Adjusting for the acute phase response is essential to interpret iron status indicators among young Zanzibari children prone to chronic malaria and helminth infections

C-reactive protein as an early biomarker for malaria infection and monitoring of malaria severity: a meta-analysis

This study investigated whether C-reactive protein (CRP) can be used as a marker for the early detection and monitoring of malaria severity. Potentially relevant studies were searched in Medline (PubMed), Scopus, and Web of Science. Differences in CRP between (1) severe malaria and uncomplicated malaria, (2) uncomplicated malaria and asymptomatic malaria, (3) uncomplicated malaria and febrile/healthy controls, and (4) asymptomatic malaria and febrile/healthy controls were estimated using random-effects models. Twenty-nine studies were included for meta-analysis. The results of meta-analysis demonstrated higher mean CRP levels in (1) patients with severe malaria compared with uncomplicated malaria (p < 0.001, standard mean difference [SMD]: 1.52, 95% confidence interval [CI]: 0.91-2.12, I2: 95.1%), (2) patients with uncomplicated malaria than in those with asymptomatic malaria (p: 0.001, SMD: 1.65, 95% CI: 0.67-2.62, I2: 96.7%), (3) patients with uncomplicated malaria compared with febrile/healthy controls (p < 0.001, SMD: 2.38, 95% CI: 1.37-3.40, I2: 98.5%), and (4) patients with asymptomatic malaria compared with febrile/healthy controls (p < 0.001, SMD: 2.55, 95% CI: 1.60-3.50, I2: 99.2%). This study demonstrated CRP levels are a biomarker for the early detection and monitoring of malaria severity.

Malaria causes long-term effects on markers of iron status in children: a critical assessment of existing clinical and epidemiological tools

Background

Most epidemiological studies on the interplay between iron deficiency and malaria risk classify individuals as iron-deficient or iron-replete based on inflammation-dependent iron markers and adjustment for inflammation by using C-reactive protein (CRP) or α-1-acid glycoprotein (AGP). The validity of this approach and the usefulness of fibroblast growth factor 23 (FGF23) as a proposed inflammation-independent iron marker were tested.

Methods

Conventional iron markers and FGF23 were measured in children with acute falciparum malaria and after 1, 2, 4, and 6 weeks. Children, who were transfused or received iron supplementation in the follow-up period, were excluded, and iron stores were considered to be stable throughout. Ferritin levels 6 weeks after admission were used as a reference for admission iron status and compared with iron markers at different time points.

Results

There were long-term perturbations in iron markers during convalescence from acute malaria. None of the tested iron parameters, including FGF23, were independent of inflammation. CRP and AGP normalized faster than ferritin after malaria episodes.

Conclusion

Malaria may bias epidemiological studies based on inflammation-dependent iron markers. Better markers of iron status during and after inflammation are needed in order to test strategies for iron supplementation in populations at risk of malaria.

Anemia of Inflammation during Human Pregnancy Does Not Affect Newborn Iron Endowment

Background

To our knowledge, no studies have addressed whether maternal anemia of inflammation (AI) affects newborn iron status, and few have addressed risk factors for specific etiologies of maternal anemia.

Objectives

The study aims were to evaluate 1) the contribution of AI and iron deficiency anemia (IDA) to newborn iron endowment, 2) hepcidin as a biomarker to distinguish AI from IDA among pregnant women, and 3) risk factors for specific etiologies of maternal anemia.

Methods

We measured hematologic biomarkers in maternal blood at 12 and 32 wk of gestation and in cord blood from a randomized trial of praziquantel in 358 pregnant women with Schistosoma japonicum in The Philippines. IDA was defined as anemia with serum ferritin <30 ng/mL and non-IDA (NIDA), largely due to AI, as anemia with ferritin ≥30 ng/mL. We identified cutoffs for biomarkers to distinguish IDA from NIDA by using area under the curve (AUC) analyses and examined the impact of different causes of anemia on newborn iron status (primary outcome) by using multivariate regression modeling.

Results

Of the 358 mothers, 38% (n = 136) had IDA and 9% (n = 32) had NIDA at 32 wk of gestation. At 32 wk of gestation, serum hepcidin performed better than soluble transferrin receptor (sTfR) in identifying women with NIDA compared with the rest of the cohort (AUCs: 0.75 and 0.70, respectively) and in identifying women with NIDA among women with anemia (0.73 and 0.72, respectively). The cutoff that optimally distinguished women with NIDA from women with IDA in our cohort was 6.1 µg/L. Maternal IDA, but not NIDA, was associated with significantly lower newborn ferritin (114.4 ng/mL compared with 148.4 µg/L; P = 0.042).

Conclusions

Hepcidin performed better than sTfR in identifying pregnant women with NIDA, but its cost may limit its use. Maternal IDA, but not NIDA, is associated with decreased newborn iron stores, emphasizing the need to identify this cause and provide iron therapy. This trial was registered at www.clinicaltrials.gov as NCT00486863.

Adjusting soluble transferrin receptor concentrations for inflammation: Biomarkers Reflecting Inflammation and Nutritional Determinants of Anemia (BRINDA) project

Background: Iron deficiency is thought to be one of the most prevalent micronutrient deficiencies globally, but an accurate assessment in populations who are frequently exposed to infections is impeded by the inflammatory response, which causes iron-biomarker alterations.Objectives: We assessed the relation between soluble transferrin receptor (sTfR) concentrations and inflammation and malaria in preschool children (PSC) (age range: 6-59 mo) and women of reproductive age (WRA) (age range: 15-49 y) and investigated adjustment algorithms to account for these effects.Design: Cross-sectional data from the Biomarkers Reflecting the Inflammation and Nutritional Determinants of Anemia (BRINDA) project from 11,913 PSC in 11 surveys and from 11,173 WRA in 7 surveys were analyzed individually and combined with the use of a meta-analysis. The following 3 adjustment approaches were compared with estimated iron-deficient erythropoiesis (sTfR concentration >8.3 mg/L): 1) the exclusion of individuals with C-reactive protein (CRP) concentrations >5 mg/L or α-1-acid glycoprotein (AGP) concentrations >1 g/L, 2) the application of arithmetic correction factors, and 3) the use of regression approaches.Results: The prevalence of elevated sTfR concentrations incrementally decreased as CRP and AGP deciles decreased for PSC and WRA, but the effect was more pronounced for AGP than for CRP. Depending on the approach used to adjust for inflammation, the estimated prevalence of iron-deficient erythropoiesis decreased by 4.4-14.6 and 0.3-9.5 percentage points in PSC and WRA, respectively, compared with unadjusted values. The correction-factor approach yielded a more modest reduction in the estimated prevalence of iron-deficient erythropoiesis than did the regression approach. Mostly, adjustment for malaria in addition to AGP did not significantly change the estimated prevalence of iron-deficient erythropoiesis.Conclusions: sTfR may be useful to assess iron-deficient erythropoiesis, but inflammation influences its interpretation, and adjustment of sTfR for inflammation and malaria should be considered. More research is warranted to evaluate the proposed approaches in different settings, but this study contributes to the evidence on how and when to adjust sTfR for inflammation and malaria.

Duration of exclusive breastfeeding is a positive predictor of iron status in 6- to 10-month-old infants in rural Kenya

The prevalence of iron-deficiency anemia (IDA) is high in infants in Sub-Saharan Africa. Exclusive breastfeeding of infants to 6 months of age is recommended by the World Health Organization, but breast milk is low in iron. Some studies suggest exclusive breastfeeding, although beneficial for the infant, may increase risk for IDA in resource-limited settings. The objective of this study was to determine if duration of exclusive breastfeeding is associated with anemia and iron deficiency in rural Kenyan infants. This was a cross-sectional study of 6-10-month-old infants (n = 134) in southern coastal Kenya. Anthropometrics, hemoglobin (Hb), plasma ferritin (PF), soluble transferrin receptor (sTfR), and C-reactive protein were measured. Body iron stores were calculated from the sTfR/PF ratio. Socioeconomic factors, duration of exclusive breastfeeding, nature of complementary diet, and demographic characteristics were determined using a questionnaire. Mean ± SD age of the infants was 7.7 ± 0.8 months. Prevalence of anemia, ID, and IDA were 74.6%, 82.1%, and 64.9%, respectively. Months of exclusive breastfeeding correlated positively with Hb (r = 0.187; p < .05) and negatively with sTfR (r = -0.246; p < .05). sTfR concentrations were lower in infants exclusively breastfed at least 6 months compared with those exclusively breastfed for less than 6 months (7.6 (6.3, 9) vs. 8.9 (6.7, 13.4); p < .05). Controlling for gender, birth weight, and inflammation, months spent exclusively breastfeeding was a significant negative predictor of sTfR and a positive predictor of Hb (p < .05). The IDA prevalence in rural Kenyan infants is high, and greater duration of exclusive breastfeeding predicts better iron status and higher Hb in this age group.

Differential ferritin interpretation methods that adjust for inflammation yield discrepant iron deficiency prevalence

We reassessed the iron deficiency (ID) prevalence in a South African trial that formed part of the International Research on Infant Supplementation study by comparing four methods that account for the high prevalence of acute (28.6%) and chronic (41.8%) inflammation observed in the study. Serum ferritin (SF) was measured as marker of iron status in 192 apparently healthy, 4-13-month-old infants. Alpha-1 glycoprotein and C-reactive protein concentrations were determined to indicate chronic and acute inflammation, respectively. The ID prevalence was obtained by four methods that adjust for inflammation: (1) excluding infants with inflammation; (2) using a higher cut-off (SF < 30 μg L(-1) ); (3) using different cut-offs for infants with vs. without inflammation (SF < 30 μg L(-1) vs. SF < 12 μg L(-1) ); and (4) adjusting SF concentrations with correction factors (CFs) were compared with a reference method (SF < 12 μg L(-1) ) not accounting for inflammation. Using the higher SF cut-off method resulted in the highest ID prevalence (52.1%), followed by using two different cut-offs (31.8%), using CFs (21.9%) and excluding subjects with inflammation (17.6%). The CF method showed the best agreement with the reference method. Disregarding inflammation resulted in a significantly lower ID prevalence (17.2%). ID anaemia (IDA) prevalence ranged from 13.2% to 24.5%, with the lowest prevalence (12.0%) for the reference method. Our analysis highlights the challenge of assessing ID and IDA using only SF as marker of iron status in the presence of inflammation. We demonstrate the importance of measuring inflammation markers to account for their elevating effect on SF.

Assessment of iron status among preschool children (6 to 59 months) with and without malaria in Western Province, Kenya

Introduction

Iron deficiency is a major public health concern. Globally, iron deficiency ranks number 9 and is responsible for about 60% of all anemia cases among preschool children. In Africa iron deficiency is 43-52% while in Kenya, children under 5 years constitute the largest burden with 69% of them being deficient. There is limited iron deficiency data in Kenya. This study determined haemoglobin levels, serum ferritin levels, nutritional status and P.falciparum malaria infection in preschool children.

Methods

A household cross sectional study was undertaken among 125 preschoolers in Western province, drawn from 37 clusters. Systematic random sampling was used for sample selection. Data was collected using pretested structured questionnaires, entered in Microsoft package. Data analysis was done in Statistical package for social science (SPSS) version 20 using bivariate and multivariate logistic regression and differences were considered significant at P < 0.05.

Results

The prevalence of iron deficiency (Serum ferritin <12mg/l), anaemia (Hb < 110g/l) and plasmodium falciparum malaria were 20.8%, 25% and 6.8% respectively. There was a significant association between iron deficiency and anaemia (OR = 3.43, 95% CI: 1.33-8.84, p = 0.008). A preschool child with anaemia was 3.43 times likely to be iron deficient compared to a preschool child who was not anaemic.

Conclusion

Iron deficiency, anaemia and plasmodium falciparum malaria was prevalent among preschool children. The findings revealed a significant association between iron deficiency and anaemia. Therefore effective interventions to improve iron status will have large health benefits by greatly reducing anaemia in preschool children.

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.

In Ivorian school-age children, infection with hookworm does not reduce dietary iron absorption or systemic iron utilization, whereas afebrile Plasmodium falciparum infection reduces iron absorption by half

BACKGROUND

In sub-Saharan Africa, parasitic diseases and low bioavailable iron intake are major causes of anemia. Anemia results from inflammation, preventing iron recycling and decreasing dietary iron absorption. Hookworm, Plasmodium, and Schistosoma infections contribute to anemia, but their influence on dietary iron absorption and recycling is unknown.

OBJECTIVE

The objective was to measure inflammation biomarkers, hepcidin, iron absorption, and utilization pre- and posttreatment in children with afebrile malaria, hookworm, and Schistosoma haematobium infection.

DESIGN

Ivorian children aged 11-17 y with afebrile Plasmodium falciparum (n = 17), hookworm (n = 16), or S. haematobium infection (n = 8) consumed a syrup containing 3 mg ⁵⁷Fe as ferrous sulfate and received an intravenous infusion of 50 μg ⁵⁸Fe as ferrous citrate. Children were treated for their respective infection, and the iron studies were repeated 4 wk later. Iron and inflammation biomarkers and hepcidin were measured.

RESULTS

Geometric mean iron absorptions in the afebrile malaria and hookworm groups were 12.9% and 32.2% (P < 0.001) before treatment and 23.6% and 30.0% (P = 0.113) after treatment, respectively. Treatment of afebrile malaria reduced inflammation (P < 0.001) and serum hepcidin (P = 0.004) and improved iron absorption (P = 0.003). Treatment of hookworm infection neither affected inflammation biomarkers nor altered iron absorption. Similarly, there was a lack of treatment effects in the S. haematobium-infected group; however, the small sample size limits conclusions. Geometric mean iron utilization ranged between 79.1% and 88.0% in the afebrile malaria and hookworm groups with no significant differences pre- and posttreatment.

CONCLUSIONS

In school-age children, hookworm infection does not produce inflammation or increase serum hepcidin, and it does not influence iron absorption or utilization. In contrast, afebrile malaria causes inflammation, increases hepcidin, and reduces iron absorption but not utilization. These findings provide insights into the iron metabolism and the etiology of anemia in parasitic infections.

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.

Undernutrition, the acute phase response to infection, and its effects on micronutrient status indicators

Infection and undernutrition are prevalent in developing countries and demonstrate a synergistic relation. Undernutrition increases infection-related morbidity and mortality. The acute phase response (APR) is an innate, systemic inflammatory reaction to a wide array of disruptions in a host's homeostasis, including infection. Released from immune cells in response to deleterious stimuli, proinflammatory cytokines act on distant tissues to induce behavioral (e.g., anorexia, weakness, and fatigue) and systemic effects of the APR. Cytokines act to increase energy and protein requirements to manifest fever and support hepatic acute phase protein (APP) production. Blood concentrations of glucose and lipid are augmented to provide energy to immune cells in response to cytokines. Additionally, infection decreases intestinal absorption of nutrients and can cause direct loss of micronutrients. Traditional indicators of iron, zinc, and vitamin A status are altered during the APR, leading to inaccurate estimations of deficiency in populations with a high or unknown prevalence of infection. Blood concentrations of APPs can be measured in nutrition interventions to assess the time stage and severity of infection and correct for the APR; however, standardized cutoffs for nutrition applications are needed. Protein-energy malnutrition leads to increased gut permeability to pathogens, abnormal immune cell populations, and impaired APP response. Micronutrient deficiencies cause specific immune impairments that affect both innate and adaptive responses. This review describes the antagonistic interaction between the APR and nutritional status and emphasizes the need for integrated interventions to address undernutrition and to reduce disease burden in developing countries.

The influence of vitamin A status on iron-deficiency anaemia in anaemic adolescent schoolgirls in Myanmar

OBJECTIVE

The present study was conducted to investigate reasons for the high prevalence of anaemia among adolescent schoolgirls and to elucidate the role of vitamin A in contributing to Fe-deficiency anaemia (IDA).

DESIGN

Among 1269 schoolgirls who were previously screened for anaemia (Hb < 120 g/l), 391 anaemic girls were further assessed for Fe, vitamin A and subclinical inflammation status. Fe and vitamin A indicators were corrected for inflammation and were compared in the Fe-deficient and non-deficient groups as well as between those with and without inflammation. Logistic regression was done to determine whether vitamin A status and subclinical inflammation were risk factors for Fe deficiency. The differences in Fe status among tertiles of vitamin A concentrations were assessed using ANOVA.

SETTING

Myanmar.

SUBJECTS

Adolescent schoolgirls (n 391).

RESULTS

One-third of the anaemia (30·4%) was IDA. Prevalence of low vitamin A status (serum retinol <1·05 μmol/l) was 31·5%. Fe and vitamin A status were significantly different between the IDA and non-IDA groups and also based on their inflammation status. Logistic regression showed that low vitamin A status was a significant predictor for being Fe deficient (OR = 1·81; 95% CI 1·03, 3·19 and OR = 2·31; 1·31, 4·07 in the middle (1·056-1·298 μmol/l) and low (≤1·056 μmol/l) vitamin A tertiles, respectively). ANOVA showed that better Fe status was associated with a higher concentration of serum retinol but only in IDA.

CONCLUSIONS

Fe deficiency was not the main cause of anaemia in the present population. The role of vitamin A as well as other micronutrients should be taken into account in addressing the problem of anaemia.

The acute phase response affected traditional measures of micronutrient status in rural Zambian children during a randomized, controlled feeding trial

The acute phase response (APR) to infection can alter blood-based indicators of micronutrient status. Data from a 3-mo randomized, controlled feeding trial in rural Zambian children (n = 181, aged 3-5 y) were used to determine the impact of the APR on indicators of vitamin A and iron status using baseline and final blood samples. Concentrations of acute phase proteins were categorized as raised C-reactive protein (CRP; >5 and >10 mg/L) only, both raised CRP and α1-acid glycoprotein (AGP; >1.2 g/L), raised AGP only, and neither CRP nor AGP raised to identify the respective stages of infection: incubation, early convalescence, convalescence, and healthy state. Data were insufficient to examine the incubation stage of infection. A CRP concentration of >5 mg/L was an effective elevation cutoff point in this population to show impact on micronutrient markers. Time did not affect hemoglobin, serum ferritin, or serum retinol concentrations (P > 0.05). During early convalescence, hemoglobin decreased (14-16%; P ≤ 0.05), serum ferritin increased (279-356%; P ≤ 0.05), and serum retinol decreased (20-30%; P ≤ 0.05). Serum retinol concentrations did not change during convalescence; however, hemoglobin remained depressed (4-9%) and serum ferritin was elevated (67-132%) (both P ≤ 0.05). Modified relative dose response values were unaffected by the APR (P > 0.05) but increased between time points (16%; P ≤ 0.05), indicating a decrease in liver vitamin A reserves on the background of a semiannual vitamin A supplementation program. The observed prevalence of anemia and vitamin A deficiency assessed by serum retinol concentration was higher during the APR (P ≤ 0.05). It is important to consider the impact of infection on dietary interventions and to adjust for acute phase proteins when assessing iron status or vitamin A status by serum retinol concentration alone in children.

Obese women less likely to have low serum ferritin, Nicaragua

OBJECTIVE

To examine the association between overweight and obesity and serum ferritin among women of reproductive age (15-49 years) in Nicaragua, considering the effect of α1-acid glycoprotein (AGP), a marker of inflammation.

DESIGN

We analysed data from the 2004-05 Nicaraguan Integrated Surveillance System for Nutrition Interventions. Three logistic regression models were analysed with low serum ferritin (<15 μg/l) as the dependent variable: (i) overweight or obese status and covariates; (ii) model 1 plus AGP; and (iii) model 1 restricted to only women with normal AGP levels (≤1.0 g/l).

SETTING

Nicaragua.

SUBJECTS

Included in this analysis were 832 non-pregnant mother/caregivers (15-49 years) surveyed in 2004-2005.

RESULTS

In the sample, prevalence of overweight and obesity was 31.8 % and 19.2 %, respectively, and 27.6 % had low serum ferritin. In model 1, the adjusted OR of low serum ferritin was 0.74 (95 % CI 0.52, 1.05) for overweight women and 0.42 (95 % CI 0.26, 0.65) for obese women. In model 2, AGP was significantly independently associated with low serum ferritin (adjusted OR=0.56, 95 % CI 0.34, 0.92) while the adjusted OR for overweight and obesity were largely unchanged. Excluding women with elevated AGP did not appreciably affect the relationship between overweight or obesity and low serum ferritin (model 3).

CONCLUSIONS

Overall, in this population of reproductive-age women, obese women were less likely to have low serum ferritin levels, and this was independent of inflammation as measured by AGP.

Determinants of anemia among preschool children in rural, western Kenya

Although anemia in preschool children is most often attributed to iron deficiency, other nutritional, infectious, and genetic contributors are rarely concurrently measured. In a population-based, cross-sectional survey of 858 children 6-35 months of age in western Kenya, we measured hemoglobin, malaria, inflammation, sickle cell, α-thalassemia, iron deficiency, vitamin A deficiency, anthropometry, and socio-demographic characteristics. Anemia (Hb < 11 g/dL) and severe anemia (Hb < 7 g/dL) prevalence ratios (PRs) for each exposure were determined using multivariable modeling. Anemia (71.8%) and severe anemia (8.4%) were common. Characteristics most strongly associated with anemia were malaria (PR: 1.7; 95% confidence interval [CI] = 1.5-1.9), iron deficiency (1.3; 1.2-1.4), and homozygous α-thalassemia (1.3; 1.1-1.4). Characteristics associated with severe anemia were malaria (10.2; 3.5-29.3), inflammation (6.7; 2.3-19.4), and stunting (1.6; 1.0-2.4). Overall 16.8% of anemia cases were associated with malaria, 8.3% with iron deficiency, and 6.1% with inflammation. Interventions should address malaria, iron deficiency, and non-malarial infections to decrease the burden of anemia in this population.

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.

Iron status and systemic inflammation, but not gut inflammation, strongly predict gender-specific concentrations of serum hepcidin in infants in rural Kenya

Hepcidin regulation by competing stimuli such as infection and iron deficiency has not been studied in infants and it’s yet unknown whether hepcidin regulatory pathways are fully functional in infants. In this cross-sectional study including 339 Kenyan infants aged 6.0±1.1 months (mean±SD), we assessed serum hepcidin-25, biomarkers of iron status and inflammation, and fecal calprotectin. Prevalence of inflammation, anemia, and iron deficiency was 31%, 71%, 26%, respectively. Geometric mean (±SD) serum hepcidin was 6.0 (±3.4) ng/mL, and was significantly lower in males than females. Inflammation (C-reactive protein and interleukin-6) and iron status (serum ferritin, zinc protoporphyrin and soluble transferrin receptor) were significant predictors of serum hepcidin, explaining nearly 60% of its variance. There were small, but significant differences in serum hepcidin comparing iron deficient anemic (IDA) infants without inflammation to iron-deficient anemic infants with inflammation (1.2 (±4.9) vs. 3.4 (±4.9) ng/mL; P<0.001). Fecal calprotectin correlated with blood/mucus in the stool but not with hepcidin. Similarly, the gut-linked cytokines IL-12 and IL-17 did not correlate with hepcidin. We conclude that hepcidin regulatory pathways are already functional in infancy, but serum hepcidin alone may not clearly discriminate between iron-deficient anemic infants with and without infection. We propose gender-specific reference values for serum hepcidin in iron-replete infants without inflammation.

The evolutionary significance of depression in Pathogen Host Defense (PATHOS-D)

Given the manifold ways that depression impairs Darwinian fitness, the persistence in the human genome of risk alleles for the disorder remains a much debated mystery. Evolutionary theories that view depressive symptoms as adaptive fail to provide parsimonious explanations for why even mild depressive symptoms impair fitness-relevant social functioning, whereas theories that suggest that depression is maladaptive fail to account for the high prevalence of depression risk alleles in human populations. These limitations warrant novel explanations for the origin and persistence of depression risk alleles. Accordingly, studies on risk alleles for depression were identified using PubMed and Ovid MEDLINE to examine data supporting the hypothesis that risk alleles for depression originated and have been retained in the human genome because these alleles promote pathogen host defense, which includes an integrated suite of immunological and behavioral responses to infection. Depression risk alleles identified by both candidate gene and genome-wide association study (GWAS) methodologies were found to be regularly associated with immune responses to infection that were likely to enhance survival in the ancestral environment. Moreover, data support the role of specific depressive symptoms in pathogen host defense including hyperthermia, reduced bodily iron stores, conservation/withdrawal behavior, hypervigilance and anorexia. By shifting the adaptive context of depression risk alleles from relations with conspecifics to relations with the microbial world, the Pathogen Host Defense (PATHOS-D) hypothesis provides a novel explanation for how depression can be nonadaptive in the social realm, whereas its risk alleles are nonetheless represented at prevalence rates that bespeak an adaptive function.

Associations between serum C-reactive protein and serum zinc, ferritin, and copper in Guatemalan school children

Inflammation affects trace nutrient concentrations, but research on copper and particularly in children is limited. We assessed associations between serum C-reactive protein (CRP) and zinc, iron, copper, and other biomarkers (alkaline phosphatase, hemoglobin, and albumin), in 634 healthy 6- to 11-year-old Guatemalan schoolchildren. CRP was measured by a standardized, high-sensitive method. For significant associations with CRP, we stratified nutrient concentrations across categories of CRP and compared concentrations above and below several CRP cutoff points (0.5, 1, 3, 5, and 10 mg/L), and then adjusted values using correction factors (ratios of geometric means of the nutrients in the low and high groups). Prevalence of serum zinc (<65 μg/dL0, ferritin (<15 μg/L), and copper (<90 μg/dL) deficiency were 21%, 2.1%, and 23.8%, respectively. Median (25th and 75th percentiles) CRP was 0.56 (0.26 and 1.54) mg/L. CRP concentration was positively associated with ferritin and copper concentrations (r = 0.23 and 0.29, respectively; P < 0.0001) but not with zinc and other biomarkers (P > 0.05). Regardless of CRP cutoffs, high (> cutoff) vs. low (≤ cutoff) CRP levels had higher ferritin and copper concentrations and lower prevalence of copper deficiency of <90 μg/dL (P < 0.05). Adjustment for inflammation had the greatest influence on recalculated prevalence for the CRP 0.5 mg/L cutoff. The low ferritin prevalence hardly changed (from 2.1% to 2.5%) while the low copper prevalence changed appreciably (from 23.8% to 31.2%). In conclusion, CRP was positively associated with ferritin and copper but not with zinc concentrations. Adjustment for inflammation had little effect on low ferritin prevalence, low to begin with, and a large impact on low copper prevalence. High-sensitive CRP methods and the use of very low CRP cutoffs may be more accurate than traditional CRP methods in the adjustment of serum copper concentrations for inflammation in healthy school children.

Zinc erythrocyte protoporphyrin as marker of malaria risk in pregnancy - a retrospective cross-sectional and longitudinal study

BACKGROUND

The effects of iron interventions and host iron status on infection risk have been a recurrent clinical concern, although there has been little research on this interaction in pregnant women.

METHODS

Cross-sectional and longitudinal analyses were undertaken to determine the association of whole blood zinc erythrocyte protoporphyrin (ZPP) with malaria parasitaemia in pregnant women attending antenatal and delivery care at Montfort and Chikwawa Hospitals, Shire Valley, Malawi. Prevalence of antenatal, delivery and placental malaria was assessed in relation to maternal ZPP levels. The main outcome measures were prevalence of peripheral and placental Plasmodium falciparum parasitaemia and odds ratios of malaria risk.

RESULTS

A total of 4,103 women were evaluated at first antenatal visit, of whom at delivery 1327 were screened for peripheral and 1285 for placental parasitaemia. Risk of malaria at delivery (peripheral or placental) was higher in primigravidae (p < 0.001), and lower (peripheral) with use of intermittent preventive anti-malarials during pregnancy (p < 0.001). HIV infection was associated with increased malaria parasitaemia (p < 0.02, peripheral or placental). Parasitaemia prevalence was lower in women with normal ZPP levels compared to those with raised concentrations at both first antenatal visit (all gravidae, p = 0.048, and at delivery (all gravidae, p < 0.001; primigravidae, p = 0.056). Between first antenatal visit and delivery women who transitioned from raised (at first antenatal visit) to normal ZPP values (at delivery) had lower peripheral parasitaemia prevalence at delivery compared to those who maintained normal ZPP values at both these visits (all gravidae: 0.70, 95%CI 0.4-1.1; primigravidae: 0.3, 0.1-0.8). In regression analysis this difference was lost with inclusion of HIV infection in the model.

CONCLUSIONS

Raised ZPP concentrations in pregnancy were positively associated with P. falciparum parasitaemia and were probably secondary to malaria inflammation, rather than indicating an increased malaria risk with iron deficiency. It was not possible from ZPP measurements alone to determine whether iron deficiency or repletion alters malaria susceptibility in pregnancy.

Iron deficiency protects against severe Plasmodium falciparum malaria and death in young children

BACKGROUND

Iron supplementation may increase malaria morbidity and mortality, but the effect of naturally occurring variation in iron status on malaria risk is not well studied.

METHODS

A total of 785 Tanzanian children living in an area of intense malaria transmission were enrolled at birth, and intensively monitored for parasitemia and illness including malaria for up to 3 years, with an average of 47 blood smears. We assayed plasma samples collected at routine healthy-child visits, and evaluated the impact of iron deficiency (ID) on future malaria outcomes and mortality.

RESULTS

ID at routine, well-child visits significantly decreased the odds of subsequent parasitemia (23% decrease, P < .001) and subsequent severe malaria (38% decrease, P = .04). ID was also associated with 60% lower all-cause mortality (P = .04) and 66% lower malaria-associated mortality (P = .11). When sick visits as well as routine healthy-child visits are included in analyses (average of 3 iron status assays/child), ID reduced the prevalence of parasitemia (6.6-fold), hyperparasitemia (24.0-fold), and severe malaria (4.0-fold) at the time of sample collection (all P < .001).

CONCLUSIONS

Malaria risk is influenced by physiologic iron status, and therefore iron supplementation may have adverse effects even among children with ID. Future interventional studies should assess whether treatment for ID coupled with effective malaria control can mitigate the risks of iron supplementation for children in areas of malaria transmission.

Correcting for inflammation changes estimates of iron deficiency among rural Kenyan preschool children

The assessment of iron status where infections are common is complicated by the effects of inflammation on iron indicators and in this study we compared approaches that adjust for this influence. Blood was collected in 680 children (aged 6-35 mo) and indicators of iron status [(hemoglobin (Hb), zinc protoporphyrin (ZP), ferritin, transferrin receptor (TfR), and TfR/ferritin index)] and subclinical inflammation [(the acute phase proteins (APP) C-reactive protein (CRP), and α-1-acid glycoprotein (AGP)] were determined. Malaria parasitemia was assessed. Subclinical inflammation was defined as CRP >5 mg/L and/or AGP >1 g/L). Four groups were defined based on APP levels: reference (normal CRP and AGP), incubation (raised CRP and normal AGP), early convalescence (raised CRP and AGP), and late convalescence (normal CRP and raised AGP). Correction factors (CF) were estimated as the ratios of geometric means of iron indicators to the reference group of those for each inflammation group. Corrected values of iron indicators within inflammation groups were obtained by multiplying values by their respective group CF. CRP correlated with AGP (r = 0.65; P < 0.001), ferritin (r = 0.38; P < 0.001), Hb (r = -0.27; P < 0.001), and ZP (r = 0.16; P < 0.001); AGP was correlated with ferritin (r = 0.39; P < 0.001), Hb (r = -0.29; P < 0.001), and ZP (r = 0.24; P < 0.001). Use of CF to adjust for inflammation increased the prevalence of ID based on ferritin < 12 μg/L by 34% (from 27 to 41%). Applying the CF strengthened the expected relationship between Hb and ferritin (r = 0.10; P = 0.013 vs. r = 0.20; P < 0.001, before and after adjustment, respectively). Although the use of CF to adjust for inflammation appears indicated, further work is needed to confirm that this approach improves the accuracy of assessment of ID.

Serum, plasma, and dried blood spot high-sensitivity C-reactive protein enzyme immunoassay for population research

C-reactive protein (CRP) is used as a biomarker of morbidity and mortality risk in studies of population health, and is essential to interpretation of several micronutrient biomarkers. There is thus a need for a robust high-sensitivity CRP (hsCRP) measurement method for large-scale, non-clinical studies. We developed an efficient, inexpensive assay suitable for quantifying CRP across the physiological range using any blood specimen type. The ELISA uses readily available monoclonal antibodies to measure CRP in serum, plasma, or dried blood spots (DBS) made from venous or capillary blood. Assay performance was evaluated by standard methods, including comparison with a previously described assay. Effects of specimen type were tested by measuring CRP in 52 matched serum, plasma, and venous and capillary dried blood spot specimens. Long- and short-term CRP stability were evaluated. Assessments of assay limits of detection, linearity, recovery, imprecision, and concordance with an established method (Pearson correlation=0.988, n=20) demonstrated the validity of the new assay. CRP measurements in serum, plasma, and DBS had Pearson correlations from 0.974 to 0.995, n=52, but CRP in serum was on average 1.6 times (SD 0.37) higher than in DBS. CRP was stable in frozen serum for up to 34 months, but DBS CRP declined quickly with exposure to ambient temperatures, and across long-term storage at -20°C. This hsCRP assay is a robust and inexpensive tool designed for use in large-scale population health research. Our results indicate that DBS CRP is less stable than previously reported.

Adjusting plasma ferritin concentrations to remove the effects of subclinical inflammation in the assessment of iron deficiency: a meta-analysis

BACKGROUND

The World Health Organization recommends serum ferritin concentrations as the best indicator of iron deficiency (ID). Unfortunately, ferritin increases with infections; hence, the prevalence of ID is underestimated.

OBJECTIVE

The objective was to estimate the increase in ferritin in 32 studies of apparently healthy persons by using 2 acute-phase proteins (APPs), C-reactive protein (CRP) and alpha(1)-acid glycoprotein (AGP), individually and in combination, and to calculate factors to remove the influence of inflammation from ferritin concentrations.

DESIGN

We estimated the increase in ferritin associated with inflammation (ie, CRP gt 5 mg/L and/or AGP gt 1 g/L). The 32 studies comprised infants (5 studies), children (7 studies), men (4 studies), and women (16 studies) (n = 8796 subjects). In 2-group analyses (either CRP or AGP), we compared the ratios of log ferritin with or without inflammation in 30 studies. In addition, in 22 studies, the data allowed a comparison of ratios of log ferritin between 4 subgroups: reference (no elevated APP), incubation (elevated CRP only), early convalescence (both APP and CRP elevated), and late convalescence (elevated AGP only).

RESULTS

In the 2-group analysis, inflammation increased ferritin by 49.6% (CRP) or 38.2% (AGP; both P lt 0.001). Elevated AGP was more common than CRP in young persons than in adults. In the 4-group analysis, ferritin was 30%, 90%, and 36% (all P lt 0.001) higher in the incubation, early convalescence, and late convalescence subgroups, respectively, with corresponding correction factors of 0.77, 0.53, and 0.75. Overall, inflammation increased ferritin by ap 30% and was associated with a 14% (CI: 7%, 21%) underestimation of ID.

CONCLUSIONS

Measures of both APP and CRP are needed to estimate the full effect of inflammation and can be used to correct ferritin concentrations. Few differences were observed between age and sex subgroups.