What it means
Heparin and low molecular weight heparins (such as enoxaparin) work largely by blocking factor Xa, a key step in clotting. This test measures that effect directly. It guides unfractionated heparin infusions in many hospitals, and it checks enoxaparin dosing in clients with kidney disease, very high or low body weight, or pregnancy.
For the nurse
Time the draw exactly as ordered and record when the last dose was given; for a heparin infusion, draw from the arm without the infusion.
At a glance
| Normal range | No anticoagulant: none detected. Usual targets: heparin infusion 0.3–0.7 units/mL; twice-daily enoxaparin about 0.5–1.0 units/mL, drawn about 4 hours after a dose. Targets vary by protocol. |
|---|---|
| Also written | anti-Xa, anti-Xa level, heparin anti-Xa |
Related terms
anticoagulant
A drug that slows the blood's ability to form clots.
heparin
An anticoagulant drug, given by injection or IV, that keeps blood clots from forming or growing.