Background: Coronary heart disease is the major cause of death in the developed world. Platelet activation and aggregation are central processes in the pathophysiology of coronary heart disease. Mean platelet volume (MPV), a determinant of platelet function, is a newly emerging risk factor for atherothrombosis. The present study was designed to evaluate levels of MPV in subclinical hypothyroidic subjects compared with euthyroidic subjects in a cross-sectional study.
Material and methods: Thirty-six subclinical hypothyroidic subjects and 20 euthyroidic control subjects matched for age, gender, and body mass index were selected.
Results: Metabolic parameters and platelet counts were not different among the study groups (<i>p</i>>0.05). The level of MPV was significantly higher in the subclinical hypothyroidic group than in the euthyroidic group (9.9±0.9 fl vs. 9.2±0.7 fl, <i>p</i><0.001). The anti-TPO levels positively correlated to MPV levels in the subclinical hypothyroidic group (<i>p</i><0.05).
Conclusions: These results suggest that subjects with subclinical hypothyroidism tend to have increased platelet activation. Increased platelet activity could contribute to increasing the risk of atherothrombotic complications in subclinical hypothyroidism.

Keywords: Cross-Sectional Studies, Hypothyroidism - physiopathology, Immunoassay, Platelet Activation - physiology, Platelet Count