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.