Overshooting the INR (International Normalised Ratio), e.g.

" Comment:
The challenge is to lower the INR quickly without overshooting and leading to thrombosis. The small dose of vitamin K is the secret in this subset of patients
This is only part of the solution. The larger problem is ? what caused the increase in the INR? To maintain constancy in coumadin therapy, the patient must remain constant in all respects. Any change in health status, diet, or medication (the list is long indeed, including over-the-counter), has the potential to change the power of the anticoagulation. I wonder how patients manage to keep stable. Many do, but many also get into trouble. "


i.e. to bring the INR down, but keep it within certain limits.

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Note added at 2002-07-31 09:07:59 (GMT)
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Some additional information:

What is the Protime?

The \"protime\" (or \"prothrombin time\") is a method of measuring how well the body clots.

Why is the protime used to gauge liver function?
Since the liver makes the proteins (called clotting \"factors\") in the blood that make blood clot, the protime is a measure of how well the liver is doing what it should be. If the liver is failing then it stops making enough clotting factors, and the protime becomes abnormally \"prolonged\".

What is the normal protime?

The normal protime is determined by the laboratory each day by testing normal blood. Any specimens that day are then compared to the \"control\" normal value. Usually a normal control protime is about 11 seconds. When the protime is 22 seconds, it is said to be \"twice control\". Generally a protime is considered to be prolonged if it is more than 1.2 times the control time.

ref. http://www.transweb.org/qa/qa_txp/faq_protime.html

International Normalized Ratio (INR)

The accuracy of the Prothrombin Time (PT) is known to be very system-dependent. The World Health Organization has addressed this system variability problem by (1) the establishment of primary and secondary international reference preparations of thromboplastin and (2) the development of a statistical model for the calibration of thromboplastins to derive the International Sensitivity Index (ISI) and the INR.

The INR uses the ISI to equate all thromboplastins to the reference thromboplastin through the following equation:

INR = (patient PT/mean normal PT)ISI

Thus, the INR can be calculated using the working prothrombin time ratio once the ISI of the thromboplastin is known.

Documented differences in PT results in several interlaboratory trials led the International Committee on Thrombosis and Hemostasis to make a joint recommendation in 1983 to express all PTs as INRs and that manufacturers indicate the ISI of their thromboplastin reagents.

Recommendations for extent of anticoagulation based on INR can be found in \"The Sixth ACCP Consensus Conference on Antithrombotic Therapy\" published in the January 2001 (Supplement) issue of Chest . This contains recommendations of many specialists for the prevention of thromboembolism. It addresses anticoagulation in various diseases, conditions and other related topics. In brief they \"A recommendation of an INR of 2.0 to 3.0 is made for most indications. For further monitoring recommendations refer to the Consensus Conference publication.

Patients are widely variable in response to oral anticoagulation. In addition, early efforts to use the INR among laboratories has had some problems. The guidelines can be helpful in monitoring patients but they should not replace sound clinical judgment.

Studies have shown that low ISI (high sensitivity) reagents are optimal. The laboratory will choose reagents with ISI <1.5. For further information about the current lot of reagent, please contact the Hemostasis/Thrombosis Laboratory at (319) 356-3573.

References:
1. Hirsh, J. et al, Oral Anticoagulants, Chest 2001;119:85-215.
International Normalized Ratio (INR)

The accuracy of the Prothrombin Time (PT) is known to be very system-dependent. The World Health Organization has addressed this system variability problem by (1) the establishment of primary and secondary international reference preparations of thromboplastin and (2) the development of a statistical model for the calibration of thromboplastins to derive the International Sensitivity Index (ISI) and the INR.

The INR uses the ISI to equate all thromboplastins to the reference thromboplastin through the following equation:

INR = (patient PT/mean normal PT)ISI

Thus, the INR can be calculated using the working prothrombin time ratio once the ISI of the thromboplastin is known.

Documented differences in PT results in several interlaboratory trials led the International Committee on Thrombosis and Hemostasis to make a joint recommendation in 1983 to express all PTs as INRs and that manufacturers indicate the ISI of their thromboplastin reagents.

Recommendations for extent of anticoagulation based on INR can be found in \"The Sixth ACCP Consensus Conference on Antithrombotic Therapy\" published in the January 2001 (Supplement) issue of Chest . This contains recommendations of many specialists for the prevention of thromboembolism. It addresses anticoagulation in various diseases, conditions and other related topics. In brief they \"A recommendation of an INR of 2.0 to 3.0 is made for most indications. For further monitoring recommendations refer to the Consensus Conference publication.

Patients are widely variable in response to oral anticoagulation. In addition, early efforts to use the INR among laboratories has had some problems. The guidelines can be helpful in monitoring patients but they should not replace sound clinical judgment.

Studies have shown that low ISI (high sensitivity) reagents are optimal. The laboratory will choose reagents with ISI <1.5. For further information about the current lot of reagent, please contact the Hemostasis/Thrombosis Laboratory at (319) 356-3573.

References:
1. Hirsh, J. et al, Oral Anticoagulants, Chest 2001;119:85-215.




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Note added at 2002-07-31 09:09:06 (GMT)
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You may prefer to use \'overestimating\'.

Hope all this helps!