Comparison of red cell and whole blood volume as performed using both chromium-51-tagged red cells and iodine-125-tagged albumin and using I-131-tagged albumin and extrapolated red cell volume.

BACKGROUND Our facility's current blood volume measurement protocol has involved separate measurement of plasma and red cell volumes. The purpose of this study is to determine whether measurement with a recently FDA-approved, one-compartment semiautomated system provides similar accuracy. METHODS Blood volume measurement was performed on 27 volunteers using our current protocol followed immediately by semiautomated plasma volume measurement and red cell volume calculation with a recently available system (BVA-100). RESULTS Double labeling for red cell mass and plasma volume required approximately 5 hours of technologist and processing time; measurement with the BVA-100 required approximately 1.5 hours or less, a saving of 3.5 hours time per test. Whole blood and red cell volume each exhibited a Pearson correlation of 0.96, and plasma volume exhibited a Spearman rank correlation of 0.90. Average percent difference between the measurement methods was 2.2% for whole blood volume, 0.9% for red cell volume, and 3.3% for plasma volume. The mean ratio between the mean body hematocrit and measured venous hematocrit (f ratio) was 0.91, with a standard deviation of 0.0405. CONCLUSIONS The BVA-100 has significant advantages in terms of time and ease of use. The 2 tests can be considered equivalent methods for blood volume measurements.