The volume of the human erythrocyte and plasma alkaline phosphatase activity.

Changes in mean red cell count (RCC), mean cell volume (MCV) and plasma alkaline phosphatase activity (ALP) were observed in a group of 33 normal male university students at a 7-week interval. Linear regression analysis shows a negative linear relationship between changes in RCC and MCV (r = -0.77, P less than 0.0005) while a positive correlation was found for changes both in ALP activity and in MCV (r = +0.37, P less than 0.025). Multiple regression analysis indicates that 70% of the variation in MCV could be accounted for by changes in RCC and plasma ALP activity (r = +0.84, P less than 0.0025).