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

Prevalence of iron deficiency and related factors in Spanish adolescents

Iron deficiency anaemia continues to be the world's most important cause of years lived with disability in children and adolescents. Assessment of iron deficiency traditionally depended on laboratory parameters that may be modified by inflammation states, including obesity, which is nowadays a current condition in adolescent population of high-income countries. The present study ascertains the prevalence of iron deficiency and its related factors in adolescents, using the serum transferrin receptor and the reticulocyte haemoglobin content, in order to avoid this confusing effect of classical parameters. A cross-sectional study was conducted on a population-based representative sample for teenagers in Almería (Spain), of 405 subjects aged 12 to 16 years. Iron deficiency was present in 13.3% of adolescents, but iron deficiency anaemia only in 1.2%. Multivariate logistic regression analyses showed that being part of an immigrant family, a low iron bioavailability diet, meat consumption below four times a week and fish consumption below twice a week, were independent risk factors for iron deficiency.Conclusion: This study provides an estimate iron deficiency prevalence of 13.3% in Spanish healthy adolescents, avoiding potential confounding factors through the use of new iron status parameters, based on a wide representative sample of adolescents from the city of Almería. What is Known: • For children and adolescents, iron deficiency anaemia continues to be the world's most important cause of years lived with disability. • Assessment of iron deficiency has traditionally depended on laboratory parameters that may be modified by inflammatory states, including obesity. What is New: • Iron deficiency prevalence and their related factors were analysed in Spanish adolescents, avoiding potential confounding factors through the use of sTfR and CHr. • Being part of an immigrant family and consuming a low iron bioavailability diet are independent risk factors for iron deficiency.

Soluble transferrin receptor and soluble transferrin receptor/log ferritin index in diagnosis of iron deficiency anemia in pediatric inflammatory bowel disease

BACKGROUND

There is no single reliable marker of iron homeostasis in inflammatory bowel disease.

AIMS

To determine diagnostic usefulness of soluble transferrin receptor and soluble transferrin receptor/log ferritin index in iron deficiency anemia in children with inflammatory bowel disease.

METHODS

We assessed soluble transferrin receptor in serum and calculated soluble transferrin receptor/log ferritin index in 75 children with inflammatory bowel disease. Diagnostic ability to identify iron deficiency anemia was examined by receiver operating characteristic analysis.

RESULTS

Study group comprised 27 cases of iron deficiency anemia, 6 anemia of chronic disease with iron deficiency, 5 anemia of chronic disease. Soluble transferrin receptor was significantly increased in children with iron deficiency anemia (median: 1.63 μg/ml) compared to non-anemic children (median: 1.02 μg/ml). Soluble transferrin receptor/log ferritin index was significantly higher in iron deficiency anemia (median: 1.76) than in anemia of chronic disease (median: 0.55), anemia of chronic disease with iron deficiency (median: 0.68) or patients without anemia (median: 0.72). Soluble transferrin receptor and its index were not correlated with disease activity or inflammatory markers. Diagnostic power for soluble transferrin receptor/log ferritin index (0.864) was superior to soluble transferrin receptor (0.768) in iron deficiency anemia recognition.

CONCLUSION

Soluble transferrin receptor/log ferritin index has better diagnostic utility than soluble transferrin receptor for iron deficiency anemia detection in pediatric inflammatory bowel disease.

The usefulness of reticulocyte haemoglobin content, serum transferrin receptor and the sTfR-ferritin index to identify iron deficiency in healthy children aged 1-16 years

This cross-sectional study, conducted on a population-based representative sample, evaluates the usefulness of reticulocyte haemoglobin content (CHr), serum transferrin receptor (sTfR) and sTfR/log ferritin (sTfR-F index) to recognise iron deficiency (ID) without anaemia, provides specific cut-off points for age and gender, and proposes a new definition of ID. A total of 1239 healthy children and adolescents aged 1-16 years were included. Complete blood count, iron biomarkers, erythropoietin, C-reactive protein, CHr, sTfR, and sTfR-F index were determined. ROC curves were obtained and sensitivity, specificity, predictive values, likelihood ratios, and accuracy for each specific cut-off points were calculated. Seventy-three had ID without anaemia. Area under the curve for sTfR-F index, sTfR and CHr were 0.97 (CI95% 0.95-0.99), 0.87 (CI95% 0.82-0.92) and 0.68 (CI95% 0.61-0.74), respectively. The following cut-off points defined ID: sTfR-F Index > 1.5 (1-5 years and 12-16 years boys) and > 1.4 (6-11 years and 12-16 years girls); sTfR (mg/L) > 1.9 (1-5 years), > 1.8 (6-11 years), > 1.75 (12-16 years girls) and > 1.95 (12-16 years boys); and CHr (pg) < 27 (1-5 years) and < 28.5 (6-16 years).Conclusions: CHr, sTfR and the sTfR-F index are useful parameters to discriminate ID without anaemia in children and adolescents, and specific cut-off values have been established. The combination of these new markers offers an alternative definition of ID with suitable discriminatory power. What is Known: • In adults, reticulocyte haemoglobin content (CHr), serum transferrin receptor (sTfR) and sTfR/log ferritin index (sTfR-F index) have been evaluated and recognised as reliable indicators of iron deficiency (ID). • Clinical manifestations of ID may be present in stages prior to anaemia, and the diagnosis of ID without anaemia continues to pose problems. What is New: • CHr, sTfR and the sTfR-F index are useful parameters in diagnosis of ID in childhood and adolescence when anaemia is not present. • We propose a new strategy for the diagnosis of ID in childhood and adolescence, based on the combination of these measures, which offer greater discriminatory power than the classical parameters.

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.

Iron status and anaemia in Sri Lankan secondary school children: A cross-sectional survey

BACKGROUND

Iron deficiency, the most common micronutrient disorder and cause of anaemia globally, impairs growth, cognition, behaviour and resistance to infection.

METHODS/RESULTS

As part of a national survey of inherited haemoglobin variants in 7526 students from 72 secondary schools purposefully selected from the 25 districts of Sri Lanka, we studied 5912 students with a normal haemoglobin genotype. Median age was 16.0 (IQR 15.0-17.0) years and 3189 (53.9%) students were males. Most students were Sinhalese (65.7%), with fewer Tamils (23.1%) and Muslims (11.2%). Anaemia occurred in 470 students and was more common in females (11.1%) than males (5.6%). Haemoglobin, serum ferritin, transferrin receptor and iron were determined in 1196 students with low red cell indices and a structured sample of those with normal red cell indices (n = 513). The findings were weighted to estimate the frequencies of iron deficiency and iron deficiency anaemia classified according to WHO criteria. Iron depletion (serum ferritin <15ug/ml) occurred in 19.2% and cellular iron deficiency (low serum ferritin and transferrin receptor >28.1 nmol/l) in 11.6% students. Iron deficiency anaemia (cellular iron deficiency with low haemoglobin) occurred in only 130/2794 (4.6%) females and 28/2789 (1.0%) males. Iron biomarkers were normal in 83/470 (14.6%) students with anaemia. In multiple regression analysis, the odds for iron depletion and cellular iron deficiency were about one-third in males compared with females, and the odds for iron deficiency anaemia were about one fifth in males compared to females. Tamil ethnicity and age <16 years increased the risk of all three stages of iron deficiency and living at high altitude significantly reduced the risk of iron depletion.

CONCLUSIONS

Low iron status and anaemia remain common problems in Sri Lankan secondary school students especially females, younger students and the socioeconomically disadvantaged Tamil population. More research is needed to identify factors other than low iron status that contribute to anaemia in adolescents.

Reference Values of Reticulocyte Hemoglobin Content and Their Relation With Other Indicators of Iron Status in Healthy Children

Reticulocyte hemoglobin content (CHr) is considered an indicator of functional iron deficiency, but is understudied in children. The goals of this study are to determine the reference intervals for CHr in healthy children, and their relation with iron parameters, erythropoiesis, and individual conditions. A total of 902 children without iron deficiency, aged 1 to 11 years were analyzed in a cross-sectional study. Besides a physical examination of the subjects and a questionnaire completed by their parents, the complete blood count, serum transferrin receptor, ferritin, transferrin saturation, erythrocyte protoporphyrin, serum erythropoietin, C-reactive protein, and CHr levels were measured. Changes in CHr, iron status, and erythropoiesis at different age intervals were analyzed and linear multiple regression was used to identify the factors that determine CHr variability. Mean value obtained for CHr was 30.9±1.8 pg (P2.5-P97.5: 26.9 to 34.3 pg), but the influence of age on CHr (the values increased with age) and on the iron parameters justified the establishment of different reference ranges. In addition to age, nutritional status, hematologic measurements, reticulocytes, transferrin saturation, and erythrocyte protoporphyrin accounted for 39% of CHr variability.

Reference values of serum transferrin receptor (sTfR) and sTfR/log ferritin index in healthy children

ABSTARCT The aims of this study were to determine appropriate reference ranges for serum transferrin receptor (sTfR) and sTfR/log ferritin (sTfR-F index) in healthy children and their relationship with iron parameters, erythropoiesis, and other conditions presented by the subject. A total of 902 children with normal iron status, aged 1-11 years, were included in a cross-sectional study. A physical examination was conducted and z-score of body mass index (zBMI) obtained. Complete blood count, iron biomarkers, erythropoietin, C-reactive protein, sTfR, and sTfR/log ferritin were determined. Linear multiple regression was applied to identify the factors that determined sTfR and sTfR-F index variability. Mean values for sTfR and sTfR-F index were 1.22 ± 0.28 mg/L (95% confidence interval [CI]: 1.2-1.23) and 0.87 ± 0.25 (95% CI: 0.85-0.88). The reference intervals (2.5th to 97.5th percentiles [P2.5-P97.5]) were 0.78-1.9 mg/L and 0.49-1.46, respectively. sTfR and sTfR-F values decreased with age (P <.03 and P <.0001, respectively). No changes were observed with sex. Changes in sTfR and sTfR-F index were consistent with ferritin and erythropoietin variations. Iron biomarkers, erythropoietin, and zBMI predicted 19% and 18.1% of the sTfR and sTfR-F index variability. The results provide reference ranges for sTfR and sTfR-F index in healthy children for clinical use in the assessment of body iron status. Both biomarkers are predicted by iron parameters, erythropoietin, and zBMI.