Platelet Development

• Platelet Development

AUTHOR(S)

Paul HARRISON

Oxford Haemophilia Centre & Thrombosis Unit, Churchill Hospital

SUMMARY

This review provides an overview of platelet develop-ment and will give the required background for under-standing the clinical relevance of measuring the Immature Platelet Fraction ( IPF ) as an index of throm-bopoiesis. The normal average platelet count within humans is 150-400×10^９ cells per litre and is maintained within fairly narrow limits ( count and MPV ) within any individual on a day to day basis. Abnormalities in platelet production results in clinically significant disorders e.g. thrombocytopenia ( <150×10^９ /L ) or thrombocythemia ( > 600×10^９ /L ) which can either significantly increase the risk of bleeding or thrombosis respectively. As platelets are anucleated cells with limited protein biosynthetic capability their normal lifespan is also comparatively short ( –10 days ) relative to other blood cells. Assuming an average adult blood volume of –5 litres, approximately 1×10^１１ platelets are therefore produced every single day ( equivalent to 1.2×10^６ platelets/second ) to maintain the normal platelet count under steady state conditions. However the capacity to increase platelet production can increase to greater than –10 fold this number if required for example in severe haemorrhagic conditions. In this review we will therefore review the current knowledge on platelet development and the regulation of platelet production or thrombopoiesis in health and disease.

KEY WORDS

Platelet, Megakaryocyte, Thrombopoietin, Thrombopoiesis, Immature Platelet Fraction