Blood Tests

Thrombophiliacs with Protein S Deficiency usually take oral anticoagulant medication and can expect to have their blood tested on a regular basis so that their INR can be measured. A phlebotomist takes the blood sample which is then sent to a laboratory where a prothrombin time (PT) test is carried out.

International Normalised Ratio - INR

An International Normalised Ratio (INR) of 1 is assigned to the time is takes for normal blood to clot. Blood with an INR of 2 takes twice as long to clot and so on. Your INR will probably vary from time to time because it is sensitive to factors such as other medications, alcohol and dieting (all of which need to be moderated or controlled).

The therapeutic range (for example between INR=2.5 and INR=4.0) for the clotting time of your blood will be determined by your haematologist. Regular blood tests are carried out to ensure that your dosage of tablets is giving the desired effect.

An INR that is too low indicates increased risk of further thrombosis and a high INR indicates possible excessive bleeding tendencies. If your INR is outside the therapeutic range then your haematologist will advise you if you need to change the dosage of your medication. It is important that you follow professional advice rather than making your own decisions regarding your treatment.


Phlebotomists are trained to draw blood samples by venipuncture, skin puncture, or arterial collection for medical tests and blood donations. In the practice of phlebotomy, safety precautions must be taken to prevent the transmission of infectious diseases. Phlebotomists must adhere to strict policies and procedures while treating the patient with care. They may also be involved in the training of student doctors, nurses and dentists giving tuition in venous blood specimen collection and handling, skin puncture collection techniques, patient communication, ethics, professionalism in health care settings, infection control, and safety in blood collection.

An Interview With The Vampire

Blood testing is carried out about once a month - more often if closer monitoring is required and less often if your INR is relatively stable. Many people have their blood taken on a routine basis. It can be a daunting prospect if you are new to the experience but in time you will find that regular blood tests taken to monitor your INR are not too uncomfortable.

Depending on how busy your blood testing clinic gets, you can be in and out in less than ten minutes. But it is not a good idea to rush about as even the most hardened of visitors will occasionally find they get a bit faint or the phlebotomist has trouble finding a suitable vein.

In time you will find that regular Blood Tests taken to monitor your INR are not too uncomfortable.

Remember to be polite and if you get the chance give other patients a smile - it may give enormous confidence to someone who is terrified of needles to see someone in the same position that looks calm, especially young children.

If you travel frequently, are home-bound, or live in a rural area, or if you have had any complications associated with your therapy you may want to consider getting a home testing kit.
Last updated: Thursday, 1st August 2013, © 2000-2017

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