Transferrin receptor in serum. A new tool in the diagnosis and prevention of iron deficiency in blood donors

Heart Failure-Related Iron Deficiency Anemia Pathophysiology and Laboratory Diagnosis

PURPOSE OF REVIEW

The goal of the current review is to give an overview regarding the pathophysiology of iron deficiency in heart failure and how different laboratory tests change in the setting of heart failure.

RECENT FINDINGS

Recent studies have questioned the current employed definition of iron deficiency in the field of heart failure, as patients with ferritin < 100ng/ml but TSAT > 20% have a better prognosis, no iron deficiency on bone marrow staining, and altered treatment response to ferric carboxymaltose. This review summarizes changes in iron parameters in the setting of heart failure and underscores the importance of a reduced bioavailability of iron documented by a low serum iron or TSAT, irrespective of the presence of anemia.

The relationship between measurement of in vivo brain glutamate and markers of iron metabolism: A proton magnetic resonance spectroscopy study in healthy adults

Fundamental human studies which address associations between glutamate and iron metabolism are needed. Basic research reports associations between glutamate and iron metabolism. Human studies report sex differences in iron metabolism and glutamate concentrations, which suggest that these relationships may differ by sex. We hypothesised associations would be apparent between in vivo glutamate and peripheral markers of iron metabolism, and these associations would differ by sex. To test this, we recruited 40 healthy adults (20 men, 20 women) and measured (a) standard clinical biomarker concentrations for iron metabolism and (b) an in vivo proxy for glutamate concentration, glutamate with glutamine in relation to total creatine containing metabolites using proton magnetic resonance spectroscopy studies with a two-dimensional chemical shift imaging slice, with voxels located in bilateral dorsolateral prefrontal cortices, anterior cingulate cortices and frontal white matter. Only the female group reported significant associations between peripheral markers of iron metabolism and Glx:tCr concentration: (a) right dorsolateral prefrontal cortex Glx:tCr associated positively with serum transferrin (r = .60, p = .006) and negatively with transferrin saturation (r = -.62, p = .004) and (b) right frontal white matter Glx:tCr associated negatively with iron concentration (r = -.59, p = .008) and transferrin saturation (r = -.65, p = .002). Our results support associations between iron metabolism and our proxy for in vivo glutamate concentration (Glx:tCr). These associations were limited to women, suggesting a stronger regulatory control between iron and glutamate metabolism. These associations support additional fundamental research into the molecular mechanisms of this regulatory control.

The effect of donation activity dwarfs the effect of lifestyle, diet and targeted iron supplementation on blood donor iron stores

The iron status of blood donors is a subject of concern for blood establishments. The Finnish Red Cross Blood Service addresses iron loss in blood donors by proposing systematic iron supplementation for demographic at-risk donor groups. We measured blood count, ferritin and soluble transferrin receptor (sTfR) and acquired lifestyle and health information from 2200 blood donors of the FinDonor 10000 cohort. We used modern data analysis methods to estimate iron status and factors affecting it with a special focus on the effects of the blood service's iron supplementation policy. Low ferritin (< 15 μg/L), an indicator of low iron stores, was present in 20.6% of pre-menopausal women, 10.6% of post-menopausal women and 6% of men. Anemia co-occurred with iron deficiency more frequently in pre-menopausal women (21 out of 25 cases) than in men (3/6) or post-menopausal women (1/2). In multivariable regression analyses, lifestyle, dietary, and blood donation factors explained up to 38% of the variance in ferritin levels but only ~10% of the variance in sTfR levels. Days since previous donation were positively associated with ferritin levels in all groups while the number of donations during the past 2 years was negatively associated with ferritin levels in pre-menopausal women and men. FRCBS-provided iron supplementation was negatively associated with ferritin levels in men only. Relative importance analyses showed that donation activity accounted for most of the explained variance in ferritin levels while iron supplementation explained less than 1%. Variation in ferritin levels was not significantly associated with variation in self-reported health. Donation activity was the most important factor affecting blood donor iron levels, far ahead of e.g. red-meat consumption or iron supplementation. Importantly, self-reported health of donors with lower iron stores was not lower than self-reported health of donors with higher iron stores.

Donor protection: Iron supplementation for frequent blood donors in Korea

OBJECTIVE

This study aimed to evaluate the effect of oral iron supplementation in frequent donors in Korea, based solely on donation history.

STUDY DESIGN

The hemoglobin (Hb) level, ferritin level, soluble transferrin receptor (sTfR), total iron binding capacity (TIBC), and transferrin saturation of frequent donors at high risk for iron deficiency were compared to those of first donors. The frequent donors took iron supplements for 4 weeks and the same tests were repeated after 2 and 4 weeks to evaluate their effects.

RESULT

A total of 53 male and 57 female frequent donors were recruited. After 4-week iron supplementation, among the men, the prevalence of a: low Hb level (<13.0 g/dL) decreased from 25% to 2%; low ferritin level (<15.0 ng/mL) decreased from 58% to 4%; iron deficient erythropoiesis (IDE) (log(sTfR/ferritin) ≥ 2.07) decreased from 77% to 33%. Among the women, the percentage of a: low Hb level (<12.0 g/dL) decreased from 44% to 9%; low ferritin level decreased from 79% to 11%; IDE decreased from 95% to 47%. In total, 15 male (28.3%) and 29 female (56.9%) blood donors reported undesirable side effects related to iron supplementation. No serious adverse events were reported.

CONCLUSION

Ferritin level, a reliable indicator of iron status, increased and IDE decreased significantly after four-week iron supplementation in the female, but not in the male, donor group, compared to those of control donors. Four-week oral iron supplement was not enough to restore iron storage level in the male donor group.

Cross sectional, comparative study of serum erythropoietin, transferrin receptor, ferritin levels and other hematological indices in normal pregnancies and iron deficiency anemia during pregnancy

OBJECTIVE

To test the correlation of the serum erythropoietin levels, serum transferrrin receptor levels and serum ferritin levels along with other hematological parameters in normal pregnant and anemic pregnant patients.

STUDY DESIGN

In a prospective study, 120 pregnant women were recruited between 18 and 36 weeks of gestation; 53 normal pregnant patients, 67 anemic pregnant patients, in which, 17 had mild, 30 had moderate anemia, 20 had severe anemia. A blood sample was taken. The various hematological parameters, hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), total iron binding capacity (TIBC), serum ferritin, percentage saturation of iron, serum erythropoietin (SEPO) levels, serum transferrin receptors (STfRS) were performed. For statistics, Student's 't' test, Pearson's Chi test, Mann Whitney test and Bartlett test were used as per data.

RESULTS AND CONCLUSION

MCV was significantly reduced in anemic pregnancies as compared to non-anemic pregnancies (80.2±9.6 vs 94.12±9.8fl, p=0.001), MCHC was also reduced in them (30.2±3.38% vs 34.2±2.33%, p=0.176), TIBC was significantly increased in anemic pregnancies (343.31±28.54% vs 322.88±23.84%, p=0.001), serum ferritin was significantly reduced (24.9±10.48μg/L vs 31.03±9.98μg/L, p=0.001), percentage saturation of iron was also reduced (53.85±13.21% vs 62.04±15.79%, p=0.0024), serum erythropoietin levels were significantly higher in anemic women (26.24±26.61mU/ml vs 18.12±19.08mU/ml, p=0.064). The levels were significantly higher in severe anemia (46.5±46.8mU/ml than in moderate anemia 27.4±28.1mU/ml and mild anemia 22.8±22.8mU/ml. Serum transferrin receptors were significantly higher in anemic pregnancies than in non-anemic pregnancies (1.40±0.0802μg/ml vs 1.08±0.641μg/ml, p=0.019) with rise being higher in severe anemia (2.28±0.986μg/ml) than in moderate (1.4±0.816μg/ml) and mild anemia (1.16±0.702μg/ml).

CONCLUSION

Various hematological parameters especially sTfR, serum erythropoietin, serum ferritin and sTfR/log ferritin levels correlate with the severity of anemia.

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.

Iron stores in regular blood donors in Lagos, Nigeria

Background

Apart from challenging the bone marrow to increase its red cell production, thereby producing more blood for the donor, regular blood donation has been shown to have several benefits, one of which is preventing accumulation of body iron which can cause free radical formation in the body. This study was carried out to assess body iron stores in regular blood donors.

Methods

A total of 52 regular (study) and 30 first-time (control) volunteer blood donors were studied prospectively. Twenty milliliters of venous blood was drawn from each subject, 5 mL of which was put into sodium ethylenediamine tetra-acetic acid specimen bottles for a full blood count, including red blood cell indices. The remaining sample was allowed to clot in a plain container, and the serum was then retrieved for serum ferritin, serum iron, and serum transferrin receptor measurement by enzyme-linked immunosorbent assay.

Results

Mean hemoglobin and packed cell volume in the study group (13.47 ± 2.36 g/dL and 42.00 ± 7.10, respectively, P = 0.303) were not significantly higher than in the control group (12.98 ± 1.30 g/dL and 39.76 ± 4.41, respectively, P = 0.119). Mean serum ferritin was 102.46 ± 80.26 ng/mL in the control group and 41.46 ± 40.33 ng/mL in the study group (P = 0.001). Mean serum ferritin for women in the study group (28.02 ± 25.00 ng/mL) was significantly lower than for women in the control group (56.35 ± 34.03 ng/mL, P = 0.014). Similarly, men in the study group had a lower mean serum ferritin (48.57 ± 45.17 ng/mL) than men in the control group (145.49 ± 87.74 ng/mL, P = 0.00). The mean serum transferrin receptor value was higher in the study group (1.56 ± 0.88 μg/mL) than in the control group (1.19 ± 0.38 μg/mL, P = 0.033).

Conclusion

These findings suggest that hemoglobin concentration, packed cell volume, and serum iron levels are not significantly affected by regular blood donation and that regular blood donors appear to have reduced iron stores compared with controls.

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.

Iron status in Norwegian blood donors: comparison of iron status in new blood donors registered in 1993-1997 and in 2005-2006

BACKGROUND AND OBJECTIVES

The impact of a poor iron status on the difficulties to keep recruitment of new donors at pace with the ongoing increased demand for blood transfusions was studied by comparing the iron status of new donors recruited in 1993-1997 and in 2005-2006.

MATERIALS AND METHODS

Iron status was defined by haemoglobin and serum ferritin. Inclusion criteria for approving new donors were haemoglobin >/= 12.5 g/dl for women and >/= 13.5 g/dl for men, and serum ferritin > 15 microg/l for both genders. Data were gathered retrospectively from 943 subjects (55% women) in the 1990 ties and prospectively from 1013 subjects (63% women) 10 years later.

RESULTS

In women, there was a significant fall in haemoglobin and serum ferritin mean values from 13.2 to 13.1 g/dl and from 30.9 to 26.9 microg/l, respectively. Rejection due to low haemoglobin was significantly increased from 14% to 24%. In men, there were minor changes that did not affect rejection rates.

CONCLUSION

Iron status of women who want to serve as blood donors has deteriorated in the last 10 years, leading to an increased rejection due to haemoglobin below the inclusion criterion for blood donors.

The value of routine ferritin measurement in blood donors

BACKGROUND

Iron store deficiency is a common side effect of whole blood donation. Early recognition and reversal of excessive iron loss may avoid symptomatic iron store depletion in blood donors and reduce volunteer loss due to iron deficiency (ID) anemia.

STUDY DESIGN AND METHODS

Between 1996 and 2009, a total of 160,612 visits with the intention to donate blood by 23,557 healthy volunteers were recorded at our center. As of 2004, routine serum ferritin testing and additional counseling of donors at risk for donation-induced anemia were implemented. We analyzed the impact of this measure on the hemoglobin (Hb) levels and anemia occurrence in our donor population and in particular in women of childbearing age. Donation rejections due to low Hb counts, the intervals to next donation, and return rates thereafter were also assessed.

RESULTS

The introduction of routine serum ferritin analysis resulted in an increase of mean Hb levels in blood donors particularly in women of childbearing age. The incidence of predonation anemia and donation ineligibility due to a low Hb concentration decreased significantly. The return intervals of donors rejected on account of low Hb levels were shortened; however, the return rates thereafter were also curtailed.

CONCLUSIONS

Systematic serum ferritin measurements allowed an optimized management of ID in our donors and efficacious prevention of ID anemia.

Iron acquisition, assimilation and regulation in mycobacteria

Iron is as crucial to the pathogen as it is to the host. The tuberculosis causing bacillus, Mycobacterium tuberculosis (M.tb), is an exceptionally efficient pathogen that has evolved proficient mechanisms to sequester iron from the host despite its thick mycolate-rich outer covering and a highly impermeable membrane of phagolysosome within which it persists inside an infected host macrophage. Further, both overindulgence and moderation of iron inside a host are a threat to mycobacterial persistence. While for removing iron from the host reservoirs, mycobacteria synthesize molecules that have several times higher affinity for iron than their host counterparts, they also synthesize molecules for efficient storage of excess iron. This is supported by tightly regulated iron dependent global gene expressions. In this review we discuss the various molecules and pathways evolved by mycobacteria for an efficient iron metabolism. We also discuss the less investigated players, like iron responsive proteins and iron responsive elements in mycobacteria, and highlight the lacunae in our current understanding of iron acquisition and utilization in mycobacteria with an ultimate aim to make iron metabolism as a possible anti-mycobacterial target.

The responses of serum transferrin receptors to iron supplements in subjects with iron-deficiency erythropoiesis and iron-deficiency anaemia

We aimed to study the response of serum transferrin receptors (sTfR) to Fe supplementation in women of childbearing age with Fe-deficiency erythropoiesis (IDE) and Fe-deficiency anaemia (IDA). Primary screening was performed in 942 women ranging in age from 18 to 45 years. After Fe-related biochemical indices such as serum ferritin, Zn protoporphyrin and Hb were determined, the subjects were divided into four groups: normal, Fe store depletion, IDE and IDA. A total of 131 women were randomly selected from the normal, IDE and IDA groups. Subsequently, seventy-six women with IDE and IDA were given various doses of Fe (14 mg/d for IDE; 28 mg/d for IDA) with ferrousl-threonate capsules for twelve consecutive weeks. After receiving Fe supplements, the levels of Fe and sTfR were determined at weeks 0, 3, 6, 9 and 12.The levels of sTfR in women of childbearing age with IDE and IDA were significantly higher than those in the normal group. After receiving Fe supplements, the levels of sTfR were significantly decreased in women of childbearing age with IDE and IDA, while the levels of serum ferritin were significantly increased. In conclusion, STfR can be used as a reliable indicator for assessing the efficacy of Fe supplements.

Levels of serum transferrin receptor and its response to Fe-supplement in Fe-deficient children

The object of the present study was to investigate the levels of serum transferrin receptor (sTfR) and its response to Fe supplementation in Fe-deficient children and the role of sTfR in detecting Fe deficiency and assessing the efficacy of Fe supplementation. According to the diagnostic standard, 1006 children, aged 6-14 years in Fangshan district, Beijing, Peoples Republic of China, were divided into four groups: normal; Fe store depletion (IDs); Fe deficiency erythropoiesis (IDE); Fe deficiency anaemia (IDA). sTfR was determined and transferrin receptor-ferritin (TfR-F) index was calculated in 238 children, sixty-four normal and 174 Fe deficient. Children were administered a NaFeEDTA capsule containing 60 mg Fe once per week for the IDs and IDE groups and three times per week for the IDA group for nine consecutive weeks. The parameters reflecting Fe status and sTfR were determined before and after Fe supplementation. The levels of sTfR and TfR-F index in Fe-deficient children were significantly higher than those in the normal group. The receiver operating characteristic curve showed that sTfR has proper diagnostic efficacy for functional Fe deficiency. After Fe supplementation, the level of sTfR was significantly decreased in children with IDs, but not in children with IDE and IDA, while TfR-F index was significantly decreased in Fe-deficient children. sTfR is a reliable indicator for detecting functional Fe deficiency, and TfR-F index is a sensitive parameter for assessing the efficacy of Fe supplementation.