INR is monitored through blood tests. In outpatient settings, it may be measured in a laboratory, or some patients may use a point-of-care testing device at home. The frequency of testing depends on the stability of the patient's INR and their overall risk profile. Initially, INR may be checked daily or every other day after starting warfarin or adjusting the dose, but once stabilized, it can be monitored less frequently, such as once every 2 to 4 weeks.
