Reticulocyte maturity pattern analysis as a predictive marker of erythropoiesis in paediatrics. Part I: Evaluation of age-dependent reference values.

Reticulocyte quantification in peripheral blood samples is a commonly used diagnostic indicator of erythropoietic activity. A methodology based on flow cytometry additionally separates reticulocytes into three groups by fluorescence staining of the residual RNA. This identifies cells as high (HFR), medium (MFR) and low (LFR) fluorescence intensity reticulocytes. In the present study an automated counter was evaluated and tested for its clinical applicability in paediatrics. In part I, reference intervals for different periods of childhood were determined. Except for the neonatal period there was no age-dependence so that children aged one week to 16 years have been summarized in one group. The wide variations we found in preterm children can be explained by different erythropoietic stimuli as the result of anaemia in infants with very low birthweight. No significant differences could be found between the sexes, not even at the onset of puberty. When using the reticulocyte maturity pattern analysis in clinical practice, the data give a helpful indication of the efficiency of the erythropoietic system.