The human body is an integration of complex system of tissues, each with a definite function. Normally, the body has a certain mechanism in store to defend various delicate body organs in case of an attack or damage.
The involvement of antibodies in the immune system, self-healing processes, and coagulation, among others, are some of the ways the body applies to protect itself from certain wears and damages. Here, a certain test called International Normalization Ratio (INR) that relates to coagulation is discussed.
Coagulation involves a defensive strategy implemented by the body against bleeding whenever damage to blood vessels is present. Besides the action carried out by blood platelets, the body releases clotting factors to help cease the bleeding.
However, there are some circumstances that can lead to blood coagulation even with no apparent bleeding. Individuals/patients experiencing unnecessary blood coagulation stands to have a higher chance of developing thromboembolic conditions like pulmonary embolism, stroke, or heart attack.
Since blood clotting can sometimes prove perilous to health, there will be a need to take blood tests like INR. An INR test is used to determine the clotting ability of the blood.
The INR Test
1. INR is a Standard.
The International Normalization Ratio is a value for certain laboratory tests aimed at determining how long the blood takes to clot.
For you to understand INR better there is need to understand PT test. PT is an abbreviation for prothrombin time. It is a test that is meant to determine the time it takes for the blood to clot.
To perform the PT test, blood is drawn and sent to the laboratory for examination. In the laboratory, a reagent is introduced into the blood to initiate the blood clotting process. The time taken for the blood to clot (in seconds) is noted down.
The choice of reagent in the PT test is not usually confined to a particular reagent. There are a lot of reagents that can be used. Each of them is different. The results are comparatively different, too. This means that a PT test result that uses reagent X can be different from a PT test result that uses reagent Y.
For consistency, the results with various reagents are converted into standard units that are comparatively similar to each other, no matter the reagent used. The standard units are the ones that are referred to as the INR. In short, the test is used to report the outcome of PT tests.
2. The Target.
The test is usually meant for patients who are taking medications with capacity to interfere with the blood clotting process. For instance, the intake of heparin which is a medication intended to prevent coagulation; or intake of warfarin which can be seen in patients with heart-related problems. Individuals who suffer from stroke may find anti-clotting medications helpful.
The INR test determines whether the anti-clotting drugs are effective in the treatment of the patient or whether a different dose is needed. For patients who are at risk of excessive bleeding, even with bruises or minor accidents where the blood does not clot quickly as normal, the results of an INR test will be a very valuable data in order for the doctor to make necessary adjustments with the treatment being provided.
The test may also be useful in diagnosing and managing some disorders like liver disease and bleeding problems.
3. The need for the INR test.
Normally, INR tests are usually conducted in patients who are taking warfarin with an aim of striking a balance between the risk of excessive bleeding and coagulation.
INR results that read 4.5 indicates an increased risk of excessive bleeding. Readings lower than 2 raises the likelihood of having unwanted blood clots in the blood vessels.
Therefore, monitoring and testing is crucial because the doses used for an individual may give different results compared to another patient using the same treatment.
4. INR results.
Results of INR tests are subjective to many factors. The approach used in conducting the test may also affect the outcome. The results may also appear different from the usual outcome but may not cause a serious problem.
Results can also be subjective to factors such as age, the current health condition, and the type of medication the patient is taking. The higher the ratio, the longer the time it takes for blood coagulation. This implies that the higher the ratio, the thinner the blood.
5. Test Requirements.
Before conducting the test, the doctor may recommend certain diet changes. For instance, the doctor may restrict foods that are rich in vitamin K.
It is also crucial that the doctor is aware of all the medicines, supplements, and herbs the patient is taking. Any use of recreational drugs must also be identified.
6. INR Test interpretation.
The INR results are usually in ratio form. The ratio is not tied to time or any given value.
As noted earlier, the results may be affected by age, health conditions, among others. For those taking anti-coagulants, the INR should always read between 2 and 3.
It may also read differently due to medications being taken for the heart, e.g diltiazem. A patient suffering from a certain heart disease will have a different figure from another patient suffering from a blood clot in the leg.
7. Risks/Side Effects.
Usually, the side effects caused by an INR test are usually minor. These side effects are often experienced at the time when the blood is being drawn for lab tests.
Patients may experience minor bruises, dizziness, and sometimes bleeding. Some patients may also experience slight irritation on the arm. Others develop sores.
8. INR Types of tests.
There are two types of tests available under the INR. One is the blood draw method (a method mentioned earlier). The blood draw method involves drawing blood that is taken into the lab for the INR examination.
The second method uses a device known as the point of care device. This method involves pricking the finger and placing a drop of blood on a test strip in order for the device to interpret the results. The results are usually interpreted on the spot.
- Bushra Moiz, MBBS, FCPS, MHPE, FRCP(Edin), Anila Rashid, MBBS, FCPS, Muhammad Hasan, MBBS, FCPS, Lena Jafri, MBBS, FCPS, & Ahmed Raheem, MSc, MBA (2018). Prospective Comparison of Point-of-Care Device and Standard Analyzer for Monitoring of International Normalized Ratio in Outpatient Oral Anticoagulant Clinic.
9. The frequency of INR Test measurement
The frequency in the use of the INR test rely on state of well-being. For instance, patients under warfarin medication undergo the tests on a daily basis for at least two consecutive days until the ideal INR has been achieved and maintained.
Afterwards, the test is performed after 2-3 days for the next few weeks but with decreasing frequency. This typically depends on the stability of the results. When the INR results are stable, the frequency may drop to at least once in every four weeks.
10. Alternative INR test/monitoring.
Some countries usually recommend health practitioners to visit their patients at home or the aged care setting. This enables patients to undergo INR self-test/monitoring without having to visit the hospital.
If you prefer self-test at home, you will be trained on effective diet changes relevant to the INR test, conducting a self-test, and maintaining INR test results within the best therapeutic range.
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