Thrombophilia is the propensity to develop Thrombosis is the formation of a clot or thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system. Thromboembolism is a general term describing both thrombosis and its main complication: dislodgement of a clot and embolisation. Causes Classically, thrombosis is caused by abnormalities in one or... thrombosis (blood clots) due to an abnormality in the system of Coagulation is the thickening or congealing of any liquid into solid clots. This article is about a specific medical usage of the term with reference to human bloods mechanisms for forming scabs over wounds. The coagulation of human blood is a complex process during which blood forms solid clots... coagulation.

Indications

Searching for a coagulation abnormality is not normally undertaken in patients in whom thrombosis has an obvious other cause. For example, if the thrombosis is due to immobilisation after recent Orthopedic surgery or orthopedics (BE: orthopaedics) is the branch of surgery concerned with acute, chronic, traumatic and recurrent injuries and other disorders of the locomotor system, its musclular and bone parts. Apart from the mechanical considerations, it is also concerned with the pathology, genetics, intrinsic, extrinsic and biomechanical factors involved... orthopedic surgery, it is unlikely that an underlying cause is found.

Conversely, although thrombosis itself may occur in any person, repeated (two or more) unprovoked episodes of thrombosis and unusual sites and types of thrombosis (e.g. In medicine (gastroenterology and hepatology), Budd-Chiari syndrome is the clinical picture caused by occlusion of the hepatic vein. Signs and symptoms The syndrome presents with rapidly progressive abdominal pain, hepatomegaly (enlarged liver), ascites, and later the symptoms of hepatic dysfunction: elevated liver enzymes, encephalopathy. A slower-onset form of... Budd-Chiari syndrome) may point towards a coagulation disorder.

Increasingly, Habitual abortions are repeated pregnancies that end in miscarriage of the fetus. There is no increased risk to the woman unless she has had three or more spontaneous miscarriages (aka spontaneous abortions). There are various causes for habitual abortions, and some are treatable. An important example is the increased risk... habitual abortion is seen as an indication for thrombophilia screening. Up to 20% of women presenting with recurrent pregnancy loss may have a coagulation disorder.

Classification

Thrombophilia can be classified in various forms.

• The most common classification is by the nature of the thrombosis: Section of an artery An artery or arterial is also a class of highway. Arteries are muscular tubes that carry blood flow away from the heart to the tissues and organs of the body ( by contrast, veins are the return path tubes). The arterial layer that is in direct contect... arterial, In geology, a vein is a regularly shaped and lengthy occurrence of an ore; a lode. In biology, a vein is a blood vessel which returns blood from the microvasculature to the heart. Veins form part of the circulatory system. The vessels carrying blood away from the heart are known... venous or combined.
• Crowther & Kelton (2003) propose to classify the abnormality by the molecular deficiency, type I being the (severe) deficiencies of inhibitors, and type II being the less severe elevation of coagulation factors.
• Acquired vs. congenital

Types

Common types:

• Factor V Leiden (sometimes Factor VLeiden) is a hypercoagulability disorder in which Factor V, one of the coagulation factors, cannot be deactivated. Factor V Leiden is the most common hereditary hypercoagulability clotting disorder amongst Eurasians, possibly affecting up to 5% of the population of the U.S. It is named... Factor V, Leiden type (3% of the population are Heterozygote cells are diploid or polyploid and have different alleles at a locus (position) on homologous chromosomes. When a human is referred to as a heterozygote, or being heterozygous for a specific gene, it means that he or she carries two different versions of that gene on the two corresponding... heterozygous for FVL).
• Thrombin (activated Factor II) is a coagulation protein that has many effects in the coagulation cascade. It is in fact an enzyme of the serine protease type (EC 3.4.21.5), and therefore acts by cleaving proteins at certain locations. Its main action is to turn fibrinogen into fibrin... Prothrombin mutation (G20210A, 5'UTR).
• High The metabolic intermediate homocysteine is an amino acid created by the single carbon chemistry of S-adenosyl-methionine. It can be converted back to methionine, or converted to cysteine or taurine via the transsulfuration pathway. Homocysteine is attracting attention because a high level of blood serum homocysteine is now considered... homocysteine levels due to MTHFR, or Methylene-tetra-hydrofolate reductase is an enzyme that exists in human cells that assists with metabolism and the reduction of blood homocysteine levels. References MTHFR and homocysteine, Dr. Stephan Moll, retrieved 28 December 2004. Categories: Chemistry stubs ... MTHFR mutation or vitamin deficiency (vitamins B6, B12 and folic acid).
• Antiphospholipid syndrome, or antiphospholipid antibody syndrome, is a disorder of coagulation, and causes thrombosis in both arteries and veins, as well as recurrent miscarriage. It is due to the autoimmune production of antibodies against cell membrane constituents. It is occasionally referred to as Hughes syndrome after the rheumatologist Dr Graham... Antiphospholipid antibodies
  • anticardiolipin antibodies and/or
  • Lupus anticoagulant is an autoimmune disorder caused by antibodies that bind to phospholipids and proteins associated with the cell membrane. This antibody has the peculiar nature of causing a delay in coagulation in laboratory tests (the partial thromboplastin time) while clinically predisposing for thrombosis. It is also known as lupus... lupus anticoagulants
• Kidneys viewed from behind with spine removed The kidneys are bean-shaped excretory organs in vertebrates. Part of the urinary system, the kidneys filter wastes (especially urea) from the blood and excrete them, along with water, as urine. The medical field that studies the kidneys and diseases affecting the kidney... Renal disease (renal loss of antithrombin)

Rare forms:

• Plasmin is an important degrading enzyme (EC 3.4.21.7) of many proteins of blood plasma but specifically of fibrin clots. This process is termed fibrinolysis. It is a serine protease that is released as plasminogen into the circulation and activated by tissue plasminogen activator (tPA), thrombin, fibrin and... Plasminogen and Fibrinolysis is the process where a fibrin clot, the product of coagulation, is broken down. Its main enzyme, plasmin, cuts the fibrin mesh at various places, leading to the production of circulating fragments that are cleared by other proteinases or by the kidney and liver. Physiology Plasmin is produced in... fibrinolysis disorders.
• Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease characterised by aplastic anemia, thrombosis and red urine in the morning due to breakdown of red blood cells. Signs and symptoms As the name implies, the hemoglobin appears in urine in attacks (paroxysms). The symptom in itself is harmless, although excessive hemolysis... Paroxysmal nocturnal hemoglobinuria
• Protein C deficiency.
• Protein S deficiency is a disorder associated with increased risk of thrombosis. Decreased levels or impaired function of protein S, a vitamin K-dependant physiological anticoagulant leads to decreased degradation of factor Va and factor VIIIa and an increased propensity to venous thrombosis. Types There are three types of hereditary... Protein S deficiency.
• Antithrombin is a small molecule that inactivates several enzymes of the coagulation system. Its affinity for these molecules (i.e. its effectivity) is enhanced by heparin. Function Antithrombin is a serpin (serine protease inhibitor) that inactivates a number of enzymes from the coagulation system, namely Factor X, Factor IX and... Antithrombin III deficiency.

Testing

Tests for thrombophilia include The prothrombin time (PT) and its derived measures of prothrombin ratio (PR) and international normalized ratio (INR) are measures of the extrinsic pathway of coagulation. They are used to determine the clotting tendency of blood, in the measure of warfarin dosage, liver damage and vitamin K status. The reference range... prothrombin time and INR, The partial thromboplastin time (PTT) or activated partial thromboplastin time (aPTT) is a commonly performed test for the system of coagulation, especially its intrinsic pathway. Apart from detecting abnormalities in blood clotting, it is also used to monitor the effectivity of treatment with heparin, a major anticoagulant. Methodology The PTT... partial thromboplastin time, thrombin time, Fibrin is a protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a mesh that forms a haemostatic plug or clot (in conjunction with platelets) over a wound site. Fibrin is made from its zymogen fibrinogen, a soluble plasma glycoprotein that is... fibrinogen levels, Antiphospholipid syndrome, or antiphospholipid antibody syndrome, is a disorder of coagulation, and causes thrombosis in both arteries and veins, as well as recurrent miscarriage. It is due to the autoimmune production of antibodies against cell membrane constituents. It is occasionally referred to as Hughes syndrome after the rheumatologist Dr Graham... antiphospholipid antibody levels (IgG- and IgM-anticardiolipin, dillute Russell viper venom time and lupus anticoagulant), Protein C is a major physiological anticoagulant. It is a vitamin K-dependant serine protease enzyme (EC 3.4.21.69) that is activated by thrombin into activated protein C (APC). The activated form (with protein S as a cofactor) degrades Factor Va and Factor VIIIa, which are themselves cofactors... protein C, Protein S is a vitamin K-dependent plasma glycoprotein synthesized in the liver and it functions as a cofactor to Protein C in the inactivation of Factors Va and VIIIa. In the circulation, Protein S exists in two forms: a free form and a complex form bound to complement protein... protein S and antithombin (both levels and activity), activated protein C resistance (APC resistance), Factor V Leiden (sometimes Factor VLeiden) is a hypercoagulability disorder in which Factor V, one of the coagulation factors, cannot be deactivated. Factor V Leiden is the most common hereditary hypercoagulability clotting disorder amongst Eurasians, possibly affecting up to 5% of the population of the U.S. It is named... factor V Leiden and Thrombin (activated Factor II) is a coagulation protein that has many effects in the coagulation cascade. It is in fact an enzyme of the serine protease type (EC 3.4.21.5), and therefore acts by cleaving proteins at certain locations. Its main action is to turn fibrinogen into fibrin... thrombin mutation. Many laboratories add on various other tests, depending on local policy and guidelines.

Reference

• Crowther MA, Kelton JG. Congenital thrombophilic states associated with venous thrombosis: a qualitative overview and proposed classification system. Ann Intern Med 2003;138:128-34. PDF fulltext. (http://www.annals.org/cgi/reprint/138/2/128) PMID 12529095.