Analysis of red cell mass and plasma volume in patients with polycythemia vera

Full text: Polycythemia vera (PV) was first described in 1892. The primary objective during the evaluation of erythrocytosis is to ascertain the presence or absence of PV. Because of prognostic and treatment differences, PV must be distinguished from relative polycythemia and secondary erythrocytosis. A retrospective analysis of RCM and plasma volume data are presented with special attention to different methods of RCM interpretation. A total 104 patients was studied (26 women and 78 men). Measurements of RCM and plasma volume were performed using chromium-51 labeled red cells. Results were expressed in millilitres by using the actual patient weight and using body surface area. There was a high prevalence of overweight or obesity in our population. However adipose tissue is relatively avascular, can lack precision of measurement of RCM in obese individuals. Pearson et al. showed that the results from 98% of males and 99% of females fall between ± 25% of the mean value at any given surface area. Using these limits as the reference range, we accepted the diagnosis of absolute erythrocytosis when an individual measured RCM is more than 25% above their predicted value