Summary
Effects of the quality and the time of venepuncture on factor VII coagulant activity
(VIIC) and the concentrations of fibrinogen, prothrombin fragment 1 + 2 (F1 + 2) and fibrinopeptide A (FPA) were sought in 2665 men, of whom 2334 were re-examined
after about one year. Venepunctures were categorised as satisfactory, not fully satisfactory
or unsatisfactory according to pre-defined criteria. Neither the quality nor timing
of the venepuncture influenced VIICor fibrinogen concentration. However, at baseline and re-examination F1 + 2and FPA were increased on average by about 9% and 45% respectively when venepunctures
were not fully satisfactory, and by about 11% and 100% when unsatisfactory. Plasma
collected after 1500 h had slightly but significantly lower levels of F1 + 2and FPA than samples taken earlier, possibly due to circadian rhythm. The results
emphasise the need for careful surveillance of the venepuncture procedure and the
value of FPA when using F1+ 2as a marker of risk of thrombosis.
