Interpretation of Measured Red Cell Mass in the Diagnosis of Polycythaemia

Abstract

Expression of predicted and measured [human] red cell mass (RCM) in terms of ml/kg body wt lacks precision. The use of formulae for prediction of normal mean red cell mass derived from the blood volume prediction (BV) of Nadler et al. was examined. A more accurate determination of mean normal predicted red cell mass (MNRCM) may be obtained by using the following formulae: 0.47 .times. 0.91 .times. BV = MNRCM for males and 0.43 .times. 0.91 .times. BV = MNRCM for females. The MNRCM given by these formulae agree with those given by predictions based on lean body mass and surface area. Examination of the 95% confidence limits of the Nadler prediction indicates that males with measured RCM greater than 25% and females with measured RCM greater than 30% above their MNRCM may be regarded as having polycythemia.