Increased in vivo and in vitro platelet function in type II- and type IV-hyperlipoproteinemia

Abstract

<h2>Abstract</h2> Platelet function in vivo and in vitro was examined in 10 patients with type IIa-, 8 patients with type IIb-, and 16 patients with type IV-hyperlipidemia (HLP) and 24 control subjects closely matched for age and sex. Patients with type IIb- and IV-HLP showed significantly shorter template bleeding times in the presence of similar blood platelet concentrations. Increased platelet factor 3-availability in intact platelet-rich plasma (PRP) and PRP exposed to collagen was observed in all patient groups. Plasma antiheparin activity was increased in patients with type IIa- and type IV-HLP. Platelet adhesiveness, platelet aggregation and ¹⁴C-serotonin release in response to ADP, epinephrine and collagen, as well as plasma von Willebrand factor activity, were generally not increased in either patient group. Increased platelet function in endogenous HLP may be related to both increased platelet turnover secondary to premature atherosclerotic disease and abnormalities of platelet lipid composition induced by HLP-plasma.