Iron Status of Preadolescents Without Clinical Pallor Attending a Tertiary Care Hospital in South India- A Cross-Sectional Analytical Study

OBJECTIVES

To determine the prevalence of Iron Deficiency (ID) in children without clinical pallor using serum ferritin and the new parameters, soluble transferrin receptor (sTfR) & the ratio of sTfR/log10 serum ferritin (sTfR-F index), as suggested by WHO. Also to assess whether these new parameters could individually predict the presence of ID.

METHODS

Consecutive 230 healthy children aged 9-11 y without clinical pallor underwent estimation of Hemoglobin (Hb), C-Reactive Protein (CRP), serum ferritin, sTfR, and sTfR-F index levels in their blood. The abilities of the sTfR and sTfR-F index in predicting ID were determined by comparing with the gold standard (normal CRP and less serum ferritin), plotting Receiver-operating characteristic (ROC) curve, and noting the area under the curve (AUC).

RESULTS

The blood reports of 114 boys and 106 girls (total = 220) were available for analysis. Overall, 57 (31 girls, 26 boys) children had ID; among children with low CRP, 45 had ID, as suggested by low serum ferritin levels. Among children with high CRP, 12 had evidence of ID as evidenced by elevated sTfR and/or sTfR-F index. The positive predictive values of both sTfR and sTfR-F were low (32.9% and 35.9%, respectively) than the negative predictive values (85.6% and 95.3%, respectively).

CONCLUSIONS

The proportion of children identified to have ID using serum ferritin, sTfR, and sTfR-index was 25.9%. sTfR and/or sTfR-F index are unlikely to be ideal individual predictors of ID.

Prevalence and Implications of Low Reticulocyte-Hemoglobin Levels among Extreme Preterm Neonates: A Single-Center Retrospective Study

This retrospective cohort study aims to determine the epidemiology of iron deficiency among extreme preterm neonates and the association of iron-deficient status during the NICU stay with neurodevelopmental outcomes at 18−24 months. Neonates ≤29 weeks gestational age (GA) born between June 2016 and December 2019, who received routine iron supplementation were enrolled. Iron deficiency was defined as reticulocyte−hemoglobin (Ret-Hb) levels ≤ 29 pg at 36 weeks corrected age. A subcohort of neonates completed standardized developmental assessment at 18−24 months corrected age. Significant neurodevelopmental impairment (sNDI) was defined as either Bayley Scales of Infant Development score < 70 or cerebral palsy or blindness or hearing aided. Among a cohort of 215 neonates [GA 25.8 (1.7) weeks, birthweight 885 (232) g], prevalence of iron deficiency was 55%, 21%, 26%, and 13%, in neonates <24 weeks, 24−25 + 6 weeks, 26−27 + 6 weeks, and ≥ 28 weeks GA, respectively. Male sex and receipt of corticosteroid therapy were associated with iron-deficiency. In the subcohort analysis (n = 69), there was no statistically significant association between Ret-Hb levels at 36 weeks corrected age and the risk of sNDI [OR 0.99 (95% CI 0.85−1.2)]. Male infants and those who received postnatal corticosteroids are likely to have iron-limited erythropoiesis at corrected term despite routine iron-supplementation; however, low Ret-Hb levels during the neonatal period were not associated with significant neurological disability in early childhood.

Effect of Daily Iron Supplementation on Infantile Iron Homeostasis in Preterm Infants

Objective: The aim of this study was to investigate the effects of unified iron supplementation and identify the factors related to the iron homeostasis among preterm infants. Method: A total of 250 preterm infants were divided into neonatal anemic (NA, n = 154) and non-neonatal anemic group (NNA, n = 96). Iron supplements at a dose of 2 mg/kg per day were given from 40 weeks' gestational age to 6 months. Iron status parameters were measured at 3 and 6 months, respectively. Prevalence of iron deficiency (ID) and iron deficiency anemia (IDA), and the correlated factors were analyzed. Growth and side-effects were monitored. Results: There were no significant differences for the prevalence of ID or IDA between the two groups. Multivariate regression analyses showed that higher Hb at birth and early treatment of blood transfusion reduced the risk of ID/IDA at 3 months (all p < 0.05); while higher level of Hb at 3 months (p = 0.004) and formula feeding reduced the occurrence of ID/IDA at 6 months (p < 0.05); males had a 3.35 times higher risk to develop ID/IDA than girls (p = 0.021). No differences in growth and side effects were found. Conclusion: A daily dose of 2 mg/kg iron supplement is beneficial to maintain iron homeostasis in majority preterm infants within 6 months regardless of their neonatal anemia history. Under the routine iron supplementation, Hb level at birth and at 3 months, early treatment of blood transfusion, gender and feeding patterns are the major factors affecting the prevalence of ID/IDA among preterm infants in infancy.

Biomarkers of Senescence during Aging as Possible Warnings to Use Preventive Measures

Human life expectancy is increasing significantly over time thanks to the improved possibility for people to take care of themselves and the higher availability of food, drugs, hygiene, services, and assistance. The increase in the average age of the population worldwide is, however, becoming a real concern, since aging is associated with the rapid increase in chronic inflammatory pathologies and degenerative diseases, very frequently dependent on senescent phenomena that occur alongside with senescence. Therefore, the search for reliable biomarkers that can diagnose the possible onset or predict the risk of developing a disease associated with aging is a crucial target of current medicine. In this review, we construct a synopsis of the main addressable biomarkers to study the development of aging and the associated ailments.

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.

Lower Plasma Soluble Transferrin Receptor Range in Healthy Indian Pediatric Cohort as Compared to Asian and Western Data

Soluble serum transferrin receptor is derived from erythroid transferrin receptor expressed on surface of developing erythroid cells. It can be detected in blood using sensitive ELISA methodology and blood levels reflect physiological iron dependent erythropoiesis state in bone marrow. Normal adult levels vary from 2 to 5 mg/l. However, pediatric studies are few and describe normal ranges to the tune of 1.0-3.0 mg/l, which are relatively lower than that of adults. In present study 40 healthy children (2-12 years) were evaluated to establish normal soluble transferrin receptor range. The mean transferrin receptor levels were 0.39 mg/l with a range of 0.17-2.1 mg/l. The levels were low as compared to mean levels described in other studies from West and our country (4.39 and 2.0 mg/l respectively). Since, no internationally standard method for reporting and testing for transferrin receptor levels are yet available, hence it is imperative to establish normal control ranges in different population cohorts, especially in pediatric age group, to better interpret their levels in diagnostic context.

Very low prevalence of iron deficiency among young French children: A national cross-sectional hospital-based survey

Although iron deficiency (ID) is considered the most frequent micronutrient deficiency in industrialized countries and is associated with impaired neurodevelopment when occurring in early years, accurate recent estimations of its prevalence are lacking. Our objective was to estimate ID prevalence and associated sociodemographic markers in young children in France. The Saturn-Inf national cross-sectional hospital-based survey recruited 3,831 French children <6 years old between 2008 and 2009 to assess lead poisoning prevalence and to establish a biobank. This secondary analysis measured serum ferritinemia (SF) in sera kept frozen at -80 °C for children with sufficient serum aliquots and C-reactive protein <10 mg/L. For the 657 participating children (17% of the Saturn-Inf study), the median age was 3.9 years (interquartile range: 2.2-5.1); 52% were boys. The median SF was 44 μg/L (interquartile range: 28-71). ID prevalence was 2.8% (95% confidence interval [1.7, 4.7]) and 3.2% (95% confidence interval [2.0, 5.1]) with an SF threshold of 10 and 12 μg/L, respectively. Low SF was significantly associated (p < .05) with mother being a migrant (32 vs. 45 μg/L for a mother born in France) or unemployed (37 vs. 50 μg/L for a mother employed). In this first national cross-sectional hospital-based study in France, ID prevalence was much lower than that in other French and European studies performed in underprivileged populations but close to the lowest values observed in other population-based studies in Europe.

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.

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.

Survey of anaemia and Helicobacter pylori infection in adolescent girls in Suihua, China and enhancement of iron intervention effects by H. pylori eradication

In the present study, we investigated the prevalence of anaemia and Fe deficiency anaemia (IDA) and explored the relationship between Helicobacter pylori infection and IDA in adolescent girls. A total of 1037 adolescent girls from Suihua, China were enrolled. Hb, serum ferritin (SF), serum transferrin receptor (sTfR) and serum IgG antibodies to H. pylori were measured. Participants with IDA and co-existing H. pylori infection (n 80) who had an intake of >25 mg/d of Fe were assigned randomly to the intervention and control groups. Patients in the intervention group were administered a 12-week course of oral EDTA-Na-Fe (60 mg Fe/dose, three times a week) and a 2-week course of colloidal bismuth subcitrate, amoxicillin and metronidazole. Subjects in the control group were administered EDTA-Na-Fe alone. Hb, SF and sTfR were reassessed 3 months after the 12-week regimen ended. Prevalence of anaemia, Fe deficiency (defined as SF < 12·0 μg/l), IDA and H. pylori infection in the population of 1037 was 19.5, 40.4, 17.1 and 31.2 %, respectively. The prevalence of H. pylori infection in the IDA group was 46.9 %, while the non-anaemic group had 28.1 % prevalence. A significant increase in Hb and SF and a decrease in sTfR value were found in the intervention group and the H. pylori-negative group. Findings suggest that IDA is still one of the prominent problems in adolescent girls. There is an association between H. pylori infection and IDA. Treatment of H. pylori infection is associated with a more rapid response to oral Fe therapy.

Pediatric reference intervals determined in ambulatory and hospitalized children and juveniles

OBJECTIVES

The aim of this study was to determine reference intervals in children and juveniles with nine recently developed and widely used laboratory methods.

METHODS

More than 800 ambulatory and hospitalized individuals of the University pediatry were carefully selected according to clinical status and chemical profile in an a posteriori process over a period of two and a half years. The reference group with well-balanced gender proportions and steady age distribution between 1 day and 17 years was subdivided in five age classes. The laboratory methods were: the enzyme methods ALT, AST, LDH and GGT, all reliably reference standardized with traceability to the IFCC reference methods at 37 degrees C; ALT and AST without pyridoxal-phosphate activation; ALP as not yet approved IFCC method; the soluble transferrin receptor (sTfR) and ferritin, the latter being the only heterogeneous procedure.

RESULTS

The results confirm in most cases the typical age concentration relationship of the measured quantities documented for similar methods. In some critical cases, in particular for sTfR and ferritin, the study produces limits which differ distinctly from those earlier reported. Gender differentiation was outlined according to statistical calculations.

CONCLUSION

Proposals for reference intervals were derived from the central 95 percentile values.

Predictors of serum ferritin and serum soluble transferrin receptor in newborns and their associations with iron status during the first 2 y of life

BACKGROUND

Adequate iron status at birth may prevent iron deficiency in early childhood.

OBJECTIVES

We aimed to identify predictors of serum ferritin (SF) and serum soluble transferrin receptor (sTfR) in healthy newborns and to relate these iron indexes to iron status in the first 2 y of life.

DESIGN

Using bivariate correlations and linear regression, we related various factors in pregnancy to SF (n=363) and sTfR (n=350) in healthy, term infants. Measurements of cord SF and sTfR were compared with those of SF and sTfR at 6, 12, and 24 mo. All 4 measurements were available for 191 and 169 infants for SF and sTfR, respectively.

RESULTS

Geometric mean (and 95% CI) cord SF and sTfR measurements were 159 (148, 171) microg/L and 7.3 (7.0, 7.6) mg/L, respectively. Cord SF correlated with sTfR (rho=-0.21, P<0.001). In regression analysis, cord SF correlated with smoking and the use of iron supplements during pregnancy (partial r=-0.12 and 0.16; P<0.05 for both). Cord sTfR was associated with first trimester BMI, gestational age, and male sex (partial r=0.30, 0.24, and 0.19, respectively; P<0.01 for all). Cord SF correlated with SF at 6, 12, and 24 mo (rho=0.45, 0.31, and 0.16 respectively; P<0.05 for all). At age 6 mo, 16 of 17 infants with SF <15 mug/L were boys.

CONCLUSIONS

Cessation of smoking and adequate iron prophylaxis during pregnancy may improve iron status in infancy. Cord SF is a predictor of iron status in the first 2 y of life. Boys are at particular risk of low iron status in early infancy.

Serum transferrin receptor in children: usefulness for determinating the nature of anemia in infection

OBJECTIVES

To know the variations of serum transferrin receptor (sTfR) and its indices depending on the status of body iron and the presence of infection in children, to evaluate their usefulness for recognizing the nature of anemia in infection, and to know the role of erythropoietic activity in these conditions.

DESIGN AND METHODS

Three hundred and sixty-eight children between 1 and 10 years were included: 206 healthy children; 60 iron deficient anemic children (IDA); 102 with anemia and infectious disease, 58 of them meeting criteria for IDA. We measured hemoglobin, red cell indices, reticulocytes, transferrin saturation, serum ferritin, erythrocyte protoporphyrin, serum erythropoietin, and sTfR. Statistic method: ANOVA test, multiple linear regression, and ROC curve.

RESULTS

sTfR, sTfR/ferritin ratio, and sTfR-logferritin index values were found to increase significantly in IDA children. These values were significantly lower in infectious anemia than iron deficiency states. Serum erythropoietin only was elevated significantly in iron deficiency states. In children without infection, mean corpuscular hemoglobin, erythrocyte protoporphirin, erythropoietin logarithm, and total-iron-binding-capacity logarithm predicted 81% of sTfR variability. sTfR and its indices showed a very high sensitivity and specificity for recognizing iron deficiency states. In children with IDA and infection sensitivity for sTfR/ferritin ratio was low (area under the curve: 0.71; 95% confidence interval: 0.64-0.88). For discriminating the nature of anemia in infection the cut-off point obtained for sTfR, sTfR/ferritin ratio, and sTfR-F index were 3, 70, and 1.8, respectively, and their sensitivity and specificity were also very high.

CONCLUSIONS

sTfR, sTfR/ferritin ratio, and sTfR-F index are useful parameters for recognizing iron deficiency and the nature of anemia in infection. In IDA+infection, sTfR/ferritin ratio should not be recommended in the diagnosis of iron deficiency. In iron deficiency, erythropoietic activity has a secondary role as predictor factor of sTfR levels.

Comparative effectiveness of zinc protoporphyrin and hemoglobin concentrations in identifying iron deficiency in a group of low-income, preschool-aged children: practical implications of recent illness

OBJECTIVE

The goal was to assess the influence of recent infection on screening tests for iron depletion (zinc protoporphyrin and hemoglobin) among low-income, preschool-aged children.

METHODS

This cross-sectional study was conducted at community sites and ambulatory care clinics in Hartford, Connecticut, and included 180 preschool-aged children. Iron depletion was defined as serum ferritin levels of < or = 15 microg/L. Recent illness was defined by parent or guardian (caretaker) report or evidence of elevated C-reactive protein concentrations. History of anemia was determined through medical records review. Sensitivity, specificity and positive predictive values of hemoglobin and zinc protoporphyrin were calculated overall and for children with and without recent illness.

RESULTS

At enrollment, more than one half of the children had a recent illness, and 57.5% had a history of anemia. More than one third had iron depletion. Serum ferritin levels were significantly higher among recently ill children. Secondary to recent illness, the positive predictive value of elevated zinc protoporphyrin, but not low hemoglobin, was reduced significantly. Zinc protoporphyrin levels of >69 micromol/mol heme identified significantly more iron-deficient children.

CONCLUSIONS

Compared with anemia, elevated zinc protoporphyrin levels identified significantly more iron-deficient children. Recently ill children were one half as likely to have low serum ferritin levels, compared with children without recent illness. The negative effect of recent illness on the positive predictive value of zinc protoporphyrin when ferritin is used to determine iron status has many practical implications.

Anemia, iron deficiency, and iron deficiency anemia in 12-36-mo-old children from low-income families

BACKGROUND

Iron deficiency (ID) is the most common nutritional deficiency in the world and remains relatively common in at-risk groups in the United States. The actual prevalence of anemia, ID, and iron deficiency anemia (IDA) in California remains unclear.

OBJECTIVE

The objective was to determine the prevalence of anemia, low iron stores, ID, and IDA in children participating in the Special Supplemental Nutrition Program for Women, Infants and Children (WIC) population, and to assess the value of using hemoglobin to predict ID.

DESIGN

This was a cross-sectional study of a convenience sample of 12-36-mo-old children from WIC clinics in 2 California counties.

RESULTS

The prevalence of anemia was 11.1% (hemoglobin <110 g/L at 12-24 mo or <111 g/L at 24-36 mo). Study- and literature-determined abnormal values for iron measures were as follows: serum ferritin <or=8.7 or <10.0 microg/L, serum transferrin receptor >or=8.4 or >10.0 microg/mL, and transferrin saturation <or=13.2% or <10.0%, respectively. The prevalences of low iron stores (low ferritin) were 24.8% and 29.0%, of ID (>or=2 abnormal iron measures) were 16.2% and 8.8%, and of IDA (ID with low hemoglobin) were 3.4% and 3.2% on the basis of study- and literature-determined cutoffs, respectively. Hemoglobin concentration was used to predict study- and literature-determined ID on the basis of receiver operating characteristic curves. The sensitivity of low hemoglobin in predicting study- and literature-determined ID was low (23.2% and 40.0%, respectively).

CONCLUSIONS

Anemia and ID were prevalent in this WIC sample, but IDA was uncommon. Low hemoglobin is a poor predictor of ID.

Iron deficiency: a concise review

Iron deficiency is a major worldwide health problem. There is recent evidence that the anemia is only the last manifestation of the syndrome and that symptoms occur before the anemia is manifest. Advances in outlining the physiology of iron deficiency have been made, gaps remain in the current understanding. While oral iron supplement remains the mainstay, some indications for the intravenous administration have developed. This review will highlight the epidemiology, physiology, clinical presentation, and treatment options.

Receptor sérico de transferrina en niños sanos. Valor diagnóstico en la anemia infecciosa y en la ferropénica

BACKGROUND

The serum transferrin receptor (TfR) presents certain advantages over other parameters of cellular iron status because it does not vary in acute or chronic diseases.

OBJECTIVE

To establish reference ranges of TfR in healthy children for our laboratory, to define the distribution of this variable in children with acute illness and in those with iron deficiency, and to evaluate the diagnostic yield of TfR, the transferrin-receptor/ferritin ratio (TfR/F) and the transferrin-receptor-ferritin index (TfR-F) in distinguishing ferropenic from infectious anemia.

PATIENTS AND METHODS

A descriptive, cross-sectional analysis was conducted in 132 children aged from 6 months to 16 years for a period of 18 months. The subjects were classified in three groups: healthy children, children with acute illness, and children with iron deficiency. The distribution of TfR and its diagnostic yield were evaluated.

RESULTS

Of the 132 subjects, 30 were excluded because they lacked one or more of the parameters under analysis and 19 were excluded because they showed a thalassemic trait. In the 30 healthy children, the mean TfR concentration was 1.2 mg/l (SD 0.36) and the median was 1.02 (IQR 0.7-1.7). In the 32 children with acute illness, with or without anemia, TfR values were similar to those found in healthy children (p > 0.05). TfR values were higher in children with iron deficiency (21 patients; mean TfR value: 1.67 mg/l SD 0:98) than in healthy children but this difference was not statistically significant (p 0.08). The highest TfR values were found in the group with ferropenic anemia (mean TfR value: 2.13 mg/l SD 1.14) with a statistically significant difference between healthy children (p 0.04) and those with iron deficiency without anemia (p 0.01). The TfR/F ratio showed an optimal diagnostic yield in distinguishing ferropenic from acute disease anemia. If this ratio is higher than 80.7 ferropenia can be suspected as the cause of the anemia with a global value of the test of 100 % (95 % CI: 75.91-99.42).

CONCLUSIONS

TfR could be useful in evaluating intracellular iron status in children. Acute disease does not alter TfR values and, in combination with ferritin, TfR offers an optimal diagnostical yield in distinguishing ferropenic from acute illness anemia.

Frequencies of C282Y and H63D mutations and transferrin saturation indices in the Korean population

Hereditary hemochromatosis (HHC) is an autosomal recessive disorder that damages various organs because of the deposition of excess iron. At the human hemochromatosis (HFE) gene, two mutations of C282Y and H63D have been reported. The frequencies of C282Y and H63D mutations vary among ethnic groups. At present, the most suitable screening test for HHC is the assessment of transferrin saturation (TS). We investigated the distribution of TS and the frequencies of C282Y and H63D mutations among Koreans. TS was measured in 2152 subjects who visited the health promotion center for a checkup. The mean (+/-SD) of TS was 41.7+/-15.4%. We randomly selected 240 subjects and tested them for C282Y and H63D mutations using PCR-restriction fragment length polymorphism (RFLP). All 240 randomly selected samples were found to be G/G homozygous non-mutated for C282Y. Of the 240 subjects, 18 (7.5%) were found to be C/G heterozygous and 222 subjects were C/C homozygous non-mutated for H63D. In this study, the C282Y mutation was not found in the Korean population, and the H63D mutation showed allele frequency of 3.8%. The mean TS in this study was higher than that of Caucasians.

Increased serum soluble transferrin receptor concentration detects subclinical iron deficiency in healthy adolescent girls

The objective of this study was to investigate whether the measurement of serum soluble transferrin receptor could detect subclinical iron deficiency in adolescent girls, and to assess the possible specificity-compromising effects of growth, menarche, and intensive physical activity. The study population consisted of 191 physically active (control) girls aged 9-15 years. Dietary iron intake was estimated at baseline, and after 6 and 12 months. Iron status of the subjects was assessed by haematological laboratory tests at 6 and 12 months. A 3-month iron and multivitamin supplementation was started after the visit at 6 months. The supplementation consistently decreased soluble transferrin receptor concentrations in subjects with initial values greater than 2.4 mg/l, which was determined by regression analysis to be the cut-off value for iron-deficient erythropoiesis. The 95% reference interval in the iron-replete subjects (0.9-2.4 mg/l) was consistent with this finding. In our population, the incidence of subclinical iron deficiency was 10%. Growth or physical activity had no effect on the iron status. This study shows that, similarly to adults, soluble transferrin receptor measurement can be used to detect subclinical iron deficiency in adolescents (competitive athletes or normal controls). We suggest that soluble transferrin receptor concentrations above 2.4 mg/l indicate clinically relevant iron deficiency in adolescents.

Marked increase in serum transferrin receptor among Thai children with Hb-E-beta-thalassaemia

OBJECTIVE

To determine the serum transferrin receptor (sTfR) level in patients with Hb-E-beta-thalassaemia attending a paediatric haematology clinic.

METHODS

Sixty-four patients with Hb-E-beta-thalassaemia aged 2.9-10.8 years were attending a paediatric haematology clinic at King Chulalongkorn Memorial Hospital, Bangkok, Thailand. Circulating transferrin receptor was measured, as was the complete blood count and percentage of reticulocytes. A transfusion regimen recommended by the Thalassaemia International Federation was used whenever parents agreed to the treatment.

RESULTS

In patients with Hb-E-beta-thalassaemia, the concentration of sTfR varied from 1.88 to 28.44 mg/L (mean +/- SD 13.99 +/- 5.37), while in the control group, it varied from 0.95 to 2.56 mg/L (mean +/- SD 1.58 +/- 0.41; n = 31). The sTfR level correlated inversely to a single measurement of haemoglobin in the same specimen (r = - 0.433; P = 0.00) and was elevated compared to the control group (P = 0.00; alpha < 0.05). In addition, the sTfR level correlated inversely to mean pre-transfusion haemoglobin (r = - 0.36; P = 0.003).

CONCLUSIONS

The level of sTfR is elevated in children with Hb-E-beta-thalassaemia. The sTfR level can be used as an adjunct real-time assessment of erythropoietic activity, comparable with mean pre-transfusion haemoglobin. Measurement of sTfR is easy using most automated chemical analyzers, and material can be obtained from routine specimen collections. Further studies should be carried out in a larger population to verify the benefits of this test to patients.

Transferrin receptor in tissue and serum: updated clinical significance of soluble receptor

The transferrin receptor is an essential component of cellular uptake of iron, and it binds to serum transferrin. Recently, 2 different types of transferrin receptors have been recognized: transferrin receptor (TfR or transferrin receptor 1) and transferrin receptor 2. Most cells possess a ubiquitous system controlling the biosynthesis of TfR at the posttranscriptional level to avoid excess iron influx into the cells through TfR. During the process of recycling of transferrin receptors, some are shed and appear as soluble or serum transferrin receptors. Measurement of serum transferrin receptor is a new marker of iron metabolism that reflects body iron stores and total erythropoiesis. It has been shown that serum transferrin receptor to ferritin ratios have significant predictive value for differentiating iron deficiency anemia from non-iron deficiency anemia, such as anemia of chronic disorders, whereas serum ferritin is the only significant independent predictor of iron deficiency anemia.

Sex differences in iron status during infancy

BACKGROUND

It is commonly assumed that there is no difference in iron status between male and female infants, despite a lack of studies addressing this question.

OBJECTIVE

To study sex differences in different measures of iron status in infants.

METHODS

At 4 months of age, 263 term, breastfed infants (121 Swedish and 142 Honduran) were randomized to receive iron supplements or placebo until 9 months of age. Blood samples at 4, 6, and 9 months of age were analyzed for hemoglobin (Hb), mean cell volume (MCV), zinc protoporphyrin (ZPP), plasma ferritin, and transferrin receptors (TfR).

RESULTS

At 4, 6, and 9 months, boys had significantly lower Hb, MCV, and ferritin and higher ZPP and TfR than girls. At 9 months, boys had a 10-fold higher risk of being classified as having iron deficiency anemia. The differences at 9 months in MCV (71.6 vs 75.1 fL) and ZPP (59 vs 49 micro mol/mol heme) remained significant after controlling for iron supplementation, site, growth variables, and other possible confounders. For ferritin, there was a remaining sex difference at 9 months among Swedish (29 vs 53 micro g/L) but not Honduran infants. For Hb and TfR, sex differences at 9 months were larger in unsupplemented infants, especially in those with a birth weight of <3500 g.

CONCLUSIONS

There are substantial sex differences in Hb and other indicators of iron status during infancy. Some of these may be genetically determined, whereas others seem to reflect an increased incidence of true iron deficiency in boys.

Discriminating between iron deficiency anemia and anemia of chronic disease using traditional indices of iron status vs transferrin receptor concentration

We compared the ability of soluble serum transferrin receptor (TfR) concentration, quantified using the R&D Systems (Minneapolis, MN) enzyme-linked immunosorbent TfR assay, with other, more traditional indicators of iron status (total iron binding capacity [TIBC], mean corpuscular volume [MCV], percent transferrin saturation [%TS], RBC distribution width [RDW], and serum iron concentration [SIC]) for discriminating between patients with iron deficiency anemia (IDA) or anemia of chronic disease (ACD). The TfR concentration was determined in 72 serum samples selected from men and nonpregnant women classified biochemically on the basis of ferritin concentration as having IDA (n = 41) or ACD (n = 31). By using receiver operating characteristic curve analysis, the diagnostic accuracy of the various indicators of iron status that we evaluated for discriminating between IDA and ACD decreased in the following order: TIBC > TfR > MCV > (%TS = RDW) > SIC. There was no significant difference between the diagnostic accuracy of TIBC and TfR. Thus, the routine measurement of TfR offers no advantage over TIBC for discriminating between people with biochemically defined IDA or ACD.

Usefulness of serum transferrin receptor and serum ferritin in diagnosis of iron deficiency in infancy

BACKGROUND

The serum transferrin receptor (TfR) and the ratio of TfR to serum ferritin (TfR:SF) have been shown to be useful as early indicators of iron deficiency.

OBJECTIVE

The objective of this study was to evaluate the performance of TfR and TfR:SF in the assessment of iron deficiency in infants and to analyze age-related changes in both variables.

DESIGN

A total of 716 blood samples obtained from 515 healthy infants aged 8-15 mo were studied.

RESULTS

In 144 samples in which all other laboratory indicators of iron status were within the reference range, the median and 95% CI for TfR and TfR:SF were 8.5 mg/L (95% CI: 5.9, 13.5) and 497 (95% CI: 134, 975), respectively. TfR and TfR:SF were significantly correlated with the other laboratory indicators of iron status. Furthermore, as the severity of iron deficiency progressed, there was a gradual increase in mean TfR concentration (P: < 0.00001; analysis of variance). The sensitivity of TfR > 13.5 mg/L and TfR:SF > 975 in the diagnosis of iron deficiency was 23.6% and 68.4%, respectively. The specificity was 98.3% and 63.3% for TfR and TfR:SF, respectively. The sensitivity and specificity of SF < 10 microg/L were 63.7% and 60.8%, respectively. Receiver operator characteristic analysis showed that TfR and TfR:SF were more accurate than was SF alone in the diagnosis of iron deficiency.

CONCLUSIONS

TfR and TfR:SF showed age-related changes; TfR and TfR:SF appear to be better diagnostic tests for iron deficiency in infants than SF.