Warfarin's therapeutic range

In order to get the therapeutic range of warfarin, you need to know your patient's prothrombin time (PT). Normal PT varies from different persons, so after knowing the normal PT of a patient, the doctor will administer or order warfarin and he or she will check the PT every now and then to see if it reaches 1.5 to 2 times the normal because this is the therapeutic range then you will get your desired effect. The nurse's role is the check the lab values and see to it that it falls between 1.5 to 2 times the normal. If the results fall below normal then we are not reaching the therapeutic range, if it falls over the normal value then there is a risk of bleeding. Always assess your patient and be ready to administer the antidote Vitamin K as per doctor's order.

Take note that other factors may affect your lab values, green leafy vegetables, liver, multivitamins and other  food rich in Vitamin K may counter the effect of warfarin, on the other hand some drugs like aspirin may also potentiate its effect.

The same principle applies to heparin except that in heparin you have to check the Partial thromboplastin time (PTT) instead of the PT, and the antidote is protamine sulfate. Therapeutic range for heparin is 1.5 to 2.5. Visit this link for more LAB VALUES