Chromogenic Substrate Assay
Used to monitor treatment with low-molecular weight heparins: danaproid, enoxaparin, dalteparin, fragmin, lovenox
Normal individuals have no low molecular weight heparin activity.
Target Therapeutic Range:
Enoxaparin 1.0 mg/kg SC twice daily, 5 hours after dose 0.5 - 1.0 IU/mL;
Enoxaparin 1.5 mg/kg SC once per day, 5 hours after dose 1.0 - 2.0 IU/mL;
Enoxaparin 1.0 mg/kg SC once per day
Trough <0.4 IU/mL drawn just prior to next dose.<li>
<b>Critical value </b> is >2.0 IU/mL.
- Coagulation Factor Xa Inhibition
- Factor Xa Inhibition
- Heparin (LMWH) Anti-Xa Assay
- Heparin, Low Molecular Weight
- Low Molecular Weight Heparin
- LMWH Anti-Xa
- XA INHIB
- Anti-Xa, LMWH
- Anti-Xa LMW Heparin
- Chromogenic Xa
- Xa Chromogenic
- Factor 10a Inhibition
- Anti-10a LMWH
STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).
Collect specimen in a blue top 3.2% sodium citrate Vacutainer® tube. Mix by inversion. Specimen should arrive at lab within 23 hours of collection; transport at room temperature. Alternatively, centrifuge, aliquot plasma into a plastic tube, and freeze the specimen within 24 hours of collection. Transport frozen specimen on dry ice. Collection of the blood through lines that have been previously flushed with heparin should be avoided. If the blood must be drawn through a VAD (vascular access device), the line should be flushed with 5 mL of saline and the first 5 mL of blood or six dead space volumes of the VAD discarded.
Specimen must be received in lab within 23 hours of collection to allow for adequate processing and testing time. Alternatively, aliquot and freeze within 24 hours of collection.
Sample should be drawn after 3 doses of enoxaparin, at steady state.
The peak level is recommended and should be drawn 4-6 hours post dose.
Trough level is preferred in renally impaired patients.