The following recommendations are to assist clinicians in selecting which laboratory tests to use for monitoring heparin, low molecular weight heparin, direct thrombin inhibitors and/or oral anticoagulant therapy as well as the therapeutic/reference range for the tests. This guideline is mandated by the College of American Pathologists, (HEM.23575).
Guidelines for Anticoagulation Monitoring:
Testing Available at ITxM Diagnostics
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ANTICOAGULANT
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ITxM DIAGNOSTICS TEST NAME AND ORDER CODE
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THERAPEUTIC/REFERENCE RANGE (est. by ITxMD)
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Warfarin (Coumadin®)
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PT/INR (5359)
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INR: 2.0 – 4.0 (Therapeutic)
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Unfractionated Heparin (UFH)
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Heparin Level/Anti-Xa Level (547L) – please indicate Unfractionated heparin when ordering
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0.3 – 0.7 IU/mL (Therapeutic)
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Low Molecular Weight Heparin (LMWH)
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Heparin Level/Anti-Xa Level (547L) – please indicate type of heparin (Lovenox, Fragmin) when ordering
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0.6 – 1.0 IU/mL (Therapeutic)
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Direct Thrombin Inhibitors (DTI):
Dabigatran
Other
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Dabigatran Level (5997)
aPTT (5363)*
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>40.0 ng/mL (Reference)**
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Fondaparinux(Arixtra®)
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Fondaparinux Level (5762)
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0.62 - 1.26 mg/L (Therapeutic)
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*No therapeutic ranges or recommendations available for use of aPTT for monitoring DTI through ITxM Diagnostics. aPTT may be prolonged with DTI.
**Dabigatran therapeutic levels are reached within 30 minutes to 2 hours following oral administration, but may be prolonged if taken with food. Steady state is reached within 2 to 3 days. Steady state geometric mean Dabigatran peak plasma concentration measured 2 hours after 150 mg Dabigatran administration twice daily was on average 175 ng/ml with a range of 117-275 ng/ml (25th-75th percentile range). The Dabigatran geometric mean trough concentration measured at trough in the morning at the end of the dosing interval (i.e., 12 hours after the 150 mg Dabigatran evening dose) was on average 91.0 ng/ml with a range of 61-143 ng/ml (25th-75th percentile). The drug is excreted unchanged via the kidneys (~80%) with the remainder excreted via bile. Circulating half life is 12-17 hours.