Thrombophilia

Thrombophilia (also known as hypercoagulability or a prothrombotic state) is an abnormality of blood coagulation that increases the risk of thrombosis. It can be identified in 50% of people who experience unprovoked thrombosis.

While many individuals may have detectable thrombophilic abnormalities, thrombosis often develops only in the presence of additional risk factors.

Signs and Symptoms

The most common conditions associated with thrombophilia are deep vein thrombosis (DVT) and pulmonary embolism (PE), collectively known as venous thromboembolism (VTE). DVT typically occurs in the legs and is characterised by pain, swelling, and redness. The clot may migrate to the lungs, causing PE, which can lead to sudden shortness of breath, chest pain, palpitations, and potentially catastrophic outcomes like collapse and cardiac arrest.

Thrombosis can also occur in unusual sites such as the veins of the brain, liver, mesentery, kidneys, and arms. Thrombophilia has been linked to recurrent miscarriage and pregnancy complications like intrauterine growth restriction, stillbirth, severe pre-eclampsia, and abruptio placentae.

Causes

Thrombophilia can be congenital or acquired.

Congenital

The most common congenital thrombophilias are due to overactivity of coagulation factors, such as factor V Leiden and prothrombin G20210A mutations. Rare forms include deficiencies in natural anticoagulants like antithrombin III, protein C, and protein S. Blood group also plays a role, with non-O blood groups having a higher risk.

Acquired

Acquired conditions that increase thrombosis risk include antiphospholipid syndrome, heparin-induced thrombocytopenia (HIT), paroxysmal nocturnal hemoglobinuria (PNH), and various hematologic conditions. Cancer, nephrotic syndrome, inflammatory bowel disease, pregnancy, use of estrogens, and obesity are also significant risk factors.

Mechanism

Thrombosis results from a combination of factors such as abnormalities in blood vessel walls, blood flow, and blood consistency. Thrombophilia specifically involves abnormalities in blood consistency due to imbalances in coagulation factors. The coagulation process involves a cascade of activations leading to the formation of a fibrin clot, which is regulated by various inhibitors. In thrombophilia, this balance is disturbed, increasing the likelihood of clot formation.

Diagnosis

Diagnosis involves a range of tests including complete blood count, prothrombin time, partial thromboplastin time, and specific tests for various antibodies and genetic mutations. The extent of testing depends on clinical judgement and initial evaluation results. Hereditary cases require at least two abnormal tests plus a family history of thrombosis.

Screening

Screening for thrombophilia is debated. It is generally recommended for those with recurrent thromboembolism, unusual thrombosis sites, or a strong personal or family history. Routine screening is not advised for those with thrombosis due to obvious triggers. Specific guidelines exist for screening in cases like recurrent miscarriage and before using oral contraceptives.

Treatment

There is no specific treatment for thrombophilia unless it is secondary to an underlying condition. Long-term anticoagulation may be considered for those with unprovoked or recurrent thrombosis or high-risk thrombophilia. The decision to use anticoagulation is balanced against the risk of bleeding. Women with thrombophilia who are pregnant or planning pregnancy may require low molecular weight heparin instead of warfarin.

Prognosis

The risk of developing thrombosis varies. For instance, the cumulative risk by age 60 is about 12% in those without thrombophilia, but much higher in those with deficiencies in natural anticoagulants. Factor V Leiden and prothrombin mutation carriers have a slightly higher risk, often dependent on additional factors like immobilisation.

Epidemiology

Major thrombophilias like antithrombin deficiency, protein C deficiency, and protein S deficiency are rare. Minor thrombophilias like factor V Leiden and prothrombin mutation are more common, particularly in Northern European populations. The prevalence of antiphospholipid syndrome varies due to different definitions in studies.

History

Rudolf Virchow categorised abnormalities in blood consistency as a factor in thrombosis in 1856. The first identified thrombophilia was antithrombin deficiency in 1965, followed by protein C and protein S deficiencies in the 1980s. Antiphospholipid syndrome was detailed in the 1980s, and common genetic thrombophilias like factor V Leiden and prothrombin mutation were described in the 1990s.

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Self-assessment MCQs (single best answer)

What is the primary characteristic of thrombophilia?

Which of the following is a common condition associated with thrombophilia?

[mcq 527.10] Chronic kidney disease [wrong 527.10] No, chronic kidney disease is not directly related to thrombophilia. [end feedback 527.10]

Thrombophilia can be identified in what percentage of people who experience unprovoked thrombosis?
[mcq 527.11] 10% [wrong 527.11] No, the percentage is higher than 10%. [end feedback 527.11]
[mcq 527.12] 25% [wrong 527.12] No, the percentage is higher than 25%. [end feedback 527.12]
[mcq 527.13] 50% [right 527.13] Well done! This is correct. Thrombophilia can be identified in about 50% of people with unprovoked thrombosis. [end feedback 527.13]
[mcq 527.14] 75% [wrong 527.14] No, the percentage is lower than 75%. [end feedback 527.14]
[mcq 527.15] 90% [wrong 527.15] No, the percentage is lower than 90%. [end feedback 527.15]

Which of the following is a congenital cause of thrombophilia?
[mcq 527.16] Antiphospholipid syndrome [wrong 527.16] No, antiphospholipid syndrome is an acquired condition, not congenital. [end feedback 527.16]
[mcq 527.17] Heparin-induced thrombocytopenia [wrong 527.17] No, heparin-induced thrombocytopenia is an acquired condition resulting from heparin use, not congenital. [end feedback 527.17]
[mcq 527.18] Factor V Leiden mutation [right 527.18] Well done! This is correct. Factor V Leiden mutation is a congenital cause of thrombophilia. [end feedback 527.18]
[mcq 527.19] Nephrotic syndrome [wrong 527.19] No, nephrotic syndrome is an acquired condition, not congenital. [end feedback 527.19]
[mcq 527.20] Cancer [wrong 527.20] No, cancer is not a congenital condition but an acquired one. [end feedback 527.20]

Which acquired condition is associated with an increased risk of thrombosis?
[mcq 527.21] Factor V Leiden [wrong 527.21] No, Factor V Leiden is a congenital condition, not acquired. [end feedback 527.21]
[mcq 527.22] Protein S deficiency [wrong 527.22] No, Protein S deficiency is usually a congenital condition. [end feedback 527.22]
[mcq 527.23] Antithrombin III deficiency [wrong 527.23] No, Antithrombin III deficiency is typically congenital. [end feedback 527.23]
[mcq 527.24] Antiphospholipid syndrome [right 527.24] Well done! This is correct. Antiphospholipid syndrome is an acquired condition that increases the risk of thrombosis. [end feedback 527.24]
[mcq 527.25] Prothrombin G20210A mutation [wrong 527.25] No, Prothrombin G20210A mutation is a congenital condition. [end feedback 527.25]

What is a common site for deep vein thrombosis (DVT)?
[mcq 527.26] Arms [wrong 527.26] No, while DVT can occur in the arms, it is more commonly found in the legs. [end feedback 527.26]
[mcq 527.27] Brain [wrong 527.27] No, the brain is not a common site for deep vein thrombosis. [end feedback 527.27]
[mcq 527.28] Legs [right 527.28] Well done! This is correct. The legs are the most common site for deep vein thrombosis. [end feedback 527.28]
[mcq 527.29] Liver [wrong 527.29] No, the liver is not a common site for deep vein thrombosis. [end feedback 527.29]
[mcq 527.30] Kidneys [wrong 527.30] No, the kidneys are not a common site for deep vein thrombosis. [end feedback 527.30]

Which anticoagulant is often recommended for prolonged use in individuals at high risk of repeated thrombosis due to thrombophilia?
[mcq 527.31] Aspirin [wrong 527.31] No, aspirin is not typically recommended for prolonged use in high-risk thrombophilia patients. [end feedback 527.31]
[mcq 527.32] Heparin [wrong 527.32] No, heparin is usually used for short-term anticoagulation. [end feedback 527.32]
[mcq 527.33] Warfarin [right 527.33] Well done! This is correct. Warfarin is often recommended for prolonged use in individuals at high risk of repeated thrombosis due to thrombophilia. [end feedback 527.33]
[mcq 527.34] Clopidogrel [wrong 527.34] No, clopidogrel is not typically used for this purpose. [end feedback 527.34]
[mcq 527.35] Dabigatran [wrong 527.35] No, while dabigatran can be used for anticoagulation, warfarin is more commonly recommended for prolonged use in high-risk thrombophilia patients. [end feedback 527.35]

Which diagnostic test is NOT typically used to diagnose thrombophilia?
[mcq 527.36] Complete blood count [wrong 527.36] No, a complete blood count can be part of the diagnostic process for thrombophilia. [end feedback 527.36]
[mcq 527.37] Prothrombin time [wrong 527.37] No, prothrombin time is used to assess blood clotting functions and can be relevant in diagnosing thrombophilia. [end feedback 527.37]
[mcq 527.38] Partial thromboplastin time [wrong 527.38] No, partial thromboplastin time is also used to evaluate clotting factors and can be relevant. [end feedback 527.38]
[mcq 527.39] Electrocardiogram (ECG) [right 527.39] Well done! This is correct. ECG is not used for diagnosing thrombophilia, as it measures the electrical activity of the heart. [end feedback 527.39]
[mcq 527.40] Specific tests for antibodies and genetic mutations [wrong 527.40] No, specific tests for antibodies and genetic mutations are indeed used to diagnose thrombophilia. [end feedback 527.40]

Who first categorised abnormalities in blood consistency as a factor in thrombosis?
[mcq 527.41] Rudolf Virchow [right 527.41] Well done! This is correct. Rudolf Virchow first categorised abnormalities in blood consistency as a factor in thrombosis. [end feedback 527.41]
[mcq 527.42] William Harvey [wrong 527.42] No, William Harvey is known for his work on blood circulation, not specifically thrombosis. [end feedback 527.42]
[mcq 527.43] Louis Pasteur [wrong 527.43] No, Louis Pasteur is known for his work in microbiology, not thrombosis. [end feedback 527.43]
[mcq 527.44] Edward Jenner [wrong 527.44] No, Edward Jenner is known for developing the smallpox vaccine, not for work on thrombosis. [end feedback 527.44]
[mcq 527.45] Alexander Fleming [wrong 527.45] No, Alexander Fleming is known for discovering penicillin, not for research on thrombosis. [end feedback 527.45]

Which of the following is NOT a symptom of pulmonary embolism (PE)?
[mcq 527.46] Shortness of breath [wrong 527.46] No, shortness of breath is a common symptom of pulmonary embolism. [end feedback 527.46]
[mcq 527.47] Chest pain [wrong 527.47] No, chest pain is a common symptom of pulmonary embolism. [end feedback 527.47]
[mcq 527.48] Palpitations [wrong 527.48] No, palpitations can be a symptom of pulmonary embolism. [end feedback 527.48]
[mcq 527.49] High fever [right 527.49] Well done! This is correct. High fever is not typically a symptom of pulmonary embolism. [end feedback 527.49]
[mcq 527.50] Sudden collapse [wrong 527.50] No, sudden collapse can be a symptom of pulmonary embolism. [end feedback 527.50]