Abstract: The present invention concerns a composition comprising an aqueous medium, a reagent for assessing fibrinogen biological activity and a reagent for assessing the activity of a reagent used for determining platelet count. In one particular embodiment the composition comprises an aqueous medium, an antibody for fibrinogen and fixed platelets substantially free of fibrinogen antibody binding sites. Also disclosed is a method for conducting a control for an assay for platelet function activity and a control for the platelet count assay. The method comprises utilizing a common control for the assays wherein the control does not cross-react with itself or with reagents for conducting the assays. In a particular embodiment the common control comprises an aqueous medium, a reagent for assessing fibrinogen biological activity and a reagent for binding to the reagent used for determining platelet count. Also disclosed are kits for carrying out methods in accordance with the present invention.

Abstract: Methodology which avoids the problems associated with interference from whole blood is provided for instrumented determination of platelet binding function. Particularly, small particles to which fibrinogen is bound, and which contain an infrared light absorbing dye, are used to determine the binding of platelets in a whole blood sample to the fibrinogen. Agglutination of the platelets with the coated particles is determined by a change in infrared light absorption characteristics.