Waldenstrom's Macroglobulinemia: Correlation Between Expanded Plasma Volume and Increased Serum Viscosity

In 17 patients with Waldenström’s Macroglobulinemia, total chromiumspace, red cell mass, plasma volume and relative serum viscosities were determined; aldosterone excretion was determined in 12. Ten of the 15 patients whomanifested elevated serum viscosity at some time during the course of studypresented signs and symptoms of hyperviscosity syndrome. All patients had increased total blood volume. Fifteen had moderate decreases in red cell massbut all had elevations of plasma volume far in excess of that required to compensate for the lowered cell mass. The degree of the increase in plasma volumecorrelated (r = 0.74) with the degree of abnormality in relative serum viscosity. Aldosterone excretion in such patients was normal to low. It is concluded that the plasma volume increase is correlated with serum viscosity andis mediated by sodium retention mechanisms not involving modification ofaldosterone secretion.