Erythrocyte volume, plasma volume, and lean body mass in adult men and women.

T HE RANGES of normal erythrocyte and plasma volumes reported in the literature are wide. Comparisons between different persons and separation of normal from pathologic states are difficult, particularly in subjects of unusual size or body proportions. Attempts to reduce the wide range of normal have been made by relating blood volume to weight, height, combined height and weight, surface area, somatotype, and lean body mass.111 There is no general agreement as to what index of body size is best suited for use as a standard for blood volume measurements.1’2’6’12 In this study, erythrocyte volume, plasma volume, lean body mass (from total body water), and thickness of various skinfolds were measured in normal and obese subjects. Equations predicting erythrocyte and plasma volumes from various indices of body size were calculated and a normal standard for use in clinical laboratories is suggested. The accuracy of indirectly estimating one component of the blood (cells or plasma) from measurement of the other component of the blood and the venous hematocrit is examined.