Prothrombin with INR and Partial Thromboplastin Times (PTT)

Prothrombin with INR and Partial Thromboplastin Times (PTT)

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The tests are usually ordered for patients prior to surgery to ensure normal clotting ability.  The PT and PTT Blood Tests are useful in the diagnosis of excessive, unexplained bleeding in patients who are not taking blood-thinning medications. These bleeding disorders include conditions such as nosebleeds, bruising, heavy menstrual periods, blood in the stool and/or urine, and bleeding gums, among others,

Doctors usually require this test before surgeries to ensure someone can coagulate properly during an operation.

Prothrombin with INR and Partial Thromboplastin Times - PT/INR: A screening test for abnormalities of coagulation factors that are involved in the extrinsic pathway. Also used to monitor the effects of Warfarin therapy and to study patients with hereditary and acquired clotting disorders.

The PT and PTT Blood Tests are helpful in the diagnosis of excessive, unexplained bleeding in patients who are not taking blood-thinning medications. These bleeding disorders include nosebleeds, bruising, heavy menstrual periods, blood in the stool and/or urine, and bleeding gums. The tests are sometimes ordered for patients before surgery to ensure normal clotting ability.

A “prolonged” result means a blood clot takes longer than normal to form. There are a variety of causes for this, including coagulation/clotting factor deficiency/dysfunction, vitamin K deficiency, liver disease, inhibition by specific antibodies, and others. The general interpretation of PT & PTT Blood Test results can be summarized as follows:

  • PT prolonged, PTT prolonged: Dysfunctional or insufficient coagulation factor I, II, V, or X; acute disseminated intravascular coagulation (DIC) (abnormal activation of coagulation factors); severe liver disease.

  • PT prolonged, PTT normal: Dysfunctional or insufficient coagulation factor VII, chronic low-grade DIC, insufficient vitamin K, liver disease, warfarin (anticoagulant) therapy.

  • PT normal, PTT prolonged: Dysfunctional or insufficient coagulation factor VIII, IX, or XI; severe von Willebrand disease (hereditary bleeding disorder); the presence of lupus anticoagulant.

  • PT normal, PTT normal or slightly prolonged: Normal clotting ability, mild deficiencies in other coagulation factors, a mild form of von Willebrand disease.

Are you familiar with the terms INR and PTT? If not, don't worry. This essential guide will walk you through everything you need to know about mastering Prothrombin. We've got you covered, from understanding why these tests are necessary and when to get them done to the preparation required and the interpretation of the test results. We'll also answer common questions like whether you can do this test at home, what food and medications can affect the results, and more. Additionally, we'll provide information on related tests and sources for further reading. Stay tuned as we delve into this important aspect of healthcare and show you how to buy an affordable INR and PTT test on

Prothrombin with INR and Partial Thromboplastin Times (PTT): At a Glance

Measurements of blood clotting ability rely on tests like prothrombin time (PT) and international normalized ratio (INR). These tests are particularly important for patients taking anticoagulant medications, such as warfarin. Monitoring PT and INR values helps determine the appropriate anticoagulant dosage and evaluate the risk of bleeding or clotting. Another vital test, the partial thromboplastin time (PTT), assesses a different aspect of the clotting process. Healthcare professionals involved in managing patients with coagulation disorders or undergoing anticoagulant therapy must understand and interpret PT, INR, and PTT results effectively.

Why Get Tested for Prothrombin Time with INR?

Regular testing for PT and INR is crucial for individuals on blood-thinning medications like warfarin. It helps monitor blood clotting, assess medication effectiveness, and reduce the risk of complications. Especially important for those with conditions like atrial fibrillation or deep vein thrombosis. Testing also gives healthcare professionals a specimen to analyze and make informed decisions regarding the patient's treatment plan. Physicians also order the  PTT test for patients scheduled for surgery to ensure that the patient has not clotting issues that could endanger him or her during the operation.

When To Get Tested?

If you are taking anticoagulant medication or have a bleeding disorder, getting tested for INR and PTT is important. Your healthcare provider will determine the frequency based on your condition and treatment plan. Following their instructions and scheduling regular testing will help ensure proper management of your prothrombin levels.

Is a Sample Required?

Yes, a blood sample is necessary for both INR and PTT tests. The sample is typically taken from the arm using a needle prick and sent to a lab for analysis. It's crucial to follow any fasting or medication guidelines your healthcare provider gives before the test.

What Test Preparation is Needed?

Test preparation for INR and PTT blood tests may differ based on your medical condition and medications. Preparations may include fasting or avoiding specific medications that affect clotting factors. Follow your healthcare provider's instructions and inform them of any medication, supplement, or herbal remedy usage to ensure accurate test results.

What is Being Tested?

The tests being conducted are the INR (International Normalized Ratio) and PTT (Partial Thromboplastin Time) tests, which are used to monitor blood clotting. The INR test measures how your blood clotting time compares to a standardized control sample, while the PTT test measures your blood's response to specific substances. These tests help identify clotting disorders and ensure that anticoagulant medication is at the appropriate dosage.

Common Questions About Prothrombin Time with INR

The Prothrombin with INR and Partial Thromboplastin Times (PTT) blood tests are crucial in monitoring blood clotting and detecting clotting disorders. These tests offer insights into the coagulation process and help healthcare providers assess the effectiveness of anticoagulant therapy. It is essential to understand the purpose of these tests, their conduct, and the implications of abnormal results. Patients often have queries regarding the influence of food and medications on PT and INR test results. Additionally, they may question the need for consistent testing times and the reasons behind varying PT/INR results despite stable medication dosages.

How is the test used?

The prothrombin time (PT) test measures how long blood takes to clot, mainly to monitor the effectiveness of anticoagulant medications. It's also used to diagnose bleeding disorders and liver disease. Results are reported as an international normalized ratio (INR) for standardization.

When is it ordered?

PT and INR tests are typically ordered to monitor blood-thinning medications, investigate unexplained bleeding or clotting disorders, assess bleeding risk before surgeries, and evaluate blood clotting function in specific medical conditions like liver disease or vitamin K deficiency.

What does the test result mean?

The test result is measured using the INR and PTT. A higher INR suggests a longer clotting time, while a longer PTT may indicate a bleeding disorder. Consulting a healthcare professional is crucial for interpreting the results and deciding on suitable treatment or monitoring.

Interpretation of PT and PTT in Patients with a Bleeding or Clotting Syndrome

PT (Prothrombin Time) and PTT (Partial Thromboplastin Time) are vital laboratory tests used to assess the clotting ability of a patient's blood in cases of bleeding or clotting disorders. These tests measure the duration it takes for blood to clot; abnormal results can indicate potential issues with clotting factors. In patients presenting with bleeding disorders, an extended PT or PTT may suggest a deficiency in essential clotting factors like Factor II (prothrombin), Factor V, or Factor VII. Conversely, a shortened PT or PTT may indicate an excess of clotting factors in patients with clotting disorders, as observed in Factor V Leiden mutation or lupus anticoagulant. Accurate interpretation of PT and PTT results in conjunction with clinical symptoms and other laboratory tests is necessary to establish the underlying cause of bleeding or clotting abnormalities.

What foods and medications can affect PT and INR results?

Certain foods rich in vitamin K, like leafy greens and broccoli, can impact PT and INR results. Medications such as antibiotics and anti-inflammatory drugs can also affect these levels. It's crucial to inform your healthcare provider about any dietary changes or medications you're taking, as they may need to adjust dosages or suggest dietary modifications based on your PT and INR results.

I am being treated with warfarin (Coumadin®). Should I avoid eating foods that are rich in vitamin K, and will limiting these foods cause an increased risk of vitamin K deficiency?

If you are being treated with warfarin (Coumadin®), it is crucial to maintain a consistent intake of vitamin K-rich foods. Avoiding or drastically limiting these foods can lead to an increased risk of vitamin K deficiency and may affect the effectiveness of warfarin. Instead, strive for a balanced diet and consult your healthcare provider to manage your warfarin therapy properly.

Should I have a PTT done at the same time of day?

It is generally advised to have a prothrombin time (PT) test done at the same time of day for consistency. This helps in identifying any patterns or fluctuations in blood clotting levels. However, follow specific instructions from your healthcare provider regarding timing. Consult with them for personalized guidance on when to schedule your PT test.

My PT/INR results vary sometimes, yet my doctor doesn’t change my prescription. Why?

Your PT/INR results can fluctuate due to various factors like diet, medication changes, or illness. Your doctor may not alter your prescription if the variations are within an acceptable range and take into account your overall health and medical history. However, it's crucial to communicate any concerns or questions you have about your PT/INR results with your doctor.

A prolonged prothrombin time with INR result can be caused by a medical condition, medications, and other factors.

Medical conditions:

  • Vitamin K deficiency, which may be secondary to malabsorption or antibiotic therapy; administration of vitamin K will lead to a significantly shorter PT or normalization within 12-24 hours
  • Liver disease (due to diminished production of clotting factors)
  • Hematocrit >55% (common in newborns and patients with polycythemia vera)
  • Disseminated intravascular coagulopathy (DIC)
  • Clotting factor deficiencies (factors II, V, VII, X, fibrinogen)


  • Direct thrombin inhibitors (ie, dabigatran, argatroban)
  • Factor Xa inhibitors (rivaroxaban, fondaparinux)
  • Excessive heparin (ie, >2.0 IU/mL)


  • Gross lipemia
  • Lupus anticoagulants. Most PT-INR reagents contain excess phospholipid that neutralize lupus anticoagulants. However, strong lupus anticoagulants can cause a mild prolongation or accentuate the prolongation of the PT when patients are on warfarin. In these situations, a chromogenic factor X assay (test code 10663) can be used rather than, or in addition to, the PT-INR to monitor warfarin.

Consider testing for vitamin K-dependent clotting factors (VII, X, II) and a nonvitamin K-dependent clotting factor (V). Together with the patient's medical history, these tests can help tell the difference between a coagulopathy caused by a lack of vitamin K, hepatic insufficiency, or a lack of a single factor.

Depending on the clinical context, a fibrinogen or DIC evaluation (D-dimer, antithrombin III activity, platelet count, fibrinogen, aPTT, and PT) may be helpful.

How to Buy an Affordable Prothrombin Time with INR Test on

Looking to purchase a high-quality and affordable INR and PTT test? Look no further than, where we understand the importance of monitoring your prothrombin levels and assessing your blood clotting ability. With our user-friendly website and extensive range of tests, finding the right option for your needs has never been easier. Our tests are accurate and reliable, providing you with the peace of mind you deserve. Once you receive your results, our team of experts is here to help you interpret and understand them thoroughly. Don't compromise your health; choose for all your INR and PTT test requirements.


Understanding your Prothrombin Time (PT) and Partial Thromboplastin Time (PTT) levels is crucial for managing your health. These tests help ensure that your blood is clotting properly and can detect any potential bleeding or clotting disorders. You and your healthcare provider can make informed decisions about your treatment plan by monitoring these levels. If you're curious about how to interpret test results, the importance of timing, or if you can do this test at home, check out our comprehensive guide. Take control of your health today - get tested and understand what those results mean for you. To buy an affordable INR and PTT test, visit now.






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