Methemoglobinemia is a rare but potentially serious condition characterized by an increased level of methemoglobin in the blood, which impairs oxygen delivery to tissues. It occurs when hemoglobin's ferrous iron (Fe2+) is oxidized to ferric iron (Fe3+), rendering it unable to bind oxygen effectively. This leads to tissue hypoxia, which can manifest clinically as cyanosis, shortness of breath, fatigue, and, in severe cases, organ dysfunction.

Background/Objectives: SARS-CoV-2 infection and COVID-19 vaccination have both been linked to post-acute alopecia, yet prevalence, patterns, and correlates remain poorly defined. We aimed to determine the prevalence and patterns of alopecia after SARS-CoV-2 infection and COVID-19 vaccination, and to identify independent correlates among Saudi adults. Methods: A cross-sectional study of 1261 Saudi adults (≥18 years) was conducted nationwide between March and July 2025 using a structured, self-administered, bilingual (Arabic/English) online questionnaire distributed via social media. Eligible participants had received at least one COVID-19 vaccine dose. Data captured demographics, vaccination type and dose history, prior SARS-CoV-2 infection, self-reported alopecia subtype guided by plain-language definitions, comorbidities, and nutritional status. Hair loss and subtypes were entirely self-reported and not clinically or dermoscopically confirmed. Chi-square tests assessed univariate associations, and multivariable logistic regression identified independent predictors of any self-reported hair loss. Results: Mean age was 28.0 ± 9.6 years; 62.1% were female, 97.7% vaccinated (76.0% Pfizer-BioNTech first dose, 58.1% three doses), and 53.6% reported prior COVID-19 infection. Overall self-reported hair loss prevalence was 62.4%, with hair loss reported by 57.5% of vaccinated and 49.7% of COVID-positive participants. Self-reported telogen effluvium was the predominant pattern (56.3%), followed by androgenetic alopecia (39.3%) and alopecia areata (2.7%). Independent correlates were female sex (aOR 4.89; 95% CI 3.78-6.32), vitamin/mineral deficiency (aOR 2.31; 1.73-3.09), iron deficiency anemia (aOR 1.89; 1.29-2.78), prior SARS-CoV-2 infection (aOR 1.31; 1.02-1.68), and COVID-19 vaccination (aOR 7.45; 2.51-22.12). Conclusions: Self-reported hair loss was reported by nearly two-thirds of Saudi adults after COVID-19 vaccination or infection. Female sex and correctable nutritional deficiencies are the strongest modifiable correlates and warrant targeted screening and counseling.

Intravenous (IV) iron is used to replenish iron stores in patients with iron-deficiency anemia (IDA) who do not benefit from oral iron supplementation. Hypophosphatemia is an increasingly recognized adverse event associated with certain IV iron formulations. Mild/moderate hypophosphatemia may be asymptomatic or present with symptoms similar to those seen in patients with IDA, including fatigue, malaise, and muscle weakness. Persistent hypophosphatemia can cause osteomalacia due to reduced bone mineralization, leading to bone pain and pseudofractures. Ferric carboxymaltose (FCM) can impact phosphate homeostasis through an increase in fibroblast growth factor 23, leading to increased urinary phosphate excretion and hypophosphatemia. In clinical trials, rates of hypophosphatemia were significantly higher in patients receiving FCM compared with other IV iron formulations, such as ferric derisomaltose and ferumoxytol. Treatment guidelines recommend monitoring serum phosphate levels in patients receiving FCM who are at risk for low phosphate or who require repeat infusions, and alternative iron formulations should be considered in at-risk patients. This narrative review summarizes current evidence regarding IV iron-induced hypophosphatemia in individuals with IDA and examines the underlying pathophysiology and clinical evidence for IV iron-induced hypophosphatemia, particularly with FCM, the populations most at risk, and the clinical consequences of persistent hypophosphatemia.

Background/Objectives: Anemia is frequently encountered in emergency departments (EDs). Although intravenous (IV) iron can be used as an alternative or adjunct to red blood cell (RBC) transfusion in selected hemodynamically stable patients, its use in the ED remains limited. This study described IV iron utilization and RBC transfusion patterns in ED patients with anemia and evaluated their associations with clinical outcomes. Methods: We conducted a single-center retrospective cohort study of patients who presented to a tertiary ED with hemoglobin (Hb) ≤ 10 g/dL between January 2019 and December 2021. Patients were categorized according to receipt of IV iron in the ED. Baseline characteristics, laboratory findings, transfusion practice, hospital length of stay (LOS), ICU admission, and in-hospital mortality were compared between groups. Results: Among 3340 patients, 89 (2.7%) received IV iron in the ED. IV iron recipients were older and had lower Hb levels than non-recipients. Gastrointestinal disorders were more frequent in the IV iron group (68.5% vs. 19.9%), and IV iron was commonly administered with ED RBC transfusion. ED transfusion (69.7% vs. 11.1%) and ICU admission (24.7% vs. 15.7%) were more frequent in the IV iron group. Among patients with available ferritin and transferrin saturation (TSAT), IV iron recipients had lower ferritin levels and more frequently showed ferritin-based or combined ferritin/TSAT findings suggestive of iron deficiency. In-hospital mortality was similar between groups (5.6% vs. 5.7%). Among hospitalized patients, median LOS was shorter in the IV iron group than in the non-IV iron group (6.6 vs. 9.7 days). Conclusions: IV iron was infrequently administered in ED patients with Hb ≤ 10 g/dL and was used mainly as an adjunct to RBC transfusion in older patients with gastrointestinal causes of anemia. Its association with shorter LOS should be interpreted cautiously. Structured ED-based anemia evaluation may help optimize IV iron use in selected patients.

Anemia represents one of the most frequent systemic complications of inflammatory bowel disease (IBD), with a consistently higher prevalence reported in patients with Crohn's disease (CD) compared with ulcerative colitis (UC). While chronic inflammation, impaired iron absorption, and intestinal blood loss are recognized contributors, microbiome-mediated mechanisms influencing host iron availability remain insufficiently explored. Emerging evidence indicates that CD-associated dysbiosis is characterized by an increased abundance of siderophore-producing bacteria, particularly members of the Enterobacteriaceae family. Because siderophores are high-affinity iron-chelating molecules capable of competing with host iron acquisition systems and partially escaping lipocalin-2-mediated sequestration, their expansion may contribute to reduced luminal iron bioavailability. In this systematic review, we analyzed comparative microbiome studies published between 2016 and 2026 that directly evaluated microbial differences between CD and UC. CD microbiota consistently demonstrated enrichment in siderophore-associated taxa relative to UC. Based on these findings, we propose that microbiome-driven iron competition may represent an additional mechanistic contributor to the increased prevalence and persistence of anemia observed in CD. Although direct in vivo quantification of siderophore activity in IBD remains limited, the convergence of ecological, functional, and strain-level microbiome evidence supports a biologically plausible interaction between microbial iron-scavenging strategies and host iron metabolism.

Iron deficiency remains a critical global nutritional challenge, and food iron fortification is the primary intervention strategy for alleviating iron deficiency anemia (IDA). In this study, iron complexes based on fibrous aggregates (FA-Fe) and amorphous aggregates (AA-Fe) of Antarctic Krill protein were fabricated to investigate their structure-activity relationships and iron supplementation efficacy. Both complexes coordinated Fe[2+] via carboxyl and amino groups, with FA-Fe exhibiting higher iron chelation capacity and structure-dependent functional divergence. In vitro digestion revealed sustained gastric release of FA-Fe, resulting in higher intestinal soluble iron content (19.05%) and bioaccessibility than AA-Fe and FeSO4. In the IDA model, FA-Fe restored hemoglobin, tissue iron stores, and iron homeostasis-related gene expression while mitigating gastric inflammation and oxidative stress, demonstrating superior biocompatibility. Thus, FA-Fe combines high efficacy with low gastrointestinal irritation, positioning structurally diverse Antarctic Krill protein aggregates as promising iron supplement carriers.

The pathophysiological basis of Parkinson's disease (PD) remains incompletely understood. However, the influence of environmental factors, such as continuous cadmium exposure, requires further investigation. Notably, common comorbidities such as iron deficiency anemia (IDA), chronic obstructive pulmonary disease (COPD), and zinc deficiency are linked with increased cadmium bioavailability, and elevated blood cadmium levels have been reported in individuals with PD. Cd (II) deposits in the midbrain, causing the accumulation of inflammatory lipids, which promote neuronal destruction. Cd-treated animals develop Parkinson-like syndromes, and cadmium exposure is associated with neuronal loss and disruption of dopaminergic receptor expression. Neurofilament light chain (NfL), a biomarker of neurodegeneration, has been found to be elevated in patients with Parkinson's disease and correlates with Cd blood concentrations. Iron deficiency promotes the secretion of FGF-23, which depletes vitamin D levels, further increasing the risk of PD. Moreover, COPD and IDA are two well-known examples of systemic hypoxia, which attracts metals bound to transferrin, such as cadmium and iron, leading to increased metal accumulation in various tissues, including the brain. Lead levels are also elevated in individuals with IDA, contributing to the risk of PD. Additionally, Cd exposure is associated with a reduced abundance of Lachnospiraceae in stool and decreased levels of butyrate, both of which are characteristic features of patients with Parkinson's disease. Therefore, this review aims to explore how COPD, IDA, and zinc deficiency-known risk factors for Parkinson's disease-lead to an increased cadmium burden and contribute to the onset and progression of the disease.

Background: Alopecia areata (AA) is a chronic autoimmune disorder characterized by non-scarring hair loss and commonly coexists with other autoimmune diseases, suggesting systemic immune dysregulation. An association between AA and iron deficiency anemia (IDA) has been proposed, though prior studies have yielded conflicting results. Objective: Our aim was to examine the association between AA and IDA in a large, population-based cohort. Methods: We conducted a retrospective case-control study using data from a health maintenance organization (HMO) serving approximately 2.35 million individuals. We included 33,401 AA patients diagnosed between 2005 and 2019, matched 1:2 by age and sex with 66,802 controls without AA. Diagnoses of AA and IDA were confirmed through clinical coding by board-certified dermatologists and primary care physicians. Statistical analyses employed Kruskal-Wallis, Pearson's χ2, and Fisher's exact tests. Results: IDA prevalence was significantly higher in AA patients than in controls (15% vs. 10%; OR 1.61, 95% CI: 1.55-1.67; p < 0.01). IDA preceded AA in 40% of cases, followed AA in 58%, and occurred concurrently in 2%. Limitations: The retrospective design limits causal inference. Conclusion: This study reinforces an association between AA and IDA, highlighting the need to assess and manage IDA as a potential treatable comorbidity in AA patients.

Maternal anemia and prenatal exposure to neurotoxic metals are widespread in low- and middle-income countries and may affect early childhood development. In Suriname, where mercury contamination from artisanal gold mining and social disparities coexist, we examined associations between maternal anemia, prenatal exposure to mercury (Hg), lead (Pb), manganese (Mn), selenium (Se), and cadmium (Cd), and early neurodevelopment. The study included 755 pregnant women and 644 children (10-26 months) from the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH) cohort. Maternal anemia was defined using WHO criteria for Hb, metals were measured in maternal blood, and child development was assessed using the Bayley Scales of Infant and Toddler Development, third edition (BSID-III-NL). Analyses used non-parametric tests, correlations, and multivariable regression. Anemia, though common (34%), was not independently associated with cognitive, language, motor, or social-emotional outcomes. However, iron status was not directly measured; therefore, the absence of an observed association should not be interpreted as evidence that maternal iron deficiency is unrelated to early neurodevelopment. Pb showed the most consistent associations, with higher prenatal levels predicting poorer cognitive, motor, and language scores. Hg demonstrated weaker but significant negative associations with several domains, while Mn and Cd showed limited direct effects. Interaction analyses suggested a potential modifying role of Se in certain metal-neurodevelopment associations; however, these findings require confirmation in future studies. Overall, these results suggest that prenatal exposure to neurotoxic metals and sociodemographic disparities may be important contributors to variation in early neurodevelopment in this population, but causal inferences cannot be made from this cross-sectional analysis.

The COVID-19 pandemic exposed vulnerabilities in global blood supply systems and accelerated the adoption of patient blood management (PBM) strategies aimed at optimizing transfusion practices in surgical care. Perioperative anemia is a key contributor to adverse outcomes and is frequently treated with allogeneic blood transfusion (ABT), which carries infectious and immunologic risks. Iron deficiency remains the most common and potentially correctable cause of perioperative anemia. This narrative review examines various approaches to perioperative anemia, strategies to minimize reliance on ABT, and alternatives within the PBM paradigm. Evidence supports the use of iron therapy, erythropoiesis-stimulating agents, antifibrinolytic strategies, and blood conservation techniques to reduce transfusion requirements and improve clinical outcomes. Lessons from the COVID-19 pandemic highlight PBM as a framework to enhance transfusion safety and sustainability. Broader implementation of PBM may improve patient outcomes, reduce unnecessary transfusions, and preserve scarce blood resources.

Yolk sac tumors, a subset of malignant germ cell tumors originating from gonadal germ cells, most often present as ovarian or testicular tumors in adolescents, sometimes in combination with different types of histology as a mixed malignant germ cell tumor. We describe a female toddler presenting with severe iron deficiency anemia who was found to have a gastric pure yolk sac tumor. Pure yolk sac tumor of the stomach has rarely been reported and is even less frequent in the pediatric population. Our review of the medical literature found 12 case reports of gastric pure yolk sac tumor, of which only 1 was in a child, a 3-year-old male. Our patient underwent subtotal gastrectomy and received adjuvant systemic chemotherapy and is tumor-free at 3 years following surgery. This is the first reported case of a gastric pure yolk sac tumor in a pediatric female, brought to clinical attention due to significant gastrointestinal blood loss.