Determination of blood volumes revealed hypervolemia in all of the four patients with macroglobulinemia and in nine of 11 with myeloma. The red blood cell (RBC) mass was normal in all patients with macroglobulinemia, but an increased plasma volume reduced the hematocrit reading to cause dilution anemia. In most patients with myeloma, the RBC mass was moderately reduced, but hypervolemia associated with an increased plasma volume also decreased the hematocrit value.
These data indicate that determining blood volumes can often aid in prescribing therapy for these patients. In some patients the results may indicate treatment with plasmapheresis, rather than with transfusions.
Kopp WL, MacKinney AA, Wasson G. Blood Volume and Hematocrit Value in Macroglobulinemia and Myeloma. Arch Intern Med. 1969;123(4):394–396. doi:10.1001/archinte.1969.00300140040009