Clinical management of iron deficiency anemia in Japan: iron prescription patterns, treatment effectiveness, and assessments.

Iron deficiency anemia is one of the most common types of anemia, but real-world clinical management practices in Japan are unclear. This study retrospectively explored iron prescription patterns, treatment effectiveness, and assessments. Patients with at least one treatment period between September 2020 and September 2022 were included and classified into three groups (ferric carboxymaltose [FCM]: 7437 patients, saccharated ferric oxide [SFO]: 98,648 patients, and oral iron: 359,547 patients). Iron-related laboratory values over time and testing proportions were evaluated. Median baseline hemoglobin levels were lowest with FCM (FCM: 8.10 g/dL, SFO: 8.70 g/dL, oral iron: 9.70 g/dL), but changes in hemoglobin levels by 12 weeks were greatest with FCM (FCM: 3.20 g/dL, SFO: 2.60 g/dL, oral iron: 1.70 g/dL). The median serum ferritin level at 8 weeks after FCM treatment was 43.70 ng/mL for ≤500 mg, versus 123.30 ng/mL for >500 to ≤1500 mg. All groups had a low proportion of serum ferritin and transferrin saturation (TSAT) testing at diagnosis (<38%), which decreased further for post-treatment assessment (<24%). This study suggests the importance of prescribing an appropriate total iron cumulative dose per the package insert, along with diagnosis and assessments based on serum ferritin/TSAT.

Investigation of biomarkers to predict outcomes in allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Various biomarkers have been developed and evaluated to predict the prognosis and complications of allogeneic hematopoietic cell transplantation (HCT). Most previous studies conducted on different biomarkers evaluated single effects such as those associated with inflammation, immunology, iron metabolism, and nutrition, and only a few studies have comprehensively analyzed markers. OBJECTIVE: The study aimed to survey comprehensive multiple markers prior to HCT and extract those that significantly predict the outcomes. STUDY DESIGN: A prospective multicenter observational study was performed. (UMIN000013506) Patients undergoing HCT for hematologic diseases were consecutively enrolled. Besides the usual clinical biomarkers, serum samples for extra-clinical biomarkers were collected and cryopreserved before starting the conditioning regimen. A total of 32 candidate biomarkers were selected, 23 from hematology, biochemistry, immunology, nutrition, and iron metabolism, and 9 from composite markers. Based on the area under the curve (AUC) values for survival, promising biomarkers was extracted. Internal validation for these markers was applied based on bootstrap methods. Setting the cut-off values for them, log-rank test was applied and outcomes including overall survival (OS), relapse, and non-relapse mortality (NRM) were evaluated using multivariate analyses. Furthermore, detailed analysis including transplant-related complications and external validation were conducted focusing on C-reactive protein (CRP) to platelet (Plt) ratio. RESULTS: A total of 152 patients with hematologic malignancies were enrolled from April 2014 to March 2017. CRP, soluble interleukin-2 receptor (IL2R), CRP to albumin (Alb) ratio, CRP to Plt ratio, Plt to IL2R ratio, and IL2R to Alb ratio were identified as promising markers. Internal validation successfully confirmed their reliability of AUC and multivariate analysis demonstrated the statistical significance between the higher and the lower markers. Above all, a higher CRP to Plt ratio was significantly associated with a lower OS (hazard ratio [HR] 2.77; 95% confidence interval [CI] 1.30-5.91; P = 0.008) and higher non-relapse mortality rates (HR 2.79; 95%CI 1.14-6.80; P = 0.024) at 180 days. Furthermore, univariate analysis showed that a higher CRP to Plt ratio was significantly associated with a higher incidence of sinusoidal obstructive syndrome (P < 0.001) and bloodstream infection (P = 0.027). An external validation test confirmed the significance of the CRP to Plt ratio for these outcomes. CONCLUSION: The multicenter prospective observational study successfully identified significant biomarkers in patients with hematologic malignancies who received HCT. In particular, CRP to Plt ratio was identified as a novel and useful biomarker for predicting transplant outcomes. Further investigations are needed to validate the novel markers, analysis of the pathophysiology, and application to treatment settings other than HCT.

[Iron deficiency anemia and newly available iron preparations].

The body does not possess an active export system for iron. Therefore, the amount of iron uptake is usually small; iron metabolism in the body should be considered a "semi-closed system." However, iron needed for erythropoiesis can be lacking in the case of continuous bleeding, and thus, iron deficiency anemia (IDA) would occur. IDA is the most common form of anemia; approximately 70% of anemia is IDA. Therefore, upper and lower endoscopies or gynecological procedures should be used to treat bleeding sites; in addition, the small intestine can now be widely observed and treated by double-balloon and capsule endoscopies. Iron replacement therapy for IDA is also important; however, oral iron administration frequently causes adverse events in the gastrointestinal tract, such as nausea and vomiting, making long-term oral iron administration difficult. Newly approved ferric citrate hydrate causes fewer adverse events for the gastrointestinal tract. For a long time, concerning intravenous (IV) iron formulation, saccharated ferric iron oxide has been the only available IV iron formulation in Japan. However, ferric carboxymaltose was recently approved, and administration at a dose of 500 mg/day can achieve a certain iron replacement with less administration. Thus, more effective treatment for patients with IDA might be achieved by these new procedures as well as oral and IV iron preparations.

[The newest information for iron metabolism: ferric carboxymaltose, a recently available treatment option for iron-deficiency anemia].

Iron-deficiency anemia (IDA) is the most common form of anemia. It is treated through iron replacement therapy, with oral iron administration as the recommended first-line treatment. However, intravenous (IV) iron formulation is at timed used owing to adverse effects of oral iron administration such as gastrointestinal symptoms. Although saccharated ferric iron oxide had been the only available IV iron formulation in Japan for a long time, ferric carboxymaltose (FCM) has recently been approved. In this review, the characteristics, efficacy, and safety of FCM will be discussed mainly by introducing the results of three clinical trials for FCM conducted in Japan. More effective treatment for patients with IDA might be achieved through the introduction of FCM administration in clinical settings.

A stealth antigen SPESP1, which is epigenetically silenced in tumors, is a suitable target for cancer immunotherapy.

Recent studies have revealed that tumor cells decrease their immunogenicity by epigenetically repressing the expression of highly immunogenic antigens to survive in immunocompetent hosts. We hypothesized that these epigenetically hidden "stealth" antigens should be favorable targets for cancer immunotherapy due to their high immunogenicity. To identify these stealth antigens, we treated human lung cell line A549 with DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5Aza) and its prodrug guadecitabine for 3 d in vitro and screened it using cDNA microarray analysis. We found that the gene encoding sperm equatorial segment protein 1 (SPESP1) was re-expressed in cell lines including solid tumors and leukemias treated with 5Aza, although SPESP1 was not detected in untreated tumor cell lines. Using normal human tissue cDNA panels, we demonstrated that SPESP1 was not detected in normal human tissue except for testis and placenta. Moreover, we found using immunohistochemistry SPESP1 re-expression in xenografts in BALB/c-nu/nu mice that received 5Aza treatment. To assess the antigenicity of SPESP1, we stimulated human CD4+ T-cells with a SPESP1-derived peptide designed using a computer algorithm. After repetitive stimulation, SPESP1-specific helper T-cells were obtained; these cells produced interferon-γ against HLA-matched tumor cell lines treated with 5Aza. We also detected SPESP1 expression in freshly collected tumor cells derived from patients with acute myeloid leukemia or lung cancer. In conclusion, SPESP1 can be classified as a stealth antigen, a molecule encoded by a gene that is epigenetically silenced in tumor cells but serves as a highly immunogenic antigen suitable for cancer immunotherapy.

Long-term phlebotomy successfully alleviated hepatic iron accumulation in a ferroportin disease patient with a mutation in SLC40A1: a case report.

BACKGROUND: Hereditary hemochromatosis is a heterogenous group of inherited iron-overload conditions that is characterized by increased intestinal absorption and deposition in vital organs. Hepcidin is a soluble regulator that acts to attenuate both intestinal iron absorption and iron release from reticuloendothelial macrophages through internalization of ferroportin-1, an iron exporter. Ferroportin disease is hereditary hemochromatosis which is affected by SLC40A1, a gene coding ferroportin-1, and phenotypically classified into two forms (classical and nonclassical). In nonclassical form, ferroportin mutations are responsible for a gain of function with full iron export capability but insensitivity to downregulation by hepcidin. Here, we report a case of nonclassical ferroportin disease. CASE PRESENTATION: A 46-year-old Japanese man showed elevated serum iron (284 µg/dl), ferritin (1722 ng/ml), transferrin saturation ratio (91.3%), and hepcidin-25 level (139.6 ng/ml). Magnetic resonance imaging (MRI) demonstrated a marked reduction in the signal intensity of the liver in T1- and T2-weighted images. The liver histology exhibited a large amount of iron that had accumulated predominantly in hepatocytes. We identified a heterozygous 1520A > G (p.H507R) mutation in the SLC40A1 gene. Phlebotomy (400 ml at a time) was monthly performed for 3 years in this patient. Importantly, the serum hepcidin level (1.0 ng/ml) was normal when the serum ferritin level was normal and hepatic iron accumulation was remarkably reduced after 3 years of phlebotomy. CONCLUSIONS: The present case demonstrated for the first time that there was a correlation between hepatic iron levels as measured by MRI and serum hepcidin levels through long-term phlebotomy in a patient with ferroportin disease with the p.H507R mutation of in SLC40A1.

Type 4B hereditary hemochromatosis due to heterozygous p.D157A mutation in SLC40A1 complicated with hypopituitarism.

Hemochromatosis is a clinical syndrome characterized by iron overload in various organs. We present here a case of type 4 hereditary hemochromatosis due to heterozygous mutation in SLC40A1 gene (p.D157A). SLC40A1 encodes ferroportin, a macromolecule only known as iron exporter from mammalian cells. He first presented symptoms correlated with hypopituitarism. Furthermore, marked hyperferritinemia and high transferrin saturation were revealed in combination with the findings of iron overload in the liver, spleen and pituitary gland by computed tomography and magnetic resonance imaging. Liver biopsy revealed iron deposition in both hepatocytes and Kupffer cells. SLC40A1 mutations are considered to cause wide heterogeneity by various ferroportin mutations. Thus, clinicopathological examinations seem to be very important for diagnosing phenotype of type 4 hemochromatosis in addition to the gene analysis. We diagnosed him as type 4B hereditary hemochromatosis (ferroportin-associated hemochromatosis) by the findings of high transferrin saturation and iron deposition in hepatocytes, and then started iron chelating treatment. We should suspect the possibility of hereditary hemochromatosis even in Japanese with severe iron overload. Although the same mutation in SLC40A1 gene (p.D157A) had been reported to cause "loss of function" phenotype, we considered that the mutation of our case caused "gain of function" phenotype.

[A case of ferroportin disease with phenotype A gene mutation in SCL40A1 resembling phenotype B manifestation influenced by alcohol consumption].

A 57-year-old man had been detected to have an elevated transaminase level. He had a history of alcohol consumption, and abdominal ultrasonography revealed an increase in the echogenicity of the liver;hence, he was diagnosed as having alcoholic liver disease. He restricted his alcohol intake, but the elevated transaminase level did not improve. Further medical examination was performed. He was found to have hyperferritinemia (serum ferritin, 6574ng/mL) and high transferrin saturation (TSAT, 90.5%). Computed tomography (CT) revealed high CT values of the liver and spleen (94 and 84HU, respectively). These findings differed from the characteristics of a typical alcoholic liver disease. Liver biopsy revealed iron deposition within the hepatocytes and Kupffer cells and liver fibrosis (F1-2). From the gene analysis of HFE, HJV, TFR2, HAMP, and SLC40A1 genes, he was heterozygous for the G>A (G490D) mutation in the ferroportin gene (SLC40A1). He was diagnosed as having ferroportin disease. It was reported that patients with a G490D mutation exhibited ferroportin disease A, which occurs owing to a loss-of-function mutation of SLC40A1. However, he was considered to have some characteristics of ferroportin disease B, which occurs owing to a gain-of-function mutation of SLC40A1. In this case, alcohol consumption might affect the progression of iron deposition in the liver. Therapeutic venesection was performed, and his hyperferritinemia with high TSAT gradually improved. In the course of the disease, other organ damages and progression of liver fibrosis did not occur.

Skeletal muscle mass is associated with toxicity, treatment tolerability, and additional or subsequent therapies in patients with hepatocellular carcinoma receiving sorafenib treatment.

BACKGROUND AND AIM: Several reports have demonstrated that skeletal muscle mass influences mortality in patients with hepatocellular carcinoma (HCC) receiving sorafenib treatment; however, there is still controversy with regard to whether skeletal muscle and adipose tissue are associated with the prognosis in HCC patients. We examined the relationship between body composition and prognosis in HCC patients. METHODS: We retrospectively analyzed 82 patients with unresectable HCC receiving sorafenib treatment. The skeletal muscle area and adipose tissue area were measured by computed tomography. Patients with low skeletal muscle index (male ≤36.2 cm2/m2, female ≤29.6 cm2/m2) and high visceral to subcutaneous adipose tissue area ratio (VSR) (male ≥ 1.33, female ≥ 0.93) were diagnosed as low skeletal muscle mass (LSMM) and high VSR, respectively. RESULTS: A total of 16 and 34 patients were classified as LSMM and high VSR, respectively. LSMM patients frequently experienced serious adverse events (SAEs) and thus had a shorter duration of sorafenib treatment than non-LSMM patients. High VSR was a significant factor for progression-free survival. LSMM patients less frequently received additional/subsequent therapies combined with sorafenib than non-LSMM patients. Multivariate Cox hazard analysis demonstrated that LSMM was a significant factor for the duration of sorafenib treatment. The treatment duration and receiving of additional/subsequent therapies were significantly associated with overall survival (OS) but not with LSMM or high VSR. CONCLUSION: LSMM was associated with the frequency of SAEs, treatment tolerability, and treatment duration. LSMM patients were less likely to receive additional/subsequent therapies than non-LSMM patients. Thus, LSMM could identify a subgroup of patients with poor OS.

Autofluorescence Imaging Reflects the Nuclear Enlargement of Tumor Cells as well as the Cell Proliferation Ability and Aberrant Status of the p53, Ki-67, and p16 Genes in Colon Neoplasms.

BACKGROUND: Autofluorescence imaging (AFI) is useful for diagnosing colon neoplasms, but what affects the AFI intensity remains unclear. This study investigated the association between AFI and the histological characteristics, aberrant methylation status, and aberrant expression in colon neoplasms. METHODS: Fifty-three patients with colorectal neoplasms who underwent AFI were enrolled. The AFI intensity (F index) was compared with the pathological findings and gene alterations. The F index was calculated using an image analysis software program. The pathological findings were assessed by the tumor crypt density, cell densities, and N/C ratio. The aberrant methylation of p16, E-cadherin, Apc, Runx3, and hMLH1 genes was determined by a methylation-specific polymerase chain reaction. The aberrant expression of p53 and Ki-67 was evaluated by immunohistochemical staining. RESULTS: An increased N/C ratio, the aberrant expression of p53, Ki-67, and the altered methylation of p16 went together with a lower F index. The other pathological findings and the methylation status showed no association with the F index. CONCLUSIONS: AFI reflects the nuclear enlargement of tumor cells, the cell proliferation ability, and the altered status of cell proliferation-related genes, indicating that AFI is a useful and practical method for predicting the dysplastic grade of tumor cells and cell proliferation.

Successful Treatment of Nivolumab-related Cholangitis with Prednisolone: A Case Report and Review of the Literature.

The patient was a 76-year-old man who was treated with nivolumab due to recurrent gastric cancer. A blood examination revealed grade 3 alkaline phosphatase (ALP) elevation. A histopathological examination revealed marked portal infiltration, including eosinophils and CD4+ and CD8+ T lymphocytes, suggesting nivolumab-related cholangitis accompanied by the features of both an immune-related adverse event (irAE) and drug-induced liver injury (DILI) with allergic reaction. The patient's ALP level immediately decreased after the administration of prednisolone. Although nivolumab-related cholangitis, a rare irAE, has been reported to be refractory to steroid therapy, patients with features of irAE and allergic DILI might immediately respond to prednisolone.

Comparison of efficacy and safety between intravenous ferric carboxymaltose and saccharated ferric oxide in Japanese patients with iron-deficiency anemia due to hypermenorrhea: a multi-center, randomized, open-label noninferiority study.

The intravenous formulation for supplementing iron currently available in Japan requires frequent administration. In contrast, ferric carboxymaltose (FCM) can improve iron-deficiency anemia (IDA) with only a small number of administrations; however, its efficacy and safety have not been established in Japanese patients. In this randomized, open-label study, we verified the noninferiority of FCM to saccharated ferric oxide (SFO) in Japanese patients with IDA due to hypermenorrhea, with the mean change from baseline to the highest observed hemoglobin level as the primary endpoint. Two hundred and thirty-eight eligible subjects (119 in FCM group, 119 in SFO group) were administered the investigational medicinal product and included in the analysis. The adjusted mean change from baseline to the highest observed hemoglobin level (95% CI) was 3.90 g/dL (3.77, 4.04) in the FCM group and 4.05 g/dL (3.92, 4.19) in the SFO group, and the difference between the groups (95% CI) was - 0.15 g/dL (- 0.35, 0.04). The noninferiority of FCM was verified. Incidence of adverse events was < 60% in both groups, and no significant difference was observed between the treatment groups. These results indicate that FCM can be a new, well-tolerated, and rapid treatment option for Japanese patients with IDA.

Safety and efficacy of intravenous ferric carboxymaltose in Japanese patients with iron-deficiency anemia caused by digestive diseases: an open-label, single-arm study.

Iron-deficiency anemia (IDA) accounts for majority of anemia. Although iron replacement therapy is effective, in Japan, conventional iron formulations have disadvantages such as gastrointestinal side effects for oral formulations and issues of frequent administration for intravenous (IV) formulations. Ferric carboxymaltose (FCM), which overcomes these limitations, is widely used as an IV iron source overseas. In this multi-center, open-label, single-arm study, we investigated the safety and efficacy of FCM up to 12 weeks after the start of administration in patients with IDA caused by digestive diseases. Thirty-nine patients diagnosed with IDA based on hemoglobin and serum ferritin levels were included. Eligible subjects were administered FCM until the total calculated iron dose (1000 or 1500 mg) was achieved over intervals of at least 1 week. A single iron dose was 500 mg. In the full analysis set (n = 39), the incidence of adverse events and adverse drug reactions was 71.8 and 48.7%, respectively. All events were as expected from the safety profile of IV iron. The mean change from baseline (10.39 g/dL) to the highest observed hemoglobin level was 3.31 g/dL. These results indicate the safety and efficacy of FCM for treating IDA caused by digestive diseases in Japanese patients.

Pseudogout Attack after Pegfilgrastim Administration in Anaplastic Large Cell Lymphoma.

A 67-year-old man with relapsed anaplastic large cell lymphoma received salvage chemotherapy, and pegfilgrastim was used to prevent febrile neutropenia. On day 18 of chemotherapy, he developed a pseudogout attack. Although the first symptoms improved, another pseudogout attack occurred when he received the second course of chemotherapy and pegfilgrastim. Filgrastim was then used for the third course of chemotherapy, and a pseudogout attack did not occur. The serum granulocyte-stimulating factor (G-CSF) level was extremely elevated only when pegfilgrastim was used, suggesting a relationship between pseudogout and G-CSF. Pseudogout should be recognized as an adverse effect of pegfilgrastim.

Pharmacokinetics, pharmacodynamics, safety, and tolerability of intravenous ferric carboxymaltose: a dose-escalation study in Japanese volunteers with iron-deficiency anemia.

Iron-deficiency anemia (IDA) is the most common form of anemia. Iron replacement therapy is an effective treatment, but oral and previously available intravenous (IV) formulations in Japan have disadvantages such as side effects, immunogenic reactions, low dose per tablet/vial, and the need for continuous administration. Ferric carboxymaltose (FCM), which overcomes these limitations, is widely used as an IV iron preparation outside of Japan. In this single-center, open-label, single-dose escalation study, we investigated the pharmacokinetics (PK), pharmacodynamics (PD), safety, and tolerability of FCM in Japanese subjects. Twenty-four Japanese IDA patients, diagnosed by hemoglobin, serum ferritin, and transferrin saturation, were assigned in equal groups to the 100, 500, 800, and 1000 mg iron dose arms. All subjects completed the study without important protocol deviations. Mean total serum iron concentrations showed a rapid, dose-dependent increase after FCM injection, reaching a maximum within 1 h. Mean reticulocyte counts significantly increased in all arms, suggesting improved hematopoietic function. Fourteen of 24 subjects experienced adverse events, but these were neither serious nor led to drug interruption. The PK/PD and safety profiles were similar in Japanese and European subjects. Ferric carboxymaltose is safe for administration in Japanese patients with IDA.

Angioimmunoblastic T-cell lymphoma and hypereosinophilic syndrome with FIP1L1/PDGFRA fusion gene effectively treated with imatinib: A case report.

RATIONALE: Hypereosinophilic syndrome (HES) is a rare disorder characterized by hypereosinophilia and organ damage. Some cases of HES are caused by the FIP1L1/PDGFRA fusion gene and respond to imatinib. FIP1L1/PDGFRA-positive HES occasionally evolves into chronic eosinophilic leukemia or into another form of myeloproliferative neoplasm; however, the development of a malignant lymphoma is very rare. We present a rare case of angioimmunoblastic T-cell lymphoma (AITL) and HES with the FIP1L1/PDGFRA gene rearrangement. PATIENT CONCERNS: A man in his 30s presented to our hospital with fever, hypereosinophilia, widespread lymphadenopathy, and splenomegaly. Laboratory tests showed hypereosinophilia, increased soluble interleukin-2 receptor, and increased vitamin B12. Positron-emission tomography with F fluorodeoxyglucose (FDG) showed positive FDG uptake in multiple enlarged lymph nodes throughout the body and the red bone marrow. A bone-marrow biopsy showed hypereosinophilia without dysplasia and an increased number of blasts. The FIP1L1/PDGFRA fusion gene was positive upon fluorescence in situ hybridization (FISH) analysis of the peripheral blood. Furthermore, biopsy of a lymph node from the neck revealed restiform hyperplasia of capillary vessels, with small lymphoma cells arranged around the capillaries. Lymphoma cells were positive for CD3, CD4, and CD10, and negative for CD20. Lymphoma cells were also positive for the FIP1L1/PDGFRA fusion gene by FISH analysis. DIAGNOSES: From these findings, the patient was diagnosed with HES and AITL with FIP1L1/PDGFRA. INTERVENTIONS: After the diagnosis, corticosteroid was administered but was ineffective. Imatinib was then administered. OUTCOMES: Imatinib was very effective for treating HES and AITL, and complete remission was achieved in both. LESSONS: This report presents the first case in which the FIP1L1/PDGFRA fusion gene was positive both in peripheral blood and lymph nodes, implying the possibility that the tumor cells acquired the FIP1L1/PDGFRA fusion gene in the early stage of hematopoietic progenitor cell developments. Imatinib was very effective in treating both HES and lymphoma, suggesting that the FIP1L1/PDGFRA fusion gene plays a key role in the pathogenesis of both HES and lymphoma.

Ferrichrome identified from Lactobacillus casei ATCC334 induces apoptosis through its iron-binding site in gastric cancer cells.

Ferrichrome is known to be a siderophore, but it was recently identified as a tumor-suppressive molecule derived from Lactobacillus casei ATCC334 ( L. casei). In the present study, we investigated the effects of ferrichrome in gastric cancer cells. Cell lines and xenograft models treated with ferrichrome demonstrated growth suppression. The expression levels of cleaved poly (adenosine diphosphate-ribose) polymerase, and cleaved caspase-9 were increased by ferrichrome treatment. Although the tumor-suppressive effects of ferrichrome were almost completely diminished by the iron chelation, the reduction in the intracellular iron by ferrichrome did not correlate with its tumor-suppressive effects. An exhaustive docking simulation indicated that iron-free ferrichrome can make stable conformations with various mammalian molecules, including transporters and receptors. In conclusion, probiotic-derived ferrichrome induced apoptosis in gastric cancer cells. The iron binding site of ferrichrome is the structure responsible for its tumor suppressive function.

Reticulocyte hemoglobin equivalent as a potential marker for diagnosis of iron deficiency.

Evaluation of parameters relating to serum ferritin and iron is critically important in the diagnosis of iron deficiency anemia (IDA). The recent development of automated systems for hematology analysis has made it possible to measure reticulocyte hemoglobin equivalent (RET-He), which is thought to reflect iron content in reticulocytes, in the same sample used for complete blood count tests. If RET-He is, indeed, capable of evaluating iron deficiency (ID), it would be useful for immediate diagnosis of IDA. In the present study, we examined the usefulness of RET-He for diagnosis of ID. Blood samples were obtained from 211 patients. Anemia was defined as hemoglobin (Hb) level of <12 g/dL. Iron deficiency was defined as serum ferritin level of <12 ng/mL. Patients were classified into four groups: IDA, ID, control, and non-ID with anemia. Patients in the IDA group had significantly lower RET-He levels than those in the control group. RET-He correlated with serum ferritin in the IDA and ID groups. The area under the curve for RET-He was 0.902, indicating that RET-He facilitates the diagnosis of ID with high accuracy. RET-He changed in parallel with changes in Hb during iron administration for 21 IDA patients. Our results indicate that RET-He may be a clinically useful marker for determining ID in the general population.