Additional Information

Confirmatory INRs Click this Link

Collection Guideline:

The following is recommended for Warfarin (Coumadin®) anticoagulant monitoring:

Monitor in patients when treated for arterial and venous thrombosis to prevent clot propagation or for prevention of thromboembolic disease in thrombophilia, atrial fibrillation, mechanical heart valves, ACS, and high-risk surgery

Monitor using INR. The INR is calculated from the following formula:

INR = (patient PT/mean normal PT)^ISI

Monitor in patients at baseline and consider daily until INR is therapeutic twice at least 24 hours apart and twice a week for 2 weeks, then once a month until therapy is complete
 

Bassett Network Therapeutic Ranges:

Oral anticoagulation therapy: 2.0 – 3.0
Mechanical valve therapy: 2.5 – 3.5

The following is recommended for Unfractionated Heparin anticoagulant monitoring:

Monitor in patients when treated for arterial and venous thrombosis to prevent clot propagation or for prevention of thromboembolic disease in thrombophilia, atrial fibrillation, mechanical heart valves, and high-risk surgery

Monitor 4-6 hours after bolus dosage and every 24 hours thereafter; if dose adjustment is needed, 6 hours after changing IV infusion

Check CBC at baseline and every other day while on therapy

Obtain baseline aPTT, PT/INR, AST, ALT and CRTN prior to starting therapy

Check PLT at baseline and every 2-3 days to detect heparin induced thrombocytopenia (HIT). If count drops 50%, consider HIT, withdraw heparin, start alternative anticoagulant, order confirmatory test for HIT

The following is recommended for Low Molecular Weight (Enoxaparin or Lovenox®) anticoagulant monitoring:

Check CBC at baseline and every 3rd day while on therapy
Obtain baseline aPTT, PT/INR, AST, ALT and CRTN prior to starting therapy
Check PLT at baseline and every 2-3 days to detect heparin induced thrombocytopenia (HIT). If count drops 50%, consider HIT, withdraw enoxaparin, start alternative anticoagulant, order confirmatory test for HIT
Monitor baseline patients for all patients
Anti-Factor Xa monitoring needed for infants, children, obese (> 150kg) or underweight patients (Women < 45kg and Men < 57kg) or those with renal disease, long-term treatment, pregnancy, or unexpected bleeding or thrombosis
Monitor anti-Factor Xa peak levels for clinical usefulness
Therapeutic administration for twice-daily SQ: collect blood 4 hours post dose
Therapeutic administration for once-daily SQ: collect blood 4 hours post dose

The following is recommended for Direct Thrombin Inhibitors (Argratroban, Lepirudin) anticoagulant monitoring:

Substitute for heparin when HIT is suspected or confirmed. Even when HIT’s only manifestation is thrombocytopenia and heparin is stopped, risk of thrombosis in subsequent 30 days approaches 50% unless alternative anticoagulant is used.
aPTT is used to prevent bleeding or thrombosis. Do not start in patients with aPTT longer than 2.5 x mean of reference interval. -Lepirudin: collect blood four (4) hours after initial dosage, adjust dosage to aPTT 1.5-3.0 x mean of reference interval. Lepirudin has only a modest effect on the PT, thus transition to warfarin may be monitored with the INR. The INR may be decreased somewhat upon discontinuation of lepirudin, however, so this should be considered when adjusting warfarin dose during the transition. Lepirudin accumulates in kidney failure, thus dose adjustments are recommended.
Argatroban: collect blood two (2) hours after initial dosage, adjust dosage to aPTT 1.5-3.0 x mean of reference interval. Argatroban increases the INR more than lepirudin. Argatroban accumulates in liver failure, thus dose adjustments are recommended. Argatroban should not be started if the baseline aPTT is >3X the midpoint of the normal range.