Age-dependent effect on the level of factor IX.

Sweeney, J D; Hoernig, L A · Am J Clin Pathol · 1993

cross_sectional · Level IV

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Abstract

Levels of factor IX:C and factor IX:Ag were measured in 120 healthy subjects with an age range of 1 to 67 years. Levels of factor IX:C were lowest in prepubertal subjects, then reached a plateau in early adult life with a secondary increase in later adult life (> 45 years). Changes in factor IX:Ag showed a similar trend. Factor IX:Ag disproportionately increased in early adult life, however, with a less pronounced increase in later life, resulting in peaking of the ratio in early adult life. It is suggested that caution be exercised in interpreting low normal factor IX:C levels in prepubertal children, and that interpretation of ratios of antigenic to coagulant activity may need to take subject age into consideration.

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