Platelet Assays and Platelet Dysfunction

Normal platelet function and number are critical for normal hemostasis and thus for rapid cessation of blood loss. This is illustrated by the range of both acquired and inherited qualitative and quantitative defects of platelets that can result in significant bleeding problems. A full clinical history and examination coupled with the application of first-line screening tests helps to define whether a patient may have an underlying platelet defect. Diagnosis is then usually confirmed by a variety of tests that include platelet aggregometry with various agonists, measurement of stored or released nucleotides, flow cytometry, and molecular biology. This chapter reviews the application of platelet function tests for the diagnosis of a wide range of platelet defects.