coagulation lab tests

specimen processing, interferences, PT, PTT

what type of vacutainer is used for coagulation tests? What anticoagulent is inside?

blue top, sodium citrate

what is the ratio of blood to sodium citrate used for coagulation tests? How strong is the sodium citrate used?

9:1, 3.2%

why do we use sodium citrate instead of EDTA for coagulation tests?

sodium citrate binds calcium reversibly

why can’t we use glass test tubes for coagulation testing?

interferes with the calcium ions

why can’t we use short draw specimens for coagulation tests?

messes up the sodium citrate to blood ratio

what is the maximum amount of time the tourniquet can remain on? Why?

1 minute, keeping it on too long elevates vWF and factor 8

when in the order of draw are coagulation tubes drawn?

after blood cultures and before the other additive tubes

when using a straight needle for a PT/PTT tests is a discard tube necessary?

no

when using a butterfly needle for a PT/PTT test is a discard tube necessary?

yes

how should sodium citrate tubes be mixed?

invert 5X and do not shake

how does an underfilled tube affect clot time?

falsely prolonged clot time

how does a hematocrit over 55% affect coagulation tests? What should be done?

less clotting factor present due to reduced plasma volume, citrate adjustment

how does an overfilled tube affect clotting time?

shortened clot time

is low hematocrit criteria for automatic rejection

no

platelet function tests are run on what kind of blood?

whole blood

centrifuged whole blood from which platelets have been removed is called what?

platelet poor plasma

what is the maximum number of platelets to qualify as platelet poor plasma?

less than 10X10³

Lupus anticoagulent assays may require what additional step before testing?

double centrifugation of whole blood

why does Lupus anticoagulent assays need an extra centrifugation step?

phospholipids in platelets interfere with the assay

at what temperature must platelet poor plasma be stored, why?

18-24 C, any hotter and factor 5&8 will be affected, any colder and factor 7 loses functionality

what does refrigeration do to platelet activity?

slows it down

PT must be tested within ____ hours

24

PTT must be tested within ____ hours or ___ hours if the patient is on Heparin

4,1

Platelet aggregation studies must be done within ____ hours

3

ppp can be stored in a -20 freezer for how long?

2 weeks

ppp can be stored in a -70 freezer for how long?

6 months

how must ppp be thawed for use? In what time frame must it be used after thawing?

rapidly at 37%, 1 hour

what are the test interferences for coagulation testing?

Hemolysis, thrombocytosis, lipemia, icterus, cryoglobulins

what are the 2 main causes of falsely prolonged clot time?

short draw, Heparin contaminationwhat are

what are the two main causes of a falsely shortened clot time?

traumatic draw, activation

what are the 4 steps of in vivo coagulation?

initiation, amplification, propagation, termination

what happens in the initiation step of in vivo coagulation?

the damage of the epithelium causing exposure to tissue factor that stimulates all your factor activity

what triggers the amplification step of in vivo coagulation?

caused by initiation platelet activity and factor activity occurring on the surface of platelets wherever possible

what happens during the propagation step of in vivo coagulation?

the activity of one platelet stimulating all the platelets next to it causing them to produce thrombin causing them to participate in turning fibrinogen into fibrin and making one strong clot

what happens during the termination step of in vivo coagulation?

regulatory pathways kick in and slow things down

what are the four coagulation studies run on platelets?

PLT count, CT (PFA-100), Aggregation studies, Adhesiveness studies

what are the 6 coagulation studies?

PT, PTT, TT, Fibrinogen assay, Factor assays, Mixing studies

what are the 4 fibrinolysis studies?

D-Dimer, Antithrombin, protein C, protein S

The PT test also called the ______ test has a reference range of ________. It uses ______ and ______ to evaluate the ______ and _____ pathways. Specifically it looks for deficiencies in factors ____, ____, ____, ____, and ______. a deficiency of any of these will lead to a/an ______ PT. Before the test is run, _____ must be added back into the specimen to replace what sodium citrate took out.

Prothrombin Time, 12.6-14.6 seconds, tissue factor, calcium, extrinsic, common, 2, 7, 5, 10, fibrinogen, increased, calcium

what factor activates the extrinsic pathway?

tissue factor

at what temperature do clotting factors function best?

37 C

How is a PT Test conducted?

mix together plasma, calcium, and tissue factor and measure time until clot formation

which clotting factors are bypassed in a PT Test?

factor 8 and factor 9

a PT test is the method of choice for monitoring patients on what type of therapy?

vitamin K antagonist anticoagulation therapy like Warfarin

what factors does Warfarin inhibit? Why?

2,7,9,10, inhibits vitamin K

what is INR?

international standardized ratio, standardizes PT primarily for vitamin K monitoring

what is ISI?

international sensitivity index

what is the formula for INR?

INR=(PT/ mean normal PT)^ISI

what is the PT reagent

tissues factor + phospholipids + CaCl2

what is the reference range for INR?

0.9-1.1

what is the therapy range for INR?

2-3

what is an elevated INR associated with?

extrinsic pathway deficiencies

what are the Limitations of PT testing?

coag tube underfilled, Hct > 55%, clotted specimen, Hemolysis, Icterus, Lipemia, Heparin therapy

an aPTT test or a _____ has a reference range of _______. It tests both the ______ pathway and the _____ pathway. The reagents for this test include _____, ______, and ____.

activated partial thromboplastin time, 25-35 seconds, intrinsic, common, CaCl2, negatively charged activator of contact phase, phospholipid component of thromboplastin

what two factor does the aPTT not detect deficiencies in?

factors 7 and 13

what are the contact factor phase reagents?

pre-kalikrein, HMWK, factor 12

in vitro factor 12a accelerates factor ___

11

in vivo factor 12a accelerates _____

the conversion of pK to Kalikrein

what does bradykinin regulate?

inflammation and pain

what can cause a prolonged aPTT?

intrinsic factor deficiencies, pK deficiency, HMWK deficiency, Lupus anticoagulant factors, heparin therapy, DIC, vitamin K deficiency

what can cause a shortened aPTT time?

clots/fibrin, unfractionated heparin, elevated fibrinogen, cancer (not liver)

When can an aPTT not be run?

when a patient is on low molecular weight heparin

TT or _____ is not a common test. It measures the conversion of ____ to ____ using the reagents _____ and _______. The reference range is _____.

Thrombin Time, fibrinogen, fibrin, low concentration bovine thrombin, undiluted plasma, less than 21 seconds

what can cause a prolonged TT?

low fibrinogen, dysfibrinogenemia, heparin contamination, anti-thrombin antibodies, abnormal fibrinogen function, thrombin inhibition due to D-Dimers

the fibrinogen assay also known as the ______ has a reference range of ____. It measures the conversion of _____ to _____ using the reagents ______, ______, and ______.

Clauss method, 220-498, fibrinogen, fibrin, thrombin, ppp, 1:10 Owren buffer

calibrations for the fibrinogen assay’s curve must be done when?

every 6 months, after maintenance, with every lot number change

The ACT test has a reference range of _____. It is a _____ test that uses ______, _____, and a _____to detect ____. it is mechanical and sends electrical wavelengths through the sample

70-180 seconds, point of care, whole blood, clotting activator, magnet, clots

Mixing studies check to see if patient ____ are fixable. It is done if there is a prolonged ____ or ____. plasma is mixed with ____ in equal parts. If the deficiency corrects then the patient has a deficiency of ______. If it doesn’t correct, the patient may have ______. Repeat _____ after incubation at 37 C for 2 hours. This last step detects factor ____ inhibitors if the test is still prolonged

coagulopathies, PT, aPTT, normal pooled plasma, one or more clotting factors, inhibitor, aPTT, 8

what are the limitations of mixing studies?

severe deficiencies, multiple factors involved, weak inhibitor

before doing a Single Factor Assay you should first complete what 5 tests?

PT, aPTT, modified TT, chromogenic factor 13, common pathway

a Single Factor Assay has 2 steps.

1) 1:1 normal _____ with ________ plasma.

2) 1:1 patient ____ plasma with ______ platelet poor plasma

plasma, factor depleted platelet poor, platelet poor plasma, factor depleted platelet poor plasma

what is a factor 13 and clot solubility test?

an ELISA test and urea solubility test to evaluate clot stability

what are the steps of a clot solubility test?

add thrombin and Ca reagent to citrated plasma, wait for clot and remove clot to new tube, add 5 moles urea and incubate 24 hrs, if clot dissolves factor 13 is absent

Platelet counts have a reference range of _______. The formula for a platelet count is _____. less than _____ is the start of clotting issues, less than ______ is a transfusion, less than ______ is spontaneous bleeding. Elevated platelets can be due to _____, ______, or ______.

150-450X10³, PLTs = (PLTs/volume)X dilution factor, 100X10³, 50X10³, 20X10³, ALL, CLL, polycythemia vera

Bleeding time is a test that measures the ability to ______. it is measured in ____. To preform the test a cut is made and the blood is dabbed away until blood stops coming out. This test has been replaced by the _____ test.

form a platelet plug, seconds, PFA-100

the CT test or the ____ test accesses platelet function via _______. It simulates the ____ conditions blood undergoes inside the body. Prolonged CT can be due to ____, ____, ____, or ____. PFA simulates _______ and ______ but outside the body. It utilizes cartridges made of ______ and either _____ or _____.

closure time, primary hemostasis, high sheer, vWD, low PLT count, low Hct, impaired PLT function, PLT adhesion and aggregation, membrane with collagen, epinephrine, ADP

CT test is used to screen for what things?

vWD, monitoring drug therapies, increased release of vWF and factor 8

what are the limitations of CT?

low PLT count, Hct less than 35%, mild PLT defects not detected

if col/Epi < 180 sec ______

if col/Epi > 180 sec ______

if col/ADP < 120 sec ______

if col/ADP > 120 sec _____

no PLT dysfunction, Col/ADP cartridge, asprin induced dysfunction, anemia or thrombocytopenia or vWD

Coagulation QC must be run at ____ levels every ____ hours or every shift. ___ and ___ of reagents must be monitored

2, 8, temperature, lot numbers

what does anti factor 10a test?

medications that inhibit factor 10a

what does factor 5 Leiden test?

a mutation of factor 5wha

what are the 2 types of anticoagulant therapies?

indirect thrombin inhibitors and direct thrombin inhibitors

what are the two subtypes of indirect thrombin inhibitors?

vitamin K antagonists, anti-10a anticoagulants

Vitamin K antagonists are a group of anticoagulents that prevent the _______ of thrombotic factors, They interfere with ______ and prevent _______ factors from becoming fully functional. They can take up to ___ days to reach full effect and specimens are stable for _____ hours. monitoring of theraputic effects is done via the _____ test. One example of a vitamin K antagonist is _____.

thromboxylation, vitamin k recycling, newly synthesized, 5, 24, PT, Warfarin

What things can increase bleeding risk while on Warfarin?

NSAID, Asprin, antibiotics, sertraline, fungal medications, omeprazole, naproxen sodium, heart/bp meds.

What are vitamin k antagonists used to prevent?

thrombosis, thromboembolism

what is the half life of Warfarin?

36 hours

what medications can increase clotting risk when combined with warfarin?

antibiotics, antisiezure drugs, St. John’s wart, vitamin K rich foods, grapefruit juice, Liver enzymes, alcohol

what factor is the most impacted by Warfarin? What is its half life?

factor 7, 6 hours

what is the therapeutic dose for Warfarin? How long does it take? what is the INR range?

5-10 mg daily, takes 4-10 days, 2.0-3.0 if prosthetic heart valve then 2.5-3.5

What are the potential complications of Warfarin?

Hemorrhage, Fetal Warfarin syndrome, Purple toe syndrome

How are the effects of warfarin reversed in the event of a Hemorrhage? what about a non-hemorrhage?

FFP and vit. K, vit. K and prothrombin

Heparin, an _______ therapy, works by activating _____. It inhibits the activation of factors ___, ____, _____, and ____. binding of heparin changes the shape of _____. 10a prevents _____ generation and 2a prevents _____ from becoming _____. There are two types of Heparin, _____ and _____.

anti 10a anticoagulent, antithrombin, 9, 10, 11, 12, antithrombin, fibrinogen, fibrinogen, fibrin, UFH, LMWH

UFH which forms longer heparin chains is able to inactivate factors ____, _____, ____, and _____ while LMWH only inactivates ____

9, 10, 11, 12, 10a

With the use of UFH anticoagulation is ______. It is administered intravenously and inactivates factors ____, ___, ____, ____, and _____. It is used to treat ______, _____, ______, and _____. The effects can be reversed by administration of _______ which comes from _____.

rapid, 9, 10, 11, 12, 2a, venous thromboembolism, acute MI, after stent placement, cardiac injury, protamine sulfate, salmon sperm

How is UFH monitored?

via aPTT, anti-10a assay, and ACT

what is the monitoring protocol for a patient on UFH

aPTT baseline pre-treatment, follow up aPTT 4-6 hours later, daily testing after therapeutic dose is found

can patients receive UFH if they have an Antithrombin deficiency

no, use DTI instead

LMWH is ____ of the weight of heparin, it inhibits ____ and is given _____. The following anticoagulation is _____. It is used for cases of ______, ______, ______, in ______ when Warfarin can’t be used, ______ when warfarin can’t be used.

1/3, 10a, subcutaneously, rapid, deep vein thrombosis, pulmonary embolism, unstable angina, pregnancy, surgery