RED BLOOD CELL (RBC) SURVIVAL IN IRON DEFICIENT INFANTS DETERMINED BY ANALYSIS OF RBC SIZE DISTRIBUTION CURVES

Abstract

Shortened survival of iron-deficient RBC has been demonstrated by isotope labeling and cross-transfusion techniques. Survival of iron-deficient RBC in 7 infants was determined by analyzing serial changes in RBC size distribution curves during treatment. RBC size (volume) distribution curves were measured on a Coulter Channelizer. Pretreatment RBC were microcytic and had unimodal, lognormal size distribution curves. During treatment size distribution curves became bimodal as a new, larger sized population of RBC entered the circulation. Bimodal curves were separated by curve matching into large and small size RBC population curves. The area under each curve was proportional to the number of cells in that population. Initial hemoglobin (Hb) and RBC half-life determined by analysis of cell size distribution curves in the 7 infants were:Severity of anemia correlated with shortened RBC survival (r=0.86) RBC survival in these 7 infants was shorter than survival of 51Cr labeled cells in non-anemic infants (p< 0.001). Analysis of RBC size distribution curves is a useful method of measuring RBC survival when correction of anemia produces a change in RBC size. Measurement can be accomplished on microliter quantities of blood without using isotopes.