A longitudinal investigation of changes in red blood cell (RBC) size distribution and zinc protoporphyrin/haemoglobin (ZPP/Hb) ratio was performed.
In the course of the first few weeks after birth RBC size distribution histograms show a loss of macrocytic RBCs demonstrated by a rapid decrease of the fraction of macrocytes, whereas the degree of RBC volume dispersion decreases simultaneously. Within this period a significant change in the fraction of microcytes was not observed. At about 6 months of age, a marked shift of RBC size distribution histograms towards lower volumes occurs. Concomitant with the lower MCV values, the values for the absolute distribution width at half peak height (ADW0.5) also showed an obvious decrease.
At birth, ZPP/Hb ratios are about three times higher than those of adult subjects and decrease slowly during infancy. This suggests that iron deficiency is unlikely in the first months of life.
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