- Standard blood sampling is performed in the morning, on an empty stomach (no less than 8 to 12 hours after last meal).
- Drinking alcohol (including beer) is forbidden.
- Physical loads or extensive work is not recommended.
- It is strictly forbidden to smoke on the day of sampling since nicotine is a toxin which damages blood vessels and affects hemostastis substantially.
- It is preferable to refrain from taking any medicinal products that affect blood clotting -- above all, this is true for indirect (acetylsalicylic acid) and direct (heparin) anticoagulants.
- It is also recommended to refrain from taking pharmaceuticals that increase hemostatic activity (oral contraceptives, hormonal drugs, etc.).
- Blood sampling during menstruation is not performed.
- When collecting blood samples for the INR test from patients taking warfarin and other indirect anticoagulants:
- sampling for the INR test, as well as administration of pharmaceuticals, is performed in accordance with a strict schedule: every day during dosage selection -- usually this takes 10 to 14 days (if the dose is correct, the INR value should be 2 to 3), and two to three weeks afterwards.
Some indications to an unscheduled INR change are:
- protracted cold or an acute infectious process;
- a need to adjust therapy of concomitant disorders;
- a change of climate (flying or moving to a long distance);
- changes in the diet, work and rest pattern or physical loads;
- bleeding (from the nose or gums, or excessive menstruation), prolonged bleeding following minor skin damage;
- appearance of blood in feces, urine, sputum or vomit matter;
- during anticoagultion therapy -- pain in joints accompanied by swelling and lumpiness.
Individuals that depend on blood thinning pharmaceuticals shall always remember that any change in their life is a good reason to have an International Normalization Ratio (INR) test taken.