Comparison of multiple red cell volume methods performed concurrently in premature infants following allogeneic transfusion

BACKGROUND: Study of the pathophysiology and treatment of anemia of prematurity is facilitated by direct measurement of red cell volume (RCV) utilizing microliter quantities of blood samples. Our objective was to compare concurrent measurements of multiple direct RCV methods in infants. METHODS: Eighteen preterm infants receiving clinically-indicated transfusions had concurrent flow cytometric determinations of RCV and 24 h red blood cell (RBC) recovery based on donor-recipient differences of biotin–labeled RBCs (BioRBCs), Kidd antigen mismatched RBCs, and HbF positive (HbF(+)) RBCs. HPLC was also used to measure HbF and HbA protein concentrations for RCV determination. RESULTS: Concurrent RCV measurements using BioRBCs (18 and 54 μg/ml), Kidd antigen, and HbF flow cytometry were not statistically different compared to RCVs measured using the reference BioRBC density (6 μg/ml). In contrast, the HbF HPLC method over estimated RCV by 45% compared to the reference method. All methods demonstrated 100% 24 h post-transfusion RBC recovery (PTR(24)). CONCLUSIONS: Because BioRBC, Kidd antigen, and HbF flow cytometry are safe and accurate methods requiring <10 μl of patient blood to determine RCV and PTR(24) in preterm infants, they can be useful in clinical and research studies of anemia and other conditions.