Joint Model of Iron and Hepcidin During the Menstrual Cycle in Healthy Women

The effect of iron supplementation on menstrual bleeding volume and hemoglobin level during menstrual bleeding : A randomized clinical trial

BACKGROUND

Many women around the world avoid taking iron supplements during their menstrual bleeding, thinking that menstrual bleeding will increase after taking these supplements. Due to the lack of relevant scientific evidence in this regard, this study was performed to determine the effect of iron supplementation on menstrual blood volume and hemoglobin level during menstrual bleeding.

MATERIALS AND METHODS

In this three-blind randomized clinical trial, 160 non-anemic female students of Rafsanjan University of Medical Sciences were selected through a public call and then they were randomly assigned to two intervention and control groups. The intervention group was given a ferrous sulfate tablet containsing 50 mg of elemental iron daily in the first four days of bleeding for three consecutive menstrual cycles, and the control group received a placebo simultaneously. Before and after the intervention, the level of hemoglobin was measured and the Higham chart was completed in each menstrual cycle by the participants of the two groups. The obtained data were analyzed using the SPSS software version 21 and Chi-square, independent t-test, paired t-test, analysis of variance with repeated measures, and nonparametric tests.

RESULTS

Before performing the intervention, the mean Higham score and hemoglobin level of the two groups were not statistically significant (P = 0.307, P = 0.670). The mean Higham score after each intervention was not statistically significant between the two groups over time or when considering the interaction of the time group (P = 0.77, P = 0.916). The hemoglobin level of these two groups did not change significantly after the intervention compared with that before the intervention (P = 0.444).

CONCLUSION

Compared with a placebo, taking iron supplements containing 50 mg of elemental iron during the first four days of menstrual bleeding in non-anemic women did not change the volume of menstrual bleeding and hemoglobin level.

Iron regulation and absorption in athletes: contemporary thinking and recommendations

PURPOSE OF REVIEW

This review examines recent developments in our understanding of iron regulation/absorption around exercise, with specific attention paid towards the female athlete.

RECENT FINDINGS

Building on the well accepted knowledge that hepcidin concentrations increase in the 3-6 h period following an acute bout of exercise, recent studies have shown that this links to a reduced fractional iron absorption from the gut during feedings provided 2 h postexercise. Further, a window of enhanced iron absorption has recently been identified to occur 30 min either side of exercise commencement/completion, which allows for strategic iron intake to optimize absorption around exercise. Finally, there is burgeoning evidence to show that iron status and iron regulation change throughout the menstrual cycle and with hormonal contraceptive use, which could have implications for iron status in female athletes.

SUMMARY

Exercise can affect iron regulatory hormone activity, which subsequently impairs iron absorption, potentially contributing to the high rates of iron deficiency seen in athletes. Future research should continue to examine strategies to optimize iron absorption, with consideration to the timing, mode and intensity of exercise, the time of day, and in females, the menstrual cycle/menstrual status.

Menstrual Cycle-Associated Changes in Micronutrient Biomarkers Concentration: A Prospective Cohort Study

To evaluate variations in micronutrient biomarker concentrations and deficiencies across the menstrual cycle in a cohort of healthy women. This prospective cohort study was conducted among healthy women of reproductive age living in the State College area, Pennsylvania, (n = 45). Data collection occurred at the early follicular phase, the late follicular phase, and the midluteal phase. Fasting blood samples were collected to measure micronutrient biomarkers. At the early follicular phase, the mean ± SD concentrations for zinc, copper, magnesium, and retinol were 81.8 ± 16.2 µg/dL, 80.1 ± 12.8 µg/dL, 17.9 ± 1.4 mg/L, and 39.4 ± 9.3 µg/dL, respectively. The geometric mean (95% CI) for manganese, iron and ferritin concentrations were 1.51 [1.21, 1.87] µg/L, 106.7 [90.8, 125.4] µg/dL, and 26.4 [20.5, 34.0] µg/L, respectively. Mean concentrations of zinc and magnesium declined by 6.6% (p = 0.009) and 4.6% (p < 0.001) from the early follicular phase to the midluteal phase, respectively. Other biomarkers remained relatively constant across the cycle. At the early follicular phase, the prevalence of low serum concentrations for zinc, copper, magnesium, manganese, iron, and ferritin was 22%, 7%, 29%, 13%, 14%, and 28%, respectively. Also, in early follicular phase, 36% had anemia, and 13% specifically had iron deficiency anemia. The prevalence of magnesium deficiency was significantly higher at the midluteal phase vs. the early follicular phase (p = 0.025). Our study suggests that while many micronutrient concentrations are relatively constant across the menstrual cycle in healthy women, zinc and magnesium decline, and the prevalence of magnesium deficiency increases. Supplemental data for this article is available online at.

Changes of Hepcidin, Ferritin and Iron Levels in Cycling Purebred Spanish Mares

Several studies have demonstrated that in woman the sex hormones such as estrogen (E2) and progesterone (P4) influence iron (Fe) regulation, contributing to variations in Fe parameters along the menstrual cycle. These mechanisms based on the regulation of hepcidin (Hepc) which limits Fe availability during the cycle, remain poorly characterized in healthy mares. The objective of this study was to establish the relationship between Hepc, Fe, ferritin (Ferr), and the primary ovarian hormones E2 and P4 in cycling Purebred Spanish mares. Blood samples were taken from 31 Purebred Spanish mares day −5, on day 0, day +5 and day +16 of the cycle. Fe and Ferr significantly increased and Hepc decreased during pre- and ovulatory periods. The secretion peak of estradiol-17β (E2) was reached on day 0 and progesterone (P4) between days +5 and +16. Fe and Ferr were positively correlated (r = 0.57). Fe and Ferr were negatively correlated with Hepc (r = −0.72 and r = −0.02, respectively). E2 and P4 were negatively and positively correlated with Hepc (r = −0.753 and r = 0.54, respectively). In cycling Purebred Spanish mares there is a measurable relationship between steroid hormones and systemic Fe metabolism. Estrogenic dominance in the pre- and ovulatory period allows for a more effective iron status, mediated by hepcidin inhibition. However, P4 during the luteal phase substantially reduces serum Fe and iron stores, possibly related to Hepc stimulation. Future research is required to clarify the relationship between steroid hormones and iron metabolism at the molecular level in equids.

A contemporary understanding of iron metabolism in active premenopausal females

Iron metabolism research in the past decade has identified menstrual blood loss as a key contributor to the prevalence of iron deficiency in premenopausal females. The reproductive hormones estrogen and progesterone influence iron regulation and contribute to variations in iron parameters throughout the menstrual cycle. Despite the high prevalence of iron deficiency in premenopausal females, scant research has investigated female-specific causes and treatments for iron deficiency. In this review, we provide a comprehensive discussion of factors that influence iron status in active premenopausal females, with a focus on the menstrual cycle. We also outline several practical guidelines for monitoring, diagnosing, and treating iron deficiency in premenopausal females. Finally, we highlight several areas for further research to enhance the understanding of iron metabolism in this at-risk population.

Methodological Considerations for Investigating Iron Status and Regulation in Exercise and Sport Science Studies

Iron deficiency is a common health issue in active and athlete populations. Accordingly, research into iron status, regulation, absorption, and iron deficiency treatment strategies is increasing at a rapid rate. However, despite the increase in the quantity of research, various methodological issues need to be addressed as we progress our knowledge in this area. The purpose of this review is to highlight specific considerations for conducting iron-related research in active and athlete populations. First, we discuss the methodological importance of assessment and interpretation of iron status, with reference to blood collection protocols, participant screening procedures, and biomarker selection. Next, we consider numerous variables that should be accounted for in the design of iron-related research studies, such as the iron regulatory hormone hepcidin and its interaction with exercise, in addition to an examination of female physiology and its impact on iron metabolism. Subsequently, we explore dietary iron and nutrient interactions that impact iron regulation and absorption, with recommendations made for optimal methodological control. Consideration is then given to key features of long-term study designs, such as the monitoring of training load, oral iron supplementation, dietary analysis, and general lifestyle factors. Finally, we conclude our recommendations with an exploration of stable iron isotope tracers as a methodology to measure iron absorption. Ultimately, it is our intention that this review can be used as a guide to improve study design, biomarker analysis, and reporting of findings, to maximize the quality of future research outputs in iron-related research focused on active and athlete populations.

Interplay of serum hepcidin with female sex hormones, metabolic syndrome, and abdominal fat distribution among premenopausal and postmenopausal women

Background and purpose

Hepcidin is the central regulatory molecule of systemic iron homeostasis. Serum ferritin, insulin resistance (IR) and metabolic syndrome (MetS), female sex hormones, and abdominal fat distribution are related to each other and all are linked to menopausal state. Our study was the first to assess the impact of these parameters on hepcidin level among premenopausal women (group I) during the early follicular phase (group I-F) and mid-luteal-phase (group I-L) of the same reproductive cycle and among postmenopausal women (group II). Serum iron parameters, estrogen, progesterone and hepcidin, and plasma insulin were assessed. Abdominal subcutaneous fat (SCF) and peritoneal visceral fat (PVF) thickness were measured by unenhanced- CT. Group I and group II were divided into MetS and non-MetS subgroups.

Results

The entire group II and MetS-stratified subgroups had significant higher hepcidin level than corresponding group I-F and group I-L. Group I-L had significant higher hepcidin than group I-F. Among group I-F, group I-L, and group II, MetS subgroups had higher hepcidin but not hepcidin/ ferritin ratio (H/F) than corresponding non-MetS; and hepcidin had positive correlations with ferritin, insulin, IR, and SCF. In group I-F and group II, hepcidin had positive correlations with estrogen and progesterone; hepcidin levels increase significantly and linearly with increasing number of MetS features; and cut off values of hepcidin for prediction of MetS were 5.8 ≥ and ≥ 10.3 ng/ml respectively. Main contributors to hepcidin were iron and ferritin in all groups, SCF and progesterone in group I-F, and insulin, progesterone, and MetS in group II. H/F ratio was higher in group II.

Conclusion

Postmenopausal state (postMS), MetS, and luteal phase are independently associated with high hepcidin level. Serum iron parameters (iron and ferritin) as main regulators of hepcidin are preserved regardless of menopausal state. Its regulation differs based on menopausal state: IR, MetS, and progesterone in postMS meanwhile abdominal SCF and progesterone in premenopausal states. Despite positive associations of estrogen and progesterone with hepcidin, they do not explain its higher level in postMS. Hepcidin levels linearly increase with number of Mets feature and it had high sensitivity for diagnosis of MetS.

Iron status in athletic females, a shift in perspective on an old paradigm

Iron deficiency is a common nutrient deficiency within athletes, with sport scientists and medical professionals recognizing that athletes require regular monitoring of their iron status during intense training periods. Revised considerations for athlete iron screening and monitoring have suggested that males get screened biannually during heavy training periods and females require screening biannually or quarterly, depending on their previous history of iron deficiency. The prevalence of iron deficiency in female athletes is higher than their male counterparts and is often cited as being a result of the presence of a menstrual cycle in the premenopausal years. This review has sought to revise our current understanding of female physiology and the interaction between primary reproductive hormones (oestrogen and progesterone) and iron homoeostasis in females. The review highlights an apparent symbiotic relationship between iron metabolism and the menstrual cycle that requires additional research as well as identifying areas of the menstrual cycle that may be primed for nutritional iron supplementation.

Inflammatory Markers and Hepcidin are Elevated but Serum Iron is Lower in Obese Women of Reproductive Age

Limited evidence suggests that serum iron and hepcidin concentrations are dysregulated in obesity and inflammation. The objective of the present study was to compare C-reactive protein, interleukin-6, circulating levels of hepcidin, serum lipids, and iron status in obese vs. normal-weight women of childbearing age. Healthy women aged 18–30 years were recruited for the study (n = 47: 25 obese and 22 normal weight). Fasting blood samples were obtained to measure serum lipids (total cholesterol, HDL, LDL cholesterol, triglycerides, non-HDL cholesterol), complete blood count, serum iron, total iron-binding capacity, transferrin saturation, serum ferritin, hepcidin, C-reactive protein, and interleukin-6. Obese women had significantly higher mean serum C-reactive protein (p < 0.001), interleukin-6 (p < 0.001), hepcidin (p = 0.024), triglycerides (p < 0.001) and total cholesterol/HDL ratio (p < 0.001) but lower HDL (p = 0.001) and serum iron/hepcidin ratio (p = 0.011) compared with normal-weight women. BMI correlated positively with inflammatory markers, triglycerides, LDL and total cholesterol/HDL ratio, and negatively with HDL and serum iron/hepcidin ratio. Serum iron correlated negatively with ferritin in the obese group (p = 0.030) but positively in normal weight women (p = 0.002). BMI and ferritin were the only predictors of serum iron/hepcidin ratio accounting for 23% of the variation among subjects. Studies are needed to examine anti-inflammatory dietary approaches that can improve iron biomarkers in obese women.

Transcriptional Landscape of Waddlia chondrophila Aberrant Bodies Induced by Iron Starvation

Chronic infections caused by obligate intracellular bacteria belonging to the Chlamydiales order are related to the formation of persistent developmental forms called aberrant bodies (ABs), which undergo DNA replication without cell division. These enlarged bacteria develop and persist upon exposure to different stressful conditions such as β-lactam antibiotics, iron deprivation and interferon-γ. However, the mechanisms behind ABs biogenesis remain uncharted. Using an RNA-sequencing approach, we compared the transcriptional profile of ABs induced by iron starvation to untreated bacteria in the Chlamydia-related species Waddliachondrophila, a potential agent of abortion in ruminants and miscarriage in humans. Consistent with the growth arrest observed following iron depletion, our results indicate a significant reduction in the expression of genes related to energy production, carbohydrate and amino acid metabolism and cell wall/envelope biogenesis, compared to untreated, actively replicating bacteria. Conversely, three putative toxin-antitoxin modules were among the most up-regulated genes upon iron starvation, suggesting that their activation might be involved in growth arrest in adverse conditions, an uncommon feature in obligate intracellular bacteria. Our work represents the first complete transcriptomic profile of a Chlamydia-related species in stressful conditions and sets the grounds for further investigations on the mechanisms underlying chlamydial persistence.

Hepcidin secretion was not directly proportional to intracellular iron-loading in recombinant-TfR1 HepG2 cells: short communication

Hepcidin is the master regulator of systemic iron homeostasis and its dysregulation is observed in several chronic liver diseases. Unlike the extracellular iron-sensing mechanisms, the intracellular iron-sensing mechanisms in the hepatocytes that lead to hepcidin induction and secretion are incompletely understood. Here, we aimed to understand the direct role of intracellular iron-loading on hepcidin mRNA and peptide secretion using our previously characterised recombinant HepG2 cells that over-express the cell-surface iron-importer protein transferrin receptor-1. Gene expression of hepcidin (HAMP) was determined by real-time PCR. Intracellular iron levels and secreted hepcidin peptide levels were measured by ferrozine assay and immunoassay, respectively. These measurements were compared in the recombinant and wild-type HepG2 cells under basal conditions at 30 min, 2 h, 4 h and 24 h. Data showed that in the recombinant cells, intracellular iron content was higher than wild-type cells at 30 min (3.1-fold, p < 0.01), 2 h (4.6-fold, p < 0.01), 4 h (4.6-fold, p < 0.01) and 24 h (1.9-fold, p < 0.01). Hepcidin (HAMP) mRNA expression was higher than wild-type cells at 30 min (5.9-fold; p = 0.05) and 24 h (6.1-fold; p < 0.03), but at 4 h, the expression was lower than that in wild-type cells (p < 0.05). However, hepcidin secretion levels in the recombinant cells were similar to those in wild-type cells at all time-points, except at 4 h, when the level was lower than wild-type cells (p < 0.01). High intracellular iron in recombinant HepG2 cells did not proportionally increase hepcidin peptide secretion. This suggests a limited role of elevated intracellular iron in hepcidin secretion.

Iron status and hepcidin levels as potential regulators of haemoglobin homeostasis in overweight and obese women of childbearing age

Objectives

Overweight is considered a risk factor for anaemia. However, the mechanisms underlying anaemia development in overweight and obese people remain unclear. This study analysed the correlation of iron status (soluble transferrin receptor [sTfR]/log ferritin ratio) and hepcidin levels with haemoglobin (Hb) levels in overweight and obese women of childbearing age.

Methods

In this cross-sectional study, we recruited 66 women aged 20–29 years with a body mass index ≥23 kg/m². We gathered data on informed consent, demographic characteristics, questionnaire responses, anthropometric and laboratory values. A Spearman correlation test was performed to determine the correlation.

Results

The mean levels of ferritin and sTfR were 10.2 ± 8.12 and 22.2 ± 7.96 ng/ml, respectively, and the mean sTfR/log ferritin ratio was 29.3 ± 17.65 nmol/L. The mean hepcidin levels were 9.0 ± 3.05 ng/ml. In total, 75.8% of subjects had low ferritin levels, high sTfR (51.5%) levels, and a high sTfR/log ferritin ratio (87.9%). The sTfR levels (r = −0.359; p = 0.003) and sTfR/log ferritin ratio (r = −0.375; p = 0.002) were negatively correlated with Hb levels. There was no correlation between the levels of hepcidin and Hb (r = −0.140; p = 0.264), but there was a positive correlation between ferritin and Hb levels (r = 0.350; p = 0.004).

Conclusion

This study showed a correlation between iron status and Hb levels in overweight and obese women of childbearing age. All the women had erythropoiesis with iron deficiency anaemia. We recommend that overweight and obese women undergo further iron parameters for the detection of early anaemia. In this group, the consumption of foods that enhance iron absorption, such as ascorbic acid, should be encouraged.

Iron balance and iron supplementation for the female athlete: A practical approach

Maintaining a positive iron balance is essential for female athletes to avoid the effects of iron deficiency and anaemia and to maintain or improve performance. A major function of iron is in the production of the oxygen and carbon dioxide carrying molecule, haemoglobin, via erythropoiesis. Iron balance is under the control of a number of factors including the peptide hormone hepcidin, dietary iron intake and absorption, environmental stressors (e.g. altitude), exercise, menstrual blood loss and genetics. Menstruating females, particularly those with heavy menstrual bleeding are at an elevated risk of iron deficiency. Haemoglobin concentration [Hb] and serum ferritin (sFer) are traditionally used to identify iron deficiency, however, in isolation these may have limited value in athletes due to: (1) the effects of fluctuations in plasma volume in response to training or the environment on [Hb], (2) the influence of inflammation on sFer and (3) the absence of sport, gender and individually specific normative data. A more detailed and longitudinal examination of haematology, menstrual cycle pattern, biochemistry, exercise physiology, environmental factors and training load can offer a superior characterisation of iron status and help to direct appropriate interventions that will avoid iron deficiency or iron overload. Supplementation is often required in iron deficiency; however, nutritional strategies to increase iron intake, rest and descent from altitude can also be effective and will help to prevent future iron deficient episodes. In severe cases or where there is a time-critical need, such as major championships, iron injections may be appropriate.