Red blood cell counts and hemoglobin determinations have been thought by some investigators to fluctuate but little in an individual during the day and by others to show large variations. As it is important to know whether isolated counts should be considered in relation to the time of day of the count and the activity of the person, this study was initiated to determine the variations of erythrocytes and hemoglobin values during short periods of time. It was found that with accurate technic, the red blood corpuscles and the hemoglobin determinations remain remarkably constant during the day, and that there are no significant changes due to rest, moderate activity or food. Real differences may occur, however, between counts for separate days and between averages for longer periods of time
TOTAL COUNTS OF ERYTHROCYTES
—The inaccuracy that may attend blood counting has invalidated many experiments in which this technic has
SMITH C. NORMAL VARIATIONS IN ERYTHROCYTE AND HEMOGLOBIN VALUES IN WOMEN. Arch Intern Med (Chic). 1931;47(2):206–229. doi:10.1001/archinte.1931.00140200042005
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