Seasonal variation of platelets in a cohort of Italian blood donors: a preliminary report

BACKGROUND: Since available data are not univocal, the aim of this study was to explore the existence of a seasonal variation in platelet count. METHODS: The study was based on the database of the Italian Association of Blood Volunteers (AVIS), section of Ferrara, Italy, 2001–2010. Hematological data (170,238 exams referring to 16,422 donors) were categorized into seasonal and monthly intervals, and conventional and chronobiological analyses were applied. RESULTS: Platelets and plateletcrit were significantly higher in winter-autumn, with a main peak in December-February (average +3.4% and +4.6%, respectively, P <0.001 for both). CONCLUSIONS: Although seasonal variations have been reported for several acute cardiovascular diseases, it is extremely unlikely that such a slight increase in platelet count in winter alone may be considered as a risk factor.