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Annotations Maintenance And Monitoring
  • Target INR is 2-3 for most patients. Children with mechanical/prosthetic valves or recurrent thrombotic events as described above should have a target INR of 2.5-3.5
  • Discontinue heparin/LMWH once the INR is > 2 for 2 consecutive days and at least 5 days of heparin/LMWH have been given. Anticipate a small decline in INR the following day
  • INR monitoring recommendations
    • Baseline before initiating warfarin therapy
    • Daily until therapeutic range has been reached and sustained for 2 consecutive days/loading protocol complete
    • Within 3 days of discharge from the hospital
    • 5-7 days after initiating a new dose
    • Once a stable INR between 2-3 (2.5-3.5 for mechanical/prosthetic valves) has been noted on two INRs taken 7 days apart INRs can be obtained weekly. When stable for 4 to 8 weeks, then go to INR every 2-4 weeks.
    • Must be monitored at least once a month once stable
    • Most children require INRs every 2 weeks
  • Duration of therapy
    • DVT with an underlying cause -3 months, with possible extension based on clinical situation; consult Hematology
    • Idiopathic DVT - 6 months
    • Mechanical heart valves - indefinite
    • Recurrent thromboembolic events - indefinite
    • Antiphospholipid antibody syndrome - indefinite


These guidelines do not establish a standard of care to be followed in every case. It is recognized that each case is different and those individuals involved in providing health care are expected to use their judgment in determining what is in the best interests of the patient based on the circumstances existing at the time. It is impossible to anticipate all possible situations that may exist and to prepare guidelines for each. Accordingly these guidelines should guide care with the understanding that departures from them may be required at times.

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