Partial thromboplastin time (PTT) and activated partial thromboplastin time (aPTT) are used to test for the same functions; however, in aPTT, an activator is added that speeds up the clotting time and results in a
narrower reference range
.
What is the difference between PT and PTT?
The PTT is used to evaluate the
coagulation factors XII, XI, IX, VIII, X, V, II (prothrombin)
, and I (fibrinogen) as well as prekallikrein (PK) and high molecular weight kininogen (HK). A PT test evaluates the coagulation factors VII, X, V, II, and I (fibrinogen).
What does PT and aPTT test for?
Tests that
assess blood clotting
, known as coagulation studies, include prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR).
What is the difference between PT PTT and INR?
The prothrombin time (PT) is a test that helps evaluate your ability to appropriately form blood clots. The international normalized ratio or INR is a calculation based on results of a PT that is used to monitor individuals who are being treated with the blood-thinning medication (anticoagulant) warfarin (Coumadin®).
How do you read aPTT and PT?
A normal PT with an abnormal aPTT means that the defect lies within the intrinsic pathway, and a deficiency of factor VIII, IX, X, or XIII is suggested. A normal aPTT with an abnormal PT means that the defect lies within the extrinsic pathway and suggests a possible factor VII deficiency.
What is a normal PT level?
Most of the time, results are given as what is called INR (international normalized ratio). If you are not taking blood thinning medicines, such as warfarin, the normal range for your PT results is:
11 to 13.5 seconds
.
INR of 0.8 to 1.1
.
What happens if PTT is high?
An abnormal (too long) PTT result may also be due to:
Bleeding disorders
, a group of conditions in which there is a problem with the body’s blood clotting process. Disorder in which the proteins that control blood clotting become over active ( disseminated intravascular coagulation ) Liver disease.
What happens if aPTT is high?
A prolonged aPTT usually means that
clotting is taking longer to occur than expected
(but is associated with increased risk of blood clots if due to a lupus anticoagulant) and may be caused by a variety of factors (see the list below).
What is the normal range for aPTT test?
A normal range is
around 21 to 35 seconds
. But test results will vary depending on equipment and methods used. So standard normal results will differ in each lab. If your aPTT takes longer than normal, it may mean several things.
What is bleeding time test used for?
Bleeding time is a medical test that measures how fast small blood vessels in the skin stop bleeding. The bleeding time test is used to
evaluate how well a person’s blood is clotting
. The test evaluates how long it takes the vessels cut to constrict and how long it takes for platelets in the blood to seal off the hole.
What is a normal value for a PT INR?
In healthy people an
INR of 1.1 or below is considered normal
. An INR range of 2.0 to 3.0 is generally an effective therapeutic range for people taking warfarin for disorders such as atrial fibrillation or a blood clot in the leg or lung.
What does an INR of 1.5 mean?
A result of 1.0, up to 1.5,
is therefore normal
. A low INR result means your blood is ‘not thin enough’ or coagulates too easily and puts you at risk of developing a blood clot. A high INR result means your blood coagulates too slowly and you risk bleeding.
How is PT INR calculated?
The INR is derived from prothrombin time (PT) which is calculated as a ratio of the patient’s PT to a control PT standardized for the potency of the thromboplastin reagent developed by the World Health Organization (WHO) using the following formula:
INR = Patient PT ÷ Control PT
.
What is a high aPTT level?
A typical aPTT value is 30 to 40 seconds. If you get the test because you’re taking heparin, you’d want your PTT results to be more like 120 to 140 seconds, and your aPTT to be
60 to 80 seconds
. If your number is higher than normal, it could mean several things, from a bleeding disorder to liver disease.
What is the principle of prothrombin time?
The Prothrombin Time is a
one-stage test based upon the time required for a fibrin clot to form after the addition of Tissue Factor (TF – historically known as tissue thromboplastin)
, phospholipid and calcium to de-calcified, platelet poor plasma.
How do I lower my prothrombin time?
Increased intake of supplements that contain vitamin K
.
High intake of vitamin K-rich foods
.
Fasting
may reduce factors II, VII, and X, subsequently decreasing PT.
