Higher mean platelet volume is accompanied with hyperthyroidism in patients with Graves' disease

Purpose: Graves' disease (GD) is an autoimmune disease that is the most common cause of thyrotoxicosis. Thyrotoxicosis can cause a decrease in platelet survival time. Inflammation is an important stimulus for platelets and mean platelet volume (MPV) could be used a diagnostic marker which is an important determinant of platelet activity. In this study we aimed to evaluate whether MPV would be a useful inflammatory marker for evaluation of disease activity in patients with Graves' disease. Materials and Methods: Two hundred twenty-nine patients (GD patients (Group 1); n=102 and patients with euthyroid nodular goiter (Group 2); n=127) were included in this retrospective study. Serum TSH, fT3, fT4 and MPV levels were recorded at presentation and at first euthyroid period under ATD treatment in GD patients and at presentation in patients with euthyroid nodular goiter. Results: The mean age was 40.3 +/- 13.5 in Group 1 and 50.2 +/- 11.6 in Group 2. Mean initial MPV level did not differ between groups; 8.3 +/- 1.2 fL and 8.3 +/- 1.1 fL, respectively (p=0.9). We found that mean initial MPV was higher than the first euthyroid period MPV in Group 1; Graves' group (8.3 +/- 1.2 fL vs 8.0 +/- 1.3 fL, p=0.02). Conclusion: Higher initial MPV levels in Graves patients and significant drop following the restoration of hyperthyroidism may be due to hypermetabolism of hyperthyroidism.