What factors could affect my test results?
Various medications can affect the results. These include medicines used to help prevent blood clots, such as the following:
Warfarin
Aspirin
Other anticoagulants, such as direct thrombin inhibitors and factor Xa inhibitors
Heparin
Other medications that can affect the results:
Some steroids
Antibiotics
Estrogen medications
Antacids
If the blood sample is not collected correctly, the test results may also be affected.
How do I prepare for this test?
You usually do not need to prepare for this test. Your healthcare provider will tell you if you will need to avoid eating or drinking in the hours leading up to the test. You may ask him to stop taking any medications that may affect the test results, especially those preventing blood clotting. Make sure your healthcare provider knows all the medicines, herbs, vitamins, and supplements you use. This includes over-the-counter medications and any illegal drugs you may be using.
What is this test?
Prothrombin time is one of several tests used to assess whether your blood is clotting properly. Blood clotting is necessary to help stop bleeding. Proteins in the blood called clotting factors (coagulants) help make the blood sticky and clot. They make it go from a liquid to a solid-state.
As soon as you begin to bleed, either internally or on the body’s surface, platelets in the blood collect around the bleeding area. Then platelets and clotting factors react to thicken the blood and stop bleeding. Blood problems, including deficiencies in clotting factors or platelets, can usually prevent the blood from clotting and cause abnormal bleeding.
The liver generally produces clotting factors. Prothrombin is a type of clotting factor. When bleeding occurs in any part of the body, prothrombin quickly turns into thrombin. The prothrombin time test is used to measure how quickly prothrombin converts to thrombin to stop bleeding. If the prothrombin does not convert at the standard rate, the cause could be a blood clotting disorder.
The prothrombin time test can help diagnose inherited disorders and other conditions that can affect blood clotting. Among them are the following:
Vitamin K deficiency
Deficiency in clotting factors I, II, V, VII, or X
Liver diseases
Hemophilia
Bone marrow problems
Von Willebrand disease
Immune system problems
Some types of cancer, including leukemia
Why should I have this test?
You may need it if you have symptoms of a bleeding disorder. They may include the following:
Abnormal menstrual periods in women
Frequent nosebleeds
Bleeding occurs more quickly.
Bruises that form more easily
Excessive bleeding
The appearance of blood in the stool
You may need to have this test regularly if you take a blood thinner, such as warfarin. This is to make sure you are taking the correct dose.
You may also need this test before surgery or a procedure. This is to make sure that the blood is clotting generally not to have bleeding problems after the surgery or procedure.
What other tests could I have along with this one?
You may need other tests to measure the ability of your blood to clot normally. They may include the following:
Thrombin time test or TT
Activated Partial Thromboplastin Time (aPTT)
Other tests to measure different aspects of blood clotting, such as platelet function
The prothrombin time (PT) test measures the time it takes for a clot to form in a blood sample. A clot is a thick mass of blood that the body produces to seal blood leaks through wounds, cuts, or scrapes to prevent excessive bleeding.
The ability of blood to clot requires the participation of platelets (also called “thrombocytes”) and proteins called “clotting factors.” Platelets are oval-shaped cells that are made in the bone marrow. Most clotting factors are manufactured ican in the liver.
What is the test requested for:
The PT test is ordered to assess the activity of five different clotting factors (I, II, V, VII, and X). The clotting time is lengthened when any of these factors is not detected but in an insufficient quantity or is defective.
Causes of increased Prothrombin Time:
Liver diseases: Liver cirrhosis and acute liver failure cause increased prothrombin time due to insufficient production of coagulation proteins. In these cases, there is no improvement after the use of vitamin K.
Vitamin K deficiency: Vitamin K is an essential cofactor for the activation of coagulation proteins, so its deficiency prolongs the prothrombin time. The causes of vitamin K deficiency are multiple: use of antibiotics, bile duct obstruction, inadequate intake or malabsorption. The use of vitamin K is beneficial in patients with jaundice since a correction indicates adequate production of coagulation proteins by the liver.
What do my test results mean?
Test results may vary based on your age, gender, medical history, the method used for testing, and other factors. The results may not mean you have a problem. To find out what they mean, talk to your healthcare provider.
The result of this test is generally expressed in seconds. The average clotting time is generally between 11 and 13 seconds. If your blood doesn’t clot within that normal range, you may have a bleeding or clotting disorder.
Suppose this test is done because you are taking a blood thinner, such as warfarin. In that case, the result is usually expressed as a number that compares your result to an expected value, known as the international normalized ratio (INR). . Healthcare providers generally look for the INR to be between 2.0 and 3.0 in people taking a blood thinner, such as warfarin.
How is this test done?
For the test, a blood sample is required. A needle is used to draw blood from a vein in the arm or hand.
Does this test involve any risks?
Taking a blood sample with a needle carries risks. These include bleeding, infection, bruising, or feeling dizzy. When your arm or hand is pricked with the needle, you may feel a slight stinging or pain. Afterward, the area may be sore.
