Send to

Choose Destination
See comment in PubMed Commons below
Thromb Haemost. 1993 Aug 2;70(2):281-5.

Protein C activity in healthy volunteers--influence of age, sex, smoking and oral contraceptives.

Author information

  • 1Department of Haematology, Royal Infirmary, Glasgow, Scotland, United Kingdom.


Interpretation of protein C (PC) levels in a given individual has several limitations. A normal PC activity does not necessarily exclude a genetic deficiency nor can a reduced level confirm it. Measuring PC amidolytic activity in 9,648 healthy blood donors has allowed identification of demographic factors which cause variation in PC activity and further hinder interpretation. PC activity displays a log normal distribution and significant variation with age. This is most marked in young adult males when mean PC activity rises from 0.86 iu/ml (15-19 years) to 1.04 iu/ml (45-49 years; P < 0.0001). Pre-menopausal females, who for most age ranges, have mean PC activity below their male contemporaries, show a less marked rise with age until the menopause when PC activity rises further. The use of hormonal contraceptive preparations is associated with an increase in mean PC activity of 0.05-0.08 iu/ml while smoking habit has no influence on PC activity. In view of these findings we strongly recommend the use of age and sex restricted reference ranges when interpreting PC activity.

[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Loading ...
    Write to the Help Desk