Protein C activity and antigen levels in childhood.
Hereditary protein C deficiency is an important risk factor for thrombosis. To enable its diagnosis shortly after birth, we determined reference values of protein C antigen and activity levels for the first 3 months of life. To establish an age-related range of protein C levels we also determined median values for individuals up to 18 years of age. A good correlation between the two levels was seen from the 3rd/4th month of life onwards, whereas in the first 2 months the activity levels were significantly lower than the antigen levels. This was not due to interference by the increased plasma citrate concentration at high haematocrit values, and may suggest a dysfunctional protein C molecule in the neonatal period. We found a rapid rise in protein C activity and antigen levels until the age of 7-9 months, followed by a slower progression toward adolescence. In contrast to previous reports, our results indicate that adult values are probably not achieved until sometime during the 2nd decade of life.
van Teunenbroek
A
A
Department of Paediatrics, Academic Medical Centre, Amsterdam, The Netherlands.
Peters
M
M
Sturk
A
A
Borm
J J
JJ
Breederveld
C
C
D000293:Adolescent; D000328:Adult; D000941:Antigens / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006400:Hematocrit; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011486:Protein C / Q000032:analysis* / Q000276:immunology; D020151:Protein C Deficiency
D000941:Antigens; D011486:Protein C