Heparin Anti-Xa (Unfractionated)

Hematology / Coagulation

Normal Reference Ranges

Adult

0.3 - 0.7 (Therapeutic range) IU/mL

Pediatric

0.3 - 0.7 (Therapeutic range) IU/mL

Clinical Significance

Measures plasma heparin concentration by assessing inhibition of Factor Xa. Preferred monitoring standard for unfractionated heparin in patients with baseline elevated aPTT or heparin resistance.

Causes of High

  • Heparin overdose
  • Renal impairment

Causes of Low

  • Subtherapeutic heparin dosing
  • Inadequate anticoagulation