Antithrombin III deficiency
Encyclopedia
Antithrombin III deficiency is a rare
hereditary disorder that generally comes to light when a patient suffers recurrent venous thrombosis
and pulmonary embolism
. Inheritance is usually autosomal dominant, though a few recessive
cases have been noted.
The disorder was first described by Egeberg in 1965.
The patients are treated with anticoagulant
s or, more rarely, with antithrombin concentrate.
In renal failure
, especially nephrotic syndrome
, antithrombin is lost in the urine, leading to a higher activity of Factor II and Factor X
and in increased tendency to thrombosis
.
However, vitamin K does affect the metabolic reaction of warfarin. While an undiagnosed patient would not be affected by fluctuating levels of vitamin K, a patient taking warfarin must be aware of their intake of vitamin K, as it can adversely affect their INR. Seeing as most patients with an antithrombin deficiency take warfarin as both a therapeutic medicine and to prevent recurring thrombosis, not heparin, vitamin K does play a role in the day-to-day life of someone with an antithrombin deficiency. Heparin is only used to dissolve a dangerous DVT, not as a therapeutic medicine.
Heparin is used in bridge therapy when initiating a patient on warfarin when in a hospital setting. It can be used in DVT prophylaxis and treatment, acute coronary syndromes, and ST-segment elevated MI.
Rare disease
A rare disease, also referred to as an orphan disease, is any disease that affects a small percentage of the population.Most rare diseases are genetic, and thus are present throughout the person's entire life, even if symptoms do not immediately appear...
hereditary disorder that generally comes to light when a patient suffers recurrent venous thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
and pulmonary embolism
Pulmonary embolism
Pulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...
. Inheritance is usually autosomal dominant, though a few recessive
Recessive
In genetics, the term "recessive gene" refers to an allele that causes a phenotype that is only seen in a homozygous genotype and never in a heterozygous genotype. Every person has two copies of every gene on autosomal chromosomes, one from mother and one from father...
cases have been noted.
The disorder was first described by Egeberg in 1965.
The patients are treated with anticoagulant
Anticoagulant
An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...
s or, more rarely, with antithrombin concentrate.
In renal failure
Renal failure
Renal failure or kidney failure describes a medical condition in which the kidneys fail to adequately filter toxins and waste products from the blood...
, especially nephrotic syndrome
Nephrotic syndrome
Nephrotic syndrome is a nonspecific disorder in which the kidneys are damaged, causing them to leak large amounts of protein from the blood into the urine....
, antithrombin is lost in the urine, leading to a higher activity of Factor II and Factor X
Factor X
Factor X, also known by the eponym Stuart-Prower factor or as prothrombinase, is an enzyme of the coagulation cascade. It is a serine endopeptidase .-Physiology:...
and in increased tendency to thrombosis
Thrombosis
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...
.
Heparin resistance
Patients with AT3 deficiency need higher doses of heparin. AT3 is known to slowly break up fibrin and factor X. When heparin binds to AT3, AT3 will break up fibrin and factor X faster. AT3 is not dependent on vitamin K so unlike warfarin, giving vitamin K will not reverse the effects of heparin.However, vitamin K does affect the metabolic reaction of warfarin. While an undiagnosed patient would not be affected by fluctuating levels of vitamin K, a patient taking warfarin must be aware of their intake of vitamin K, as it can adversely affect their INR. Seeing as most patients with an antithrombin deficiency take warfarin as both a therapeutic medicine and to prevent recurring thrombosis, not heparin, vitamin K does play a role in the day-to-day life of someone with an antithrombin deficiency. Heparin is only used to dissolve a dangerous DVT, not as a therapeutic medicine.
Heparin is used in bridge therapy when initiating a patient on warfarin when in a hospital setting. It can be used in DVT prophylaxis and treatment, acute coronary syndromes, and ST-segment elevated MI.
External links
- Information on antithrombin from UIUC
- Non-profit advocacy group for patients and families with antithrombin deficiency