<prompt> Low molecular weight heparins are used very frequently to prevent propagation of thrombus in children with stroke. What is the laboratory test used in blood to monitor the LMW Heparins?Anti factor X aFactor XaThrombinAntithrombin  <response>: Low Molecular Weight Heparin LMWH use in children: Because of ease of dosing and need for less monitoring, LMWH is used more frequently in pediatric patients. Unlike unfractionated Heparin, which is monitored using the aPTT, LMWH is monitored anti-Xa activity. LMWH formulation that has been used most often in pediatric patients is enoxaparin Recommended standard staing dose of enoxaparin for infants 2 mo is 1.5 mgkgdose subcutaneously every 12 hr; for patients 2 mo it is 1 mgkg subcutaneously every 12 hr. Peak levels are achieved 2-6 hr following an injection. 