Comparison of radioisotope methods and a nonradioisotope method to measure the RBC volume and RBC survival in the baboon.

BACKGROUND: RBC volume, 24-hour posttransfusion survival, and life span can be measured with radioisotopes and nonradioactive procedures. STUDY DESIGN AND METHODS: RBC volume was measured directly with autologous baboon RBCs labeled with biotin-X-N-hydroxysuccinimide (NHS), 51 Cr, 99m Tc, and 111 In-oxine and indirectly from the 125 I plasma volume and the total body Hct. Twenty-four-hour posttransfusion survival and life span were measured in autologous fresh baboon RBCs labeled with 51 Cr, 111 In-oxine, 99m Tc, and biotin-X-NHS. RESULTS: Significantly larger RBC volumes were observed when the fresh autologous RBCs were labeled with 51 Cr, 111 In-oxine, or 99m Tc than when they were labeled with the nonradioactive biotin-X-NHS. Twenty-four-hour posttransfusion survival values were significantly lower in the RBCs labeled with 111 In-oxine or 99m Tc than in the RBCs labeled with 51 Cr. CONCLUSIONS: The greater in vivo elution of 51 Cr, 111 In-oxine, and 99m Tc than that of biotin-X-NHS influenced the measurements of RBC volume, 24-hour posttransfusion survival, and life span of the fresh baboon RBCs.