Test Overview
Chromogenic Substrate Assay
Used to monitor treatment with unfractionated (standard) heparin.
The therapeutic range is 0.3 - 0.7 IU/mL. Critical value: > 1.0 IU/ml.
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.
Test Details
2 hours
- Heparin, Unfractionated
- Heparin, Standard
- Unfractionated Heparin
- Standard Heparin
- UFH Anti-Xa
- Anti-Xa, UFH
- Heparin (UFH) Anti-Xa Assay
- Anti-Xa Unfractionated Heparin
- Factor Xa Inhibition
- Coagulation Factor Xa Inhibition
- Chromogenic Xa
- Xa Chromogenic
- Factor 10a Inhibition
- Anti-10a UFH
STAT requests for this test will be performed on a STAT basis (supervisory staff approval is not required).
Specimen Requirements
Collect specimen in a blue top (citrate 3.2%) tube. Mix by inversion. Specimen should arrive at lab within one hour of collection; transport at room temperature. Alternatively, centrifuge, aliquot plasma into a plastic vial, and freeze the specimen within 1 hour 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 one hour of collection. Alternatively, aliquot and freeze within 1 hour of collection.