Upgrade to remove ads
Only $35.99/year

Hematology Lab Medicine Coagulation Studies

Terms in this set (57)

Test used to help detect and diagnose a bleeding disorder or excessive clotting disorder
prothrombin time (PT)
Evaluate coagulation factors that are part of different groups of chemical reaction pathways in the cascade, called the intrinsic, extrinsic, and common pathways.
PTT and PT tests
Screening test that helps evaluate a person's ability to appropriately form blood clots. Usually ordered with a PT study as well.
PTT or aPTT (known as partial thromboplastin time or activated PTT)
Evaluates how well all of the coagulation factors in the extrinsic and common pathways of the coagulation cascade work together.
PT test
PT test included factors
o I (Fibrinogen),
o II (Prothrombin),
o V
o VII
o X.
PTT or aPTT included factors
XII, XI, IX, VIII, X, V, II (prothrombin), and I (fibrinogen) as well as prekallikrein (PK) and high molecular weight kininogen (HK).
Longer than that of normal bleeding time— it means that one of the clotting factors in the system measured is impaired, inactive, absent or defective
prolonged PT or aPTT result
Monitor the anticoagulant drug warfarin to make sure that the drug is producing the desired effect. Plus a bunch of other shit.
Indications for ordering a PT
PTT is used primarily to investigate unexplained
bleeding or clotting
Normal INR =
1.0
Primary indication for ordering an INR
Used to monitor individuals who are being treated with the anticoagulant medication warfarin (Coumadin®).
INR range for people taking warfarin is _____ to _____ for basic "blood-thinning" needs. For some who have a high risk of a blood clot, the INR needs to be higher - about _____ to _____. Most common range is _____to_____.
2.0 to 3.0
2.5 to 3.5
2.0 to 3.0
If the INR is below _____, it is subtherapeutic and the patient is at higher than desired risk for a thromboembolic event.
2.0
If the INR is above _____, it is supratherapeutic and the patient is at higher than desired risk for a bleeding event
3.0
A mixing study is used to study the cause of a
prolonged PT
This study can determine if the cause is a deficiency of one or more factors or an inhibitor.
mixing study
In a mixing study, platelet-free, normal plasma that has all coagulation factors (near 100% activity for each) is mixed with the patient sample. When addition of normal plasma fails to correct the clotting time into the normal range, the cause of the abnormal test is likely a?
inhibitor
· Unexplained or prolonged bleeding
· A harmful blood clot (thrombosis)
· Abnormal PT and PTT test results
· Symptoms and signs of disseminated intravascular coagulation (DIC) or undergoing treatment for DIC or abnormal fibrinolysis
· Symptoms suggesting an inherited or acquired coagulation factor (clotting protein) deficiency or dysfunction
· Been diagnosed with an acquired bleeding disorder to evaluate and monitor clotting ability (over time)
situations when fibrinogen tests should be ordered
May be performed when there is an abnormally low result on a fibrinogen activity test to help determine whether it is due to low fibrinogen or fibrinogen that does not function properly.
fibrinogen antigen test
Low fibrinogen levels that persist over time (chronic) may be related to the body's inability to produce fibrinogen due to:
End-stage liver disease or severe malnutrition
Disseminated intravascular coagulation (DIC)
Abnormal fibrinolysis
Reduced fibrinogen levels may also occur following
rapid, large-volume blood transfusions
o Infections
o Cancer
o Coronary heart disease, heart attack
o Stroke
o Inflammatory disorders (like rheumatoid arthritis and glomerulonephritis, a form of kidney disease)
o Trauma
o Peripheral artery disease
o Heavy smoking
Things that can cause Increased fibrinogen levels:
One of the final fibrin degradation protein fragments produced when a blood clot gets dissolved in the body. It is normally undetectable or detectable at a very low level unless the body is forming and breaking down blood clots. Then, its level in the blood can significantly rise.
D-dimer
· For a person who is at low or intermediate risk for blood clotting (thrombosis) and/or thrombotic embolism, the strength of the __________ test is that it can be used in a hospital emergency room setting to determine the likelihood of a clot's presence.
D-dimer
(D-dimer level is below a predetermined cut-off threshold) indicates that it is highly unlikely that a thrombus is present.
A negative D-dimer test
Cannot predict whether or not a clot is present. It indicates that further diagnostic procedures are required (e.g., ultrasound, CT angiography).
positive D-dimer test
Some of the conditions that the D-dimer test is used to help rule out include:
DVT
Pulmonary embolism
Stroke
Diseases and conditions that cause hypercoagulability
Disseminated intravascular coagulation (DIC)
Factor 8 deficiency
hemophilia A
Factor 9 deficiency
hemophilia B
Typically ordered when someone has a prolonged prothrombin time (PT) and/or partial thromboplastin time (PTT) when someone has signs and symptoms of a bleeding disorder, such as unexplained bruising, bleeding gums, excess bleeding from small cuts, or frequent nose bleeds.
Coagulation factor tests
Factor activity may be measured when a that a patient has an acquired condition that is causing bleeding, such as
vitamin K deficiency or liver disease
Factor testing may be done when a healthcare practitioner suspects that a patient has an inherited coagulation factor deficiency such as ___________ or _________, especially when bleeding episodes begin early in life or when a close relative has an inherited factor deficiency.
Von Willebrand disease or hemophilia A
· Von Willebrand factor (VWF) testing measures the amount of the __________ present in blood and determines how well it functions.
protein
Ordered after initial screening tests for a bleeding disorder (such as platelet function tests, PT, PTT) have been performed to investigate someone's personal or family history of excessive or recurrent bleeding episodes
VWF testing
o Frequent or repeated nose bleeds
o Excessive bleeding from the gums after dental procedures
o Excessive bruising after minor knocks or injuries
o Heavy and/or prolonged menstrual bleeding in women
o Blood in urine or stool
o Prolonged bleeding after surgery
The signs and symptoms that may prompt testing vary depending on the type of VWD an individual has
The most common inherited bleeding disorder
von Willebrand factor
Responsible for helping platelets stick to the injured blood vessel wall. It is also the carrier protein for factor VIII.
The von Willebrand factor (vWF)
Genetic mutations that are associated with an increased risk of developing inappropriate blood clots.
Factor V Leiden and prothrombin 20210 (PT 20210 or Factor II mutation)
Most common inherited predisposition to excessive clotting.
Factor V Leiden mutation
· Has a first deep venous thrombosis (DVT) or venous thromboembolism (VTE) before age 50 that is unprovoked
· Has recurring DVT or PE
· Has a blood clot in an unusual part of the body such as the veins of the liver (hepatic), the kidneys (renal), the brain (cerebral), the gut and pelvis (mesenteric), or in the eye veins
· Has a personal or family history of recurrent DVT or VTE
· Has a first VTE related to oral contraceptive use, pregnancy or hormone replacement therapy
· Experiences unexplained miscarriages, especially those occurring in the second or third trimester of pregnancy
Reasons when a patient should be tested for a Factor V Leiden mutation or a Prothrombin 20210 mutation.
Two proteins in the blood that help regulate blood clot formation—in essence they are natural anticoagulants
Protein C and protein S
This protein acts as a principal cofactor to protein C. The two work together to help regulate and control blood clot formation by inactivating specific coagulation factors (factors V and VIII) that are required to generate and form blood clots.
Proteins S
This has the net effect of slowing down clot formation, much like brakes slow a speeding car. Therefore, if there is not enough protein C or S or they are not functioning normally, clot formation can go unchecked, possibly leading to excessive clotting. These conditions can range from mild to severe.
protein C and protein S deficiency
May be due to an underlying condition (acquired), such as liver disease, kidney disease, severe infections or cancer, or can be inherited, passed from parent to child.
Deficient or dysfunctional protein C or protein S
List the 3 antiphospholipids antibodies
lupus anticoagulant antibody, cardiolipin antibodies, and beta-2 glycoprotein 1 antibody
One of three primary antiphospholipid antibodies that are associated with an increased risk of thrombosis and antiphospholipid antibody syndrome (APS), an autoimmune disorder characterized by excess blood clot formation, organ failures, and pregnancy complications.
The lupus anticoagulant antibody
Individually and together, they increase a person's tendency to clot inappropriately. People with APS are at greater risk for clotting if they test positive for all three antibodies.
cardiolipin antibodies and beta-2 glycoprotein 1 antibody
Are frequently ordered since they are the most common antiphospholipid antibodies.
Cardiolipin antibodies
Antiphospholipid antibody test ordered if a person has a prolonged PTT test.
Lupus anticoagulant assays
May be ordered along with the other antiphospholipid antibodies to detect their presence and to provide additional information.
Beta-2 glycoprotein 1 testing
Serious, sometimes life-threatening condition in which the proteins in the blood involved in blood clotting become overactive.
Disseminated intravascular coagulation (DIC)
Tests for DIC
CBC
Blood smears
PT/PTT
D-dimer
Fibrinogen
CBC finding in DIC
platelets are often low
___________ from individuals with DIC often show decreased number of platelets and presence of large platelets and fragmented red cells (schistocytes).
Blood smears
Often prolonged with DIC as coagulation factors are consumed
PT/PTT
It is often markedly elevated with DIC; if normal, then DIC is unlikely.
D-dimer
One of the clotting factors; is low with DIC
Fibrinogen
Students also viewed