Reference Values of Reticulocyte Hemoglobin Content in Healthy Adolescents.

Assessing iron status in a pediatric population is not easy, as it is based on parameters that undergo physiological variations in childhood and adolescence. Analysis of the reticulocyte hemoglobin content (CHr) to screen for iron deficiency may increase the accuracy of diagnosis, but, to date, reference values in healthy adolescents have not been adequately determined. A cross-sectional study was conducted on a population-based representative sample in the city of Almería (Spain), with 253 healthy non-iron-deficient (ID) subjects, aged 12 to 16 years. The mean CHr value was 31.6±1.3 pg. The CHr 2.5 percentile was 28.7 pg. There were no significant differences as regards age or sex. In the multivariate linear regression analysis, sex did not influence the variability of CHr, but it was related to age. CHr was influenced by hemoglobin and the Mentzer index, as well as by functional iron indicators such as erythrocyte protoporphyrin and serum transferrin receptor. These independent variables predicted two thirds of the variability in healthy adolescents (R=0.55). This study provides CHr reference ranges in healthy adolescents for use in clinical practice for the early detection of ID states. In populations with similar sociodemographic characteristics, values above the 2.5 percentile rule out ID, as values under the 2.5 percentile could be suggestive of functional ID.

Reference values of serum transferrin receptor and sTfR/log ferritin index in healthy adolescents.

Adolescence is a period of increased iron requirements, which impact on iron status. The purpose of this research is to determine the reference intervals for serum transferrin receptor (sTfR) and sTfR/log ferritin index (sTfR-F index) in healthy adolescents, and their relation with iron parameters and erythropoiesis. A total of 253 healthy adolescents without overweight, aged 12 to 16 years, were selected in a cross-sectional study. Hemoglobin, red cell indices, reticulocyte hemoglobin content (rHb), reticulocytes, ferritin, transferrin saturation, erythrocyte protoporphirin, erythropoietin, C-reactive protein, sTfR, and sTfR-F index were measured. Changes in erythropoiesis and iron status in the age interval were observed and analyzed, and linear multiple regression was applied to identify the factors that determine the variability of sTfR and sTfR-F index. Mean values for sTfR and sTfR-F index were 1.32 ± 0.3 mg/L (95% CI, 1.3-1.36) and 0.9 ± 0.25 (95% CI, 0.87-0.93). The reference intervals were 0.84 to 1.97 mg/L and 0.51 to 1.44, respectively. sTfR and sTfR-F index values were significantly higher in boys (1.39 ± 0.3 vs. 1.23 ± 0.26 mg/L, P<0.0001 and 0.93 ± 0.37 vs. 0.86 ± 0.22, P<0.04) and decreased with age (P<0.0001 and 0.04, respectively). No changes were recorded in erythropoietin. Age, sex, pubertal status, and ferritin predicted 24.1% of sTfR variability and age, sex, pubertal status, transferrin saturation, rHb, erythrocytes, and reticulocytes predicted 15% of sTfR-F index variability.