ANTI-XA ACTIVITY IN CHILDREN ON TREATMENT AND PROPHYLAXIS WITH LOW MOLECULAR WEIGHT HEPARIN

Snezhana Stoencheva

doi:10.35120/medisij040451s

Authors

Snezhana Stoencheva Department of Clinical Laboratory, Faculty of Medicine, Medical University of Plovdiv, University Hospital “St. George”, Plovdiv, Bulgaria Author

DOI:

https://doi.org/10.35120/medisij040451s

Keywords:

anti-Xa activity, children, low molecular weight heparin, thrombosis

Abstract

In recent years, the use of low molecular weight heparins (LMWHs) for the prevention and treatment of thrombosis in children has increased. This is due to the increased percentage of critically ill children and the rate of thrombotic events. The efficacy and dose-dependent laboratory and clinical response data to achieve target levels in treatment and prophylaxis with LMWH have not yet been clarified. According to recommendations from leading experts in the field, monitoring of anti-Xa activity is mandatory in children receiving LMWH. However, there are still many questions about the most appropriate dose and time to achieve target anti-Xa levels. Objective: To investigate and monitor anti-Xa activity in pediatric patients of different age groups undergoing prophylaxis or treatment with LMWH. Material and Methods: We studied 22 children (mean age of 11.77±1.6 years) with malignant diseases, ischemic stroke, cerebral venous sinus thrombosis, deep vein thrombosis (DVT) and multisystem inflammatory syndrome. 41% (n=9) of the children were on treatment with LMWH and 59% (n=13) on prophylaxis, with the dose adjusted for age and weight. Plasma levels of anti-Xa activity were determined by chromogenic anti-Xa assay on a Sysmex CS 2500 coagulation system, using LMWH-specific calibrators and controls. Screening coagulation tests were also performed. Results: In 30.7% (n=4) of the children on prophylaxis, plasma levels of anti-Xa activity were lower than the recommended prophylactic range and in 55.5% (n=5) of the children on treatment, anti-Xa levels were below the therapeutic range. Conclusion: Our findings support current clinical recommendations that emphasize personalized dose adjustment guided by serial anti-Xa measurements. Active and dynamic monitoring of plasma levels of anti-Xa activity in pediatric patients on treatment and prophylaxis with LMWH is essential for optimizing the efficacy of anticoagulant therapy while minimizing its adverse effects.

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References

American Society of Hematology. (2025, May 27). ASH and ISTH publish revised clinical practice guidelines for pediatric venous thromboembolism [Press release]. https://www.hematology.org/newsroom/press-releases/2025/ash-and-isth-revised-guidelines-for-pediatric-vte

Altuwayjiri, A., AlDarwish, A., & Alshuraim, R. (2023). An Evaluation of the Appropriateness of Initial Enoxaparin Dosing Among Pediatric Patients. Cureus, 15(11), e48830.

Bennett, E., Delgado-Corcoran, C., Pannucci, C. J., Wilcox, R., Heyrend, C., & Faustino, E. V. (2022). Outcomes of Prophylactic Enoxaparin Against Venous Thromboembolism in Hospitalized Children. Hospital pediatrics, 12(6), 617–625.

Derbalah, A., Duffull, S., Sherwin, C. M., Job, K., & Al-Sallami, H. (2022). Optimal dosing of enoxaparin in overweight and obese children. British journal of clinical pharmacology, 88(12), 5348–5358.

Dinh, C. N., Moffett, B. S., Galati, M., Lee-Kim, Y., Yee, D. L., & Mahoney, D. (2019). A Critical Evaluation of Enoxaparin Dose Adjustment Guidelines in Children. The journal of pediatric pharmacology and therapeutics: JPPT: the official journal of PPAG, 24(2), 128–133.

Faustino, E. V. S., Shabanova, V., Raffini, L. J., et al. (2021). Efficacy of early prophylaxis against catheter-associated thrombosis in critically ill children: A Bayesian phase 2b randomized clinical trial. Critical Care Medicine, 49(3), e235–e246.

Hepponstall, M., Chan, A., & Monagle, P. (2017). Anticoagulation therapy in neonates, children and adolescents. Blood Cells, Molecules and Diseases, 67, 41–47.

Kanan, M., Alotaibi, N. M., Anzan, K. B., et al. (2024). Systematic review and meta-analysis of individualized enoxaparin dose optimization in critically ill pediatrics: A path towards enhanced therapeutic outcomes. Pharmacy Practice (Granada), 22(2), 1-12.

Koury, J., Hellinga, R., Rose, J., Abraham, S., & Subbaswamy, A. (2021). Evaluation of Anticoagulant Monitoring in Pediatric Patients Receiving Enoxaparin for Treatment of Venous Thrombosis. The journal of pediatric pharmacology and therapeutics: JPPT: the official journal of PPAG, 26(4), 346–351.

Monagle, P., Chan, A. K. C., Goldenberg, N. A., Ichord, R. N., Journeycake, J. M., Nowak-Göttl, U., & Vesely, S. K. (2012). Antithrombotic therapy in neonates and children: Antithrombotic therapy and prevention of thrombosis, 9th ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest, 141(2, Suppl.), e737S–e801S.

Rodriguez, V., Mitchell, B. S., Stanek, J., Vasko, K., Giver, J., Monda, K., Canini, J., Dunn, A. A., & Kumar, R. (2024). Improving Anticoagulation Care for Pediatric Oncology Patients: A Quality Improvement Initiative. Pediatric quality & safety, 9(1), e720.

Samji, N., Bhatt, M. D., & Kulkarni, K. (2022). Challenges in Management of VTE in Children with Cancer: Risk Factors and Treatment Options. Frontiers in pediatrics, 10, 855162.

Verweij, M., van Weissenbruch, M. M., & Klaassen, I. L. M. (2024). Balancing safety and efficacy of low-molecular-weight heparins in neonates: a systematic review. Research and practice in thrombosis and hemostasis, 8(7), 102601.

Wang, Y., Yin, Q., Liao, J., et al. (2025). Addressing challenges in pediatric thrombosis: A comprehensive guideline development. Frontiers in Pediatrics, 13, 1519517.

Wysocki, E. L., Kuhn, A., Steinbrenner, J., Tyrrell, L., Abdel-Rasoul, M., Dunn, A., & Cloyd, C. (2021). Enoxaparin Dose Requirements to Achieve Therapeutic Low-molecular-weight Heparin Anti-factor Xa Levels in Infants and Young Children. Journal of pediatric hematology/oncology, 43(7), e946–e950.