Glossary of Blood Clot and Clotting Disorder Terms
Activated Partial Thromboplastin Time (aPTT )…
A blood test that measures the length of time (in seconds) that it takes
for clotting to occur when certain substances are added to the liquid
portion of blood in a test tube.
It is used to detect clotting factor deficiencies and to monitor heparin’s
effectiveness.
Anticoagulant …
A type
of medication, commonly referred to as a blood thinner, that causes the blood to
take a longer time to form a blood clot.
Used to prevent the formation of blood clots or to treat blood clots.
they may be given by injection, either into a vein or under the skin (e.g.,
heparin, low-molecular-weight heparin), or by mouth (warfarin).
Antiphospholipid Antibody Syndrome (APS) … This rare autoimmune
disorder is characterized by recurrent blood clots and/or miscarriages in which
there is an elevated antiphospholipid antibody level in the blood. APS may occur
in those with lupus or related autoimmune diseases. It may also occur as a
primary syndrome (Primary ABS) in otherwise healthy individuals.
Antiphospholipid Antibody … This antibody, which is directed against one’s own tissues
(autoantibody), is associated with an increased risk for forming blood clots
and/or recurrent miscarriages.
Antithrombin III…
A
protein found in our bloodstream that controls our clotting mechanism and
prevents excessive clotting. It functions as a naturally occurring mild blood
thinner.
Antithrombin III Deficiency (AT-III)… AT-III deficiency is a disorder that increases the risk for blood clots.
It can be (a) acquired, or (b) inherited, or (c) based on a misinterpretation of
lab tests (values can be temporarily low at the time of the acute clot or during
heparin therapy).
Artery…
Any of
the blood vessels that carry blood away from the heart and to the various parts
of the body.
Arterial Blood Gas (ABG) … A technique used primarily to measure the oxygen level of the blood with
precision.
Atrial Fibrillation …
An abnormal rhythm or heartbeat pattern involving the atria or upper chambers of
the heart. It can interrupt the normal flow of blood through the heart, allowing
clots to form. These clots can potentially travel through the arteries, lodge in
the brain and cause strokes.
Budd Chairi Syndrome…
Thrombosis of the (hepatic) veins coming from the liver, usually presenting
with abdominal pain, enlargement of the liver and fluid in the abdomen.
CDC…
The
Centers for Disease Control and Prevention is a government health care
agency, located in Atlanta, GA,
whose mission is the prevention and treatment of disease.
Clotting Disorders… A
term
used to describe a group of conditions in which there is an increased tendency,
often repeated and over an extended period of time, for excessive clotting.
Chronic Thromboembolic Pulmonary Hypertension (CTEPH)…
High blood pressure in the lungs that occurs in a small percentage of those who
have had pulmonary embolism. The problem usually progresses but may be cured
with surgery.
Coagulation…
The process of blood clotting.
Coagulometer… A device used to measure the INR for warfarin monitoring.
Coumadin®…
A brand
name for warfarin, an anticoagulation (blood thinning) medicine.
Deep Vein Thrombosis (DVT)…
A blood clot anywhere in the deep veins of the legs, pelvis or arms. A DVT
occurs most often in the legs, and may break off and travel to other parts of
the body, most commonly the lungs.
D-Dimers… A
breakdown product of fibrin, a substance present in a blood clot. D-dimers are
not generally present in the blood unless a clot has begun to form. However, the
presence of D-Dimers does not guarantee that a clot is present. If D-dimers are
absent, it is very unlikely that a clot has begun to form.
Duplex Ultrasound…
This method combines two kinds of ultrasound. The conventional ultrasound shows
the structure of blood vessels and the Doppler ultrasound shows the movement of
red blood cells through the vessels. It produces images that can be color coded
to show physicians where blood flow is severely blocked as well as the speed and
direction of blood flow.
Economy Class Syndrome… The occurrence of deep vein thrombosis (DVT) in airline travelers due to
cramped conditions compounded by inactivity, especially on long haul
flights. The term was first coined in the late 1980's when it was observed that
people who had traveled long distances by
plane were at an increased risk
for blood clots, especially DVT, resulting often in a pulmonary embolism.
Endothelium… The
lining of a blood vessel. A patient is more susceptible to a blood clot when the
endothelium is damaged from trauma or a previous blood clot.
Factor V deficiency…
An
inherited bleeding disorder in which the clotting factor V (five) is low. The
disorder is very rare, occurring in only 1 in 1,000,000 people. This is not the
same as factor V Leiden.
Factor V Leiden
(FVL)…
An inherited blood clotting disorder that is found in 5%
of Caucasian Americans and 1.2% of African-Americans. One can be heterozygous
(have one abnormal gene), homozygous (have two abnormal genes) or normal (not
have any abnormal genes). The genetic test for factor V Leiden has been
available since 1994.
Fibrin… This is
a solid substance (formed from fibrinogen) that makes a clot harder to break up.
It forms the mesh or net that holds platelets in place.
Fibrinogen… A
specialized protein or clotting factor found in blood. When a blood vessel is
injured, thrombin, another clotting factor, is activated and changes fibrinogen
to fibrin.
Fitted Elastic Compression Stockings…These provide counter-pressure to veins and help return fluid that has
leaked out back into circulation. Ideally, they exert a pressure of at least 30
to 40 mm Hg at the ankle with less pressure at the knee.
Fresh Frozen Plasma…
This is used to reverse warfarin by replacing clotting factors.
Genetic Counseling…
Genetic counseling is the process of helping people understand and adapt to the
medical, psychological and familial implications of genetic contributions to
disease. It includes
interpreting family and medical histories to assess
the chance of disease occurring or recurring;
Hematologist… A
physician specializing in the treatment of blood disorders.
Heparin…
An anticoagulant medicine (“ blood
thinner”) routinely prescribed for the treatment of clotting disorders.
Heterozygous…
Having
one abnormal gene. If you are heterozygote for factor V Leiden, you have
inherited the trait from one parent.
Homocysteine…
An amino
acid found in the blood. High homocysteine levels are a risk factor for blood
clots in the veins (DVT, PE) or arteries (heart attack, stroke), and hardening
of the arteries (atherosclerosis).
Hypercoagulable…This
refers to an increased tendency to form blood clots, due to an inherited state
or acquired disorder.
Hyperhomocysteinemia…
A
condition where elevated homocysteine levels are present in the blood that may
damage the lining of blood vessels and lead to the formation of blood clots.
Homocystinuria…
A
rare hereditary disease due to a deficiency of an enzyme needed to prevent the
buildup of homocysteine in the blood.
Homozygous…
Having
two abnormal genes. If you are homozygote for factor V Leiden, you inherited an
abnormal gene from both parents.
INR (International Normalized Ratio)…
This blood test result helps
physicians monitor patients taking anticoagulant medications. It measures the
blood’s ability to clot based on the prothrombin time (PT), the time it takes
for blood to clot in a test tube.
Low Molecular Weight Heparin (LMWH)…
An injectable form of heparin (a blood thinner) that is given underneath
the skin. LMWH lasts longer, must be monitored differently and generally has
fewer side effects than standard heparin. It is often used as an alternative to
heparin or as bridging therapy for patients on warfarin, when dental work or
surgery are needed or during pregnancy. Examples of brand names are Lovenox®,
Fragmin®, and Innohep®.
Lupus Anticoagulant… A
type of antiphospholipid antibody associated with an increased risk for blood
clots.
Lysis…
The
process by which a clot is dissolved or destroyed. It can occur naturally over
time or be accomplished by clot-busting drugs.
Lytic therapy…
A
clot-busting medication given in the hospital into the blood vessel to break up
clots. The treatment has a risk of bleeding. Drug names are tPA, streptokinase,
and urokinase.
Magnetic Resonance Imaging (MRI)…
A test that images clots in the body. While MRI does a better job of
imaging the veins in the pelvis, abdomen and chest than ultrasound, ultrasound
for the legs is generally adequate.
MTHFR…
Stands
for Methylene-Tetra-Hydro-Folate-Reductase. Some individuals with the homozygous MTHFR mutation have
elevated homocysteine levels. Elevated homocysteine levels are a risk factor for
blood clots. The individuals with MTHFR mutations who have normal homocysteine
levels are not at increased risk for clots. Thus, the MTHFR mutation by itself
is not a clotting disorder.
Myocardial Infarction…
Heart attack. The death of an area of heart muscle.
Plasma… The
liquid portion of blood that contains the clotting factors.
Plasminogen…
A
substance naturally produced by the body that helps
break down blood clots.
Platelets…
Small
particles in the blood that control bleeding; they form clusters to plug small
holes in blood vessels and assist in the clotting process.
Polycythemia… The
presence of too many red blood cells, which, if severe, may predispose a patient
to DVT.
Post-Phlebitic/Post-Thrombotic Syndrome…
Long-term, recurring leg symptoms that affect some patients as a result of
permanent injury to veins and their valves from DVT.
Protein C Deficiency…
Protein C deficiency is an uncommon clotting disorder: approximately 1 per 700
people has inherited protein C deficiency. Since we all have two genes for every
protein (one from mother and one from father), people can have two normal genes
(healthy), one mutated protein C gene (heterozygous), or two mutated genes
(homozygous). Individuals with protein C deficiency are typically heterozygous.
Homozygous individuals have such a severe clotting problem, that they typically
die immediately after birth because of clotting everywhere; this is termed &;Purpura
fulminans.&;
Protein C deficiency can be caused by more than 100 different mutations in the
protein C gene. This makes genetic testing for the defect very difficult,
time-consuming, and expensive; it is therefore not done in routine clinical
practice. A few academic institutions with a special interest in protein C
deficiency perform genetic testing for research purposes. In some people protein
C deficiency is due to acquired (non-inherited) causes, and may be temporary.
Protein S Deficiency…
Protein S deficiency is an uncommon clotting disorder: approximately 1 per 500
to 1 per 3,000 people has inherited protein S deficiency. Since we all have two
genes for every protein (one from mother and one from father), people can have
two normal genes (healthy), one mutated protein S gene (heterozygous), or two
mutated genes (homozygous). Individuals with protein S deficiency are typically
heterozygous. Homozygous individuals have such a severe clotting problem, that
they typically die immediately after birth because of clotting everywhere; this
is termed &;Purpura fulminans.&;
Protein S deficiency can be caused by more than 100 different mutations in the
protein S gene. This makes genetic testing for the defect very difficult,
time-consuming, and expensive; it is therefore not done in routine clinical
practice. A few academic institutions with a special interest in protein S
deficiency perform genetic testing for research purposes. In some people protein
S deficiency is due to acquired (non-inherited) causes, and may be temporary.
Prothrombin Deficiency…
Prothrombin (= factor II) is 1 of the approximately 15 clotting proteins
that is needed to stop us from bleeding. If you are low in prothrombin, you have
a tendency to bleed.
Prothrombin 20210 mutation…
The prothrombin 20210 mutation (= factor II 20210 mutation) is a very
common mutation and is a mild risk factor for deep vein thrombosis (DVT) and
pulmonary embolism (PE).G20210A?
PT (Prothrombin Time Test)…
The prothrombin time test, also called PT, helps measure how well blood is
able to clot. The test provides a control for long-term anticoagulant therapy
that usually involves the use of warfarin. It is also known as INR or Protime.
PTT (Partial Thromboplastin Time)… A blood test that measures the length of time (in seconds) that it takes
for clotting to occur when certain substances are added to the liquid portion of
blood in a test tube. It is used to
detect clotting factor deficiencies and to monitor heparin’s effectiveness.
Pulmonary Angiogram…The
most definitive test to diagnose PE, this is an invasive test requiring
injection of a dye through a catheter (IV line) into the body.
Pulmonary Embolism (PE)…
A clot in the blood vessels in
the lungs, making it difficult to breathe. Pulmonary embolism may be fatal.
Pulmonary Infarction…
The death of a small area of lung resulting from pulmonary embolism. It occurs
in a small, dead-end pulmonary artery and often causes pain in the back or
chest.
Pulse Oximetry… A
noninvasive (no blood needed) method used to monitor the percentage of
hemoglobin that is saturated with oxygen.
Spontaneous DVT… A
clot that forms when there are no identified risk factors. Of those who develop
a spontaneous DVT, 20-40% have an inherited or acquired predisposition to
thrombosis or thrombophilia.
Stroke…
A
condition that occurs when oxygen-rich blood is prevented from reaching an area
of the brain; it can lead to death of brain cells in that area.
Superficial Thrombophlebitis… Also called superficial vein thrombosis, this is when a blood clot or
clots form in veins nearer to the surface.
Tissue Factor… A
protein exposed to the blood when a blood vessel is injured. The tissue factor
sets off a chain reaction – the coagulation cascade – that activates a series of
clotting factors.
Thrombin… The
clotting factor that converts fibrinogen to fibrin.
Thrombocytopenia … A
low platelet count.
Thrombocytosis (Thrombocythemia) … Too many platelets in the blood. It may predispose a patient to
thrombosis.
Thrombophilia …
A
hereditary or acquired predisposition to develop blood clots. It is also
referred to as hypercoagulable state or hypercoagulability.
Thrombosis (aka thrombus) …
A blood clot that forms within a blood vessel. When the blockage occurs in
a heart artery, it is called a coronary thrombosis.
Thrombus … A blood
clot.
Transient Ischemic Attack (TIA)…
Often called a “mini stroke” but transient (short term) in nature–symptoms
last less than 48 hours.
Vena Cava… A very
large vein that returns blood from organs and extremities to the right side of
the heart.
Vena Caval Filter… A
device inserted to prevent PE in patients with DVT and/or PE when anticoagulants
fail or cannot be used.
Venography/Venogram…
An X-ray that takes pictures of blood flow through the veins in a certain area
of the body. During the test, a special dye (contrast material) is put into the
veins so they can be seen clearly on an X-ray picture.
Venous thromboembolism (VTE)… The collective term for deep vein thrombosis and pulmonary embolism.
Vitamin K…
A
vitamin essential to the production of the active forms of clotting factors II,
VII, IX and X in the liver.
Virchow’s Triad…
The 3 factors identified with the development of blood clots: blood vessel
injury, interruption of blood flow and thrombophilia (the increased tendency
toward blood clotting).
Ventilation-Perfusion Scan (VQ Scan)… A test used to evaluate both air
flow (Ventilation/V) and blood flow (Perfusion/Q) in the lungs to
determine whether a person has experienced a pulmonary embolism.
Warfarin
A blood
thinning medicine. Brand name: Coumadin®
This glossary has been adapted from “100 Questions &
Answers about Deep Vein Thrombosis and Pulmonary Embolism” by Audra H. James,
MD, Thomas L. Ortel, MD, PhD, and Victor F. Tapson, MD, Copyright © 2008, Jones
and Barlett Publishers, Sudbury, MA.
