The blood volume of infants: I. The full-term infant in the first year of life

Abstract

<h2>Summary</h2> The subjects of this study were 126normal full-term infants on whom 223 plasma volume determinations were made using a T-1824 dye dilution technique. Of these infants, 2 observations were made on 47, and 3 or more serial observations were made on 20. Total blood and erythrocyte volumesand total circulating hemoglobin mass values were calculated from the plasma volume, venous hematocrit, and hemoglobin concentration. No reliable average blood volume could be observed in either the neonatal period or during the succeeding 11 months of life, owing to a wide range of values throughout the year. The average erythrocyte volume, circulating hemoglobin mass, and total hemoglobin iron values did not return to neonatal levels until 16 weeks after birth. Assessment of anemia in the infant from blood loss, iron deficiency, or other causes can be aided by the determination of the erythrocyte volume and hemoglobin mass. We believe that more reliance can be placed on these values than on those of the hemoglobin concentration and hematocrit because of the considerable number of infants who demonstrate hypo- or hypervolemia. In these states paradoxical values of hemoglobin concentration and hematocrit are frequently encountered which yield misleading information.