title: The relationship between total red cell volume, plasma volume and venous haematocrit.
abstract: Total red cell volume (TRCV) and plasma volume (PV) have been measured in 130 cases including 65 polycythaemic patients and 65 patients with a wide variety of disorders. Patients with gross splenomegaly were excluded from the study. The regression of TRCV on venous haematocrit (VHct) was found to be curvilinear, a single exponential function providing a good approximation ( r=0.92, P less than 0.001). No significant difference was found between the mean PVs of the polycythaemic and control groups (40.97 and 42.94 ml/kg respectively) although a slight but highly significant negative correlation was observed between PV and VHct (r = 0.47, P less than 0.001). This most marked for patients with VHcts below 0.30, for whom a separate plot yielded a correlation coefficient of 0.75. Total blood volume (TBV) and VHct were found to be positively correlated (r = 0.57, P less than 0.001) as would be expected from the TRCV and PV data. The significance of these findings is discussed.
mesh_terms: D001810:Blood Volume; D004912:Erythrocytes; D005260:Female; D006400:Hematocrit; D006801:Humans; D008297:Male; D011086:Polycythemia / Q000097:blood*; D014680:Veins