A-PTT

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Partial Thromboplastin Time

Partial thromboplastin time (PTT) is a blood test that measures the time it

takes blood to clot. A PTT test can be used to screen for bleeding

abnormalities.

At least a dozen blood proteins, or blood factors, are needed to clot blood

and stop bleeding (coagulation). The partial thromboplastin time is an

important coagulation test because the time it takes your blood to clot may

be affected by:

Medications you take to preent the formation of blood clots (blood!

thinning medication), such as heparin. The actiated partial

thromboplastin time (APTT) test is used after taking blood!thinners to

determine the most effectie dosage of medication that preents blood

clots.

"o# leels of blood proteins (blood clotting factors).

A decrease in actiity of any of the factors.

The absence of any of the factors.

The presence of a substance that blocks the actiity of any of the

factors.

Another blood clotting test, called prothrombin time (PT), measures the

function of seeral other clotting factors. Prothrombin time is often

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measured along #ith partial thromboplastin time to ealuate bleeding

abnormalities. These t#o tests together screen for problems #ith the

normal blood clotting process and can detect most blood clotting problems

caused by abnormal amounts of or abnormal function of coagulation

factors.

Why It Is Done

Partial thromboplastin time (PTT) is done to:

$etermine a possible cause of abnormal bleeding or bruising.

%creen for deficiencies of certain blood clotting factors. The lack of

some clotting factors can cause bleeding disorders such as hemophilia.

%creen for conditions that cause abnormal clotting or blood clot

formation. &onditions such as antiphospholipid antibody syndrome or

lupus anticoagulant syndrome deelop #hen the immune system

produces antibodiesthat attack certain blood clotting factors, causing

the blood to clot easily in eins and arteries.

%creen blood clotting time before a surgery.

The actiated partial thromboplastin time (APTT) test is used to determine

the most effectie dosage of some medications, such as heparin, that

preent blood clots. 'f the test is done for this purpose, an APTT may

initially be repeated eery fe# hours. hen the correct dosage is found,

the freuency of testing is decreased.

How To Prepare
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Many medications can affect PTT test results. Tell your health professional

about all medications you are taking, both prescription and

nonprescription, before haing this test. *o other special preparations are

reuired before haing this test.

How It Is Done

The health professional dra#ing blood #ill:

rap an elastic band around your upper arm to stop the flo# of

blood. This makes the eins belo# the band larger so it is easier to put

a needle into the ein.

&lean the needle site #ith alcohol.

Put the needle into the ein. More than one needle stick may be

needed.

Attach a tube to the needle to fill it #ith blood.

+emoe the band from your arm #hen enough blood is collected.

Apply a gauze pad or cotton ball oer the needle site as the needle

is remoed.

Apply pressure to the site and then a bandage.

How It Feels

ou may feel nothing at all from the needle puncture, or you may feel a

brief sting or pinch as the needle goes through the skin. %ome people feel

a stinging pain #hile the needle is in the ein. -o#eer, many people do

not feel any pain (or hae only minor discomfort) once the needle is

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positioned in the ein. The amount of pain you feel depends on the skill of

the health professional dra#ing the blood, the condition of your eins, and

your sensitiity to pain.

Risks

Blood test

There is ery little risk of complications from haing blood dra#n from a

ein.

ou may deelop a small bruise at the puncture site. ou can reduce

the risk of bruising by keeping pressure on the site for seeral minutes

after the needle is #ithdra#n.

+arely, the ein may become inflamed after the blood sample is

taken. This condition is called phlebitis and is usually treated #ith a

#arm compress applied seeral times daily.

&ontinued bleeding can be a problem for people #ith bleeding

disorders. Aspirin, #arfarin (&oumadin), and other blood!thinning

medications can also make bleeding more likely. 'f you hae bleeding or

clotting problems, or if you take blood!thinning medication, tell your

health professional before your blood is dra#n.

Results

Partial thromboplastin time (PTT) is a blood test that measures the time it

takes blood to clot.

Normal

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*ormal alues may ary from lab to lab.

Partial thromboplastin time (PTT): /012 seconds

Actiated partial thromboplastin time

(APTT):

3204 seconds

The heparin dosage for people being treated to preent the formation of

blood clots is usually ad5usted so that the PTT or APTT is about 6.2 to 3.2

times the normal alue.

Abnormal values

A longer!than!normal PTT or APTT can indicate a deficiency or

abnormality of one of the blood clotting factors or another substance

needed to clot blood. A deficiency of one or more of these factors

results in a bleeding disorder (such as hemophiliaor on illebrand7s

disease).

A long PTT or APTT can be caused by lier disease, kidney disease

(such as nephrotic syndrome), or treatment #ith medications such as

heparin or #arfarin (&oumadin) that are used to preent the formation

of blood clots.

A long PTT may be caused by conditions such as antiphospholipid

antibody syndrome and lupus anticoagulant syndrome that can cause

abnormal clotting or blood clot formation. These syndromes are a

complication of lupusin #hich the immune system produces antibodies

that attack certain blood clotting factors, causing the blood to clot easily

in eins and arteries.
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PTT can be increased #hen aspirin is used during heparin therapy,

so the PTT alue needs to be closely monitored.

What Ae!ts the Test

8actors that can interfere #ith your test and the accuracy of the results

include:

%ome herbal products or natural remedies.

%ome medications, such as antihistamines.

What To Think About

The partial thromboplastin time (PTT) and actiated partial

thromboplastin time (APTT) may be normal in people #ho hae

inherited bleeding disorders #ith only mild symptoms.

The APTT is used to monitor treatment of people #ho are receiing

heparin or other blood!thinning medication to preent the formation of

blood clots.

%ometimes people #ho are receiing heparin hae an increased

APTT because of other substances in their blood and not because of

blood!thinning treatment. A test called the heparin neutralization assay

may be done to determine #hether this is the case.

Another blood clotting test, called prothrombin time (PT), measures

the function of seeral other clotting factors. Prothrombin time is often

measured along #ith partial thromboplastin time to ealuate bleeding

abnormalities. 8or more information, see the medical test Prothrombin

Time (PT).
http://health.yahoo.com/article/healthwise--hw203083/http://health.yahoo.com/article/healthwise--hw203083/http://health.yahoo.com/article/healthwise--hw203083/http://health.yahoo.com/article/healthwise--hw203083/

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A"PTT


Activated Partial Thromboplastin Time, APTT (Activated Parital ThromboplastinTime), PTT (Partial Thromboplastin Time)

Test #verview

Partial thromboplastin time (PTT) is a blood test that measures the time ittakes your blood to clot. A PTT test can be used to check for bleedingproblems.

About 12 blood clotting factors are needed for blood to clot (coagulation). Thepartial thromboplastin time is an important test because the time it takes yourblood to clot may be affected by

!lood"thinning medicine, such as heparin. Another test, the activated

partial thromboplastin time (APTT) test, is a better test to find out ifthe right dose of heparin is being used.

#o$ levels of blood clotting factors.

A change in the activity of any of the clotting factors.

The absence of any of the clotting factors.

%ther substances, called inhibitors, that affect the clotting factors.

An increase in the use of the clotting factors.

Another blood clotting test, called prothrombin time (PT), measures otherclotting factors. Partial thromboplastin time and prothrombin time are oftendone at the same time to check for bleeding problems caused by a problem$ith the clotting factors.

Why It Is Done

Partial thromboplastin time (PTT) is done to

&ind a cause of abnormal bleeding or bruising.

'heck for lo$ levels of blood clotting factors. The lack of some clotting

factors can cause bleeding disorders such as hemophilia.

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'heck for conditions that cause clotting problems. 'onditions such as

antiphospholipid antibody syndrome or lupus anticoagulant syndromedevelop $hen the immune system makes antibodiesthat attack bloodclotting factors. This can cause the blood to clot easily in veins andarteries.

'heck blood clotting time before a surgery. 'heck to see $hether the dose of anti"clotting medicine is right.

The activated partial thromboplastin time (APTT) test is used after you takeblood"thinners to see if the right dose of medicine is being used. f the test isdone for this purpose, an APTT may be done every fe$ hours. hen the correctdose of medicine is found, you $ill not need so many tests.

How To Prepare

*any medicines can change the results of this test. !e sure to tell your doctor

about all the nonprescription and prescription medicines you take.

How It Is Done

The health professional dra$ing blood $ill

rap an elastic band around your upper arm to stop the flo$ of blood.

This makes the veins belo$ the band larger so it is easier to put a needleinto the vein.

'lean the needle site $ith alcohol.

Put the needle into the vein. *ore than one needle stick may be needed.

Attach a tube to the needle to fill it $ith blood. +emove the band from your arm $hen enough blood is collected.

Put a gaue pad or cotton ball over the needle site as the needle is

removed. Put pressure to the site and then a bandage.

How It Feels

The blood sample is taken from a vein in your arm. An elastic band is $rappedaround your upper arm. t may feel tight. -ou may feel nothing at all from the

needle, or you may feel a uick sting or pinch.

Risks

There is very little chance of a problem from having blood sample taken from avein.

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-ou may get a small bruise at the site. -ou can lo$er the chance of

bruising by keeping pressure on the site for several minutes. n rare cases, the vein may become s$ollen after the blood sample is

taken. This problem is called phlebitis. A $arm compress can be usedseveral times a day to treat this.

%ngoing bleeding can be a problem for people $ith bleeding disorders.Aspirin, $arfarin ('oumadin), and other blood"thinning medicines canmake bleeding more likely. f you have bleeding or clotting problems, orif you take blood"thinning medicine, tell your doctor before your bloodsample is taken.

Results

Partial thromboplastin time (PTT) is a blood test that measures the time ittakes your blood to clot. /ormal values may vary from lab to lab.

Normal

Partial thromboplastin time

Partial thromboplastin time (PTT):03 seconds

Activated partial thromboplastin time (APTT):45 seconds

The heparin dose is changed so that the PTT or APTT result is about 1.6 to 2.6times the normal value.

Abnormal values

A longer"than"normal PTT or APTT can mean a lack of or lo$ level of one

of the blood clotting factors or another substance needed to clot blood.This can cause bleeding disorders, such as hemophiliaor von illebrand7sdisease.

A longer"than"normal PTT or APTT can be caused by liver disease, kidneydisease (such as nephrotic syndrome), or treatment $ith blood thinners,

such as heparin or $arfarin ('oumadin). A longer"than"normal PTT may be caused by conditions such as

antiphospholipid antibody syndrome and lupus anticoagulant syndromethat cause clotting problems. These syndromes are a complication oflupusin $hich the immune system makes antibodiesthat attack bloodclotting factors. This can cause the blood to clot easily in veins andarteries.

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The PTT can get longer $hen you are using heparin, so your PTT value

needs to be closely checked.

What Ae!ts the Test

+easons you may not be able to have the test or $hy the results may not behelpful include

Taking some herbal products or natural remedies.

Taking some medicines, such as antihistamines or aspirin.

What To Think About

The partial thromboplastin time (PTT) and activated partial

thromboplastin time (APTT) may be normal in people $ho have inheritedbleeding disorders but have only mild symptoms.

The APTT is used to check treatment of people $ho are using heparin orother blood"thinning medicine to prevent blood clots.

8ometimes people $ho use heparin have a higher APTT because of othersubstances in their blood and not because of blood"thinning medicines. Atest called the heparin neutraliation assay may be done to see if this istrue.

Another blood clotting test, called prothrombin time (PT), measures

other clotting factors. Partial thromboplastin time and prothrombin timeare often done at the same time to check for bleeding problems. &ormore information, see the medical test Prothrombin Time (PT).

An PTT or APTT is done regularly in people $ho have bleeding or clotting

problems. The tests are also done before procedures or surgeries $heretoo much bleeding may be a concern.

Reeren!es

#ther Works $onsulted

'hernecky '', !erger !9, eds. (25). #aboratory Tests and :iagnostic

Procedures, 5th ed. Philadelphia 8aunders. &ischbach &T, :unning *! , eds. (25). *anual of #aboratory and

:iagnostic Tests, 3th ed. Philadelphia #ippincott illiams and ilkins.

Pagana ;:, Pagana T9 (20). *osby

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Return to Encyclopedia Index P

Definition

The partial thromboplastin time (PTT) test is a blood test that isdone to investigate bleeding disorders and to monitor patients takingan anticlotting drug (heparin).

Purpose

Diagnosis

!lood clotting (coagulation) depends on the action of substances inthe blood called clotting factors. *easuring the partialthromboplastin time helps to assess $hich specific clotting factorsmay be missing or defective.

Monitoring

'ertain surgical procedures and diseases cause blood clots to form$ithin blood vessels. =eparin is used to treat these clots. The PTTtest can be used to monitor the effect of heparin on a patient7scoagulation system.

Precautions

'ertain medications besides heparin can affect the results of the PPTtest. These include antihistamines, vitamin ' (ascorbic acid),aspirin, and chlorpromaine (Thoraine).

Description

hen a body tissue is in>ured and begins to bleed, it starts aseuence of clotting factor activities called the coagulation cascade,$hich leads to the formation of a blood clot. The cascade has threepath$ays e?trinsic, intrinsic, and common. *any of the thirteenkno$n clotting factors in human blood are shared by both path$ays@
http://www.healthatoz.com/healthatoz/Atoz/common/standard/transform.jsp?requestURI=/healthatoz/Atoz/ency/p_encyindex.jsphttp://www.healthatoz.com/healthatoz/Atoz/common/standard/transform.jsp?requestURI=/healthatoz/Atoz/ency/partial_thromboplastin_time.jsp&mode=printhttp://www.healthatoz.com/healthatoz/Atoz/tl/misc/email/email.jsp?artitle=Partial%20thromboplastin%20time&url=/healthatoz/Atoz/ency/partial_thromboplastin_time.jsphttp://www.healthatoz.com/healthatoz/Atoz/common/standard/transform.jsp?requestURI=/healthatoz/Atoz/ency/p_encyindex.jsp

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several are found in only one. The PTT test evaluates the factorsfound in the intrinsic and common path$ays. t is usually done incombination $ith other tests, such as the prothrombin test, $hichevaluate the factors of the e?trinsic path$ay. The combination of

tests narro$s the list of possible missing or defective factors.

=eparin prevents clotting by blocking certain factors in the intrinsicpath$ay. The PTT test allo$s a doctor to check that there is enoughheparin in the blood to prevent clotting, but not so much as to causebleeding. The test is done before the first dose of heparin or$henever the dosage level is changed@ and again $hen the heparinhas reached a constant level in the blood. The PTT test is repeatedat scheduled intervals.

The PTT test uses blood to $hich a chemical has been added to

prevent clotting before the test begins. About 6 m# of blood aredra$n from a vein in the patient7s inner elbo$ region. 'ollection ofthe sample takes only a fe$ minutes. The blood is spun in acentrifuge, $hich separates the pale yello$ liuid part of blood(plasma) from the cells. 'alcium and activating substances areadded to the plasma to start the intrinsic path$ay of the coagulationcascade. The partial thromboplastin time is the time it takes for aclot to form, measured in seconds.

The test can be done $ithout activators, but they are usually addedto shorten the clotting time, making the test more useful for

monitoring heparin levels. hen activators are used, the test iscalled activated partial thromboplastin time or APTT.

Test results can be obtained in less than one hour. The test is usuallycovered by insurance.

Preparation

The doctor should check to see if the patient is taking any of themedications that may influence the test results. f the patient is onheparin therapy, the blood sample is dra$n one hour before the ne?t

dose of heparin.

Aftercare

Aftercare includes routine care of the puncture site. n addition,patients on heparin therapy must be $atched for signs ofspontaneous bleeding. The patient should not be left alone until thedoctor or nurse is sure that bleeding has stopped. Patients should

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also be advised to $atch for bleeding gums, bruising easily, andother signs of clotting problems@ to avoid activities that might causeminor cuts or bruises@ and to avoid using aspirin.

Risks

The patient may develop a bruise or s$elling around the puncturesite, $hich can be treated $ith moist $arm compresses. People $ithcoagulation problems may bleed for a longer period than normal.

Normal results

/ormal results vary based on the method and activators used./ormal APTT results are usually bet$een 26"5 seconds@ PTT resultsare bet$een 0"3 seconds. APTT results for a patient on heparin

should be 1.6"2.6 times normal values. An APTT longer than 1seconds indicates spontaneous bleeding.

Abnormal results

ncreased levels in a person $ith a bleeding disorder indicate aclotting factor may be missing or defective. &urther tests are doneto identify the factor involved. #iver disease decreases production offactors, increasing the PTT.

#o$ levels in a patient on heparin indicate too little heparin is in the

blood to prevent clots. =igh levels indicate too much heparin ispresent, placing the person at risk of e?cessive bleeding.

e! Terms

Activated partial thromboplastin timePartial thromboplastin time test that uses activators to shorten the

clotting time, making it more useful for heparin monitoring.

Clotting factorsSubstances in the blood that act in sequence to stop bleeding by

forming a clot.

Coagulationhe process of blood clotting.

Coagulation cascade

he sequence of biochemical activities, involving clotting factors, that

stop bleeding by forming a clot.

Common pathway

he path!ay that results from the merging of the extrinsic and

intrinsic path!ays. he common path!ay includes the final steps

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before a clot is formed.

Extrinsic pathway

"ne of three path!ays in the coagulation cascade.

Heparin

# medication that prevents blood clots.

Intrinsic pathway"ne of three path!ays in the coagulation cascade.


# test that checks the clotting factors of the intrinsic path!ay.

Plasma

he fluid part of blood, as distinguished from blood cells.

"or #our $nformation

Resources

Periodicals

$erry, $rian R., and Stephen %antel. &'eparin herapy( )urrent

Regimens and Principles of *onitoring.& Postgraduate *edicine ++

-une ++/0( /123/.


Partial thromboplastin time (PTT) is a blood test that measures the time it takes your blood to clot.

A PTT test can be used to check for bleeding problems.

About 63 blood clotting factors are needed for blood to clot (coagulation). The partial

thromboplastin time is an important test because the time it takes your blood to clot may be

affected by:

9lood!thinning medicine, such as heparin. Another test, the actiated partial

thromboplastin time (APTT) test, is a better test to find out if the right dose of heparin is being

used.

"o# leels of blood clotting factors.

A change in the actiity of any of the clotting factors.

The absence of any of the clotting factors.

ther substances, called inhibitors, that affect the clotting factors.

An increase in the use of the clotting factors.

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Another blood clotting test, called prothrombin time (PT), measures other clotting factors. Partial

thromboplastin time and prothrombin time are often done at the same time to check for bleeding

problems caused by a problem #ith the clotting factors.

Why It Is Done

Partial thromboplastin time (PTT) is done to:

8ind a cause of abnormal bleeding or bruising.

&heck for lo# leels of blood clotting factors. The lack of some clotting factors can cause

bleeding disorders such as hemophilia.

&heck for conditions that cause clotting problems. &onditions such as antiphospholipid

antibody syndrome or lupus anticoagulant syndrome deelop #hen the immune system makes

antibodiesthat attack blood clotting factors. This can cause the blood to clot easily in eins and

arteries.

&heck blood clotting time before a surgery.

&heck to see #hether the dose of anti!clotting medicine is right.

The actiated partial thromboplastin time (APTT) test is used after you take blood!thinners to see

if the right dose of medicine is being used. 'f the test is done for this purpose, an APTT may be

done eery fe# hours. hen the correct dose of medicine is found, you #ill not need so many

tests.

How To Prepare

Many medicines can change the results of this test. 9e sure to tell your doctor about all the

nonprescription and prescription medicines you take.
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