Protein C activity and antigen levels in childhood

Eur J Pediatr. 1990 Aug;149(11):774-8. doi: 10.1007/BF01957278.


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.

MeSH terms

  • Adolescent
  • Adult
  • Antigens / analysis*
  • Child
  • Child, Preschool
  • Female
  • Hematocrit
  • Humans
  • Infant
  • Infant, Newborn
  • Male
  • Middle Aged
  • Protein C / analysis*
  • Protein C / immunology
  • Protein C Deficiency


  • Antigens
  • Protein C