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

Association between menarche and iron deficiency in non-anemic young women

Background

The prevalence of iron deficiency (ID) among non-pregnant, reproductive-age US women significantly exceeds rates among males. In clinical practice ID screening relies on hemoglobin, a late-stage indicator of ID. As a single, low-cost laboratory test to diagnose ID before anemia develops is lacking, the study objective was to improve ID screening by identifying risk factors among non-anemic, iron-deficient reproductive age women.

Methods

Cross-sectional data were from the National Health and Nutrition Examination Survey (NHANES) 2003–2010. Hemoglobin identified non-anemic women. ID was defined using the body iron formula, requiring ferritin and transferrin receptor values. Logistic regression assessed the association of sociodemographic, behavioral, and reproductive risk factors in an anemia-based conceptual framework with non-anemic reproductive age women (12–49 years) with ID, as well as subsets of younger (12–21 years) and older (22–49 years) women, recognizing that risks may differ by age.

Results

Among 6216 women, 494 had ID (prevalence was 8.0%, 95% CI 7.3%, 8.6%). Among non-anemic younger women, 250 (8.7%, 95% CI 7.7%, 9.8%) had ID, compared to 244 (7.3%, 95% CI 6.4%, 8.2%) older women. Among younger women, menstruation for over 3 years was the only variable significantly associated with non-anemic ID (risk ratio 3.18, 95% CI 2.03, 4.96). No other significant risk factors were identified.

Conclusion

Menstrual years was the only risk factor significantly associated with ID among non-anemic younger women. The negative results suggest ID risk factors among non-anemic women may need to be considered separately from those associated with ID anemia.

Identifying factors predicting iron deficiency in United States adolescent females using the ferritin and the body iron models

BACKGROUND & AIMS

Iron deficiency is the most prevalent nutritional deficiency in the United States affecting 9-16% of female adolescents. With the primary purpose of detecting iron deficiency, primary care screening consists of a hemoglobin or hematocrit laboratory test. This method is simple and inexpensive, but tests for anemia, and is neither sensitive nor specific for iron deficiency. Alternate methods for diagnosing iron deficiency using the ferritin and body iron models are not widely utilized. The study objective was to compare iron deficiency risk factors among adolescent females defined by the ferritin and body iron models to better characterize those who may benefit from iron deficiency testing as opposed to the current anemia-based screen.

METHODS

This cross-sectional study of female adolescents aged 12-21 years utilized National Health and Nutrition Examination Survey 2003-2006 data. Anemia was defined by standard hemoglobin cutoffs. The ferritin model defines iron deficiency through transferrin saturation, ferritin and erythrocyte protoporphyrin laboratory testing. Body iron calculates iron status with a formula involving transferrin receptor and ferritin. Bivariate and multivariable analyses examined associations between questionnaire responses and iron deficiency defined by each model.

RESULTS

Among 1765 participants, 2.7% were anemic. Iron deficiency prevalence was 13.1% and 9.1% by the ferritin and body iron models, respectively. Based on the model, anemia-based screening had a sensitivity of 15.6-18.8% for iron deficiency. Multivariable associations for ferritin model iron deficiency included age, race/ethnicity, activity level and medroxyprogresterone acetate injection. Age and food insecurity were significant using the body iron model.

CONCLUSIONS

Universal anemia-based screening misses the majority of iron-deficient adolescent females. The common risk factor identified here, adolescent age, may both inform preventive care guidelines on age-based screenings and prospective studies of adolescent iron deficiency risk factors.

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.

Haematinic deficiency and macrocytosis in middle-aged and older adults

OBJECTIVE

To assess the prevalence and determinants of haematinic deficiency (lack of B12 folate or iron) and macrocytosis in blood from a national population-based study of middle-aged and older adults.

METHODS

A cross-sectional study involving 1,207 adults aged ≥45 years, recruited from a sub-study of the Irish National Survey of Lifestyle Attitudes and Nutrition (SLÁN 2007). Participants completed a health and lifestyle questionnaire and a standard food frequency questionnaire. Non-fasting blood samples were obtained for measurement of full blood count and expert morphological assessment, serum ferritin, soluble transferrin receptor assay (sTfR), B12, folate and coeliac antibodies. Blood samples were also assayed for thyroid function (T4, TSH), liver function, aminotransferase (AST) and gamma-glutamyl transferase (GGT).

RESULTS

The overall prevalence (95% C.I.) of anaemia (Hb <13.5 g/dl men and 11.3 g/dl women) was 4.6% (2.9%-6.4%) in men and 1.0% (0.2%-1.9%) in women. Iron deficiency (ferritin <17 ng/ml men and <11 ng/ml in women) was detected in 6.3% of participants (3.7% in males and 8.7% in females, p<0.001). Based on both low ferritin and raised sTfR (>21 nmol/ml) only 2.3% were iron-deficient. 3.0% and 2.7% were found to have low levels of serum folate (<2.3 ng/ml) and serum B12 (<120 ng/l) respectively. Clinically significant macrocytosis (MCV>99fl) was detected in 8.4% of subjects. Strong, significant and independent associations with macrocytosis were observed for lower social status, current smoking status, moderate to heavy alcohol intake, elevated GGT levels, deficiency of folate and vitamin B12, hypothyroidism and coeliac disease. The population attributable fraction (PAF) for macrocytosis associated with elevated GGT (25.0%) and smoking (24.6%) was higher than for excess alcohol intake (6.3%), folate deficiency (10.5%) or vitamin B12 (3.4%).

CONCLUSIONS

Haematinic deficiency and macrocytosis are common in middle-aged/older adults in Ireland. Macrocytosis is more likely to be attributable to an elevated GGT and smoking than vitamin B12 or folate deficiency.

Aspectos gerais da deficiência de ferro no esporte, suas implicações no desempenho e importância do diagnóstico precoce

A ingestão inadequada de ferro pode trazer consequências deletérias ao desempenho atlético. Os aspectos negativos provenientes da deficiência orgânica de ferro estão diretamente relacionados com os níveis de depleção desse mineral, que, em sua última instância, tem como principal agravo o desenvolvimento da anemia ferropriva. O presente artigo esclarece que, além da omissão férrica dietética, existem vários fatores agregados que não estão vinculados apenas à dieta, mas que, no conjunto, podem interferir sobre o balanço negativo do ferro, principalmente em atletas. Dentre os fatores etiológicos associados à prática esportiva, os mais evidentes são as hemorragias gastrintestinais, as hemólises por impacto e por radicais livres e as perdas férricas através da transpiração. Nota-se a suma importância do controle da ingestão de ferro e da manutenção de uma vigilância para a detecção precoce da deficiência desse mineral, evitando alteração na produção normal de hemoglobina e de outros compostos essenciais, o que pode causar redução considerável no desempenho do indivíduo, principalmente aeróbico. Embora seja crucial o papel da suplementação no restabelecimento do indivíduo com deficiência de ferro, a automedicação é contraindicada, devido às consequências negativas associadas às altas doses desse mineral. A abordagem desse tema é de extrema relevância para o meio esportivo, contendo informações sobre a anemia esportiva e o diagnóstico da deficiência de ferro, em uma revisão que visa o esclarecimento dos principais fatores etiológicos envolvidos.

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.