The cutoff value of serum ferritin for the diagnosis of iron deficiency in community-residing older persons

Iron deficiency and biomarkers of inflammation: a 3-year prospective analysis of the DO-HEALTH trial

Background

The longitudinal association between iron deficiency and inflammatory biomarkers levels has not been fully explored among relatively healthy older adults.

Aims

To assess whether iron deficiency at baseline and at any yearly follow-up time point, with or without anemia, was associated with changes from baseline in high-sensitivity C-reactive protein (hs-CRP) and interleukin-6 (IL-6) levels over 3 years.

Methods

This is a post-hoc observational analysis of DO-HEALTH, a double-blind, randomized controlled trial including 2157 European community-dwelling adults age 70+. The outcomes were changes from baseline in hs-CRP and IL-6 levels, measured at 12, 24, and 36 months of follow-up. Iron deficiency was defined by soluble transferrin receptor levels > 28.1 nmol/L and baseline anemia by hemoglobin levels < 130 g/L for men and < 120 g/L for women.

Results

In total, 2141 participants were included in the analyses (mean age: 74.9 years, 61.5% of women, 26.8% with iron deficiency). Baseline iron deficiency was associated with greater increase in IL-6 levels (mean difference in change: 0.52 ng/L, 95%CI 0.03–1.00, P = .04) over 3 years. Iron deficiency at any yearly time point was associated with higher increases in hs-CRP (mean difference in change: 1.62 mg/L, 95%CI 0.98–2.26, P < .001) and IL-6 levels (mean difference in change: 1.33 ng/L, 95%CI 0.87–1.79, P < .001) over 3 years. No significant interaction between iron deficiency and anemia was found, suggesting that the results are independent of the anemic status.

Conclusions

These findings suggest that iron deficiency may play a role in low-grade chronic inflammation among relatively healthy older adults.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-021-01955-3.

Iron Deficiency and Incident Infections among Community-Dwelling Adults Age 70 Years and Older: Results from the DO-HEALTH Study

OBJECTIVES

To assess if baseline iron deficiency, with or without anemia, is associated with incident infections over 3 years among community-dwelling older adults.

DESIGN

Prospective secondary analysis of DO-HEALTH, a 3-year randomized, double-blind controlled trial.

SETTING AND PARTICIPANTS

2157 community-dwelling adults age 70+ from 5 European countries with good cognitive function and mobility and no major health events in the 5 years prior to enrollment Measurements: Incident infections, their severity and type were recorded every 3 months throughout the 3-year follow-up. Iron deficiency was defined as soluble transferrin receptor (sTfR) levels > 28.1 nmol/l and anemia as hemoglobin levels < 120 g/l for women and 130 g/l for men. We applied negative binomial mixed effects regression models with random effects for countries, and controlling for treatment allocation, age, sex, body mass index, polypharmacy, number of comorbidities, smoking status, living situation, alcohol intake, frailty status, and physical activity levels. A pre-defined stratified analysis was performed to explore if the associations between iron deficiency and infections were consistent by baseline anemia status.

RESULTS

In total, 2141 participants were included in the analyses (mean age 74.9 years, 61.5% of women, 26.8% with iron deficiency). Across all participants, baseline iron deficiency was not associated with incident overall infections, but was associated with a 63% greater rate of incident severe infections requiring hospitalization (incidence rate ratio [IRR] 1.63, 95% Confidence Interval [CI] 1.11-2.41, p=0.01). This association was more pronounced among the 2000 participants who did not have anemia at baseline (IRR=1.80, 95% CI 1.20-2.69, p=0.005).

CONCLUSION

Based on this prospective study among generally healthy European community-dwelling older adults, iron deficiency was not associated with the incidence rate of overall infections but may increase the incidence of severe infections. Intervention studies are needed to prove the causality of this observation.

Iron Depletion, Iron Deficiency, and Iron Deficiency Anaemia Among Children Under 5 Years Old in Kilimanjaro, Northern Tanzania: A Hospital-Based Cross-Sectional Study

Background:

Iron depletion results from reduced iron stores, and it is an early stage of disease progression before iron deficiency, which leads to iron deficiency anaemia (IDA). IDA is associated with delayed infant growth and development, diminished cognitive function, poor academic performance, decreased exercise tolerance, and impaired immune function. This study aimed to determine the prevalence of iron depletion and IDA and factors associated with low ferritin levels among children under 5-years-old receiving care at Kilimanjaro Christian Medical Centre (KCMC) in Moshi, Tanzania.

Methods:

Under-5 children presenting at KCMC were successively enrolled and screened for iron depletion and IDA using complete blood count and serum ferritin levels. The generally accepted World Health Organization cut-off levels for normal haemoglobin (Hb) and ferritin level were used. Iron depletion, iron deficiency, and IDA prevalences were estimated in relation to the combination measures of haemoglobin, mean corpuscular volume, and ferritin levels. Dietary and sociodemographic characteristic of the children were recorded after parents or caretakers provided informed consent. Data analysis was conducted using SPSS version 21.0.

Results:

A total of 303 children aged 2 to 59 months were enrolled in the study. Anaemia was detected in169 (55.8%) children. Children aged 2 to 12 months had a higher prevalence of anaemia (n=101, 60.1%). The overall prevalences of iron depletion, iron deficiency with no anaemia, and IDA were 2.6% (n=8), 9.6% (n=29), and 28.1% (n=84), respectively. Low ferritin levels were detected in 124 (40.9%) children. Drinking more than 500 ml of cow's milk per day was associated with an increased risk of anaemia (adjusted odds ratio [AOR] 5.6; 95% confidence interval [CI], 2.6 to 12.1) relative to those not drinking cow's milk. Children whose families had meals that included beef more than 3 times per week were less likely to have low ferritin (AOR 0.6; 95% CI, 0.3 to 1.3), though the difference was not significant.

Conclusion:

The IDA prevalence among children in the Kilimanjaro area was high, with more than 50% of infants being anaemic. Drinking cow's milk was associated with an increased risk of IDA. Future community-based research is recommended to elucidate more details about iron deficiency in the general population.

Intakes, Adequacy, and Biomarker Status of Iron, Folate, and Vitamin B12 in Māori and Non-Māori Octogenarians: Life and Living in Advanced Age: A Cohort Study in New Zealand (LiLACS NZ)

Advanced-age adults may be at risk of iron, folate, and vitamin B12 deficiency due to low food intake and poor absorption. This study aimed to investigate the intake and adequacy of iron, folate, and vitamin B12 and their relationship with respective biomarker status. Face-to-face interviews with 216 Māori and 362 non-Māori included a detailed dietary assessment using 2 × 24-h multiple pass recalls. Serum ferritin, serum iron, total iron binding capacity, transferrin saturation, red blood cell folate, serum folate, serum vitamin B12 and hemoglobin were available at baseline. Regression techniques were used to estimate the association between dietary intake and biomarkers. The Estimated Average Requirement (EAR) was met by most participants (>88%) for dietary iron and vitamin B12 (>74%) but less than half (>42%) for folate. Increased dietary folate intake was associated with increased red blood cell (RBC) folate for Māori (p = 0.001), non-Māori (p = 0.014) and serum folate for Māori (p < 0.001). Folate intake >215 µg/day was associated with reduced risk of deficiency in RBC folate for Māori (p = 0.001). Strategies are needed to optimize the intake and bioavailability of foods rich in folate. There were no significant associations between dietary iron and vitamin B12 intake and their respective biomarkers, serum iron and serum vitamin B12.

Ability of serum ferritin to diagnose iron deficiency anemia in an elderly cohort

Background

Diagnosis and treatment of iron deficiency anemia in older subjects improves their quality of life. Serum ferritin as a marker of iron stores is an acute phase protein. In older subjects who usually have many concomitant chronic medical conditions, serum ferritin may increase in response to inflammatory processes irrespective of iron stores. This study was performed to determine the diagnostic properties of serum ferritin in the diagnosis of iron deficiency anemia in older subjects.

Methods

This case–control study included all the inhabitants of Amirkola town who participated in the Amirkola Health and Aging Project. Diagnosis of anemia was confirmed based on a hemoglobin level <13 g/dL in men and <12 g/dL in women and iron deficiency anemia by percent transferrin saturation <15%. A receiver operating characteristic curve was constructed to determine an optimal serum ferritin cutoff value to differentiate patients with and without iron deficiency anemia at the highest sensitivity and specificity.

Results

Eighty patients with iron deficiency anemia and 160 cases of anemia without iron deficiency (mean age: 72.9 ± 8 and 71.6 ± 7.6 years, respectively; p-value = 0.37) were analyzed. In iron deficiency anemia, the mean serum ferritin was significantly lower (p-value = 0.036) compared to patients without iron deficiency anemia. Serum ferritin with a cutoff level of 100 ng/mL differentiated patients with and without iron deficiency anemia with a sensitivity of 60% and specificity of 59% and area under the receiver operating characteristic curve of 0.615 ± 0.040 (95% confidence interval: 0.536–0.694; p-value = 0.004).

Conclusion

These findings indicate that in elderly subjects, iron deficiency anemia may develop with higher levels of serum ferritin. Hence, the conventional cutoff of serum ferritin for the diagnosis of iron deficiency anemia in young adults is not appropriate for the elderly population.

Using Soluble Transferrin Receptor and Taking Inflammation into Account When Defining Serum Ferritin Cutoffs Improved the Diagnosis of Iron Deficiency in a Group of Canadian Preschool Inuit Children from Nunavik

The prevalence of iron depletion, iron deficient erythropoiesis (IDE), and iron deficiency anemia (IDA) was assessed in preschool Inuit children using soluble transferrin receptor (sTfR) and traditional indicators of iron status while disregarding or taking inflammation into account when defining SF cutoffs. Iron depletion was defined as follows: (1) SF < 15 μg/L regardless of the C-reactive protein (CRP) level and (2) SF < 15 or <50 μg/L with CRP ≤ 5 or >5 mg/L, respectively. IDE corresponded to iron depletion combined with total iron binding capacity > 72 μmol/L and/or transferrin saturation < 16%. Iron depletion and IDE affected almost half of the children when accounting for inflammation, compared to one-third when the SF cutoff was defined regardless of CRP level (P < 0.0001). The prevalence of IDE adjusted for inflammation (45.1%) was very similar to the prevalence observed when sTfR was used as a sole marker of IDE (47.4%). The prevalence of anemia was 15%. The prevalence of IDA (IDE + hemoglobin < 110 g/L) was higher when accounting for than when disregarding inflammation (8.0% versus 6.2%, P = 0.083). Using sTfR and different SF cutoffs for children with versus without inflammation improved the diagnosis of iron depletion and IDE. Our results confirm that Inuit children are at particularly high risk for iron deficiency.

A Review of Cutoffs for Nutritional Biomarkers

The nutritional status of an individual or population needs to be assessed through valid and reliable biomarkers. Cutoffs generally have an underlying relation to health status and are one of the important quantitative criteria against which biomarker outputs are compared. For this reason, cutoffs are integral for surveys, surveillance, screening, interventions, monitoring, and evaluation. Despite their importance, nutritional biomarker cutoffs have not been adequately addressed in the literature. Furthermore, the field has not reached a consensus on which cutoff to use for each biomarker, and different cutoffs are often used for the same biomarkers in published studies. This review provides a comprehensive overview of cutoffs related to nutritional biomarkers and highlights some of the high-priority research gaps and challenges of using micronutrient case studies.

Case-control study of anaemia among middle-aged and elderly women in three rural areas of China

OBJECTIVES

To propose a feasible suggestion to reduce the high prevalence of anaemia in middle-aged and elderly women by investigating risk factors, particularly nutritional factors, and analysing the effect on anaemia in three different rural areas of China.

DESIGN

A case-control study.

SETTING

Three counties of China.

PARTICIPANTS

Women aged 50-75 years in the three counties.

MAIN OUTCOME MEASURES

Adjusted OR (95% CI) of anaemia associated with diet, lifestyle and blood biochemical indices.

RESULTS

Compared with controls, women with anaemia had lower body mass index (22.1 (3.2) kg/m(2) vs 23.2 (3.5) kg/m(2); p<0.001), a higher experience of shortage of food (45.0% vs 36.5%; p<0.001), less soy food intake (0.5 (0.3, 26.7) g/day vs 5.6 (0.4, 27.8) g/day; p<0.048), lower serum iron (13.4 (5.4) μmol/L vs 16.4 (5.7) μmol/L; p<0.001), lower ferritin (109.6 (85.6) ng/mL vs 131.0 (92.0) ng/mL; p<0.001), lower transferrin saturation levels (22.5 (9.5)% vs 26.8 (9.6)%; p<0.001) and higher levels of free erythrocyte protoporphyrin (42.4 (21.2) μg/dL vs 39.6 (17.8) μg/dL; p<0.001). Anaemia was significantly associated with BMI(OR=0.90, 95% CI (0.87 to 0.92)), food shortage experience (OR=1.39, 95% CI (1.15 to 1.69)), total protein (OR=0.66, 95%CI (0.54 to 0.80)), Albumin (OR=0.72, 95%CI (0.59 to 0.87)) in univariate analysis. Multivariate analysis showed that body mass index, experience of food shortage, total protein and albumin were independently related to anaemia.

CONCLUSIONS

Among middle-aged and elderly women in rural China, the nutrition status of anaemic cases is far below that of controls. Lower body mass index and a greater experience of food shortage are closely related to anaemia. Improving the blood protein status by consuming protein-sufficient foods such as soy food is a feasible approach for elderly anaemic women. Further research is needed on the effect of chronic inflammation and infectious disease on anaemia in elderly women in rural China.

Iron deficiency among non-anemic under-five children in enugu, South-East, Nigeria

Background:

Iron deficiency has been described as the world most common nutritional deficiency and the commonest cause of nutritional anemia in infancy and childhood. The deleterious behavioral and cognitive deficit associated with iron-deficiency anemia could be irreversible. Therefore, the latter should be prevented by early detection of iron deficiency in the non-anemic groups.

Aim:

To determine the prevalence of iron deficiency in the non-anemic under-five children and to document its variation among the age classes of these children.

Subjects and Methods:

Under-five children presenting at a tertiary hospital were consecutively enrolled, Serum ferritin levels of the subjects were used to assess the iron status and serum ferrritin level of less than 12 ng/ml was considered as iron deficiency. Data were analyzed using SPSS version 15.0. Chi-square tests were employed as necessary for test of significance in each of the characteristics of the population at P ≤ 0.05.

Results:

A total of 178 non anemic under-five children were studied, their mean hematocrit and serum ferrritin values were 35.5 (2.8%) and 54.9 (76.1) ng/ml respectively. Forty-nine (27.5% [49/178]) of the study population was iron deficient and there was no significant difference in the prevalence of iron deficiency among the age classes (P = 0.75).

Conclusion:

This study has documented a high prevalence of iron deficiency in non-anemic under-five children presenting at the outpatient department and emergency room of a tertiary health facility in Enugu. All the age classes were relatively affected. A further research into the causes of iron deficiency in this age group is recommended.

Hematological parameters and prevalence of anemia among free-living elderly in south Brazil

OBJECTIVE

The aims of this study were to analyze the hematological parameters, the prevalence of anemia and the association between anemia and socioeconomic conditions in an elderly community-based population.

METHODS

A population-based study was performed as part of the Multidimensional Study of the Elderly in Porto Alegre, Brazil (EMIPOA). An initial total of 1058 community residents aged 60 years and older were interviewed. Of these, 392 agreed to have a physical evaluation and a blood sample was taken from each. The hematological parameters analyzed in the blood samples included the hemoglobin concentration, mean cell volume (MCV), mean corpuscular hemoglobin concentration (MCHC) and red cell distribution width (RDW). The association between the variables and the diagnosis of anemia was assessed using the chi-squared test and a multiple logistic regression model.

RESULTS

The overall prevalence of anemia was 12.8%. Anemia was present in 13.7% of women and in 10.4% of men. Normocytic normochromic anemia without anisocytosis was the most common type of anemia (46%). The assessment of erythrocyte morphology showed significant differences between anemic and non-anemic individuals (microcytosis = 12% vs. 1.5%, hypochromia = 40% vs. 8.8%, and anisocytosis = 26% vs. 7%). In the analysis of socioeconomic conditions, significant differences were found in respect to age and race.

CONCLUSION

The prevalence of anemia increases with age and is associated with race, microcytosis, hypochromia and anisocytosis. Anemia is not a condition that should be associated only with the aging process, as it may be due to pathological conditions that occur most frequently in this age group. As a result, a diagnosis of anemia warrants adequate clinical attention.

Iron deficiency anemia in women across the life span

Anemia is a global health issue with disproportionately high prevalence in women. In addition to being an independent risk factor for decreased quality of life and increased morbidity and mortality, anemia in women has been linked to unfavorable outcomes of pregnancy and other issues for children born to anemic women. Iron deficiency is the leading cause of anemia in many populations. Guidelines recommend proactive screening for anemia, particularly in the preoperative setting. Once anemia is diagnosed, treatment should be based on etiology (most commonly, iron deficiency followed, in order of prevalence, by inflammation or chronic disease). Iron supplementation (oral and intravenous) offers safe and effective treatment for anemia associated with iron deficiency. Anemia of chronic disease may be more challenging to treat, and attention must be given to the underlying disease, along with use of hematinic agents. Given its enormous impact on the health and well-being of women and the availability of simple and effective treatment options, anemia should never be left unmanaged.

Ferritin above 100 mcg/L could rule out colon cancer, but not gastric or rectal cancer in patients with involuntary weight loss

BACKGROUND

A tenth of patients with involuntary weight loss (IWL) have gastrointestinal cancer. Ferritin is the first parameter to be modified during the process leading to iron deficiency anaemia, therefore it should be the most sensitive. The aim of this study was to assess the ability of ferritin to rule out gastrointestinal cancer in patients with involuntary weight loss.

METHODS

All consecutive patients with IWL admitted in a secondary care university hospital were prospectively studied. Ferritin, haemoglobin with erythrocyte indices and serum iron were recorded for all patients. The reference standard was bidirectional endoscopy and/or 6 months follow-up.

RESULTS

290 patients were included, a quarter had cancer, of which 22 (7.6%) had gastrointestinal cancer (8 gastric cancer, 1 ileum cancer, 13 colorectal cancer). Ferritin had the best area under the curve (AUC), both for gastrointestinal cancer (0.746, CI: 0.691-0.794), and colorectal cancer (0.765, CI: 0.713-0.813), compared to the other parameters of iron deficiency. In the diagnosis of colorectal cancer, ferritin with a cut-off value of 100 mcg/L had a sensitivity of 93% (CI: 69-100%), and negative likelihood ratio of 0.13, with a negative predictive value of 99% (96-100%), while for gastrointestinal cancer, the sensitivity was lower (89%, CI: 67-95%), with a negative likelihood ratio of 0.24. There were three false negative patients, two with gastric cancer, and one with rectal cancer.

CONCLUSION

In patients with involuntary weight loss, a ferritin above 100mcg/L could rule out colon cancer, but not gastric or rectal cancer.

Relationship between depressive symptoms, anemia, and iron status in older residents from a national survey population

OBJECTIVE

To investigate the association between iron deficiency status and depressive symptoms in a national community sample of older people.

METHODS

Cross-sectional data were analyzed from 1875 participants 65 years and older who had participated in the 2005 Health Survey for England. Serum hemoglobin (Hb), ferritin, and transferrin receptor levels and depressive symptoms (Geriatric Depression Scale) had been measured. Covariates included age, sex, occupation, multivitamin intake, smoking status, body mass index, hypertension, heart disease, stroke, diabetes, and cancer.

RESULTS

Depressive symptoms were associated with anemia (Hb <12.0 g/dL for women and <13.0 g/dL for men; present in 10.8%; odds ratio [OR] = 1.53 [95% confidence interval = 1.08-2.18]) after adjustment for age, sex, social class, multivitamin intake, smoking status, and body mass index, but this association was reduced substantially after further adjustment for physical health status (OR = 1.14). Low serum ferritin level (<45 ng/mL; present in 21.6%) was associated with depressive symptoms after full adjustment (OR = 1.37 [95% confidence interval = 1.03-1.81]). Linear models, however, revealed significant associations between higher number of depressive symptoms and lower Hb level and higher serum transferrin receptor level but not with ferritin levels.

CONCLUSIONS

Iron deficiency commonly co-occurs with depressive symptoms in older people, although the association with anemia is accounted for by physical health status and may primarily reflect anemia of chronic disease.

Commentary: Iron deficiency and hair loss: problems with measurement of iron

Iron is involved in many critical physiologic processes within the hair follicle, suggesting that iron deficiency could disrupt hair synthesis. However, studies of iron as a cause of hair loss have produced conflicting results. Some of the discrepancies may relate to limitations of assays for iron deficiency. This commentary discusses the sensitivity and specificity of available tests for iron deficiency and presents practical guidelines for testing and supplementation.

Glucose oxidase-doped magnetic silica nanostrutures as labels for localized signal amplification of electrochemical immunosensors

Herein, we report a novel glucose oxidase (GOD)-doped magnetic silica nanostructure and its possible application in the clinical immunoassays. The doped nanostructures were initially synthesized using the reverse micelle method, and ferritin antibodies (anti-Ft) were then labeled to the surface of the nanostructures, which were employed as signal antibodies for ultrasensitive detection of ferritin (Ft) in the sandwich-type electrochemical enzyme immunoassays. The doped nanostructures were characterized using transmission electron microscopy (TEM), UV-vis absorption spectrometry and vibrating sample magnetometer (VSM). The advantages of the doped nanostructures as labels were investigated in comparison with the conventional label method. Under the optimal conditions, the nanostructures-based immunoassay toward ferritin standards displays a wide dynamic range from 0.1 to 400 ng mL(-1) with a low detection limit of 10 pg mL(-1) ferritin (at 3sigma), which is three-fold higher in the sensitivity than that of directly using GOD-labeled antibodies. The assay results for clinical serum samples with the developed method received in excellent accordance with results obtained from the referenced standard enzyme-linked immunosorbent assay (ELISA) method.