What causes the increase in platelet mean volume in thyroid pathological conditions

We have read with interest the reports published in this journal by Ford at al. (3), van Doormaal et al. (1) and Haubenstock et al. (2) on the abnormalities of platelet count (PC) and mean platelet volume (MPV) in patients with hyperthyroidism and hypothyroidism. We believe that the results of these authors are rather inconclusive and here report our results on PC and MPV measurements in a large group of patients with various thyroid diseases