Prevalence of iron deficiency in the United States

Iron supplementation improves progressive fatigue resistance during dynamic knee extensor exercise in iron-depleted, nonanemic women

BACKGROUND

Tissue iron depletion may negatively affect endurance performance and muscle fatigability.

OBJECTIVE

We investigated tissue-level iron depletion and progressive fatigue of the quadriceps during dynamic knee-extension exercise in young women.

DESIGN

Twenty iron-depleted (serum ferritin < 20 micro g/L), nonanemic (hemoglobin > 110 g/L) women (macro x +/- SEM age: 29.1 +/- 1.2 y) received iron (iron group) or placebo (placebo group) for 6 wk in a randomized, double-blind trial (n = 10 per group). A protocol integrating 2-3-s maximal voluntary static contractions (MVCs) with dynamic knee extensions was used to assess fatigue.

RESULTS

No significant differences between the groups in baseline iron status, MVC at rest, or MVC at the end of the protocol were observed. After treatment, serum iron and transferrin saturation increased significantly in the iron group (P = 0.02 and P = 0.03, respectively). Serum transferrin receptor concentrations increased significantly in the placebo group (P < 0.01) but not in the iron group. After treatment, the rate of decrease in MVC was attenuated in the iron group but not in the placebo group (P = 0.01). In the iron group, MVC at the sixth minute of the fatigue protocol and MVC at the end of the protocol were approximately 15% (P = 0.04) and approximately 27% higher (P < 0.01), respectively, after treatment. These improvements were not related to changes in iron-status indexes or tissue iron stores, although power was low (< 0.50) to detect these relations.

CONCLUSIONS

Iron supplementation was associated with a significant improvement in muscle fatigability. Interpretation regarding the direct role of tissue iron status is limited by the study's low power to detect relations between tissue iron improvement and decreased muscle fatigue.

Inevitable iron loss by human adolescents, with calculations of the requirement for absorbed iron

In growing individuals, the requirement for absorbed iron consists of iron needed for growth and iron needed to replace inevitable iron loss. We were able to estimate inevitable iron loss by adolescents because total body iron of the adolescents had been enriched with the stable isotope, (58)Fe, as the result of earlier studies of iron absorption. During an interval beginning at least 1.56 y after isotope administration (a time sufficient for complete mixing of the isotope with total body iron) and extending for no less than 3.29 y, we determined the isotopic enrichment of circulating iron. On the basis of several assumptions, we calculated total body (58)Fe and total body iron at the beginning and end of the interval. Because of complete mixing of the isotope with total body iron, fractional total (58)Fe loss was the same as fractional loss of total iron. In males, the fractional loss of iron was 9.70%/y and the quantitative loss was 256 mg/y or 0.70 mg/d. In females, the fractional loss of iron was 14.60%/y and the quantitative loss was 306 mg/y or 0.84 mg/d. Using several assumptions, we then calculated that the iron requirement for growth during this interval was 0.76 mg/d for males and 0.31 mg/d for females. Adding the iron loss to the iron requirement for growth, the requirement for absorbed iron was estimated to be 1.46 mg/d for males and 1.15 mg/d for females.

Prevention of iron deficiency anemia in adolescent and adult pregnancies

OBJECTIVE

Worldwide attention over iron deficiency anemia (IDA) in pregnancy has shifted recently from providing supplements during pregnancy to attempting to ensure that women, especially adolescents, have adequate iron stores prior to conception. We sought to determine whether adolescent and/or adult women still need supplements during pregnancy to avoid IDA, even if iron stores are adequate, and whether the IDA translates into maternal and/or infant morbidity and mortality.

DESIGN

Randomized, double-blind clinical trial with placebo control.

SETTING

Multicenter clinic setting in central Wisconsin.

PARTICIPANTS

Adolescent women 18 years or less in their first pregnancy, and adult women 19 years or older, who were found to be healthy and iron sufficient at their first prenatal visit.

METHODS

Participants were randomized to receive iron supplementation (60 mg/day elemental iron) or placebo. Serum ferritin of 12 ng/mL or less with simultaneous hemoglobin of 11 g/dL or less defined IDA. When IDA occurred at the second trimester, a therapeutic supplement of 180 mg of elemental iron per day was initiated.

RESULTS

Forty-seven percent of all placebo-supplemented and 16% of all iron-supplemented patients exhibited IDA (p<0.001); 59% of adolescent placebo-supplemented and 20% of adolescent iron-supplemented patients exhibited IDA (p=0.021). Nausea, vomiting, diarrhea, and constipation were not significantly different in the iron supplemented group compared to the placebo group, and no significant differences were seen in maternal or neonatal health, but the number of women studied was limiting for analysis of these adverse events.

CONCLUSION

IDA is common in healthy, iron-sufficient adolescent pregnant women during the second trimester, and body stores of iron decline in both adolescent and adult pregnancies. The incidence of IDA during adolescent and adult pregnancies is substantially reduced with 60 mg of elemental iron per day. However, there remains no clear evidence that maternal or neonatal health will benefit from correcting these deficits.

Non-anemic iron depletion, oral iron supplementation and indices of copper status in college-aged females

OBJECTIVES

Indices of copper status, specifically serum copper and ceruloplasmin concentrations and erythrocyte superoxide dismutase activity, and iron status, including serum ferritin, transferrin receptors, hemoglobin and hematocrit, were studied in 27 college-aged females with adequate iron versus low iron stores.

METHODS

Serum copper and ceruloplasmin concentrations, erythrocyte superoxide dismutase activity, serum ferritin, transferrin receptors, hemoglobin and hematocrit were studied in 15 females with non-anemic iron depletion before and after five weeks of iron supplementation and in 12 healthy iron-adequate females aged 19 to 28 years.

RESULTS

Mean hemoglobin, hematocrit and ferritin concentrations of the control group (144 +/- 11 g/L, 43 +/- 3% and 38 +/- 15 micro g/L, respectively) were significantly higher than those of the iron depleted group prior to supplementation (134 +/- 9 g/L, 39 +/- 2% and 11 +/- 6 micro g/L, respectively). The serum transferrin receptor to serum ferritin ratio was significantly greater for the iron depleted group prior to supplementation (890 +/- 753) versus the control group (151 +/- 61). Mean serum copper and ceruloplasmin concentrations and erythrocyte superoxide dismutase activity of the iron-adequate control group (20.0 +/- 5.7 micro mol/L, 463 +/- 142 mg/L and 527 +/- 124 U/mL, respectively) were significantly higher than those of the iron depleted group (12.4 +/- 3.8 micro mol/L, 350 +/- 108 mg/L and 353 +/- 186 U/mL, respectively) prior to supplementation. Following iron supplementation, hematocrit and ferritin concentrations of the iron depleted group significantly increased to 42 +/- 3% and 26 +/- 8 micro g/L, respectively. Mean serum transferrin receptor concentrations and the serum transferrin receptor to ferritin ratios significantly decreased in the iron depleted group following supplementation (6.1 +/- 1.6 mg/L to 4.6 +/- 1.5 mg/L and 890 +/- 753 to 198 +/- 114, respectively). Iron supplementation also significantly increased the mean serum copper concentration to 14.2 +/- 5.4 micro mol/L and, in subjects with serum ferritin concentrations </=12 micro g/L, the mean serum ceruloplasmin concentration.

CONCLUSIONS

Non-anemic iron depletion characterized by low iron stores is associated with negative impacts on copper status. Iron supplements improved indices of iron status and serum copper and ceruloplasmin concentrations. Whether the diminished serum copper and ceruloplasmin concentrations and superoxide dismutase activity are associated with free radical damage to iron depleted cells requires further investigation.

The diagnostic criteria for iron deficiency in infants should be reevaluated

Diagnostic criteria for iron deficiency (ID) and iron deficiency anemia (IDA) in infants are poorly defined. Our aim was to establish appropriate cut-off values for hemoglobin (Hb), plasma ferritin, erythrocyte mean cell volume (MCV), zinc protoporphyrin (ZPP) and soluble transferrin receptors (TfR) in infancy. Exclusively breast-fed infants (n = 263) in Honduras and Sweden were randomly assigned to receive iron supplementation or placebo, and blood samples were obtained at 4, 6 and 9 mo of age. Reference ranges were determined using three different approaches for defining iron-replete infants. The usefulness of several variables for predicting the Hb response to iron was evaluated. We found the following 2 SD cut-off values in iron-replete infants: Hb <105 g/L at 4-6 mo and <100 g/L at 9 mo; ZPP >75 micro mol/mol heme at 4-6 mo and >90 micro mol/mol heme at 9 mo; ferritin <20 micro g/L at 4 mo, <9 micro g/L at 6 mo and <5 micro g/L at 9 mo; and TfR >11 mg/L at 4-9 mo. The Hb response to iron was not a useful definition of IDA at 4 mo of age. Hb, MCV and ZPP at 6 mo as well as growth variables predicted the Hb response at 6-9 mo, but ferritin and TfR at 6 mo did not. We conclude that there is need for a reevaluation of the definitions of ID and IDA in infants.

Issues related to iron replacement in chronic kidney disease

Recent epidemiologic studies show that iron deficiency occurs in the vast majority of patients with chronic kidney disease (CKD). In patients with CKD, increased iron losses and, to a lesser extent, poor oral absorption, can lead to iron-deficiency anemia. Correction of iron-deficiency anemia is preferable by the oral route, however, data on oral iron use are limited in this population. In CKD patients, parenteral iron administered with recombinant human erythropoietin (rHuEpo), is the best potential option for the correction of anemia. Nondextran iron preparations are preferable because of a reduced incidence of serious adverse events. Parenteral iron in CKD patients may not be entirely innocuous and, although commonly used, have not received Food and Drug Administration approval for use in this patient population. Exposure to intravenous (IV) iron may lead to oxidative stress, renal injury, infection, cardiovascular disease, and osteomalacia. Studies are needed to confirm the existence and magnitude of these complications. The current data suggest that the overall risk-benefit ratio favors use of IV iron when compared with untreated or partially treated iron-deficiency anemia.

Anaemia and iron-deficiency anaemia in south-east Anatolia

PURPOSE

To determine the prevalence of anaemia and iron-deficiency anaemia (IDA) in Kahramanmaras, a province in the south-eastern Anatolia.

METHODS

The study was performed on 1491 persons of both sexes aged 2-69. All were volunteers. Haematological parameters were determined and haemoglobin (Hb) electrophoresis was carried out in all subjects, and only for those with haemoglobin levels below normal were subsequent measurements of ferritin and Hb A2 made to detect iron deficiency and rule out beta-thalassaemia.

RESULTS

The means of all the haematological parameters for all age groups and sexes were found to be lower than the reference values given in the literature. Anaemia was found to be present in all age groups, especially in children aged 2-5 yr and women aged 19-40 yr (34.5% and 40.0%, respectively). IDA in the same age groups was 15.5% and 23.8%, respectively.

CONCLUSION

The high rate of IDA raises serious concern about nutritional disease risks in the region. An inexpensive oral iron therapy and education as to the importance of iron for their health would help to provide optimal health for the population concerned, especially for mothers-to-be and children.

A practical approach to the evaluation of the anemic child

Anemia is a sign of disease and not a final diagnosis. The clinician's goal is to define the underlying cause. The anemia may be due to decreased production or Increased destruction or loss of red blood cells. Integration of the results of the initial CBC. particularly the RBC indices, the peripheral blood smear, the history and the physical examination can help organize the focus of further evaluations and, ultimately, minimize the number of tests needed to make a firm diagnosis.

Prolonged bottle use and its association with iron deficiency anemia and overweight: a preliminary study

To determine the prevalence of prolonged bottle feeding practices in young children, and its association with body mass index (BMI) and iron deficiency anemia (IDA), we conducted a cross-sectional survey study at 3 Bronx, NY, WIC sites. Caregivers of 95 predominantly Hispanic and African-American WIC-enrolled children aged 18-56 months presenting for recertification completed questionnaires. Half were overweight (>85th% BMI) and 36% were obese (>95th% BMI); 21% met CDC criteria for anemia. Two thirds (63%) received daily bottles of milk or sweet liquids. Daily bottle use ranged from 3 to 10 (mean=3.3, median=3). Bottle use was significantly associated with obesity (>95th% BMI, p<0.0005), not significant with overweight (>85th% BMI, p<0.06) and statistically significant with IDA.

Iron deficiency and gastrointestinal malignancy: a population-based cohort study

PURPOSE

We investigated whether iron deficiency, with or without anemia, is associated with an increased likelihood of gastrointestinal malignancy.

SUBJECTS AND METHODS

Data were obtained from the first National Health and Nutrition Examination Survey and Epidemiologic Followup Study, a nationally representative, prospective cohort study that measured hemoglobin levels and iron saturation and recorded follow-up diagnoses. We included persons 25 to 74 years of age with no previous gastrointestinal malignancy. Anemia was defined as a hemoglobin value below the fifth percentile for each age group and sex. Iron deficiency was defined as an iron saturation below 15%.

RESULTS

Eighteen (0.2%) gastrointestinal malignancies were identified among the 9024 participants during the first 2 years of follow-up. None of the 442 premenopausal women with iron deficiency (92 with anemia and 350 without anemia) were diagnosed with gastrointestinal malignancy. Among men and postmenopausal women, the proportion diagnosed with gastrointestinal malignancy was 31 times greater (95% confidence interval [CI]: 9 to 107) in those with iron deficiency anemia (3/51 [6%]) and five times greater (95% CI: 1 to 21) in those with iron deficiency without anemia (2/223 [1%]), compared with those with normal hemoglobin levels and iron saturation (11/5733 [0.2%]).

CONCLUSIONS

Gastrointestinal malignancy is uncommon in iron-deficient premenopausal women with or without anemia. Among men and postmenopausal women, gastrointestinal malignancy is significantly more common in those with iron deficiency than in persons with normal serum iron saturation and hemoglobin levels.

Perioperative blood transfusion therapy in pediatric patients

In general, transfusion guidelines for non-neonatal pediatric patients are similar to those for adults. However, some differences do exist and certain precautions may be necessary particularly in the setting of massive transfusions. We review these differences as they apply to general pediatric surgery outside of the neonatal period, with respect to the transfusion of red blood cells (RBCs), platelets, fresh-frozen plasma (FFP), and cryoprecipitate. We include a discussion of the indications for transfusion and practical considerations such as dosing and administration. Finally, we briefly review the use of directed donations and specialized (irradiated, CMV seronegative) blood components.

Developmental trajectories of poorly nourished toddlers that received a micronutrient supplement with and without energy

Experimental and quasi-experimental studies on the effects of nutritional supplements on development in young children generally include snapshots of development. Developmental outcomes are better revealed when multiple assessments are made over time. We compared the effects of a micronutrient intervention with and without supplementary energy on the mental and motor growth curves of poorly nourished toddlers in West Java. Subjects (12-mo-old cohort, n = 33; 18-mo-old cohort, n = 42) were randomly assigned to receive energy + micronutrients (E + M) or micronutrients (M) daily for 12 mo. The cohort/treatment groups were then classified as either relatively short or tall. Within the 12-mo cohort, the baseline mean length Z-scores ranged from -2.53 to -1.29 and the baseline mean weight Z-scores ranged from -3.05 to -2.18. The same pretreatment anthropometrics for the older cohort ranged from -3.22 to -1.59 and from -3.42 to -2.26. Mental and motor development scores (Bayley) were obtained at baseline and every 2 mo for 12 mo. There was a Cohort x Length Category x Supplement interaction for mental slopes (P < 0.01). Slopes for tall-E + M (b = 5.35) and tall-M children (b = 5.39) in the 18-mo cohort were equivalent, but slopes for short-E + M (b = 6.13) and short-M (b = 4.67) children differed greatly (P = 0.03). On the basis of this finding and findings previously reported from this study, we concluded that the unfavorable developmental response to the M supplement that was restricted to the shortest children within an already disadvantaged group.

Low income postpartum women are at risk of iron deficiency

We estimated the prevalence of postpartum iron deficiency, anemia and iron deficiency anemia in the United States and compared risk of iron deficiency between women 0-24 mo postpartum (n = 680) and never-pregnant women, 20-40 y old (n = 587). We used data from National Health and Nutrition Examination Survey, 1988-1994. Iron deficiency was defined as abnormal values for > or = 2 of 3 iron status measures (serum ferritin, free erythrocyte protoporphyrin, transferrin saturation). Iron deficiency prevalences for women 0-6, 7-12 and 13-24 mo postpartum were 12.7, 12.4 and 7.8%, respectively, and 6.5% among never-pregnant women. After adjustment for confounding, the risk of iron deficiency among women with a poverty index ratio < or = 130% who were 0-6, 7-12 and 13-24 mo postpartum was 4.1 (95% confidence interval 2.0, 7.2), 3.1 (1.3, 6.5) and 2.0 (0.8, 4.1) times as great, respectively, as never-pregnant women with a poverty index ratio > 130%, but risk was not elevated for never-pregnant women with a poverty index ratio < or = 130%. Compared with the same referent, the risk of iron deficiency was not meaningfully different for women with a poverty index ratio > 130% who were 0-6, 7-12 or 13-24 mo postpartum. Given that low income postpartum women bear a substantially greater iron deficiency risk than never-pregnant women, more attention should be given to preventing iron deficiency among low income women during and after pregnancy.

Neurologic manifestations of iron deficiency in childhood

Iron deficiency is a common disorder in pediatric patients. Although the most common manifestation is that of anemia, iron deficiency is frequently the source of a host of neurologic disorders presenting to general pediatric neurologic practices. These disorders include developmental delay, stroke, breath-holding episodes, pseudotumor cerebri, and cranial nerve palsies. Although frequent, the identification of iron deficiency as part of the differential diagnosis in these disorders is uncommon and frequently goes untreated. The purpose of the current review is to highlight what is understood regarding iron deficiency and it's underlying pathophysiology as it relates to the brain, and the association of iron deficiency with common neurologic pediatric disease.

Iron indexes and total antioxidant status in response to soy protein intake in perimenopausal women

BACKGROUND

Elevated iron stores, oxidative stress, and estrogen deficiency may place postmenopausal women at greater risk of heart disease and cancer than premenopausal women.

OBJECTIVE

The objective was to determine the effect of soy-protein isolate (SPI) intake and iron indexes on plasma total antioxidant status (TAS) in perimenopausal women after control for other contributing factors.

DESIGN

Perimenopausal women (n = 69) were randomly assigned (double blind) to treatment: isoflavone-rich SPI (SPI+; n = 24), isoflavone-poor SPI (SPI-; n = 24), or whey protein (control; n = 21). Each subject consumed 40 g soy or whey protein daily for 24 wk. Plasma TAS, serum ferritin, serum iron, transferrin saturation, and hemoglobin were measured at baseline, week 12, and week 24.

RESULTS

No significant time-by-treatment interactions on iron indexes or TAS were observed, whereas time had an effect on serum ferritin (P < or = 0.0001) and hemoglobin (P = 0.004) but not on TAS. Multiple regression analysis showed that at week 12, 48% (P < or = 0.0001) of the variability in TAS was accounted for by baseline TAS, alcohol intake, soy intake (soy compared with control; P = 0.016), plasma lipoprotein(a), and dietary iron. At week 24, 47% of the variability in TAS was accounted for by baseline TAS, serum ferritin, serum estrone, dietary zinc, and dietary meat, fish, and poultry.

CONCLUSIONS

SPI intake had no significant effect on iron status, but our results suggest that dietary soy protein and low iron stores may protect perimenopausal women from oxidative stress.

Prevalence of hemochromatosis-related symptoms among individuals with mutations in the HFE gene

OBJECTIVE

To determine the prevalence of hemochromatosis-related symptoms in homozygotes for the HFE mutation C282Y compared with controls without HFE mutations identified through a large screening program of subjects attending a health appraisal center.

SUBJECTS AND METHODS

Presence of symptoms commonly associated with clinical hemochromatosis was ascertained by self-report on a written questionnaire among C282Y homozygotes and HFE wild-type subjects of white or Hispanic ethnicity identified from screening 41,599 adult subjects between March 1999 and August 2001. A subset of C282Y homozygotes and wild-type subjects identified from 12,756 subjects attending the center in the final year of the study completed a standardized double-blind interview with a physician regarding the presence, duration, and severity of a larger set of symptoms. Prevalence of symptoms among C282Y homozygotes and wild-type controls ascertained by written questionnaire and interview were compared by chi2 analysis or Fisher exact test. Symptoms among subjects with other combinations of the C282Y and H63D HFE mutations were also assessed by questionnaire.

RESULTS

The 124 C282Y homozygotes who filled out the written questionnaire and the 17 C282Y homozygotes who completed the physician double-blind interview reported no significantly higher rates of arthritis or joint pain, abdominal pain, arrhythmias, darkening of skin, or other symptoms traditionally associated with hemochromatosis compared with the 22,429 wild-type controls who filled out the written questionnaire and 29 wild-type controls who completed the double-blind interview. The only symptom reported more frequently by C282Y homozygotes was loss of body hair, reported by 5 C282Y/C282Y female subjects compared with 1 wild-type male subject (P=.02) in the physician interview. Symptoms among subjects with other HFE genotypes were similar to symptoms of wild-type subjects.

CONCLUSIONS

Results of this study indicate that many of the symptoms associated with hemochromatosis are common among HFE wild types and that clinical penetrance of the C282Y/C282Y genotype in regard to these symptoms is low.

The female athlete. Before and beyond puberty

As the twentieth century progressed, the female athlete became an accepted participant of sports at all levels. This article reviews various aspects of female sports participation. After an historical perspective, selected comments are provided on psychologic and physiologic aspects. Concepts of adolescent gynecology are reviewed, including breast and menstrual problems and pregnancy. Other areas reviewed include iron deficiency anemia, stress urinary incontinence, and sports injuries in female athletes.

Nutrient requirements for preterm infant formulas

Achieving appropriate growth and nutrient accretion of preterm and low birth weight (LBW) infants is often difficult during hospitalization because of metabolic and gastrointestinal immaturity and other complicating medical conditions. Advances in the care of preterm-LBW infants, including improved nutrition, have reduced mortality rates for these infants from 9.6 to 6.2% from 1983 to 1997. The Food and Drug Administration (FDA) has responsibility for ensuring the safety and nutritional quality of infant formulas based on current scientific knowledge. Consequently, under FDA contract, an ad hoc Expert Panel was convened by the Life Sciences Research Office of the American Society for Nutritional Sciences to make recommendations for the nutrient content of formulas for preterm-LBW infants based on current scientific knowledge and expert opinion. Recommendations were developed from different criteria than that used for recommendations for term infant formula. To ensure nutrient adequacy, the Panel considered intrauterine accretion rate, organ development, factorial estimates of requirements, nutrient interactions and supplemental feeding studies. Consideration was also given to long-term developmental outcome. Some recommendations were based on current use in domestic preterm formula. Included were recommendations for nutrients not required in formula for term infants such as lactose and arginine. Recommendations, examples, and sample calculations were based on a 1000 g preterm infant consuming 120 kcal/kg and 150 mL/d of an 810 kcal/L formula. A summary of recommendations for energy and 45 nutrient components of enteral formulas for preterm-LBW infants are presented. Recommendations for five nutrient:nutrient ratios are also presented. In addition, critical areas for future research on the nutritional requirements specific for preterm-LBW infants are identified.

Tea consumption and iron status

OBJECTIVE

To give an overview of the association between tea consumption and iron status.

METHODS

A PUBMED search was performed (up to June 2001) for all publications containing the words: tea and ferritin, h(a)emoglobin, iron status or an(a)emia. Sixteen studies were evaluated in groups with high (infants, children and premenopausal women) or low prevalence of iron deficiency (men and the elderly).

RESULTS AND DISCUSSION

Of the 16 studies reviewed, six included infants and children, six premenopausal women, two men and two the elderly. In study groups with high prevalence of iron deficiency, tea consumption was inversely associated with serum ferritin and/or haemoglobin. The association disappeared when adjusting for confounding (dietary) factors, except for one study including 40% of iron deficient women. In groups with low prevalence of iron deficiency, tea consumption was not inversely associated with serum ferritin and/or haemoglobin. In those at risk for iron overload, such as middle-aged men, tea consumption may lower serum ferritin concentrations as reported in one study. This finding awaits further confirmation.

CONCLUSION

This overview shows that tea consumption does not influence iron status in Western populations in which most people have adequate iron stores as determined by serum ferritin concentrations. Only in populations of individuals with marginal iron status does there seem to be a negative association between tea consumption and iron status.

Experiences and challenges in industrialized countries: control of iron deficiency in industrialized countries

This paper provides a synopsis of the experience in combating iron deficiency in industrialized countries and identifies the reasons for the considerable success and future challenges. Significant progress has been made over the last century in reducing and even eliminating iron deficiency in many industrialized countries. Current estimates are that the prevalence of iron deficiency has declined to <20% in many of these countries, even among women and young children, compared with 30 to 70% in many developing countries. The reasons for this success cannot be attributed solely to a single approach but rather to a range of factors that have occurred over time as a result of both economic development and the implementation of specific policies. Several factors have contributed to improving both iron intakes and reducing iron losses; these include fortification, supplementation, dietary diversification and public health measures. For example, the decline in anemia in infants can be attributed to the introduction of iron-fortified formula and complementary foods in the 1960s to 1970s. Similarly, the enrichment and fortification of cereals with iron that began during World War II in North America and Europe is a result of effective public-private partnerships. Despite these successes, iron deficiency remains a public health concern in industrialized countries for selected subgroups such as women of reproductive age with excess menstrual losses and pregnant women who cannot meet increased requirements from the diet alone. Constant vigilance and innovative approaches for screening and combating this problem are thus still required even in developed countries.

Marginal iron deficiency without anemia impairs aerobic adaptation among previously untrained women

BACKGROUND

Iron deficiency without anemia has been shown to reduce both muscle-tissue oxidative capacity and endurance in animals. However, the consequences of iron deficiency in humans remain unclear.

OBJECTIVE

We investigated the effects of iron supplementation on adaptation to aerobic training among marginally iron-depleted women. We hypothesized that iron supplementation for 6 wk would significantly improve iron status and maximal oxygen uptake (VO(2)max) after 4 wk of concurrent aerobic training.

DESIGN

Forty-one untrained, iron-depleted, nonanemic women were randomly assigned to receive either 50 mg FeSO(4) or a placebo twice daily for 6 wk in a double-blind trial. All subjects trained on cycle ergometers 5 d/wk for 4 wk, beginning on week 3 of the study.

RESULTS

Six weeks of iron supplementation significantly improved serum ferritin and serum transferrin receptor (sTfR) concentrations and transferrin saturation without affecting hemoglobin concentrations or hematocrit. Average VO(2)max and maximal respiratory exchange ratio improved in both the placebo and iron groups after training; however, the iron group experienced significantly greater improvements in VO(2)max. Both iron-status and fitness outcomes were analyzed after stratifying by baseline sTfR concentration (> and < or = 8.0 mg/L), which showed that the previously observed treatment effects were due to iron-status and fitness improvements among subjects with poor baseline iron status.

CONCLUSIONS

Our findings strongly suggest that iron deficiency without anemia but with elevated sTfR status impairs aerobic adaptation among previously untrained women and that this can be corrected with iron supplementation.

Anemia and iron deficiencies among long-term renal transplant recipients

Iron deficiency anemia after renal transplantation has not been systematically investigated. The prevalence of anemia and the indicators of iron deficiency among 438 renal transplant recipients were examined. Anemia was present in 39.7% of the patients. The prevalence of iron deficiencies, as indicated by a percentage of hypochromic red blood cells (HRBC) of >or=2.5%, was 20.1%. The majority of severely anemic patients exhibited HRBC values in the upper quartile. Positive associations of hemoglobin levels with creatinine clearance, serum transferrin levels, male gender, transferrin saturation (TSAT), polycystic kidney disease, and age were observed. Negative associations with erythropoietin therapy, use of azathioprine, serum ferritin levels, and body mass index were observed. The risk for anemia was closely related to the highest quartile of HRBC percentages (odds ratio, 2.35; 95% confidence interval, 1.48 to 3.75; P = 0.00029), whereas ferritin levels and TSAT conferred no risk for anemia. Therefore, assessment of the HRBC proportion is superior to decreased ferritin and decreased TSAT measurements for the diagnosis of iron deficiencies among renal transplant recipients.

Once weekly is superior to daily iron supplementation on height gain but not on hematological improvement among schoolchildren in Thailand

Intermittent iron supplementation has been suggested as a replacement for daily iron supplements for reducing anemia in developing countries. The effects of once weekly and daily iron supplementation on hemoglobin (Hb), serum ferritin (SF), prevalence of anemia, weight and height are compared in this study. Primary schoolchildren (n = 397) from two selected schools in the Hat Yai rural area, southern Thailand, were recruited in 1999. All children received Albendazole and then randomly received ferrous sulfate (300 mg/tablet) either daily or weekly, or a placebo for 16 wk. The average increase in Hb was not significantly different between the daily (mean +/- SD; 6.5 +/- 6.0 g/L) and weekly (5.7 +/- 6.3 g/L) groups. However, the average increase in SF was greater (P < 0.01) in the daily (mean +/- SD; 39.8 +/- 30.3 microg/L) than the weekly (13.4 +/- 17.3 microg/L) group. All cases of iron deficiency anemia were abolished in both daily and weekly groups, whereas no reduction in prevalence occurred in the placebo group. Height gain was greater in children who received weekly (mean +/- SD; 2.6 +/- 0.9 cm) than in those who received daily iron (mean +/- SD; 2.3 +/- 0.8 cm), (P < 0.01). Weight gain, weight-for-age and height-for-age were not significantly different among the intervention groups. It is concluded that a weekly iron dose is more effective than a daily dose in height gain but not in hematological improvement over 16 wk of supplementation.

Iron deficiency and iron excess damage mitochondria and mitochondrial DNA in rats

Approximately two billion people, mainly women and children, are iron deficient. Two studies examined the effects of iron deficiency and supplementation on rats. In study 1, mitochondrial functional parameters and mitochondrial DNA (mtDNA) damage were assayed in iron-deficient (< or =5 microg/day) and iron-normal (800 microg/day) rats and in both groups after daily high-iron supplementation (8,000 microg/day) for 34 days. This dose is equivalent to the daily dose commonly given to iron-deficient humans. Iron-deficient rats had lower liver mitochondrial respiratory control ratios and increased levels of oxidants in polymorphonuclear-leukocytes, as assayed by dichlorofluorescein (P < 0.05). Rhodamine 123 fluorescence of polymorphonuclear-leukocytes also increased (P < 0.05). Lowered respiratory control ratios were found in daily high-iron-supplemented rats regardless of the previous iron status (P < 0.05). mtDNA damage was observed in both iron-deficient rats and rats receiving daily high-iron supplementation, compared with iron-normal rats (P < 0.05). Study 2 compared iron-deficient rats given high doses of iron (8,000 microg) either daily or every third day and found that rats given iron supplements every third day had less mtDNA damage on the second and third day after the last dose compared to daily high iron doses. Both inadequate and excessive iron (10 x nutritional need) cause significant mitochondrial malfunction. Although excess iron has been known to cause oxidative damage, the observation of oxidant-induced damage to mitochondria from iron deficiency has been unrecognized previously. Untreated iron deficiency, as well as excessive-iron supplementation, are deleterious and emphasize the importance of maintaining optimal iron intake.

Iron metabolism: iron deficiency and iron overload

Iron is an essential cofactor in a variety of cellular processes. Except for a few unusual bacterial species, iron is indispensable for living organisms. However, free iron is toxic because of its propensity to induce the formation of dangerous free radicals. Consequently, iron balance is tightly regulated. Disorders of iron homeostasis are among the most common afflictions of humans. This review discusses inherited iron deficiency and iron overload disorders and recent insights into their pathophysiology.

Cord serum ferritin concentrations and mental and psychomotor development of children at five years of age

OBJECTIVE

Our purpose was to evaluate the association between fetal iron status and mental and psychomotor development at 5 years of age.

STUDY DESIGN

We evaluated the association of fetal iron status (umbilical cord serum ferritin concentrations) with test scores of mental and psychomotor development of 278 children. Six tests were given, including full-scale intelligence quotient (FSIQ), language ability, fine- and gross-motor skills, attention, and tractability.

RESULTS

Compared with children with cord ferritin in the 2 median quartiles, those in the lowest quartile scored lower on every test and had significantly worse language ability, fine-motor skills, and tractability. They were also 4.8-fold more likely to score poorly in fine-motor skills and 2.7-fold more likely to have poor tractability than children in the median quartiles. FSIQ in the highest quartile was slightly, but not significantly, lower than the median quartiles, but the odds ratio for having a FSIQ score of less than 70 for children in the highest quartile was 3.3 (95% CI 1.2-9.1).

CONCLUSION

Poor iron status (low ferritin) in utero appears to be associated with diminished performance in certain mental and psychomotor tests. The reason for the association between high ferritin concentrations and low FSIQ scores is unknown.

Reference distributions for serum iron and transferrin saturation: a comparison of a large cohort to the world's literature

The appropriate clinical use of serum iron and transferrin saturation (TSAT) requires satisfactory reference intervals from birth to old age, and for males and females. This study identified 54 publications from 1974 to 2001 that met the criteria used in three prior meta-analyses, and these were analyzed statistically. A summary of our review is presented along with our reference population data on these measurements. This analysis places previous publications in perspective and suggests possible reasons for the observed differences. Previous studies of the individual analytes, serum iron, transferrin, and TSAT values agree with the reference ranges presented in this study, although the entire experience over time and between sexes has not been available before. Our 95% reference ranges are somewhat broader than those of the smaller studies, but they agree well with those of the larger ones.

Erythropoiesis in women during 11 days at 4,300 m is not affected by menstrual cycle phase

Because the ovarian steroid hormones, progesterone and estrogen, have higher blood levels in the luteal (L) than in the follicular (F) phase of the menstrual cycle, and because of their known effects on ventilation and hematopoiesis, we hypothesized that less hypoxemia and less erythropoiesis would occur in the L than the F phase of the cycle after arrival at altitude. We examined erythropoiesis with menstrual cycle phase in 16 women (age 22.6 +/- 0.6 yr). At sea level, 11 of 16 women were studied during both menstrual cycle phases, and, where comparison within women was available, cycle phase did not alter erythropoietin (n = 5), reticulocyte count (n = 10), and red cell volume (n = 9). When all 16 women were taken for 11 days to 4,300-m altitude (barometric pressure = 462 mmHg), paired comparisons within women showed no differences in ovarian hormone concentrations at sea level vs. altitude on menstrual cycle day 3 or 10 for either the F (n = 11) or the L (n = 5) phase groups. Arterial oxygen saturation did not differ between the F and L groups at altitude. There were no differences by cycle phase on day 11 at 4,300 m for erythropoietin [22.9 +/- 4.7 (L) vs. 18.8 +/- 3.4 mU/ml (F)], percent reticulocytes [1.9 +/- 0.1 (L) vs. 2.1 +/- 0.3% (F)], hemoglobin [13.5 +/- 0.3 (L) vs. 13.7 +/- 0.3 g/100 ml (F)], percent hematocrit [40.6 +/- 1.4 (L) vs. 40.7 +/- 1.0% (F)], red cell volume [31.1 +/- 3.6 (L) vs. 33.0 +/- 1.6 ml/kg (F)], and blood ferritin [8.9 +/- 1.7 (L) vs. 10.2 +/- 0.9 microg/l (F)]. Blood level of erythropoietin was related (r = 0.77) to arterial oxygen saturation but not to the levels of progesterone or estradiol. We conclude that erythropoiesis was not altered by menstrual cycle phase during the first days at 4,300-m altitude.

Treatment of anemia with microencapsulated ferrous fumarate plus ascorbic acid supplied as sprinkles to complementary (weaning) foods

BACKGROUND

Standard therapy for anemia in infants is ferrous sulfate drops administered 3 times/d. Adherence to treatment, however, is often poor. One likely reason for poor adherence is the unpleasant side effects associated with drops.

OBJECTIVE

The objective was to evaluate the use of a new form of iron and a delivery system to treat anemia in infants that is likely to produce better adherence to treatment.

DESIGN

Using a prospective, randomized, controlled design, we studied 557 anemic children aged 6-18 mo (hemoglobin: 70-99 g/L) in rural Ghana. One group received a daily sachet of microencapsulated ferrous fumarate (80 mg elemental Fe) in powder form plus ascorbic acid to be sprinkled onto any complementary food eaten (sprinkles group); a control group received ferrous sulfate drops 3 times/d for 2 mo (total dose: 40 mg elemental Fe). Hemoglobin and serum ferritin concentrations were measured at baseline and at the end of treatment.

RESULTS

Successful treatment of anemia (hemoglobin > 100 g/L) occurred in 58% of the sprinkles group and in 56% of the drops group, with minimal side effects in both groups. Geometric mean ferritin concentrations increased significantly in each group from baseline to the end of treatment (P < 0.001).

CONCLUSION

Use of ferrous sulfate drops or a single daily dose of microencapsulated ferrous fumarate sprinkles plus ascorbic acid resulted in a similar rate of successful treatment of anemia without side effects. To our knowledge, this is the first demonstration of the use of microencapsulated iron sprinkles to treat anemia. Improved ease of use may favor the use of sprinkles to deliver iron.

Laboratory screening for electrolyte abnormalities and anemia in bulimia nervosa: a controlled study

OBJECTIVE

Abnormal eating patterns and recurrent purging behaviors can result in significant medical complications. The purpose of this study was to assess the frequency of abnormalities in clinical laboratory tests in patients with bulimia nervosa who reported being otherwise in good health.

METHODS

Subjects included nonhospitalized women (N = 74) who met criteria for bulimia nervosa outlined in the 3rd Rev. ed. of the Diagnostic and Statistical Manual of Mental Disorders. They also reported use of self-induced vomiting and/or laxatives as compensatory behaviors (purging subtype). The control group (N = 110) included female volunteers with no history of a psychiatric disorder. All subjects reported being in good medical health, were medication free, and were in a normal weight range. Blood samples were analyzed in the hospital clinical laboratory.

RESULTS

Compared with controls, patients showed more frequent occurrence of low values for serum potassium (6.8% vs. 0.9%; p <.05) and chloride (8.1% vs. 0.9%; p <.02). Electrolyte abnormalities occurred most often in patients with frequent bulimic episodes. Study groups did not differ significantly in frequency of abnormal hemoglobin concentrations.

DISCUSSION

These results help to clarify the expected frequency of electrolyte abnormalities in individuals with bulimia nervosa who report otherwise good medical health. The substantial frequency of hypokalemia and hypochloremia underscores the importance of an appropriate medical assessment for individuals with this disorder.

Gastrointestinal causes of refractory iron deficiency anemia in patients without gastrointestinal symptoms

BACKGROUND

The standard evaluation of a patient with iron deficiency anemia includes a complete evaluation of the gastrointestinal tract to identify a source of bleeding. However, even after a careful examination, many patients remain without a diagnosis. Because iron deficiency anemia results from iron loss or defective absorption, we sought to determine the prevalence of potential gastrointestinal sources for iron deficiency anemia in patients without gastrointestinal symptoms.

METHODS

Over a 10-month period, 668 outpatients were referred to the University Hematology Department with iron deficiency anemia, defined by a hemoglobin concentration less than 14 g/dL (less than 12 g/dL in women), mean corpuscular volume less than 80 fL, and ferritin level less than 30 microg/L. After excluding patients with obvious causes of blood loss, inadequate diet, chronic diseases, or malignancies, there were 81 eligible patients, 10 of whom refused investigation. The remaining 71 patients (51 women, median age 59 years) underwent colonoscopy, as well as gastroscopy with gastric (antrum and body) and duodenal biopsies.

RESULTS

A likely cause of iron deficiency anemia was detected in 60 patients (85%). Diseases associated with bleeding were found in 26 patients (37%), including colon cancer (10 patients), gastric cancer (2), peptic ulcer (7), hiatal hernia with linear erosions (5), colonic vascular ectasia (3), colonic polyps (2), and Crohn's disease (1). Causes not associated with bleeding were found in 36 patients (51%), including 19 with atrophic gastritis, 4 with celiac disease, and 13 with Helicobacter pylori gastritis. Six (8%) patients had coincident gastrointestinal findings, and 11 (15%) had no cause identified. Patients with an identified nonbleeding-associated cause were younger than those with a bleeding-associated cause (median, 56 vs 70 years; P = 0.001) and included 59% of women (n = 30) versus 30% of men (n = 6) (P = 0.04). Hemoglobin level was not related to the site and severity of disease.

CONCLUSION

Gastrointestinal diseases that do not usually cause bleeding are frequently associated with iron deficiency anemia in patients without gastrointestinal symptom or other potential causes of gastrointestinal bleeding.

Daily multivitamins with iron to prevent anemia in infancy: a randomized clinical trial

This study assessed the effectiveness of multivitamins (MV) with iron as prophylaxis against iron deficiency (ID) and anemia in infancy. The study was a double-blind, randomized trial at 2 urban primary care clinics. Subjects included healthy, full-term infants enrolled at their 6-month well-child visit. Parents administered MV, either with iron or without iron, by mouth daily for 3 months. At 9 months of age, 28.3% of 310 had either anemia or ID without anemia. Among infants with any adherence, anemia was found in 11.1% of the iron group and 21.7% in the noniron group (RR=0.5, 95% CI=0.3-1.0). Iron deficiency without anemia was found in 18.5% of the iron group; 14.4% of the noniron group (p=0.46). When administered daily starting at age 6 months, standard-dose multivitamins with iron appear to reduce anemia prevalence at 9 months of age.

Neonatal iron nutrition

Preterm infants are prone to iron deficiency. Their total body iron content at birth is low and gets further depleted by clinical practices such as uncompensated phlebotomy losses and exogenous erythropoietin administration during the neonatal period. Early iron deficiency appears to adversely affect cognitive development in human infants. To maintain iron sufficiency and meet the iron demands of catch-up postnatal growth, iron supplementation is prudent in preterm infants. A dose of 2-4 mg/kg/day is recommended for preterm infants who are fed exclusively human milk. A dose of 6 mg/kg/day or more is needed with the use of exogenous erythropoietin or to correct preexisting iron deficiency. However, due to the poor antioxidant capabilities of preterm infants and the potential role of iron in several oxidant-related perinatal disorders, indiscriminate iron supplementation should be avoided.

Can dietary treatment of non-anemic iron deficiency improve iron status?

OBJECTIVE

To investigate the efficacy of, first, a dietary regimen involving increased consumption of iron-rich foods and enhancers of iron absorption and decreased consumption of inhibitors of iron absorption and, second, a low dose iron chelate iron supplement, for increasing iron stores in young adult New Zealand women with mild iron deficiency (MID).

METHODS

The study was a 16 week randomized placebo-controlled intervention. Seventy-five women aged 18 to 40 years with MID (serum ferritin < 20 microg/L and hemoglobin > or = 120 g/L) were assigned to one of three groups: Placebo, Supplement (50 mg iron/day as amino acid chelate) or Diet. Participants in the Diet Group were given individual dietary counseling to increase the intake and bioavailability of dietary iron. Dietary changes were monitored by a previously validated computer-administered iron food frequency questionnaire.

RESULTS

Diet Group members significantly increased their intake of flesh foods, heme iron, vitamin C and foods cooked using cast-iron cookware and significantly decreased their phytate and calcium intakes. Serum ferritin increased in the Supplement and Diet Groups by 59% (p=0.001) and 26% (p=0.068), respectively, in comparison to the Placebo Group. The serum transferrin receptor:serum ferritin ratio decreased by 51% in the Supplement Group (p=0.001), and there was a non-significant decrease of 22% (p=0.1232) in the Diet Group.

CONCLUSIONS

This study is the first, to our knowledge, to demonstrate that an intensive dietary program has the potential to improve the iron status of women with iron deficiency.

Screening for anemia in children: AAP recommendations--a critique

The American Academy of Pediatrics (AAP) recommends screening for anemia between the ages of 9 to 12 months with additional screening between the ages of 1 and 5 years for patients at risk. The screening may be universal or selective depending on the prevalence of iron deficiency anemia in the population. Improved infant rearing practices-including wider availability, acceptance, and use of iron-fortified formulas; iron fortification of foods; and increased awareness of the importance of dietary iron supplementation especially early in life-have lead to significant decline in the incidence of anemia in the first year of life. However, incidence of iron deficiency and ensuing anemia in children between 1 and 2 years continues to be significant and an important issue. Although iron deficiency may develop soon after cessation of or inadequate iron intake, anemia secondary to iron deficiency develops gradually over a period of several weeks to months. For children who have received/are receiving iron-fortified infant formulas and foods, hemoglobin screening at 9 to 12 months of age is inappropriate as there may not have been sufficient time to develop anemia, despite the rapid growth rate at this age. Widespread implementation of hemoglobin electrophoresis included in the neonatal metabolic screening programs in many states in the United States now has resulted in earlier diagnosis of hemoglobinopathies. Screening children at 9 to 12 months of age for hemoglobinopathies is somewhat redundant now. Screening for anemia before or around 1 year of age should continue to be important for communities and children at risk. Universal screening of toddlers at a later time allows sufficient time for nutritional anemia to become evident after the child has been weaned off iron-fortified formulas, for the influence of toddler dietary fads to manifest, and for evaluation of tolerance of cow's milk protein. This may be addressed via 2 approaches. The first involves postponing the currently recommended screening or an additional screening for anemia between 15 to 18 months of age. Determination of hemoglobin (or hematocrit) is not the optimal way to identify children at risk from effects of iron deficiency as it fails to identify patients who are iron-deficient but are not anemic. Long-term psychomotor, behavioral, and developmental effects secondary to iron deficiency anemia are known but sufficient data are lacking regarding the role of iron deficiency without anemia. Development and evaluation of sensitive, specific, and cost-effective screening tools to identify children at risk for iron deficiency is important. Until such methods are instituted, the AAP should emphasize and recommend universal screening for anemia during the second year of life.

High prevalence of postpartum anemia among low-income women in the United States

OBJECTIVE

To determine the prevalence of anemia from 4 to 26 weeks post partum and to examine prenatal predictors of postpartum anemia.

STUDY DESIGN

Retrospective cohort analysis of 59,428 participants in the Special Supplemental Nutrition Program for Women, Infants, and Children in 12 US states.

RESULTS

The prevalence of postpartum anemia was 27%. Anemia rates were higher among minority women, reaching 48% among non-Hispanic black women. Of 9129 women who had normal hemoglobin in the third trimester, 21% had postpartum anemia. Prenatal anemia was the strongest predictor of postpartum anemia (adjusted odds ratio, 2.7; 95% confidence interval, 2.5-2.8). Maternal obesity, multiple birth, and not breast-feeding also predicted postpartum anemia.

CONCLUSION

The high prevalence of post partum anemia among low-income women highlights the importance of anemia screening at 4 to 6 weeks post partum. These data suggest that screening should not be limited, as it is at present, to women considered at high risk.

Helicobacter pylori-associated iron-deficiency anemia in adolescent female athletes

OBJECTIVE

The objective was to investigate the role of Helicobacter pylori infection in iron-deficiency anemia (IDA) of pubescent athletes.

STUDY DESIGN

Blood sampling and a questionnaire survey were performed on 440 regular high school students and 220 athletes of a physical education high school. Hemoglobin, serum iron, total iron-binding capacity, ferritin, and immunoglobulin G antibody to H. pylori were measured to compare the prevalence of IDA and H. pylori infection in the groups. Nutritional analysis and a questionnaire survey for socioeconomic status were undertaken to compare and control for other risk factors that might influence IDA and H. pylori infection in the groups. In those with IDA coexistent with H. pylori infection, we also determined whether IDA can be managed by H pylori eradication.

RESULTS

The prevalence rates of IDA, H pylori infection, and H. pylori -associated IDA in female athletes were higher than in the control group. The relative risk of IDA was 2.9 (95% CI, 1.5 to 5.6) for those with H. pylori infection. Athletes who exhibited H. pylori -associated IDA showed significant increases in hemoglobin, iron, and ferritin levels after H. pylori eradication. The subjects in the control group who were treated orally with iron alone showed no significant changes.

CONCLUSION

Adolescent female athletes may have development of H. pylori -associated IDA, which can be managed by H. pylori eradication.

Iron status of premenopausal women in two regions of Bangladesh: prevalence of deficiency in high and low socio-economic groups

OBJECTIVE

The objective of the study was to assess iron status in women of different physiological status of two socio-economic groups in Bangladesh.

DESIGN

Cross sectional study, using 3-day food record and blood haemoglobin, serum iron, serum ferritin concentrations.

SETTING

Two regions of Bangladesh. The Dhaka city area and west region of Nandail, Mymensingh.

SUBJECTS

Women aged 16-40 y. The low socio-economic group (group L, n=101) consisted of rural women with precarious income levels. The high socio-economic group (group H, n=90) consisted of women with high income and educational levels. The groups were composed of three sub-groups (non-pregnant non-lactating=1, pregnant = 2 and lactating = 3).

RESULTS

There was no significant difference between the corresponding sub-groups of the two socio-economic groups in dietary intake of iron. In all sub-groups, the intake of iron was much higher than the RDA level and mainly based on non-haem iron. Blood haemoglobin (B-Hb) concentration (P=0.000), serum iron concentration (P=0.005) and serum ferritin (SF) concentration (P=0.000) were affected by socio-economic status. Physiological status (PS) influenced the B-Hb concentration (P=0.000). Prevalence of anaemia ranged from 63 to 70% in group L and 27 to 66% in group H, respectively. The prevalence of empty iron store (SF concentration<12 microg/l) ranged from 35 to 59% in group L and 15 to 32% in group H, respectively. The prevalence of anaemia and iron deficiency (70 and 35% for sub-group L2; 66 and 32% for sub-group H2, respectively) were similar in the pregnant subjects of the two groups.

CONCLUSIONS

Subclinical iron deficiency was common in women of low socio-economic status. The pregnant subjects in the two groups was similar as regards iron status.

SPONSORSHIP

The study was supported by the Academy of Finland, University of Helsinki and NorFa, Norway.

Iron deficiency and cognitive achievement among school-aged children and adolescents in the United States

CONTEXT

Iron deficiency anemia in infants can cause developmental problems. However, the relationship between iron status and cognitive achievement in older children is less clear.

OBJECTIVE

To investigate the relationship between iron deficiency and cognitive test scores among a nationally representative sample of school-aged children and adolescents.

DESIGN

The National Health and Nutrition Examination Survey III 1988-1994 provides cross-sectional data for children 6 to 16 years old and contains measures of iron status including transferrin saturation, free erythrocyte protoporphyrin, and serum ferritin. Children were considered iron-deficient if any 2 of these values were abnormal for age and gender, and standard hemoglobin values were used to detect anemia. Scores from standardized tests were compared for children with normal iron status, iron deficiency without anemia, and iron deficiency with anemia. Logistic regression was used to estimate the association of iron status and below average test scores, controlling for confounding factors.

RESULTS

Among the 5398 children in the sample, 3% were iron-deficient. The prevalence of iron deficiency was highest among adolescent girls (8.7%). Average math scores were lower for children with iron deficiency with and without anemia, compared with children with normal iron status (86.4 and 87.4 vs 93.7). By logistic regression, children with iron deficiency had greater than twice the risk of scoring below average in math than did children with normal iron status (odds ratio: 2.3; 95% confidence interval: 1.1-4.4). This elevated risk was present even for iron-deficient children without anemia (odds ratio: 2.4; 95% confidence interval: 1.1-5.2).

CONCLUSIONS

We demonstrated lower standardized math scores among iron-deficient school-aged children and adolescents, including those with iron deficiency without anemia. Screening for iron deficiency without anemia may be warranted for children at risk.