Background: Use of age-adjusted reference values is crucial for correct diagnosis and management of thrombotic and hemorrhagic disease in children. They vary with utilized reagents and analyzers. Objectives: We established reference values with the Sysmex CA-1500 System and in parallel with the Behring BCS System using reagents from Siemens Healthcare Diagnostics Products GmbH. Methods: After informed consent, blood samples were obtained from 218 healthy children and 52 healthy adults, grouped as 1-6months (n=29), 7-12months (n=25), 1-5years (n=57), 6-10years (n = 57), 11-18years (n=50) and >19years (n = 52). Results: Most coagulation parameters demonstrate good comparability between analyzers with the exception of PT and APTT. Single coagulation factors fibrinogen, factor (F) II, FIX, FXI and XII were significantly decreased in the youngest children; the strongest age dependency was found for coagulation inhibitors Protein C and S, both significantly decreased in infancy and young childhood. We confirmed that high levels of von Willebrand factor are found in the youngest children without increased levels of FVIII followed by decreased von Willebrand levels in the subsequent age group. In children with blood group O a less distinct increase in time was found, compared with individuals with one of the other blood groups. Conclusions: The correlation between the CA-1500 and the BCS system was remarkable. Differences were most pronounced between children <12months and older children and adults, confirming the phenomenon of developmental hemostasis. The rationale for age-related changes in the hemostatic system remains unraveled. Our results underline the need for age-specific reference ranges.

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Journal of Thrombosis and Haemostasis
Erasmus MC: University Medical Center Rotterdam

Appel, I.M, Grimminck, B, Geerts, J, Stigter, R.L, Cnossen, M.H, & Beishuizen, A. (2012). Age dependency of coagulation parameters during childhood and puberty. Journal of Thrombosis and Haemostasis, 10(11), 2254–2263. doi:10.1111/j.1538-7836.2012.04905.x