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Thromb Haemost 1994; 72(06): 836-842
DOI: 10.1055/s-0038-1648971
Original Article
Schattauer GmbH Stuttgart

Thrombin Regulation in Children Differs from Adults in the Absence and Presence of Heparin

Maureen Andrew
The Departments of Pediatrics and Pathology, McMaster University Medical Centre, Hamilton, Ontario, Canada
,
Lesley Mitchell
The Departments of Pediatrics and Pathology, McMaster University Medical Centre, Hamilton, Ontario, Canada
,
Patsy Vegh
The Departments of Pediatrics and Pathology, McMaster University Medical Centre, Hamilton, Ontario, Canada
,
Frederick Ofosu
The Departments of Pediatrics and Pathology, McMaster University Medical Centre, Hamilton, Ontario, Canada
› Author Affiliations
Further Information

Publication History

Received 23 March 1994

Accepted after resubmission 23 August 1994

Publication Date:
06 July 2018 (online)

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Summary

The physiologic mechanisms that protect children from thromboembolic complications are not known. We investigated the regulation of thrombin in children because of its central importance to thrombosis. The capacity to generate thrombin in vitro (chromogenic assay) was decreased by 26% in plasmas from children (1-16 yrs; n = 102) compared to adults ([20-45 yrs; n = 20; p <0.001]). The addition of purified prothrombin to plasmas from children increased thrombin generation to adult values. The capacity of plasmas to inhibit 125I-α-thrombin was increased by 21% in children compared to adults (p = 0.020), with significantly more thrombin complexed to a2-macroglobulin (α2M) in children.

When DVT occur in children, adult guidelines for heparin therapy are used. At low heparin concentrations (0.1 and 0.2 U/ml), thrombin generation was decreased by 30% in children compared to adults (p <0.001). At high heparin levels (0.4 U/ml), thrombin generation was negligible in all plasmas. ATIII inhibited over 95% of thrombin in all plasmas in the presence of heparin.

In summary, thrombin regulation differs in children from adults and may protect children from thromboembolic complications. When DVT do occur, heparin requirements may differ in children compared to adults.

 

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