Platelet indices: intra-individual variation in pre- and post-menopausal females

Blood platelet counts and mean platelet volumes were determined at weekly intervals for eight weeks in 13 pre-menopausal and 11 post-menopausal females. Samples were analysed exactly two hours after blood collection on a Coulter S plus VTM particle counter. Pre-menopausal platelet counts were slightly higher than post-menopausal counts at each week, but the count was not affected by the menstrual cycle, intra-individual variation showing mean coefficients of variation (CV) of 7.4% and 5.2% respectively. The mean platelet volume was similar in pre- and post-menopausal groups at each week and showed little variability over time (mean CV 2.7% and 3.3%, respectively). Platelet parameters show little variability over time in either group and with no cyclical effects of menstruation apparent.