Case studies: iron

Circulating microRNAs and hepcidin as predictors of iron homeostasis and anemia among school children: a biochemical and cross-sectional survey analysis

BACKGROUND

MicroRNAs (miRNAs) can control several biological processes. Thus, the existence of these molecules plays a significant role in regulating human iron metabolism or homeostasis.

PURPOSE

The study aimed to determine the role of circulating microRNAs and hepcidin in controlling iron homeostasis and evaluating possible anemia among school children.

METHODS

The study was based on a biochemical and cross-sectional survey study that included three hundred fifty school children aged 12-18 years old. RT-PCR and immunoassay analysis were accomplished to estimate iron concentration, Hgb, serum ferritin (SF), soluble transferrin receptor (sTfR), total body iron stores (TIBs), total oxidative stress (TOS), total antioxidant capacity (TAC), α-1-acid glycoprotein (AGP), high sensitive C-reactive protein (hs-CRP), and miRNAs; miR-146a, miR-129b, and miR-122 in 350 school adolescents.

RESULTS

Iron disorders were cross-sectionally predicted in 28.54% of the study population; they were classified into 14.26% with ID, 5.7% with IDA, and 8.6% with iron overload. The overall proportion of iron depletion was significantly higher in girls (20.0%) than in boys (8.6%). MicroRNAs; miR-146a, miR-125b, and miR-122 were significantly upregulated with lower hepcidin expression in adolescence with ID and IDA compared to iron-overloaded subjects, whereas downregulation of these miRNAs was linked with higher hepcidin. Also, a significant correlation was recorded between miRNAs, hepcidin levels, AGP, hs-CRP, TAC, and other iron-related indicators.

CONCLUSION

Molecular microRNAs such as miR-146a, miR-125b, and miR-122 were shown to provide an additional means of controlling or regulating cellular iron uptake or metabolism either via the oxidative stress pathway or regulation of hepcidin expression via activating genes encoding Hfe and Hjv activators, which promote iron regulation. Thus, circulating miRNAs as molecular markers and serum hepcidin could provide an additional means of controlling or regulating cellular iron and be associated as valuable markers in diagnosing and treating cases with different iron deficiencies.

A Comprehensive Study: Traditional and Cutting-Edge Analytical Techniques for the Biomarker Based Detection of the Micronutrients & POC Sensing Directions for Next-Generation Diagnostic

Micronutrient deficiency is wide spread and highly affects morbidity, mortality, and well-being of human beings. Micronutrient deficiency gradually manifests into diseases, which effects pathophysiology directly or indirectly. There is an imprecision in the diagnosis of micronutrient deficiency because of two causes; the selection of the standard biomarker and the diagnostic technique used. In appropriate diagnosis could increase the severity of the disorder. Instead of a single a combination of biomarkers can give more stringent results for micronutrient testing. Several traditional analytical techniques are used for diagnosis but HPLC, ELISA & LCMS/MS are most sensitive and reliable methods used by CLSIA-certified labs. However, these techniques require well-equipped, centralized laboratory facilities. The diagnostic era moves toward the Point of Care Testing (POCT), a boon in emerging diagnostics, breaking all paradigms of traditional analytical techniques. POCT led us toward the development of biosensors, which encompasses many techniques like paper-based sensors, microfluidic chip, wearable devices, and smartphone-assisted diagnostics, which become more popular diagnostic tools. This outlook summarizes the micronutrients like vitamins A, B5, B6, B7, B9, B12 C, D, and E and Minerals like iron, calcium, zinc, magnesium, and sodium; along with its biomarkers, analytical techniques, and point of care innovation in micronutrients.

Association between maternal plasma ferritin level and infants' size at birth: a prospective cohort study in rural Bangladesh

Background: Iron supplementation in pregnancy is recommended by the WHO to prevent a major public health problem, namely, maternal iron deficiency and its consequences. There are gaps in the existing evidence regarding maternal and neonatal benefits and harms of universal iron supplementation.

Objective: To evaluate the association between maternal iron status during pregnancy and infant size at birth (birth weight and length).

Method: This present prospective cohort study was nested in a food and micronutrient supplementation trial conducted in Matlab (MINIMat study), rural Bangladesh. We randomly selected 573 women recruited into the MINIMat study from January – December 2002 who delivered singletons with available birth anthropometric information. The plasma ferritin of each mother was measured at gestational week 14 (GW14; before the start of micronutrient supplementation) and at week 30 (GW30).

Results: Multivariable linear regression revealed no association between plasma ferritin at GW14 and birth weight. However, newborns of women in the highest tertile of plasma ferritin at GW30 (median = 29 µg/L) had on average a 93-gm lower birth weight (95% CI: −172, – 14; p = 0.021) than the newborns of women in the lowest tertile (median = 8 µg/L). Logistic regression showed that odds of low birth weight were approximately two times higher [odds ratio (OR) = 2.27; 95% CI: 1.40, 3.67] among those with mothers in the highest ferritin tertile than in the lowest tertile at GW30. No association was found between maternal plasma ferritin and birth length.

Conclusion: We observed an inverse association between high plasma ferritin in the last trimester (GW30) and birth weight but not birth length. The results suggested that elevated plasma ferritin in pregnancy could have an untoward effect on birth weight.

Competition between abiogenic and biogenic metal cations in biological systems: Mechanisms of gallium's anticancer and antibacterial effect

Metal cations are key players in a plethora of essential biological processes. Over the course of evolution specific biological functions have been bestowed upon two dozen of (biogenic) metal species, some of the most frequently found being sodium, potassium, magnesium, calcium, zinc, manganese, iron, and copper. On the other hand, there is a group of less studied abiogenic metals like lithium, strontium and gallium that possess not known functions in living organisms, but, by mimicking the native ions and/or competing with them for binding to key metalloenzymes, may exert beneficial effect on humans in particular medical conditions. This review summarizes and critically examines the mechanisms of gallium's therapeutic action in anticancer and antibacterial therapies by exploiting the tools of molecular modeling and experimental biochemistry. These approaches allow for identifying key factors for Ga³⁺ beneficial effect such as the electrostatic interactions with the protein ligands, substrates or bacterial siderophores, intramolecular hydrogen bond formation, and pH and dielectric properties of the medium. Several intriguing questions concerning the gallium competition with the native ferric ion have found their answers.

Prenatal Iron Deficiency and Replete Iron Status Are Associated with Adverse Birth Outcomes, but Associations Differ in Ghana and Malawi

BACKGROUND

Previous literature suggests a U-shaped relation between hemoglobin concentration and adverse birth outcomes. There is less evidence on associations between iron status and birth outcomes.

OBJECTIVE

Our objective was to determine the associations of maternal hemoglobin concentration and iron status with birth outcomes.

METHODS

We conducted a secondary data analysis of data from 2 cohorts of pregnant women receiving iron-containing nutritional supplements (20-60 mg ferrous sulfate) in Ghana (n = 1137) and Malawi (n = 1243). Hemoglobin concentration and 2 markers of iron status [zinc protoporphyrin and soluble transferrin receptor (sTfR)] were measured at ≤20 weeks and 36 weeks of gestation. We used linear and Poisson regression models and birth outcomes included preterm birth (PTB), newborn stunting, low birth weight (LBW), and small-for-gestational-age.

RESULTS

Prevalence of iron deficiency (sTfR >6.0 mg/L) at enrollment was 9% in Ghana and 20% in Malawi. In early pregnancy, iron deficiency was associated with PTB (9% compared with 17%, adjusted RR: 1.63; 95% CI: 1.14, 2.33) and stunting (15% compared with 23%, adjusted RR: 1.44; 95% CI: 1.09, 1.94) in Malawi but not Ghana, and was not associated with LBW in either country; replete iron status (sTfR <10th percentile) was associated with stunting (9% compared with 15%, adjusted RR: 1.71; 95% CI: 1.06, 2.77) in Ghana, but not PTB or LBW, and was not associated with any birth outcomes in Malawi. In late pregnancy, iron deficiency was not related to birth outcomes in either country and iron-replete status was associated with higher risk of LBW (8% compared with 16%, adjusted RR: 1.90; 95% CI: 1.17, 3.09) and stunting (6% compared with 13%, adjusted RR: 2.14; 95% CI: 1.21, 3.77) in Ghana, but was not associated with birth outcomes in Malawi.

CONCLUSIONS

The associations of low or replete iron status with birth outcomes are population specific. Research to replicate and extend these findings would be beneficial. These trials were registered at clinicaltrials.gov as NCT00970866 (Ghana) and NCT01239693 (Malawi).

Intake of Polydextrose Alters Hematology and the Profile of Short Chain Fatty Acids in Partially Gastrectomized Rats

Polydextrose (PDX) ingestion may increase the intestinal absorption of iron. This study evaluated the effects of 7.5% polydextrose supplementation on markers of iron uptake, transport and storage in partially gastrectomized rats. Half of a batch of 40 male Wistar rats (250 g) underwent Billroth II partial gastrectomy with anterior truncal vagotomy (GXT), while the other half underwent sham gastrectomy (SHAM). At 7 postoperative days, the animals were subdivided into four groups (n = 10): Sham Control and GXT Control (no polydextrose); Sham PDX and GXT PDX (with 7.5% PDX). The animals were euthanized after 60 day of PDX treatment. Organ weight, cecal pH, the characterization and quantification of short-chain fatty acids (SCFA), hematological parameters, hepatic iron content and the expression of ferroportin (FPT) in the jejunum, cecum, colon and liver were evaluated. PDX caused changes in the cecum of the supplemented animals, where there was a decrease in pH, increase in cecal wall and marked production of SCFA, especially acetic and propionic acids (p < 0.05). Hepatic iron levels were lower in GXT animals. PDX increased hemoglobin (HGB) values by 29.2% and hematocrit (HCT) by 55.8% in the GXT PDX group compared to the GXT Control group. The GXT PDX group had lower hepatic FPT expression (p < 0.05). PDX led to increased SCFA concentration in the supplemented animals. Considering that SCFAs play a central role in the increasing nutrients uptake, this mechanism may be involved in altering the hematology profile observed in these animals but not enough to reverse iron deficiency anemia in post-gastrectomy rats.

Assessment of iron status in settings of inflammation: challenges and potential approaches

The determination of iron status is challenging when concomitant infection and inflammation are present because of confounding effects of the acute-phase response on the interpretation of most iron indicators. This review summarizes the effects of inflammation on indicators of iron status and assesses the impact of a regression analysis to adjust for inflammation on estimates of iron deficiency (ID) in low- and high-infection-burden settings. We overviewed cross-sectional data from 16 surveys for preschool children (PSC) (n = 29,765) and from 10 surveys for nonpregnant women of reproductive age (WRA) (n = 25,731) from the Biomarkers Reflecting the Inflammation and Nutritional Determinants of Anemia (BRINDA) project. Effects of C-reactive protein (CRP) and α1-acid glycoprotein (AGP) concentrations on estimates of ID according to serum ferritin (SF) (used generically to include plasma ferritin), soluble transferrin receptor (sTfR), and total body iron (TBI) were summarized in relation to infection burden (in the United States compared with other countries) and population group (PSC compared with WRA). Effects of the concentrations of CRP and AGP on SF, sTfR, and TBI were generally linear, especially in PSC. Overall, regression correction changed the estimated prevalence of ID in PSC by a median of +25 percentage points (pps) when SF concentrations were used, by -15 pps when sTfR concentrations were used, and by +14 pps when TBI was used; the estimated prevalence of ID in WRA changed by a median of +8 pps when SF concentrations were used, by -10 pps when sTfR concentrations were used, and by +3 pps when TBI was used. In the United States, inflammation correction was done only for CRP concentrations because AGP concentrations were not measured; regression correction for CRP concentrations increased the estimated prevalence of ID when SF concentrations were used by 3 pps in PSC and by 7 pps in WRA. The correction of iron-status indicators for inflammation with the use of regression correction appears to substantially change estimates of ID prevalence in low- and high-infection-burden countries. More research is needed to determine the validity of inflammation-corrected estimates, their dependence on the etiology of inflammation, and their applicability to individual iron-status assessment in clinical settings.

Iron status of toddlers, nonpregnant females, and pregnant females in the United States

Background: Total-body iron stores (TBI), which are calculated from serum ferritin and soluble transferrin receptor concentrations, can be used to assess the iron status of populations in the United States.Objective: This analysis, developed to support workshop discussions, describes the distribution of TBI and the prevalence of iron deficiency (ID) and ID anemia (IDA) among toddlers, nonpregnant females, and pregnant females.Design: We analyzed data from NHANES; toddlers aged 12-23 mo (NHANES 2003-2010), nonpregnant females aged 15-49 y (NHANES 2007-2010), and pregnant females aged 12-49 y (NHANES 1999-2010). We used SAS survey procedures to plot distributions of TBI and produce prevalence estimates of ID and IDA for each target population. All analyses were weighted to account for the complex survey design.Results: According to these data, ID prevalences (± SEs) were 15.1% ± 1.7%, 10.4% ± 0.5%, and 16.3% ± 1.3% in toddlers, nonpregnant females, and pregnant females, respectively. ID prevalence in pregnant females increased significantly with each trimester (5.3% ± 1.5%, 12.7% ± 2.3%, and 27.5% ± 3.5% in the first, second, and third trimesters, respectively). Racial disparities in the prevalence of ID among both nonpregnant and pregnant females exist, with Mexican American and non-Hispanic black females at greater risk of ID than non-Hispanic white females. IDA prevalence was 5.0% ± 0.4% and 2.6% ± 0.7% in nonpregnant and pregnant females, respectively.Conclusions: Available nationally representative data suggest that ID and IDA remain a concern in the United States. Estimates of iron-replete status cannot be made at this time in the absence of established cutoffs for iron repletion based on TBI. The study was registered at clinicaltrials.gov as NCT03274726.

Adjusting total body iron for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

Background: Total body iron (TBI) that is calculated from ferritin and soluble transferrin receptor (sTfR) allows for the evaluation of the full range of iron status from deficiency to excess. However, both ferritin and sTfR are affected by inflammation and malaria, which may require a statistical adjustment. TBI has been used to assess iron status in the United States, but its use worldwide and in settings with inflammation has been limited.Objective: We examine whether inflammation-adjusted ferritin and sTfR concentrations affect TBI values and the prevalence of low TBI (<0 mg/kg) in preschool children (PSC) (age range: 6-59 mo) and women of reproductive age (WRA) (age range: 15-49 y).Design: Cross-sectional data for PSC (8 surveys; n = 8413) and WRA (4 surveys; n = 4258) from the Biomarkers Reflecting the Inflammation and Nutritional Determinants of Anemia (BRINDA) project were analyzed individually and combined. TBI and the prevalence of low TBI were compared following 3 adjustment approaches for ferritin and sTfR: 1) the exclusion of individuals with inflammation (C-reactive protein concentration >5 mg/L or α-1-acid glycoprotein concentration >1 g/L), 2) the application of arithmetic correction factors, and 3) the use of regression correction.Results: Regardless of the method that was used to adjust ferritin and sTfR for inflammation, the adjusted mean TBI decreased in both PSC and WRA compared with unadjusted values. Subsequently, inflammation-adjusted TBI increased the prevalence of low TBI by a median of 4-14 percentage points (pps) in PSC and 1-3 pps in WRA compared with unadjusted TBI. The regression approach resulted in a greater median increase than was achieved with the exclusion or correction-factor approaches, and accounting for malaria in addition to inflammation did not have an added effect on the prevalence estimates.Conclusion: The prevalence of low TBI is underestimated if it is not adjusted by inflammation, particularly in children living in areas with a high prevalence of inflammation.

Multiple Biomarkers of Maternal Iron Predict Infant Cognitive Outcomes

This study examined relations between multiple measures of maternal iron status assessed 3 months post-partum, and infant processing speed (longest look during visual habituation), memory (novelty preference), attention (heart rate changes), and neural response variability (in auditory event-related potentials) at 3 and 9 months. Plasma iron was associated with 9-month novelty preference and longest look, and developmental changes in longest look. Hemoglobin predicted sustained attention, and both plasma iron and soluble transferrin receptors predicted neural response variability at 9 months. Improved maternal iron appears to have a positive impact on infant cognitive development even in a well-nourished, low-risk sample.

The effects of polysaccharides from the root of Angelica sinensis on tumor growth and iron metabolism in H22-bearing mice

The crude polysaccharide was obtained from the root of Angelica sinensis (AS) to investigate its effect on tumor growth and iron metabolism in H22-bearing mice. In our study, we showed that Angelica sinensis polysaccharide (ASP) was mainly composed of arabinose, glucose and galactose in a molar ratio of 1:1:1.75, with a molecular weight of 80,900 Da and a sugar content of 88.0%. Animal experimental results revealed that three doses of ASP all had anti-tumor effects with inhibition ratios of 27.11%, 31.65% and 37.05%. With respect to iron metabolism, the mean levels of serum hepcidin, interleukin-6 (IL-6), ferritin, transferrin (Tf), transferrin receptor 1 (TfR1) and transferrin receptor 2 (TfR2) in H22-bearing mice were promoted, and serum iron concentration decreased significantly. After treatment with ASP, these iron-related indicators recovered in different degrees. The findings suggested that the anti-tumor activity of ASP may be affected by its regulation on iron metabolism in H22-bearing mice.

A double blind randomised controlled trial comparing standard dose of iron supplementation for pregnant women with two screen-and-treat approaches using hepcidin as a biomarker for ready and safe to receive iron

BACKGROUND

Until recently, WHO recommended daily iron supplementation for all pregnant women (60 mg/d iron combined with 400ug/d folic acid) where anaemia rates exceeded 40 %. Recent studies indicate that this may pose a risk to pregnant women. Therefore, there is a need to explore screen-and-treat options to minimise iron exposure during pregnancy using an overall lower dosage of iron that would achieve equivalent results as being currently recommended by the WHO. However, there is a lack of agreement on how to best assess iron deficiency when infections are prevalent. Here, we test the use of hepcidin a peptide hormone and key regulator of iron metabolism, as a potential index for 'safe and ready to receive' iron.

DESIGN/METHODS

This is a 3-arm randomised-controlled proof-of-concept trial. We will test the hypothesis that a screen-and-treat approach to iron supplementation using a pre-determined hepcidin cut-off value of <2.5 ng/ml will achieve similar efficacy in preventing iron deficiency and anaemia at a lower iron dose and hence will improve safety. A sample of 462 pregnant women in rural Gambia will be randomly assigned to receive: a) UNU/UNICEF/WHO international multiple micronutrient preparation (UNIMMAP) containing 60 mg/d iron (reference arm); b) UNIMMAP containing 60 mg/d iron but based on a weekly hepcidin screening indicating if iron can be given for the next 7 days or not; c) or UNIMMAP containing 30 mg/d iron as in (b) for 12 weeks in rural Gambia. The study will test if the screen-and-treat approach is non-inferior to the reference arm using the primary endpoint of haemoglobin levels at a non-inferiority margin of 0.5 g/dl. Secondary outcomes of adverse effects, compliance and the impact of iron supplementation on susceptibility to infections will also be assessed.

DISCUSSION

This trial is expected to contribute towards minimising the exposure of pregnant women to iron that may not be needed and therefore potentially harmful. If the evidence in this study shows that the overall lower dosage of iron is non-inferior to 60 mg/day iron, this may help decrease side-effects, improve compliance and increase safety. The potential for the use of hepcidin for a simple point-of-care (PoC) diagnostic for when it is most safe and effective to give iron may improve maternal health outcomes.

TRIAL REGISTRATION

ISRCTN21955180.

Influence of diet and supplements on iron status after gastric bypass surgery

BACKGROUND

Iron deficiency is common after Roux-en-Y gastric bypass (RYGB) surgery, but there is no consensus on the optimal diet quality and quantity for restoring and preserving iron status.

OBJECTIVES

The authors explored the impact of dietary and supplemental sources of iron and absorptive factors on iron status.

SETTING

Academic, United States.

METHODS

In a cross-sectional cohort of individuals who underwent RYGB, nutrient intakes from food and supplements were measured using 3-day food records. Blood biomarkers of iron status, including concentrations of ferritin, total iron binding capacity, serum transferrin receptor (sTfR), and the sTfR:ferritin ratio, were assessed by a reference laboratory; iron deficiency was defined as having at least 2 abnormal measures. Associations between iron status biomarkers and dietary predictors were determined using regression analysis.

RESULTS

Of the 36 participants, 97% were female, the mean age was 45 years (95% confidence interval, 41-48 years), and body mass index was 32 (30-35) kg/m(2). Iron deficiency was found in 42% of participants. Dietary intake of heme iron, found in meats, was favorably associated with 3 iron status biomarkers (ferritin, β = .366; sTfR:ferritin ratio, β = -.459; and total iron binding capacity, β = -18.26; all P<.05), independent of obesity-induced inflammation. Intake of vitamin C from food contributed to iron status (ferritin, β = .010 and sTfR:ferritin ratio, β = -.011; P<.05). Use of supplementary non-heme iron, at doses recommended for prophylaxis (45 mg/d), was positively associated with serum ferritin (β = .964; P = .029).

CONCLUSIONS

For patients who have undergone RYGB, consuming high, but realistic amounts of heme iron in meat, vitamin C from food, and adherence to recommended iron supplements can prevent iron deficiency.

Markers of iron status are associated with stage of pregnancy and acute-phase response, but not with parity among pregnant women in Guinea-Bissau

While prenatal Fe supplementation prevents maternal Fe deficiency and anaemia, it is uncertain whether it improves infant health outcomes, at least when taken by Fe-replete women. Inflammation as well as physiological changes complicates the assessment of Fe status during pregnancy. In the present study, we measured the concentrations of serum ferritin and soluble transferrin receptors (sTfR), Hb and the acute-phase proteins C-reactive protein (CRP) and α1-antichymotrypsin (ACT) in a cross-sectional study among 738 pregnant women attending antenatal care in Guinea-Bissau, West Africa. Multiple linear regression analysis was used to identify the predictors of Fe status markers. The mean gestational age was 23 (sd7) weeks. Serum ferritin values were lower with progressing gestation, from 27 % lower during weeks 16–20 of gestation up to 59 % lower after 29 weeks of gestation compared with early pregnancy. Using cut-off values for Fe deficiency as established in non-pregnant individuals, 52 % of the women had sTfR levels >2·3 mg/l, while only 25 % had serum ferritin levels < 12 μg/l. Serum ferritin but also sTfR levels were elevated at increased serum CRP and ACT levels. The proportion of sTfR >2·3 mg/l decreased to 47 % after adjustment for elevated serum CRP and ACT levels. On the contrary, the proportion of serum ferritin < 12 μg/l increased to 33 % after adjustment for ACT and CRP. The high proportion of elevated serum sTfR calls for pregnancy-specific cut-offs since increased erythropoiesis is expected in response to increased plasma volume of pregnancy. The present study further underlines the need to adjust for inflammation when serum sTfR and serum ferritin are used to assess Fe status in pregnancy.

Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE)

An increasing recognition has emerged of the complexities of the global health agenda—specifically, the collision of infections and noncommunicable diseases and the dual burden of over- and undernutrition. Of particular practical concern are both 1) the need for a better understanding of the bidirectional relations between nutritional status and the development and function of the immune and inflammatory response and 2) the specific impact of the inflammatory response on the selection, use, and interpretation of nutrient biomarkers. The goal of the Inflammation and Nutritional Science for Programs/Policies and Interpretation of Research Evidence (INSPIRE) is to provide guidance for those users represented by the global food and nutrition enterprise. These include researchers (bench and clinical), clinicians providing care/treatment, those developing and evaluating programs/interventions at scale, and those responsible for generating evidence-based policy. The INSPIRE process included convening 5 thematic working groups (WGs) charged with developing summary reports around the following issues: 1) basic overview of the interactions between nutrition, immune function, and the inflammatory response; 2) examination of the evidence regarding the impact of nutrition on immune function and inflammation; 3) evaluation of the impact of inflammation and clinical conditions (acute and chronic) on nutrition; 4) examination of existing and potential new approaches to account for the impact of inflammation on biomarker interpretation and use; and 5) the presentation of new approaches to the study of these relations. Each WG was tasked with synthesizing a summary of the evidence for each of these topics and delineating the remaining gaps in our knowledge. This review consists of a summary of the INSPIRE workshop and the WG deliberations.

Asymptomatic malaria infection affects the interpretation of biomarkers of iron and vitamin A status, even after adjusting for systemic inflammation, but does not affect plasma zinc concentrations among young children in Burkina Faso

BACKGROUND

Biomarkers of iron [plasma ferritin (pF)], vitamin A [retinol binding protein (RBP)], and zinc status [plasma zinc (pZn)] are affected by the acute phase response, independent of micronutrient status.

OBJECTIVE

The objective of these analyses was to assess how asymptomatic malaria infection affects the interpretation of these biomarkers after adjustment for elevated acute phase proteins (APPs).

METHODS

Soluble transferrin receptor (sTfR), pF, RBP, and pZn concentrations were measured among 451 asymptomatic children aged 6-23 mo in Burkina Faso and adjusted for elevated APP (C-reactive protein ≥5 mg/L and/or α-1-acid-glycoprotein ≥1 g/L) based on a 4-group categorical model. Plasma histidine-rich protein II (HRP2) concentrations ≥0.75 μg/L were considered indicative of current or recent malaria parasitemia.

RESULTS

Of the children in the study, 57.4% had at least 1 elevated APP, and 48.5% had elevated HRP2. After adjusting for APP, children with elevated HRP2 had higher pF (23.5 ± 1.5 μg/L vs. 11.1 ± 0.8 μg/L; P < 0.001) and lower RBP (0.79 ± 0.01 μmol/L vs. 0.92 ± 0.01 μmol/L; P < 0.001) than those without, but there were no differences in pZn among those with and without elevated HRP2 (64.9 ± 12.7 μg/dL vs. 64.9 ± 11.1 μg/dL; P = 0.98). Children with elevated HRP2 had higher sTfR than those without (17.6 ± 0.5 mg/L vs. 12.3 ± 0.4 mg/L; P < 0.0001). After adjusting for HRP2, along with APP, the estimated prevalence of iron deficiency (pF < 12 μg/L) increased from 38.7% to 50.6% and vitamin A deficiency (RBP < 0.84 μmol/L) decreased from 33.4% to 27.7%.

CONCLUSIONS

Asymptomatic malaria is associated with indicators of micronutrient status, even after adjusting for APP. Adjusting indicators of iron and vitamin A status based only on APP may inaccurately estimate the prevalence of micronutrient deficiencies in settings with a high prevalence of malaria and inflammation. This trial was registered at clinicaltrials.gov as NCT00944853.

Effects of inflammation and Plasmodium falciparum infection on soluble transferrin receptor and plasma ferritin concentration in different age groups: a prospective longitudinal study in Côte d'Ivoire

BACKGROUND

Iron deficiency (ID) is a major cause of anemia, along with other nutritional, parasitic, and genetic factors. Accurate biomarkers are needed to estimate the relative contribution of ID to anemia. Soluble transferrin receptor (sTfR) is thought to be unaffected by inflammation.

OBJECTIVES

The objectives were to determine the difference in sTfR and plasma ferritin (PF) concentrations among infants (6-23 mo of age), school-age children (6-8 y of age), and women (15-25 y of age) with and without inflammation and with and without Plasmodium falciparum infection and to assess the effect of adjusting sTfR and PF for inflammation or for P. falciparum infection on the estimated prevalence of ID.

DESIGN

The data were derived from a 14-mo prospective longitudinal survey on anemia, which was conducted in the Taabo area, south-central Côte d'Ivoire.

RESULTS

At baseline, sTfR concentration was significantly higher in infants and school-age children with either inflammation or P. falciparum infection than in control individuals without inflammation or without P. falciparum infection. Individuals with inflammation had significantly higher PF concentrations than did subjects without inflammation. Adjustments in sTfR concentrations for inflammation or P. falciparum infection in infants and school-age children resulted in significantly lower ID prevalence. Adjustment of PF for inflammation and Plasmodium infection resulted in a higher ID prevalence in infants and women.

CONCLUSIONS

In Ivorian infants and school-age children, ID prevalence was considerably lower after adjustment of sTfR for inflammation. However, as the prevalence estimates for ID differed widely if based on sTfR or PF, caution is still needed when estimating ID prevalence in areas with a high prevalence of inflammation or malaria. This trial was registered at controlled-trials.com as ISRCTN02181959.

The influence of micronutrients in cell culture: a reflection on viability and genomic stability

Micronutrients, including minerals and vitamins, are indispensable to DNA metabolic pathways and thus are as important for life as macronutrients. Without the proper nutrients, genomic instability compromises homeostasis, leading to chronic diseases and certain types of cancer. Cell-culture media try to mimic the in vivo environment, providing in vitro models used to infer cells' responses to different stimuli. This review summarizes and discusses studies of cell-culture supplementation with micronutrients that can increase cell viability and genomic stability, with a particular focus on previous in vitro experiments. In these studies, the cell-culture media include certain vitamins and minerals at concentrations not equal to the physiological levels. In many common culture media, the sole source of micronutrients is fetal bovine serum (FBS), which contributes to only 5-10% of the media composition. Minimal attention has been dedicated to FBS composition, micronutrients in cell cultures as a whole, or the influence of micronutrients on the viability and genetics of cultured cells. Further studies better evaluating micronutrients' roles at a molecular level and influence on the genomic stability of cells are still needed.

Plasma ferritin and soluble transferrin receptor concentrations and body iron stores identify similar risk factors for iron deficiency but result in different estimates of the national prevalence of iron deficiency and iron-deficiency anemia among women and children in Cameroon

Available iron status indicators reflect different aspects of metabolism. We compared the prevalence and distribution of iron deficiency (ID) and iron-deficiency anemia (IDA) among Cameroonian women and children, as measured by plasma ferritin, and soluble transferrin receptor concentrations, body iron stores (BIS), and hemoglobin, and evaluated the impact of adjustments for inflammation on these measures. In a nationally representative survey, we randomly selected 30 clusters in each of 3 zones (north, south, and large cities) and 10 households/ cluster, each with a child aged 12-59 mo and a woman 15-49 y. Ferritin and BIS were mathematically adjusted for inflammation, using plasma C-reactive protein and α(1)-acid glycoprotein both as continuous and categorical variables. Inflammation was present in 48.0% of children and 20.8% of women and anemia was diagnosed in 57.6% of children and 38.8% of women. Depending on the iron status indicator applied, the prevalence of ID ranged from 14.2 to 68.4% among children and 11.5 to 31.8% among women, and the prevalence of IDA ranged from 12.0 to 47.4% among children and 9.0 to 19.4% among women; the proportion of anemia associated with ID ranged from 20.8 to 82.3% among children and 23.2 to 50.0% among women. The different iron indicators generally identified similar groups at greatest risk of deficiency, using both conventional and derived cutoffs: younger children, pregnant women, and women and children in the north and rural areas. Research is needed to clarify the relationships between iron status indicators, particularly in the presence of inflammation, to harmonize global data on prevalence of ID.

High prevalence of subclinical iron deficiency in whole blood donors not deferred for low hemoglobin

BACKGROUND

Blood donors that meet the hemoglobin (Hb) criteria for donation may have undetected subclinical iron deficiency. The aim of this study was to assess the prevalence of subclinical iron deficiency in whole blood donors with Hb levels above cutoff levels for donation by measuring zinc protoporphyrin (ZPP) levels. In addition, prevalence rates based on other iron variables were assessed for comparison.

STUDY DESIGN AND METHODS

The study population comprised 5280 Dutch whole blood donors, who passed the Hb criteria for donation. During donor screening, Hb levels were measured in capillary samples (finger prick), and venous blood samples were taken for measurements of ZPP and other iron variables. These variables included ferritin, transferrin saturation, soluble transferrin receptor (sTfR), hepcidin, red blood cell mean corpuscular volume (MCV), and mean cell Hb (MCH).

RESULTS

With a ZPP cutoff level of at least 100 μmol/mol heme, subclinical iron deficiency was present in 6.9% of male donors and in 9.8% of female donors. Based on other iron variables, iron deficiency was also observed. Prevalence rates ranged from 4.8% (based on transferrin saturation) to 27.4% (based on hepcidin concentration) in men and from 5.6% (based on sTfR concentration) to 24.7% (based on hepcidin concentration) in women.

CONCLUSION

Results from this study showed that subclinical iron deficiency is prevalent among blood donors that meet the Hb criteria for blood donation, based on ZPP levels and on other iron variables. This finding needs attention because these donors are at increased risk of developing iron deficiency affecting Hb formation and other cellular processes.

Comparison of indicators of iron deficiency in Kenyan children

BACKGROUND

In the absence of a feasible, noninvasive gold standard, iron deficiency (ID) is best measured by the use of multiple indicators. However, the choice of an appropriate single iron biomarker to replace the multiple-criteria model for screening for ID at the population level continues to be debated.

OBJECTIVE

We compared ID defined as ≥ 2 of 3 abnormal ferritin (< 12 μg/L), soluble transferrin receptor (TfR; > 8.3 mg/L), or zinc protoporphyrin (ZP; > 80 μmol/mol) concentrations (ie, multiple-criteria model) with ID defined by abnormal concentrations of any of the independent candidate iron biomarkers (ferritin alone, TfR alone, or ZP alone) and TfR/ferritin index (ID, > 500). Values either were adjusted for inflammation [as measured by C-reactive protein (> 5 mg/L) and α(1)-acid glycoprotein (> 1 g/L) before applying cutoffs for ID] or were unadjusted.

DESIGN

In this community-based cluster survey, capillary blood was obtained from 680 children (aged 6-35 mo) for measurement of iron status by using ferritin, TfR, and ZP.

RESULTS

On the basis of the multiple-criteria model, the mean (±SE) prevalence of ID was 61.9 ± 2.2%, whereas the prevalences based on abnormal ferritin, TfR, or ZP concentrations or an abnormal TfR/ferritin index were 26.9 ± 1.7%, 60.9 ± 2.2%, 82.8 ± 1.6%, and 43.1 ± 2.3%, respectively, for unadjusted values. The prevalences of ID were higher for adjusted values only for low ferritin and an elevated TfR/ferritin index compared with the unadjusted values. The κ statistics for agreement between the multiple-criteria model and the other iron indicators ranged from 0.35 to 0.88; TfR had the best agreement (κ = 0.88) with the multiple-criteria model. Positive predictive values of ID based on the other iron indicators in predicting ID based on the multiple-criteria model were highest for ferritin and TfR. Receiver operating characteristic curve analysis indicated that TfR (AUC = 0.94) was superior to the other indicators in diagnosing ID based on the multiple-criteria model (P < 0.001). The inflammation effect did not appear to alter these observations appreciably.

CONCLUSION

TfR better estimates the prevalence of ID in preschoolers than do ferritin, ZP, and the TfR/ferritin index on the basis of multiple indexes in a high inflammation, resource-poor setting. This trial was registered at clinicaltrials.gov as NCT101088958.