Red cell and plasma volumes in normal adults.

Despite numerous published methods for predicting normal red cell and plasma volumes, little is known of the range of normal in subjects of given body dimensions. In this study, reported results of red cell and plasma volumes in 481 normal men and 303 normal women have been used to calculate mean volumes and standard deviations (s.d.) for any given body surface area (male and female results being kept separate). All of these mean volumes, each plus or minus 2 s.d., have been plotted against body surface area. The resulting graphs of means and 95% confidence limits have tended to be curvilinear. Standard deviations have increased with increasing mean volumes, but coefficients of variation (s.d./mean) have shown considerable constancy at 11-12%. The mean values observed in this series have often differed substantially from those predicted from published formulas. Use of the presently observed means with the 11-12% coefficients of variation allows compilation for any surface area of a range of normal against which a clinically obtained volume can be compared.