title: Age-dependent effect on the level of factor IX.
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.
authors.affiliation: Hemophilia Center of Western New York, Erie County Medical Center, Buffalo 14215.
authors.forename: J D
authors.initials: JD
authors.lastname: Sweeney
authors.forename: L A
authors.initials: LA
authors.lastname: Hoernig
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D005164:Factor IX / Q000032:analysis* / Q000378:metabolism; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D005164:Factor IX