The platelet count and mean platelet volume.

The Coulter Model S-Plus Counter provides a measure of the platelet count and the mean platelet volume (MPV). An analysis of 5000 unselected blood specimens showed an inverse relationship between the number of circulating platelets and their MPV. In nearly 95% of normal adults the platelet count varied from 150 to 450 X 10(9)/l and the MPV from 7.0 to 10.5 fl. Thrombocytosis was found in iron deficiency anaemia, after trauma and acute blood loss and in rhematoid arthritis. Although there is a normal platelet distribution in pregnancy, patients with pre-eclampsia and uncomplicated hypertension in late pregnancy tended to have lower platelet counts and larger platelets than controls. A variable platelet pattern was found in infection, renal failure and treated malignant disease.