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Medically Compromised Patient Care

Course Number: 628

Drug Induced Clotting Abnormalities

It is also imperative to ask what the patient’s International Normalizing Ratio (INR) is if they are taking blood thinners, such as Warfarin (Coumadin).17 Warfarin is the most commonly used anti-coagulant drug and is best monitored by INR or PT (prothrombin time). Table 11 outlines normal and elevated INR values. It is acceptable to treat patients with an INR in the range of 2.0-3.0, but INR readings of > 3.5 require a medical consult prior to treatment. Prothrombin time should be less than 20 seconds.

Table 11. International Normalizing Ratio (INR) Values (10)
INR < 2.5
Normal range
INR 2.0-3.0
Routine care may be performed
INR > 3.5
Physician consult recommended

When patients are on antiplatelet drugs, such as Clopidogrel (Plavix), they are best monitored by a platelet count and platelet function analyzer (PFA-100), rather than an INR reading. Aspirin, Ibuprofen and other NSAIDs are also considered antiplatelet drugs and are not monitored by the INR reading. Regardless of the type of drug being used, dental practitioners should never take a patient off their anticoagulant or antiplatelet medication without consulting the patient’s hematologist first.

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New therapies are being developed, which do not require blood labs prior to dental treatment. In addition, there is limited evidence that direct-acting oral anticoagulants, such as apixaban and rivaroxaban, do not require altering therapy before dental treatment.18

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