RBCs labeled at two biotin densities permit simultaneous and repeated measurements of circulating RBC volume.
BACKGROUND
The extend potential applications of a nonradioactive method for measuring circulating RBC volume, we tested the hypothesis that RBC volume could be determined independently using two populations of RBCs labeled with low-density biotin (LDB1) and high-density biotin (HDB).


METHODS
In 10 healthy adults, autologous RBCs were labeled with HDB, LDB, or 51Cr. The labeled RBCs were mixed and transfused. RBC volume was measured in postinfusion peripheral venous blood by quantitating dilution of each population of labeled RBCs.


RESULTS
RBC volume measured using either LDB or HDB cells agreed well with RBC volume measured using 51Cr. For the regression of RBC volume by LDB versus RBC volume by 51Cr, correlation = 0.994 and slope = 0.933. For HDB versus 51Cr, correlation = 0.982 and slope = 0.953. RBC volume measured a second time in four subjects with HDB agreed well; mean CV for the differences between HDB and 51Cr were less than 5 percent.


CONCLUSIONS
Using RBCs labeled with two different densities of biotin, RBC volume can be accurately measured simultaneously and repeatedly in the same subject without radiation exposure.
Mock
Donald M
DM
Department of Biochemistry and Molecular Biology 516, University of Arkansas for Medical Sciences, 4301 W. Markham Street, Little Rock, AR 72205, USA. mockdonaldm@uams.edu
Lankford
Gary L
GL
Widness
John A
JA
Burmeister
Leon F
LF
Kahn
Daniel
D
Strauss
Ronald G
RG
D001710:Biotin; D001811:Blood Volume Determination / Q000379:methods*; D002860:Chromium Radioisotopes; D004912:Erythrocytes; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D008297:Male
D002860:Chromium Radioisotopes; D001710:Biotin