Factor V
Factor V Deficiency
Activated Protein C Resistance
Prothrombin
Factor Va
Thrombophilia
Protein C
Factor VIII
Blood Coagulation
Factor Xa
Hemorrhagic Disorders
Protein S Deficiency
Factor X
Protein S
Point Mutation
Pregnancy Complications, Hematologic
Partial Thromboplastin Time
Prothrombin Time
Blood Coagulation Factors
Blood Coagulation Disorders
Thromboembolism
Blood Coagulation Factor Inhibitors
Heterozygote
Methylenetetrahydrofolate Reductase (NADPH2)
Thromboplastin
Mutation
Plasma
Oxidoreductases Acting on CH-NH Group Donors
Evidence suggesting the regulation of a coagulation factor levels in rabbits by a transferable plasma agent. (1/888)
New Zealand white rabbits were given 30 ml of goat serum intravenously. This procedure resulted in an immediate decrease in platelet count, fibrinogen, and levels of coagulation factors II, V, VII, and X, due to consumption coagulopathy. These factors returned toward baseline levels approximately 12 hr after the injection. Plasma from rabbits who had received goat serum 48 hr previously (donor rabbits) was injected into recipient rabbits. This procedure resulted in a slight rise in the level of coagulation factor II (range, 20%-30%) and a significant rise in factors V (35%-75%), VII (35%-235%), and X (35%-75%) in the recipients. When plasma from control donor rabbits who had not received goat serum was injected into recipients, there was no change in these coagulation factors. It is postulated that the reduction in coagulation factor levels in donor rabbits induces a "coagulopoietin" for each factor or one "coagulopoietin" for all factors which stimulates increased synthesis and/or release of these factors in recipient rabbits. (+info)Prospective evaluation of the thrombotic risk in children with acute lymphoblastic leukemia carrying the MTHFR TT 677 genotype, the prothrombin G20210A variant, and further prothrombotic risk factors. (2/888)
The reported incidence of thromboembolism in children with acute lymphoblastic leukemia (ALL) treated with L-asparaginase, vincristine, and prednisone varies from 2.4% to 11.5%. The present study was designed to prospectively evaluate the role of the TT677 methylenetetrahydrofolate reductase (MTHFR) genotype, the prothrombin G20210A mutation, the factor V G1691A mutation, deficiencies of protein C, protein S, antithrombin, and increased lipoprotein (a) concentrations in leukemic children treated according to the ALL-Berlin-Frankfurt-Muenster (BFM) 90/95 study protocols with respect to the onset of vascular events. Three hundred and one consecutive leukemic children were enrolled in this study. Fifty-five of these 301 subjects investigated had one established single prothrombotic risk factor: 20 children showed the TT677 MTHFR genotype; 5 showed the heterozygous prothrombin G20210A variant; 11 were carriers of the factor V G1691A mutation (heterozygous, n = 10; homozygous, n = 1); 4 showed familial protein C, 4 protein S, and 2 antithrombin type I deficiency; 9 patients were suffering from familially increased lipoprotein (a) [Lp(a)] concentrations (>30 mg/dL). In addition, combined prothrombotic defects were found in a further 10 patients: the FV mutation was combined with the prothrombin G20210A variant (n = 1), increased Lp(a) (n = 3), protein C deficiency (n = 1), and homozygosity for the C677T MTHFR gene mutation (n = 1). Lp(a) was combined with protein C deficiency (n = 2) and the MTHFR TT 677 genotype (n = 2). Two hundred eighty-nine of the 301 patients were available for thrombosis-free survival analysis. In 32 (11%) of these 289 patients venous thromboembolism occurred. The overall thrombosis-free survival in patients with at least one prothrombotic defect was significantly reduced compared with patients without a prothrombotic defect within the hemostatic system (P <.0001). In addition, a clear-cut positive correlation (P <.0001) was found between thrombosis and the use of central lines. However, because the prothrombotic defects diagnosed in the total childhood population studied were all found within the prevalences reported for healthy Caucasian individuals, the interaction between prothrombotic risk factors, ALL treatment, and further environmental factors is likely to cause thrombotic manifestations. (+info)G20210A mutation in prothrombin gene and risk of myocardial infarction, stroke, and venous thrombosis in a large cohort of US men. (3/888)
BACKGROUND: A single base pair mutation in the prothrombin gene has recently been identified that is associated with increased prothrombin levels. Whether this mutation increases the risks of arterial and venous thrombosis among healthy individuals is controversial. METHODS AND RESULTS: In a prospective cohort of 14 916 men, we determined the prevalence of the G20210A prothrombin gene variant in 833 men who subsequently developed myocardial infarction, stroke, or venous thrombosis (cases) and in 1774 age- and smoking status-matched men who remained free of thrombosis during a 10-year follow-up (control subjects). Gene sequencing was used to confirm mutation status in a subgroup of participants. Overall, carrier rates for the G20210A mutation were similar among case and control subjects; the relative risk of developing any thrombotic event in association with the 20210A allele was 1.05 (95% CI, 0.7 to 1.6; P=0.8). We observed no evidence of association between mutation and myocardial infarction (RR=0.8, P=0.4) or stroke (RR=1.1, P=0.8). For venous thrombosis, a modest nonsignificant increase in risk was observed (RR=1.7, P=0.08) that was smaller in magnitude than that associated with factor V Leiden (RR=3.0, P<0. 001). Nine individuals carried both the prothrombin mutation and factor V Leiden (5 controls and 4 cases). One individual, a control subject, was homozygous for the prothrombin mutation. CONCLUSIONS: In a large cohort of US men, the G20210A prothrombin gene variant was not associated with increased risk of myocardial infarction or stroke. For venous thrombosis, risk estimates associated with the G20210A mutation were smaller in magnitude than risk estimates associated with factor V Leiden. (+info)Single and combined prothrombotic factors in patients with idiopathic venous thromboembolism: prevalence and risk assessment. (4/888)
The inherited thrombophilias--deficiencies of protein C, protein S, and antithrombin III--and the prothrombotic polymorphisms factor V G1691A and factor II G20210A predispose patients toward venous thromboembolism (VTE). The aim of this study was to determine the prevalence of single and combined prothrombotic factors in patients with idiopathic VTE and to estimate the associated risks. The study group consisted of 162 patients referred for work-up of thrombophilia after documented VTE. The controls were 336 consecutively admitted patients. In all subjects factor V G1691A, factor II G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T were analyzed by specific polymerase chain reactions and restriction enzymes. Activities of antithrombin III and protein C, free protein S antigen, and lupus anticoagulant were determined in a subset of 109 patients who were not receiving oral anticoagulants. The prevalences of heterozygotes and homozygotes for factor V G1691A and factor II G20210A among patients and controls were 40.1% versus 3.9% and 18.5% versus 5.4%, respectively (P=0.0001). The prevalence of homozygotes for MTHFR C677T in patients was 22.8% and in controls, 14.3% (P=0.025). Heterozygous and homozygous factor V G1691A, factor II G20210A, and homozygous MTHFR C677T were found to be independent risk factors for VTE, with odds ratios of 16.3, 3.6, and 2.1, respectively. Two or more polymorphisms were detected in 27 of 162 patients (16.7%) and in 3 of 336 controls (0.9%). Logistic regression analysis disclosed odds ratios of 58.6 (confidence interval [CI], 22.1 to 155.2) for joint occurrence of factor V and factor II polymorphisms, of 35.0 (CI, 14.5 to 84.7) for factor V and MTHFR polymorphisms, and of 7.7 (CI, 3.0 to 19.6) for factor II and MTHFR polymorphisms. Among 109 patients in whom a complete thrombophilic work-up was performed, 74% had at least 1 underlying defect. These data indicate that in most patients referred for evaluation of thrombophilia due to idiopathic VTE, 1 or more underlying genetic predispositions were discernible. The presence of >1 of the prothrombotic polymorphisms was associated with a substantial risk of VTE. (+info)Interaction between the G20210A mutation of the prothrombin gene and oral contraceptive use in deep vein thrombosis. (5/888)
Single-point mutations in the gene coding for prothrombin (factor II:A20210) or factor V (factor V:A1691) are associated with an increased risk of venous thromboembolism. The use of oral contraceptives is also a strong and independent risk factor for the disease, and the interaction between factor V:A1691 and oral contraceptives greatly increases the risk. No information is available about the interaction between oral contraceptives and mutant prothrombin. We investigated 148 women with a first, objectively confirmed episode of deep vein thrombosis and 277 healthy women as controls. Fourteen patients (9.4%) were carriers of factor II:A20210, 24 (16.2%) of factor V:A1691, and 4 (2.7%) of both defects. Among controls, the prevalence was 2.5% for either factor II:A20210 or factor V:A1691, and there was no carrier of both the mutations. The relative risk of thrombosis was 6-fold for factor II:A20210 and 9-fold for factor V:A1691. The most prevalent circumstantial risk factor in patients and the only one observed in controls was oral contraceptive use, which per se conferred a 6-fold increased risk of thrombosis. The risk increased to 16.3 and 20.0 when women with factor II:A20210 or factor V:A1691 who used oral contraceptives were compared with noncarriers and nonusers. These figures indicate a multiplicative interaction between the genetic risk factors and oral contraceptives. No difference in the type of oral contraceptives was observed between patients and controls, those of third generation being the most frequently used (73% and 80%). We conclude that carriers of the prothrombin mutation who use oral contraceptives have a markedly increased risk of deep vein thrombosis, much higher than the risk conferred by either factor alone. (+info)Synergistic effects of prothrombotic polymorphisms and atherogenic factors on the risk of myocardial infarction in young males. (6/888)
Several recent studies evaluated a possible effect of the prothrombotic polymorphisms such as 5,10 methylenetetrahydrofolate reductase (MTHFR) nt 677C --> T, factor V (F V) nt 1691G --> A (F V Leiden), and factor II (F II) nt 20210 G --> A on the risk of myocardial infarction. In the present study, we analyzed the effect of these prothrombotic polymorphisms, as well as apolipoprotein (Apo) E4, smoking, hypertension, diabetes mellitus, and hypercholesterolemia, on the risk of myocardial infarction in young males. We conducted a case-control study of 112 young males with first acute myocardial infarction (AMI) before the age of 52 and 187 healthy controls of similar age. The prevalences of heterozygotes for F V G1691A and F II G20210A were not significantly different between cases and controls (6.3% v 6.4% and 5.9% v 3.4% among cases and controls, respectively). In contrast, the prevalence of MTHFR 677T homozygosity and the allele frequency of Apo E4 were significantly higher among patients (24.1% v 10.7% and 9.4% v 5.3% among cases and controls, respectively). Concomitant presence of hypertension, hypercholesterolemia, or diabetes and one or more of the four examined polymorphisms increased the risk by almost ninefold (odds ratio [OR] = 8.66; 95% confidence interval [CI], 3.49 to 21.5) and concomitant smoking by almost 18-fold (OR = 17.6; 95% CI, 6.30 to 48.9). When all atherogenic risk factors were analyzed simultaneously by a logistic model, the combination of prothrombotic and Apo E4 polymorphisms with current smoking increased the risk 25-fold (OR = 24.7; 95% CI, 7.17 to 84.9). The presented data suggest a synergistic effect between atherogenic and thrombogenic risk factors in the pathogenesis of AMI, as was recently found in a similar cohort of women. (+info)Thrombophilia as a multigenic disease. (7/888)
BACKGROUND AND OBJECTIVE: Venous thrombosis is a common disease annually affecting 1 in 1000 individuals. The multifactorial nature of the disease is illustrated by the frequent identification of one or more predisposing genetic and/or environmental risk factors in thrombosis patients. Most of the genetic defects known today affect the function of the natural anticoagulant pathways and in particular the protein C system. This presentation focuses on the importance of the genetic factors in the pathogenesis of inherited thrombophilia with particular emphasis on those defects which affect the protein C system. INFORMATION SOURCES: Published results in articles covered by the Medline database have been integrated with our original studies in the field of thrombophilia. STATE OF THE ART AND PERSPECTIVES: The risk of venous thrombosis is increased when the hemostatic balance between pro- and anti-coagulant forces is shifted in favor of coagulation. When this is caused by an inherited defect, the resulting hypercoagulable state is a lifelong risk factor for thrombosis. Resistance to activated protein C (APC resistance) is the most common inherited hypercoagulable state found to be associated with venous thrombosis. It is caused by a single point mutation in the factor V (FV) gene, which predicts the substitution of Arg506 with a Gln. Arg506 is one of three APC-cleavage sites and the mutation results in the loss of this APC-cleavage site. The mutation is only found in Caucasians but the prevalence of the mutant FV allele (FV:Q506) varies between countries. It is found to be highly prevalent (up to 15%) in Scandinavian populations, in areas with high incidence of thrombosis. FV:Q506 is associated with a 5-10-fold increased risk of thrombosis and is found in 20-60% of Caucasian patients with thrombosis. The second most common inherited risk factor for thrombosis is a point mutation (G20210A) in the 3' untranslated region of the prothrombin gene. This mutation is present in approximately 2% of healthy individuals and in 6-7% of thrombosis patients, suggesting it to be a mild risk factor of thrombosis. Other less common genetic risk factors for thrombosis are the deficiencies of natural anticoagulant proteins such as antithrombin, protein C or protein S. Such defects are present in less than 1% of healthy individuals and together they account for 5-10% of genetic defects found in patients with venous thrombosis. Owing to the high prevalence of inherited APC resistance (FV:Q506) and of the G20210A mutation in the prothrombin gene, combinations of genetic defects are relatively common in the general population. As each genetic defect is an independent risk factor for thrombosis, individuals with multiple defects have a highly increased risk of thrombosis. As a consequence, multiple defects are often found in patients with thrombosis. (+info)Factor V Leiden and antibodies against phospholipids and protein S in a young woman with recurrent thromboses and abortion. (8/888)
We describe the case of a 39-year-old woman who suffered two iliofemoral venous thromboses, a cerebral ischemic infarct and recurrent fetal loss. Initial studies showed high levels of antiphospholipid antibodies (APAs) and a moderate thrombocytopenia. After her second miscarriage, laboratory diagnosis revealed that the woman was heterozygous for the factor V Leiden mutation and had a functional protein S deficiency as well as anti-protein S and anti-beta 2-glycoprotein I antibodies. The impairment of the protein C pathway at various points could well explain the recurrent thromboses in the patient and supports the role of a disturbed protein C system in the pathophysiology of thrombosis in patients with APAs. (+info)Factor V, also known as proaccelerin or labile factor, is a protein involved in the coagulation cascade, which is a series of chemical reactions that leads to the formation of a blood clot. Factor V acts as a cofactor for the activation of Factor X to Factor Xa, which is a critical step in the coagulation cascade.
When blood vessels are damaged, the coagulation cascade is initiated to prevent excessive bleeding. During this process, Factor V is activated by thrombin, another protein involved in coagulation, and then forms a complex with activated Factor X and calcium ions on the surface of platelets or other cells. This complex converts prothrombin to thrombin, which then converts fibrinogen to fibrin to form a stable clot.
Deficiency or dysfunction of Factor V can lead to bleeding disorders such as hemophilia B or factor V deficiency, while mutations in the gene encoding Factor V can increase the risk of thrombosis, as seen in the Factor V Leiden mutation.
Factor V deficiency is a rare bleeding disorder that is caused by a mutation in the gene that produces coagulation factor V, a protein involved in the clotting process. This condition can lead to excessive bleeding following injury or surgery, and may also cause menorrhagia (heavy menstrual periods) in women.
Factor V deficiency is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene (one from each parent) in order to develop the condition. People who inherit only one copy of the mutated gene are carriers and may have a milder form of the disorder or no symptoms at all.
Treatment for factor V deficiency typically involves replacement therapy with fresh frozen plasma or clotting factor concentrates, which can help to reduce bleeding episodes and prevent complications. In some cases, medications such as desmopressin or antifibrinolytics may also be used to manage the condition.
Activated Protein C (APC) resistance is a condition in which the body's natural anticoagulant system is impaired, leading to an increased risk of thrombosis or blood clot formation. APC is an enzyme that plays a crucial role in regulating blood coagulation by inactivating clotting factors Va and VIIIa.
APC resistance is most commonly caused by a genetic mutation in the Factor V gene, known as Factor V Leiden. This mutation results in the production of a variant form of Factor V called Factor V Leiden, which is resistant to APC-mediated inactivation. As a result, the body's ability to regulate blood clotting is impaired, leading to an increased risk of thrombosis.
APC resistance can be measured by performing a functional assay that compares the activity of APC in normal plasma versus plasma from a patient with suspected APC resistance. The assay measures the rate of inactivation of Factor Va by APC, and a reduced rate of inactivation indicates APC resistance.
It is important to note that not all individuals with APC resistance will develop thrombosis, and other factors such as age, obesity, pregnancy, oral contraceptive use, and smoking can increase the risk of thrombosis in individuals with APC resistance.
Prothrombin is a protein present in blood plasma, and it's also known as coagulation factor II. It plays a crucial role in the coagulation cascade, which is a complex series of reactions that leads to the formation of a blood clot.
When an injury occurs, the coagulation cascade is initiated to prevent excessive blood loss. Prothrombin is converted into its active form, thrombin, by another factor called factor Xa in the presence of calcium ions, phospholipids, and factor Va. Thrombin then catalyzes the conversion of fibrinogen into fibrin, forming a stable clot.
Prothrombin levels can be measured through a blood test, which is often used to diagnose or monitor conditions related to bleeding or coagulation disorders, such as liver disease or vitamin K deficiency.
Factor V, also known as proaccelerin or labile factor, is a protein involved in the coagulation cascade, which is a series of chemical reactions that leads to the formation of a blood clot. Factor V acts as a cofactor for the conversion of prothrombin to thrombin, which is a critical step in the coagulation process.
Inherited deficiencies or abnormalities in Factor V can lead to bleeding disorders. For example, Factor V Leiden is a genetic mutation that causes an increased risk of blood clots, while Factor V deficiency can cause a bleeding disorder.
It's worth noting that "Factor Va" is not a standard medical term. Factor V becomes activated and turns into Factor Va during the coagulation cascade. Therefore, it is possible that you are looking for the definition of "Factor Va" in the context of its role as an activated form of Factor V in the coagulation process.
Thrombophilia is a medical condition characterized by an increased tendency to form blood clots (thrombi) due to various genetic or acquired abnormalities in the coagulation system. These abnormalities can lead to a hypercoagulable state, which can cause thrombosis in both veins and arteries. Commonly identified thrombophilias include factor V Leiden mutation, prothrombin G20210A mutation, antithrombin deficiency, protein C deficiency, and protein S deficiency.
Acquired thrombophilias can be caused by various factors such as antiphospholipid antibody syndrome (APS), malignancies, pregnancy, oral contraceptive use, hormone replacement therapy, and certain medical conditions like inflammatory bowel disease or nephrotic syndrome.
It is essential to diagnose thrombophilia accurately, as it may influence the management of venous thromboembolism (VTE) events and guide decisions regarding prophylactic anticoagulation in high-risk situations.
Protein C is a vitamin K-dependent protease that functions as an important regulator of coagulation and inflammation. It is a plasma protein produced in the liver that, when activated, degrades clotting factors Va and VIIIa to limit thrombus formation and prevent excessive blood clotting. Protein C also has anti-inflammatory properties by inhibiting the release of pro-inflammatory cytokines and reducing endothelial cell activation. Inherited or acquired deficiencies in Protein C can lead to an increased risk of thrombosis, a condition characterized by abnormal blood clot formation within blood vessels.
Thrombin is a serine protease enzyme that plays a crucial role in the coagulation cascade, which is a complex series of biochemical reactions that leads to the formation of a blood clot (thrombus) to prevent excessive bleeding during an injury. Thrombin is formed from its precursor protein, prothrombin, through a process called activation, which involves cleavage by another enzyme called factor Xa.
Once activated, thrombin converts fibrinogen, a soluble plasma protein, into fibrin, an insoluble protein that forms the structural framework of a blood clot. Thrombin also activates other components of the coagulation cascade, such as factor XIII, which crosslinks and stabilizes the fibrin network, and platelets, which contribute to the formation and growth of the clot.
Thrombin has several regulatory mechanisms that control its activity, including feedback inhibition by antithrombin III, a plasma protein that inactivates thrombin and other serine proteases, and tissue factor pathway inhibitor (TFPI), which inhibits the activation of factor Xa, thereby preventing further thrombin formation.
Overall, thrombin is an essential enzyme in hemostasis, the process that maintains the balance between bleeding and clotting in the body. However, excessive or uncontrolled thrombin activity can lead to pathological conditions such as thrombosis, atherosclerosis, and disseminated intravascular coagulation (DIC).
Factor VIII is a protein in the blood that is essential for normal blood clotting. It is also known as antihemophilic factor (AHF). Deficiency or dysfunction of this protein results in hemophilia A, a genetic disorder characterized by prolonged bleeding and easy bruising. Factor VIII works together with other proteins to help form a clot and stop bleeding at the site of an injury. It acts as a cofactor for another clotting factor, IX, in the so-called intrinsic pathway of blood coagulation. Intravenous infusions of Factor VIII concentrate are used to treat and prevent bleeding episodes in people with hemophilia A.
Blood coagulation, also known as blood clotting, is a complex process that occurs in the body to prevent excessive bleeding when a blood vessel is damaged. This process involves several different proteins and chemical reactions that ultimately lead to the formation of a clot.
The coagulation cascade is initiated when blood comes into contact with tissue factor, which is exposed after damage to the blood vessel wall. This triggers a series of enzymatic reactions that activate clotting factors, leading to the formation of a fibrin clot. Fibrin is a protein that forms a mesh-like structure that traps platelets and red blood cells to form a stable clot.
Once the bleeding has stopped, the coagulation process is regulated and inhibited to prevent excessive clotting. The fibrinolytic system degrades the clot over time, allowing for the restoration of normal blood flow.
Abnormalities in the blood coagulation process can lead to bleeding disorders or thrombotic disorders such as deep vein thrombosis and pulmonary embolism.
Factor Xa is a serine protease that plays a crucial role in the coagulation cascade, which is a series of reactions that lead to the formation of a blood clot. It is one of the activated forms of Factor X, a pro-protein that is converted to Factor Xa through the action of other enzymes in the coagulation cascade.
Factor Xa functions as a key component of the prothrombinase complex, which also includes calcium ions, phospholipids, and activated Factor V (also known as Activated Protein C or APC). This complex is responsible for converting prothrombin to thrombin, which then converts fibrinogen to fibrin, forming a stable clot.
Inhibitors of Factor Xa are used as anticoagulants in the prevention and treatment of thromboembolic disorders such as deep vein thrombosis and pulmonary embolism. These drugs work by selectively inhibiting Factor Xa, thereby preventing the formation of the prothrombinase complex and reducing the risk of clot formation.
Hemorrhagic disorders are medical conditions characterized by abnormal bleeding due to impaired blood clotting. This can result from deficiencies in coagulation factors, platelet dysfunction, or the use of medications that interfere with normal clotting processes. Examples include hemophilia, von Willebrand disease, and disseminated intravascular coagulation (DIC). Treatment often involves replacing the missing clotting factor or administering medications to help control bleeding.
Protein S deficiency is a genetic disorder that affects the body's ability to coagulate blood properly. Protein S is a naturally occurring protein in the blood that helps regulate the clotting process by deactivating clotting factors when they are no longer needed. When Protein S levels are too low, it can lead to an increased risk of abnormal blood clots forming within blood vessels, a condition known as thrombophilia.
There are three types of Protein S deficiency: Type I (quantitative deficiency), Type II (qualitative deficiency), and Type III (dysfunctional protein). These types refer to the amount or function of Protein S in the blood. In Type I, there is a decrease in both free and total Protein S levels. In Type II, there is a decrease in functional Protein S despite normal total Protein S levels. In Type III, there is a decrease in free Protein S with normal total Protein S levels.
Protein S deficiency can be inherited or acquired. Inherited forms of the disorder are caused by genetic mutations and are usually present from birth. Acquired forms of Protein S deficiency can develop later in life due to certain medical conditions, such as liver disease, vitamin K deficiency, or the use of certain medications that affect blood clotting.
Symptoms of Protein S deficiency may include recurrent blood clots, usually in the legs (deep vein thrombosis) or lungs (pulmonary embolism), skin discoloration, pain, and swelling in the affected area. In severe cases, it can lead to complications such as chronic leg ulcers, pulmonary hypertension, or damage to the heart or lungs.
Diagnosis of Protein S deficiency typically involves blood tests to measure Protein S levels and function. Treatment may include anticoagulant medications to prevent blood clots from forming or growing larger. Lifestyle modifications such as regular exercise, maintaining a healthy weight, and avoiding smoking can also help reduce the risk of blood clots in people with Protein S deficiency.
Factor X is a protein that is essential for blood clotting, also known as coagulation. It is an enzyme that plays a crucial role in the coagulation cascade, which is a series of chemical reactions that lead to the formation of a blood clot. Factor X is activated by one of two pathways: the intrinsic pathway, which is initiated by damage to the blood vessels, or the extrinsic pathway, which is triggered by the release of tissue factor from damaged cells. Once activated, Factor X converts prothrombin to thrombin, which then converts fibrinogen to fibrin to form a stable clot.
Inherited deficiencies in Factor X can lead to bleeding disorders, while increased levels of Factor X have been associated with an increased risk of thrombosis or blood clots. Therefore, maintaining appropriate levels of Factor X is important for the proper balance between bleeding and clotting in the body.
Blood coagulation tests, also known as coagulation studies or clotting tests, are a series of medical tests used to evaluate the blood's ability to clot. These tests measure the functioning of various clotting factors and regulatory proteins involved in the coagulation cascade, which is a complex process that leads to the formation of a blood clot to prevent excessive bleeding.
The most commonly performed coagulation tests include:
1. Prothrombin Time (PT): Measures the time it takes for a sample of plasma to clot after the addition of calcium and tissue factor, which activates the extrinsic pathway of coagulation. The PT is reported in seconds and can be converted to an International Normalized Ratio (INR) to monitor anticoagulant therapy.
2. Activated Partial Thromboplastin Time (aPTT): Measures the time it takes for a sample of plasma to clot after the addition of calcium, phospholipid, and a contact activator, which activates the intrinsic pathway of coagulation. The aPTT is reported in seconds and is used to monitor heparin therapy.
3. Thrombin Time (TT): Measures the time it takes for a sample of plasma to clot after the addition of thrombin, which directly converts fibrinogen to fibrin. The TT is reported in seconds and can be used to detect the presence of fibrin degradation products or abnormalities in fibrinogen function.
4. Fibrinogen Level: Measures the amount of fibrinogen, a protein involved in clot formation, present in the blood. The level is reported in grams per liter (g/L) and can be used to assess bleeding risk or the effectiveness of fibrinogen replacement therapy.
5. D-dimer Level: Measures the amount of D-dimer, a protein fragment produced during the breakdown of a blood clot, present in the blood. The level is reported in micrograms per milliliter (µg/mL) and can be used to diagnose or exclude venous thromboembolism (VTE), such as deep vein thrombosis (DVT) or pulmonary embolism (PE).
These tests are important for the diagnosis, management, and monitoring of various bleeding and clotting disorders. They can help identify the underlying cause of abnormal bleeding or clotting, guide appropriate treatment decisions, and monitor the effectiveness of therapy. It is essential to interpret these test results in conjunction with a patient's clinical presentation and medical history.
Protein S is a vitamin K-dependent protein found in the blood that functions as a natural anticoagulant. It plays a crucial role in regulating the body's clotting system by inhibiting the activation of coagulation factors, thereby preventing excessive blood clotting. Protein S also acts as a cofactor for activated protein C, which is another important anticoagulant protein.
Protein S exists in two forms: free and bound to a protein called C4b-binding protein (C4BP). Only the free form of Protein S has biological activity in inhibiting coagulation. Inherited or acquired deficiencies in Protein S can lead to an increased risk of thrombosis, or abnormal blood clot formation, which can cause various medical conditions such as deep vein thrombosis (DVT) and pulmonary embolism (PE). Regular monitoring of Protein S levels is essential for patients with a history of thrombotic events or those who have a family history of thrombophilia.
A point mutation is a type of genetic mutation where a single nucleotide base (A, T, C, or G) in DNA is altered, deleted, or substituted with another nucleotide. Point mutations can have various effects on the organism, depending on the location of the mutation and whether it affects the function of any genes. Some point mutations may not have any noticeable effect, while others might lead to changes in the amino acids that make up proteins, potentially causing diseases or altering traits. Point mutations can occur spontaneously due to errors during DNA replication or be inherited from parents.
Thrombophlebitis is a medical condition characterized by the inflammation and clotting of blood in a vein, usually in the legs. The term thrombophlebitis comes from two words: "thrombo" which means blood clot, and "phlebitis" which refers to inflammation of the vein.
The condition can occur in superficial or deep veins. Superficial thrombophlebitis affects the veins just below the skin's surface, while deep vein thrombophlebitis (DVT) occurs in the deeper veins. DVT is a more serious condition as it can lead to complications such as pulmonary embolism if the blood clot breaks off and travels to the lungs.
Symptoms of thrombophlebitis may include redness, warmth, pain, swelling, or discomfort in the affected area. In some cases, there may be visible surface veins that are hard, tender, or ropy to touch. If left untreated, thrombophlebitis can lead to chronic venous insufficiency and other long-term complications. Treatment typically involves medications such as anticoagulants, antiplatelet agents, or thrombolytics, along with compression stockings and other supportive measures.
Hematologic pregnancy complications refer to disorders related to the blood and blood-forming tissues that occur during pregnancy. These complications can have serious consequences for both the mother and the fetus if not properly managed. Some common hematologic pregnancy complications include:
1. Anemia: A condition characterized by a decrease in the number of red blood cells or hemoglobin in the blood, which can lead to fatigue, weakness, and shortness of breath. Iron-deficiency anemia is the most common type of anemia during pregnancy.
2. Thrombocytopenia: A condition characterized by a decrease in the number of platelets (cells that help blood clot) in the blood. Mild thrombocytopenia is relatively common during pregnancy, but severe thrombocytopenia can increase the risk of bleeding during delivery.
3. Gestational thrombotic thrombocytopenic purpura (GTTP): A rare but serious disorder that can cause blood clots to form in small blood vessels throughout the body, leading to a decrease in the number of platelets and red blood cells. GTTP can cause serious complications such as stroke, kidney failure, and even death if not promptly diagnosed and treated.
4. Disseminated intravascular coagulation (DIC): A condition characterized by abnormal clotting and bleeding throughout the body. DIC can be triggered by various conditions such as severe infections, pregnancy complications, or cancer.
5. Hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome: A serious complication of pregnancy that can cause damage to the liver and lead to bleeding. HELLP syndrome is often associated with preeclampsia, a condition characterized by high blood pressure and damage to organs such as the liver and kidneys.
It's important for pregnant women to receive regular prenatal care to monitor for these and other potential complications, and to seek prompt medical attention if any concerning symptoms arise.
Partial Thromboplastin Time (PTT) is a medical laboratory test that measures the time it takes for blood to clot. It's more specifically a measure of the intrinsic and common pathways of the coagulation cascade, which are the series of chemical reactions that lead to the formation of a clot.
The test involves adding a partial thromboplastin reagent (an activator of the intrinsic pathway) and calcium to plasma, and then measuring the time it takes for a fibrin clot to form. This is compared to a control sample, and the ratio of the two times is calculated.
The PTT test is often used to help diagnose bleeding disorders or abnormal blood clotting, such as hemophilia or disseminated intravascular coagulation (DIC). It can also be used to monitor the effectiveness of anticoagulant therapy, such as heparin. Prolonged PTT results may indicate a bleeding disorder or an increased risk of bleeding, while shortened PTT results may indicate a hypercoagulable state and an increased risk of thrombosis.
Prothrombin time (PT) is a medical laboratory test that measures the time it takes for blood to clot. It's often used to evaluate the functioning of the extrinsic and common pathways of the coagulation system, which is responsible for blood clotting. Specifically, PT measures how long it takes for prothrombin (a protein produced by the liver) to be converted into thrombin, an enzyme that converts fibrinogen into fibrin and helps form a clot.
Prolonged PT may indicate a bleeding disorder or a deficiency in coagulation factors, such as vitamin K deficiency or the use of anticoagulant medications like warfarin. It's important to note that PT is often reported with an international normalized ratio (INR), which allows for standardization and comparison of results across different laboratories and reagent types.
Blood coagulation factors, also known as clotting factors, are a group of proteins that play a crucial role in the blood coagulation process. They are essential for maintaining hemostasis, which is the body's ability to stop bleeding after injury.
There are 13 known blood coagulation factors, and they are designated by Roman numerals I through XIII. These factors are produced in the liver and are normally present in an inactive form in the blood. When there is an injury to a blood vessel, the coagulation process is initiated, leading to the activation of these factors in a specific order.
The coagulation cascade involves two pathways: the intrinsic and extrinsic pathways. The intrinsic pathway is activated when there is damage to the blood vessel itself, while the extrinsic pathway is activated by tissue factor released from damaged tissues. Both pathways converge at the common pathway, leading to the formation of a fibrin clot.
Blood coagulation factors work together in a complex series of reactions that involve activation, binding, and proteolysis. When one factor is activated, it activates the next factor in the cascade, and so on. This process continues until a stable fibrin clot is formed.
Deficiencies or abnormalities in blood coagulation factors can lead to bleeding disorders such as hemophilia or thrombosis. Hemophilia is a genetic disorder that affects one or more of the coagulation factors, leading to excessive bleeding and difficulty forming clots. Thrombosis, on the other hand, occurs when there is an abnormal formation of blood clots in the blood vessels, which can lead to serious complications such as stroke or pulmonary embolism.
Blood coagulation disorders, also known as bleeding disorders or clotting disorders, refer to a group of medical conditions that affect the body's ability to form blood clots properly. Normally, when a blood vessel is injured, the body's coagulation system works to form a clot to stop the bleeding and promote healing.
In blood coagulation disorders, there can be either an increased tendency to bleed due to problems with the formation of clots (hemorrhagic disorder), or an increased tendency for clots to form inappropriately even without injury, leading to blockages in the blood vessels (thrombotic disorder).
Examples of hemorrhagic disorders include:
1. Hemophilia - a genetic disorder that affects the ability to form clots due to deficiencies in clotting factors VIII or IX.
2. Von Willebrand disease - another genetic disorder caused by a deficiency or abnormality of the von Willebrand factor, which helps platelets stick together to form a clot.
3. Liver diseases - can lead to decreased production of coagulation factors, increasing the risk of bleeding.
4. Disseminated intravascular coagulation (DIC) - a serious condition where clotting and bleeding occur simultaneously due to widespread activation of the coagulation system.
Examples of thrombotic disorders include:
1. Factor V Leiden mutation - a genetic disorder that increases the risk of inappropriate blood clot formation.
2. Antithrombin III deficiency - a genetic disorder that impairs the body's ability to break down clots, increasing the risk of thrombosis.
3. Protein C or S deficiencies - genetic disorders that lead to an increased risk of thrombosis due to impaired regulation of the coagulation system.
4. Antiphospholipid syndrome (APS) - an autoimmune disorder where the body produces antibodies against its own clotting factors, increasing the risk of thrombosis.
Treatment for blood coagulation disorders depends on the specific diagnosis and may include medications to manage bleeding or prevent clots, as well as lifestyle changes and monitoring to reduce the risk of complications.
Thrombosis is the formation of a blood clot (thrombus) inside a blood vessel, obstructing the flow of blood through the circulatory system. When a clot forms in an artery, it can cut off the supply of oxygen and nutrients to the tissues served by that artery, leading to damage or tissue death. If a thrombus forms in the heart, it can cause a heart attack. If a thrombus breaks off and travels through the bloodstream, it can lodge in a smaller vessel, causing blockage and potentially leading to damage in the organ that the vessel supplies. This is known as an embolism.
Thrombosis can occur due to various factors such as injury to the blood vessel wall, abnormalities in blood flow, or changes in the composition of the blood. Certain medical conditions, medications, and lifestyle factors can increase the risk of thrombosis. Treatment typically involves anticoagulant or thrombolytic therapy to dissolve or prevent further growth of the clot, as well as addressing any underlying causes.
Thromboembolism is a medical condition that refers to the obstruction of a blood vessel by a thrombus (blood clot) that has formed elsewhere in the body and then been transported by the bloodstream to a narrower vessel, where it becomes lodged. This process can occur in various parts of the body, leading to different types of thromboembolisms:
1. Deep Vein Thrombosis (DVT): A thrombus forms in the deep veins, usually in the legs or pelvis, and then breaks off and travels to the lungs, causing a pulmonary embolism.
2. Pulmonary Embolism (PE): A thrombus formed elsewhere, often in the deep veins of the legs, dislodges and travels to the lungs, blocking one or more pulmonary arteries. This can lead to shortness of breath, chest pain, and potentially life-threatening complications if not treated promptly.
3. Cerebral Embolism: A thrombus formed in another part of the body, such as the heart or carotid artery, dislodges and travels to the brain, causing a stroke or transient ischemic attack (TIA).
4. Arterial Thromboembolism: A thrombus forms in an artery and breaks off, traveling to another part of the body and blocking blood flow to an organ or tissue, leading to potential damage or loss of function. Examples include mesenteric ischemia (intestinal damage due to blocked blood flow) and retinal artery occlusion (vision loss due to blocked blood flow in the eye).
Prevention, early detection, and appropriate treatment are crucial for managing thromboembolism and reducing the risk of severe complications.
Blood coagulation factor inhibitors are substances that interfere with the normal blood clotting process by inhibiting the function of coagulation factors. These inhibitors can be either naturally occurring or artificially produced.
Naturally occurring coagulation factor inhibitors include antithrombin, protein C, and tissue factor pathway inhibitor (TFPI). These inhibitors play a crucial role in regulating the coagulation cascade and preventing excessive clot formation.
Artificially produced coagulation factor inhibitors are used as therapeutic agents to treat thrombotic disorders. Examples include direct oral anticoagulants (DOACs) such as apixaban, rivaroxaban, and dabigatran, which selectively inhibit specific coagulation factors (factor Xa or thrombin).
Additionally, there are also antibodies that can act as coagulation factor inhibitors. These include autoantibodies that develop in some individuals and cause bleeding disorders such as acquired hemophilia A or antiphospholipid syndrome.
A heterozygote is an individual who has inherited two different alleles (versions) of a particular gene, one from each parent. This means that the individual's genotype for that gene contains both a dominant and a recessive allele. The dominant allele will be expressed phenotypically (outwardly visible), while the recessive allele may or may not have any effect on the individual's observable traits, depending on the specific gene and its function. Heterozygotes are often represented as 'Aa', where 'A' is the dominant allele and 'a' is the recessive allele.
Thromboplastin is a substance that activates the coagulation cascade, leading to the formation of a clot (thrombus). It's primarily found in damaged or injured tissues and blood vessels, as well as in platelets (thrombocytes). There are two types of thromboplastin:
1. Extrinsic thromboplastin (also known as tissue factor): This is a transmembrane glycoprotein that is primarily found in subendothelial cells and released upon injury to the blood vessels. It initiates the extrinsic pathway of coagulation by binding to and activating Factor VII, ultimately leading to the formation of thrombin and fibrin clots.
2. Intrinsic thromboplastin (also known as plasma thromboplastin or factor III): This term is used less frequently and refers to a labile phospholipid component present in platelet membranes, which plays a role in the intrinsic pathway of coagulation.
In clinical settings, the term "thromboplastin" often refers to reagents used in laboratory tests like the prothrombin time (PT) and activated partial thromboplastin time (aPTT). These reagents contain a source of tissue factor and calcium ions to initiate and monitor the coagulation process.
A mutation is a permanent change in the DNA sequence of an organism's genome. Mutations can occur spontaneously or be caused by environmental factors such as exposure to radiation, chemicals, or viruses. They may have various effects on the organism, ranging from benign to harmful, depending on where they occur and whether they alter the function of essential proteins. In some cases, mutations can increase an individual's susceptibility to certain diseases or disorders, while in others, they may confer a survival advantage. Mutations are the driving force behind evolution, as they introduce new genetic variability into populations, which can then be acted upon by natural selection.
In the context of medicine, plasma refers to the clear, yellowish fluid that is the liquid component of blood. It's composed of water, enzymes, hormones, antibodies, clotting factors, and other proteins. Plasma serves as a transport medium for cells, nutrients, waste products, gases, and other substances throughout the body. Additionally, it plays a crucial role in the immune response and helps regulate various bodily functions.
Plasma can be collected from blood donors and processed into various therapeutic products, such as clotting factors for people with hemophilia or immunoglobulins for patients with immune deficiencies. This process is called plasma fractionation.
Oxidoreductases acting on CH-NH group donors are a class of enzymes within the larger group of oxidoreductases, which are responsible for catalyzing oxidation-reduction reactions. Specifically, this subclass of enzymes acts on CH-NH group donors, where the CH-NH group is a chemical functional group consisting of a carbon atom (C) bonded to a nitrogen atom (N) via a single covalent bond.
These enzymes play a crucial role in various biological processes by transferring electrons from the CH-NH group donor to an acceptor molecule, which results in the oxidation of the donor and reduction of the acceptor. This process can lead to the formation or breakdown of chemical bonds, and plays a key role in metabolic pathways such as amino acid degradation and nitrogen fixation.
Examples of enzymes that fall within this class include:
* Amino oxidases, which catalyze the oxidative deamination of amino acids to produce alpha-keto acids, ammonia, and hydrogen peroxide.
* Transaminases, which transfer an amino group from one molecule to another, often in the process of amino acid biosynthesis or degradation.
* Amine oxidoreductases, which catalyze the oxidation of primary amines to aldehydes and secondary amines to ketones, with the concomitant reduction of molecular oxygen to hydrogen peroxide.
Blood platelets, also known as thrombocytes, are small, colorless cell fragments in our blood that play an essential role in normal blood clotting. They are formed in the bone marrow from large cells called megakaryocytes and circulate in the blood in an inactive state until they are needed to help stop bleeding. When a blood vessel is damaged, platelets become activated and change shape, releasing chemicals that attract more platelets to the site of injury. These activated platelets then stick together to form a plug, or clot, that seals the wound and prevents further blood loss. In addition to their role in clotting, platelets also help to promote healing by releasing growth factors that stimulate the growth of new tissue.