Mean platelet volume as an indicator of platelet activation: methodological issues

Background: Mean platelet volume (MPV) is increased in patients at high risk for athero-thrombotic diseases. Thus, an elevated MPV may be a risk marker for platelet activation. Methods: Healthy subjects with normal triglyceride (TG) levels (90+/-6 mg/dl; n=40) or mild hypertriglyceridemia (161+/-79 mg/dl; n=32) were studied. MPV was measured in fasting blood samples before and after stimulation with collagen (10 mg/ml), and exposure to 4 or 37degreesC. Samples from the normotriglyceridemic subjects were tested again 4 h after consuming a high-fat drink. Results: Collagen and exposure to 4degreesC increased MPV, whereas incubation at 37degreesC lowered MPV regardless of TG level. There was no significant difference in unstimulated MPV between the fasting and the fed states in the normotriglyceridemic subjects (both 7.2+/-0.1 fl; mean+/-SEM), nor between the latter group and hypertriglyceridemic subjects (7.0+/-0.1 fl). There was a significant negative relation between MPV and fasting TG level. Conclusions: This study suggests that MPV response to low-dose collagen may be a useful indicator of platelet propensity to activation. Further studies are warranted to correlate MPV with classical platelet aggregation tests and with the use of platelet-active drugs.