12% in the SVT group and 4.5% in the control group (P < 0.0001). Patients with AD had higher plasma HC (24.4 +/- 23 micromol/L) than NT patients (12.3 +/- 7.7 micromol/L), SVT patients (9 +/- 4.9 micromol/L), and healthy controls (7.9 +/- 3 micromol/L) (P < 0.0001). In a logistic regression model lower protein C was independently associated with SVT, whereas elevated plasma HC was independently associated with AD. Measurement of plasma HC and protein C in MPD may identify patients more likely to suffer arterial disease and splanchnic vein thrombosis and who may require plasma HC lowering in the former case.

Emergent cardiovascular risk factor: homocysteine

Homocysteine is an independent, modifiable risk factor for cardiovascular disease. It is an intermediate amino acid formed during the metabolism of methionine. Plasma homocysteine is normally < or = 12 micromol/L, but when elevated has many deleterious cardiovascular effects. This review explains homocysteine metabolism, the effects of elevated homocysteine, factors contributing to high homocysteine, and its measurement. Risk factors for elevated homocysteine and intervention with B vitamins are discussed. Cardiovascular nurses are encouraged to facilitate homocysteine awareness through a variety of educational means.

Multiple thrombophilic factors in a patient with Budd-Chiari syndrome

Myeloproliferative disorders are the main cause of Budd-Chiari syndrome in western countries. Inherited or acquired thrombophilic factors have also been implicated. A novel mutation of the prothrombin gene (G-->A20210) has only been described in a few cases of Budd-Chiari syndrome so far. Venous thrombosis is often the result of multiple concomitant thrombophilic factors. We report the case of a patient with essential thrombocythemia and Budd-Chiari syndrome in which heterozygosity for both factor V Leiden and the mutation G20210A of the prothrombin gene were identified.

High prevalence of thrombophilic genotypes in patients with acute mesenteric vein thrombosis

OBJECTIVES

Mesenteric vein thrombosis is a rare but severe abdominal emergency, often requiring intestinal resection. New genetic prothrombotic defects such as factor V Leiden, the prothrombin transition G20210A, and the methylenetetrahydrofolate reductase TT677 genotype have been described in association with venous thrombosis. Our goal was to assess prevalence and clinical significance of genetic thrombophilia in mesenteric vein thrombosis.

METHODS

Twelve patients with acute mesenteric vein thrombosis were compared with 431 healthy people from the same geographical area. The factor V Leiden, the prothrombin transition G20210A, and the methylenetetrahydrofolate reductase TT677 genotype were identified by polymerase chain reaction and restriction analysis.

RESULTS

A thrombophilic genotype was present in 9 patients (75%): the methylenetetrahydrofolate reductase TT677 genotype was present in 6 (50%), the factor V Leiden in 3 (25%), and the prothrombin transition G20210A in 3 (25%). Combined mutations were present in 4 (33%) patients.

CONCLUSIONS

The factor V Leiden, the prothrombin transition G20210A, and the methylenetetrahydrofolate reductase TT677 genotype are important predisposing factors in the pathogenesis of mesenteric vein thrombosis. Their identification bears strong clinical implications for management of patients with mesenteric vein thrombosis.

Elevated plasma homocysteine levels in patients on isotretinoin therapy for cystic acne

BACKGROUND

The use of Isotretinoin (Iso) for cystic acne (CA) therapy includes marked side-effects such as dyslipidemia, increased liver enzymes, and reduction of biotinidase activity. Moreover, Homocysteine (Hcy), an amino acid, is metabolized in the liver requiring folate, vitamin B6, vitamin B12, and the activity of enzymes, i.e. cystathionine-beta-synthase. Increased blood levels of Hcy are associated with premature occlusive vascular disease.

OBJECTIVE

The aim of this study was the evaluation of Hcy levels and the responsible vitamins for its metabolism in patients with CA on Iso treatment.

METHODS AND RESULTS

Twenty-eight patients with CA were submitted to laboratory examinations before (Value 1) and after (Value 2) 45 days on Iso (0.5 mg/kg/24 h) therapy. Blood levels of Hcy and vitamin B6 were evaluated by HPLC methods, and folate and vitamin B12 using a commercial Kit. Hcy levels (Value 1 = 7.86 +/- 1.6 micromol/L; Value 2 = 13.65 +/- 3.3 micromol/L; P < 0.001) were statistically significantly increased in patients on treatment. Vitamins were unaltered, and lipids and liver enzymes increased. Significant correlation between Hcy levels, vitamins, and liver enzymes was found. Methionine loading tests performed in nine patient-volunteers showed an abnormal response post-treatment.

CONCLUSIONS

It is suggested that the elevated Hcy levels in patients after 45 days on Iso therapy could be due either to the 'inhibition' of cystathionine-beta-synthase by the drug and/or their liver dysfunction. Daily vitamin supplementation along with frequent evaluations of Hcy blood levels are recommended for the prevention of a premature occlusive vascular disease.