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Overview of Thrombotic Disorders

By

Michael B. Streiff

, MD, Johns Hopkins University School of Medicine

Reviewed/Revised Aug 2023
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Topic Resources

In healthy people, homeostatic balance Overview of Hemostasis Hemostasis, the arrest of bleeding from an injured blood vessel, requires the combined activity of Vascular factors Platelets Plasma coagulation factors Regulatory mechanisms counterbalance... read more exists between procoagulant (clotting) forces and anticoagulant and fibrinolytic forces. Numerous genetic, acquired, and environmental factors can tip the balance in favor of coagulation, leading to the pathologic formation of thrombi in veins (eg, deep venous thrombosis Deep Venous Thrombosis (DVT) Deep venous thrombosis (DVT) is clotting of blood in a deep vein of an extremity (usually calf or thigh) or the pelvis. DVT is the primary cause of pulmonary embolism. DVT results from conditions... read more Deep Venous Thrombosis (DVT) [DVT]), arteries (eg, myocardial infarction Acute Myocardial Infarction (MI) Acute myocardial infarction is myocardial necrosis resulting from acute obstruction of a coronary artery. Symptoms include chest discomfort with or without dyspnea, nausea, and/or diaphoresis... read more Acute Myocardial Infarction (MI) , ischemic stroke Ischemic Stroke Ischemic stroke is sudden neurologic deficits that result from focal cerebral ischemia associated with permanent brain infarction (eg, positive results on diffusion-weighted MRI). Common causes... read more Ischemic Stroke ), or cardiac chambers. Thrombi can obstruct blood flow at the site of formation or detach and embolize to block a distant blood vessel (eg, pulmonary embolism Pulmonary Embolism (PE) Pulmonary embolism (PE) is the occlusion of pulmonary arteries by thrombi that originate elsewhere, typically in the large veins of the legs or pelvis. Risk factors for pulmonary embolism are... read more Pulmonary Embolism (PE) , embolic stroke Ischemic Stroke Ischemic stroke is sudden neurologic deficits that result from focal cerebral ischemia associated with permanent brain infarction (eg, positive results on diffusion-weighted MRI). Common causes... read more Ischemic Stroke ).

Etiology of Thrombotic Disorders

Genetic defects that increase the propensity for venous thromboembolism include

Protein Z, a vitamin K-dependent protein, helps inactivate coagulation factor Xa. Deficiency or dysfunction of protein Z Protein Z Deficiency Because protein Z helps inactivate coagulation factor Xa, deficiency or dysfunction of protein Z predisposes to venous thrombosis (mainly in patients who also have other clotting abnormalities)... read more predisposes to venous thrombosis (mainly in patients who also have other clotting abnormalities). However, measurement of its activity is not available in most laboratories.

Acquired defects also predispose to venous and arterial thrombosis (see table ).

Other disorders and environmental factors can increase the risk of thrombosis, especially if a genetic abnormality is also present.

Table

Symptoms and Signs of Thrombotic Disorders

  • Chest pain and shortness of breath: Possible PE or myocardial infarction

  • Leg pain, warmth, redness, and swelling: DVT

  • Weakness/numbness of one side of the body, problems speaking, and problems with balance and walking: Possible ischemic stroke

  • Abdominal pain: Possible splanchnic arterial or venous thrombosis

Most of the inherited disorders do not begin to cause an increased risk of clotting until young adulthood, although clots can form at any age. Women may have a history of multiple spontaneous abortions Spontaneous Abortion Spontaneous abortion is pregnancy loss before 20 weeks gestation. Diagnosis is by pelvic examination, measurement of beta subunit of human chorionic gonadotropin, and ultrasonography. Treatment... read more .

Diagnosis of Thrombotic Disorders

Predisposing factors

Predisposing factors should always be considered. In some cases, the condition is clinically obvious (eg, recent surgery or trauma, prolonged immobilization, cancer, infection, medical illness, generalized atherosclerosis). If no predisposing factor is readily apparent, further evaluation should be considered in patients with

  • A family history of venous thrombosis (first-degree relative with venous thromboembolism before age 50 years)

  • More than one episode of venous thrombosis

  • Venous or arterial thrombosis before age 50 years

  • Unusual sites of venous thrombosis (eg, cavernous sinus, splanchnic veins)

As many as half of all patients with spontaneous DVT have a genetic predisposition. However, in many such instances, identification of an inherited thrombophilic state does not influence therapy. Therefore, society guidelines suggest targeted testing in patients at high risk of inherited thrombophilia (1, 2 Diagnosis references In healthy people, homeostatic balance exists between procoagulant (clotting) forces and anticoagulant and fibrinolytic forces. Numerous genetic, acquired, and environmental factors can tip... read more ).

Testing for predisposing congenital and acquired factors includes specific assays that measure the quantity or activity of natural anticoagulant molecules in plasma, and screening for specific gene defects, as follows:

  • Clotting assay for lupus anticoagulant

  • Clotting assay for resistance to activated protein C

  • Genetic test for factor V Leiden

  • Genetic test for prothrombin gene mutation (G20210A)

  • Factors VIII, IX, and XI activity

  • Functional assay of antithrombin

  • Functional assay of protein C

  • Functional assay of protein S

  • Antigenic assays of total and free protein S.

  • Measurement of plasma homocysteine levels

  • Immunoassays for antiphospholipid antibodies

Diagnosis references

Treatment of Thrombotic Disorders

Treatment is summarized elsewhere in THE MANUAL specific to the location of the thrombus.

DOACs include factor Xa inhibitors (rivaroxaban, apixaban, edoxaban) and the direct thrombin inhibitor dabigatran. Unlike warfarin, DOACs do not require regular laboratory monitoring, and some of these medications (apixaban, rivaroxaban) can be used in acute treatment without initial parenteral anticoagulation. In contrast to warfarin, DOACs have fewer drug-drug interactions and their effectiveness is not influenced by diet.

In the event of life-threatening bleeding, reversal agents for DOACs include targeted antidotes (idarucizumab for dabigatran; andexanet alfa for the factor Xa inhibitors) as well as non-specific prohemostatic agents such as prothrombin complex concentrates which contain factors VII, IX, X, and prothrombin (1, 4, 5 Treatment references In healthy people, homeostatic balance exists between procoagulant (clotting) forces and anticoagulant and fibrinolytic forces. Numerous genetic, acquired, and environmental factors can tip... read more ). Warfarin is reversed with vitamin K and prothrombin complex concentrates.

A major current disadvantage of DOACs is their expense.

Treatment references

  • 1. Stevens SM, Woller SC, Kreuziger LB, et al. Antithrombotic Therapy for VTE Disease: Second Update of the CHEST Guideline and Expert Panel Report [published correction appears in Chest 2022 Jul;162(1):269]. Chest 2021;160(6):e545-e608. doi:10.1016/j.chest.2021.07.055

  • 2. Ortel TL, Neumann I, Ageno W, et al. American Society of Hematology 2020 guidelines for management of venous thromboembolism: treatment of deep vein thrombosis and pulmonary embolism. Blood Adv 2020;4(19):4693-4738. doi:10.1182/bloodadvances.2020001830

  • 3. National Institute on Health and Care Excellence (NICE): Venous thromboembolic diseases: diagnosis, management and thrombophilia testing. NICE guideline [NG 158]. March 26, 2020.

  • 4. Cuker A, Burnett A, Triller D, et al: Reversal of direct oral anticoagulants: Guidance from the Anticoagulation Forum. Am J Hematol 94:697–709, 2019.

  • 5 Frontera JA, Lewin JJ 3rd, Rabinstein AA, et al. Guideline for Reversal of Antithrombotics in Intracranial Hemorrhage: A Statement for Healthcare Professionals from the Neurocritical Care Society and Society of Critical Care Medicine. Neurocrit Care. 2016;24(1):6-46. doi:10.1007/s12028-015-0222-x

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