Physiopathology of Bone Modifications in β-Thalassemia

Extramedullary haematopoiesis in patients with thalassemia: a cross-sectional description of its prevalence, clinical features and survival

INTRODUCTION

Despite knowledge advances on extramedullary haematopoiesis (EMH) in thalassemic patients, the real picture remains an open issue.

OBJECTIVES

To assess EMH prevalence in patients with thalassemia major (TM) and intermedia (TI), to describe magnetic resonance imaging (MRI) findings and to explore clinical risk factors.

METHODS

In this cross-sectional study, images and clinical records of 184 consecutive patients with thalassemia who underwent T2* MRI between 2004 and 2011 were reviewed. Association of EMH with survival was investigated for patients with available follow-up charts.

RESULTS

EMH was detected in 16/168 (9.5%) patients with TM (aged 19-49 years) and in 3/16 (18.8%) with TI (aged 36-41 years). Most (88%) had paravertebral thoracic and/or abdominal masses. Age was significantly associated with EMH risk (hazard ratio, [HR] 1.10/year; confidence interval [CI]: 1.03-1.18; p-value < 0.001), while lower pancreatic iron content by T2*MRI (HR: 0.94/ms; CI: 0.89-0.99; p-value = 0.049) was a protective factor. Estimated survival rate was superior for EMH-positive (n = 19) when compared to EMH-negative patients (n = 75) (p-value = 0.013).

CONCLUSIONS

The prevalence of EMH was 10.3% (19/184), presented mainly as tumoral masses of 3 to 10 cm. Age was a risk factor for EMH development, while lower pancreatic iron might be a protective factor in this cohort.

Bone status and HCV infection in thalassemia major patients

PURPOSE

Hepatitis C virus (HCV) infection increases the risk for osteoporosis but this relationship has not been investigated among multi-transfused patients with thalassemia major (TM). We cross-sectionally explored the association of HCV infection with bone mineral density (BMD), vitamin D, and bone turnover biomarkers in TM.

METHODS

We considered 130 TM patients (41.89 ± 5.49 years, 67 females) enrolled in the E-MIOT (Extension-Myocardial Iron Overload in Thalassemia) Network. BMD measurements taken at the lumbar spine, femoral neck and total hip were expressed as Z-scores, with a BMD Z-score ≤ -2.0 indicating low bone mass.

RESULTS

Z-scores were not associated with gender, iron overload indices, vitamin D levels, and biochemical bone turnover markers, but decreased with aging and in presence of hypogonadism and were directly correlated with body mass index (BMI). The prevalence of low bone mass was 70.7 %. Three groups of patients were identified: 78 who never contracted the infection (group 0), 72 who cleared HCV (group 1), and 29 with chronic HCV infection (CHC) (group 2). All Z-scores progressively decreased according to HCV status from group 0 to group 2. Osteocalcin levels were significantly lower in groups 2 and 1 than in group 0. CHC patients were more likely to have low bone mass compared to HCV naive patients, after adjusting for age, BMI, hypogonadism, and pancreatic iron.

CONCLUSION

In TM, CHC appears as one additive risk factor for low bone mass and osteocalcin may play a role in this association.

Exploring the potential utilities of 99mTc-labeled RBC-equilibrium radionuclide angiocardiography in transfusion-dependent β-thalassemia major patients

AIMS

99mTc-labeled RBC-equilibrium radionuclide angiocardiography (ERNA) is done in transfusion-dependent beta-thalassemia major (β-TM) patients routinely for cardiac dysfunction. This prospective study aimed at evaluating the potential of ERNA in demonstrating the bone marrow hyperplasia as an adjunct biomarker for monitoring the adequacy of blood transfusions in transfusion-dependent β-TM patients.

MATERIALS AND METHODS

One hundred and twenty-six patients of β-TM (study group) and 30 nonthalassemic patients (control) underwent ERNA study with an additional whole-body imaging. We quantitated the normalized bone marrow tracer uptake (due to marrow hyperplasia) and hepatic tracer uptake (indicator of hepatic perfusion) in both the groups on whole-body imaging. Liver and myocardial iron deposition were evaluated with T2* MRI in the thalassemic group.

RESULTS

β-TM group showed significantly increased mean normalized marrow count (MN) compared to the control group (P < 0.001) reflecting peripheral marrow hyperplasia (indirect marker for blood transfusion inadequacy). The hematological parameters in the study group showed a negative correlation with MN, without such correlation in the control group. The study group showed greater derangement in hepatic perfusion with significantly less mean normalized hepatic tracer uptake (HN) compared to the control group. Hepatic iron deposition (evaluated with T2* MRI) also showed a negative correlation with hepatic perfusion parameter (HN) assessed by ERNA, though myocardial iron deposition did not show any significant correlation with cardiac systolic/diastolic parameters evaluated by ERNA in the study group.

CONCLUSION

ERNA study with these novel parameters (MN and HN) may have the potential to assess peripheral marrow hyperplasia and derangement in hepatic perfusion in transfusion-dependent β-TM.

A systematic review of quality of life in sickle cell disease and thalassemia after stem cell transplant or gene therapy

Patients with sickle cell disease (SCD) and thalassemia experience several complications across their lifespan that lead to impairment in different health-related quality of life (HRQOL) domains. There is increasing interest in curative therapies for patients with SCD and thalassemia, including hematopoietic stem cell transplant (HSCT) and gene therapy; however, the effect of these therapies on various HRQOL domains remains unclear. Our objective was to systematically evaluate the most recent evidence for the effect of HSCT and gene therapy on HRQOL in patients with SCD and thalassemia. A systematic search of medical literature databases was conducted. A total of 16 studies (thalassemia, n = 9; SCD, n = 6; both, n = 1) involving 517 participants met inclusion criteria (thalassemia, n = 416; SCD, n = 101). HSCT was associated with a small to large positive effects in most HRQOL domains (Cohen's d; mean = 0.47; median = 0.37; range, 0.27-2.05). In thalassemia, HSCT was frequently associated with large positive effects in physical and emotional HRQOL domains (median d = 0.79 and d = 0.57, respectively). In SCD, HSCT was associated with large positive effects in all HRQOL domains. Emerging data suggest improvement in HRQOL outcomes across different domains following gene therapy in thalassemia and SCD. The quality of evidence was moderate in 13 studies (81%). HSCT has a positive impact on several HRQOL domains in patients with SCD and thalassemia; however, more longitudinal studies are warranted to assess the sustainability of these effects. Reporting HRQOL outcomes from ongoing gene therapy or gene-editing trials in SCD and thalassemia is key to better understand the benefits of such therapies.

Luspatercept: A Gigantic Step in the Treatment of Transfusion-Dependent β-Thalassemia Patients-a Quick Review

INTRODUCTION

Some studies have indicated that the use of luspatercept may be a novel and efficient treatment for β-thalassemia patients. In this article, we aimed to review the current evidence related to luspatercept prescription and its clinical effectiveness in patients with β-thalassemia.

METHODS

PubMed, Web of Science, Scopus, Trip and CENTRAL were searched up to June 2020. The inclusion criteria were English-language articles that studied the effects of luspatercept on improving anemia severity in patients with β-thalassemia in a clinical setting.

RESULTS

The search strategy yielded 273 potentially relevant articles. After searching the databases, scanning of titles, abstracts and full texts for relevancy was performed to identify suitable articles. A total of 77 articles were confirmed for full text analysis. The estimated number of patients needed to treat (NNT) for luspatercept treatment, using data derived from conducted clinical trials, according to a reduction in transfusion need of ≥ 33% or ≥ 50 from baseline, during week 13-24/week 37-48/any 12- and 24-week intervals as outcomes, was 3-5 in patients with β-thalassemia.

CONCLUSION

Based on the conducted studies, the effectiveness of luspatercept on transfusion burden and hemoglobin levels was outstanding in β-thalassemia patients. Further large and well-designed clinical studies are needed to identify any unforeseen complications subsequent to use of luspatercept, particularly when used with other treatments with potentially serious adverse effects such as anti-osteoporotic and iron chelator agents.

Forager and farmer evolutionary adaptations to malaria evidenced by 7000 years of thalassemia in Southeast Asia

Thalassemias are inherited blood disorders that are found in high prevalences in the Mediterranean, Southeast Asia and the Pacific. These diseases provide varying levels of resistance to malaria and are proposed to have emerged as an adaptive response to malaria in these regions. The transition to agriculture in the Holocene has been suggested to have influenced the selection for thalassemia in the Mediterranean as land clearance for farming encouraged interaction between Anopheles mosquitos, the vectors for malaria, and human groups. Here we document macroscopic and microscopic skeletal evidence for the presence of thalassemia in both hunter-gatherer (Con Co Ngua) and early agricultural (Man Bac) populations in northern Vietnam. Firstly, our findings demonstrate that thalassemia emerged prior to the transition to agriculture in Mainland Southeast Asia, from at least the early seventh millennium BP, contradicting a long-held assumption that agriculture was the main driver for an increase in malaria in Southeast Asia. Secondly, we describe evidence for significant malarial burden in the region during early agriculture. We argue that the introduction of farming into the region was not the initial driver of the selection for thalassemia, as it may have been in other regions of the world.

Lung Adenocarcinoma Presenting as a Soft Tissue Metastasis to the Shoulder: A Case Report

Background: Metastasis to soft tissue is rare, and the pathogenesis remains unclear. Soft tissue metastases (STMs) have varied presentations; existing reports are few. Herein, we report a case of STMs of the shoulder with a rich characterization. Case presentation: A 93-year-old man presented to our hospital with pain and swelling of the left shoulder for one week. Magnetic resonance imaging (MRI) showed a T1 low-intensity and T2 high-intensity mass. We suspected a primary sarcoma and performed a needle biopsy. However, on histopathological examination, the findings were suggestive of lung adenocarcinoma. Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography-computed tomography also revealed FDG accumulation in the right lung, thus confirming the diagnosis. Conclusion: Oncologists should keep in mind that STMs of lung cancer may resemble soft-tissue sarcomas at the time of initial diagnosis.

The Adverse Impact of Thalassemia Major on Adolescents' Oral Health-related Quality of Life

BACKGROUND

Adolescents with beta-thalassemia major (βTM) had unfavorable quality of life (QOL).

OBJECTIVES

To assess oral health status of adolescents with βTM and its impact on their oral health-related QOL (OHRQoL).

SUBJECTS AND METHODS

Forty adolescents with βTM were recruited and compared with 40 age-matched and sex-matched healthy adolescents. Intraoral examination including dental caries assessment, oral hygiene index simplified (OHI-S), and Angle classification were performed. OHRQoL questionnaires were filled-out using child perception questionnaire-short form16.

RESULTS

Although the majority of adolescents with βTM had dental problems and convinced by their need for dental treatment, nearly half of them never brushed their teeth nor visited dental office. Patients showed higher frequency of class II malocclusion (P=0.017) and higher percentage of poor simplified debris index (DI-S) and OHI-S grade (P=0.008, 0.037, respectively). The median of DI-S and OHI-S were significantly higher in adolescents with βTM (P=0.009, 0.037, respectively). Adolescents with βTM had worse emotional well-being total score (P=0.049) than controls. Patients with poor oral hygiene had the worse total OHRQoL score (P=0.03). The total OHRQoL score showed significant positive correlation with oral hygiene; DI-S, calculus index-S, and OHI-S (P=0.028, 0.038, and 0.045, respectively).

CONCLUSION

βTM had a negative impact on the emotional well-being aspect.

Associations of serum sclerostin with bone mineral density, markers of bone metabolism and thalassaemia characteristics in adult patients with transfusion-dependent beta-thalassaemia

Aim of the study: To assess serum sclerostin in transfusion-dependent beta-thalassaemia patients versus healthy controls and to examine its associations with bone mineral density, bone metabolism markers and beta thalassaemia alterations.Material and methods: Sixty-two transfusion-dependent beta-thalassaemia (TDßT) patients and 30 healthy controls were evaluated for serum sclerostin, osteocalcin, beta-cross laps, osteoprotegerin and serum level of receptor activator of nuclear factor kappa-Β ligand (sRANKL). Bone mineral density was measured at the lumbar spine and femoral neck. Thalassaemia characteristics were collected from the patients' medical records.Results: A significantly higher sclerostin level (median 565.50 pmol/L) was observed in the transfusion-dependent beta-thalassaemia patients vs. the healthy controls (median 48.65 pmol/L, p < .001). Sclerostin showed significant associations with the Z-scores at the lumbar spine and femoral neck, osteocalcin, beta-cross laps, osteoprotegerin, sRANKL, pretransfusion haemoglobin, liver iron concentration and female gonadal state. Significantly higher levels of sclerostin were observed in splenectomized TDßT patients and in those with fragility fractures. Age, sex, body mass index, disease severity, serum ferritin, cardiac T2* and male gonadal state did not show significant associations with sclerostin.Conclusion: Sclerostin may play a role in the bone pathophysiology of beta-thalassaemia patients and could serve as a marker of severe osteoporosis.KEY MЕSSAGESSerum sclerostin is more than 10-fold higher in adult patients with transfusion-dependent beta-thalassaemia compared to healthy controls.Serum sclerostin is negatively associated with bone mineral density and the bone synthesis markers and positively with the bone resorption indices.Serum sclerostin is significantly associated with pre-transfusion haemoglobin, liver iron concentration, splenectomy status and fragility fracture events in adult patients with transfusion-dependent beta-thalassaemia.Serum sclerostin could serve as a marker of severe osteoporosis in beta-thalassaemia patients.

Responses of primary osteoblasts and osteoclasts from hemizygous β-globin knockout thalassemic mice with elevated plasma glucose to 1,25-dihydroxyvitamin D3

β-thalassemia is often associated with hyperglycemia, osteoporosis and increased fracture risk. However, the underlying mechanisms of the thalassemia-associated bone loss remain unclear. It might result from abnormal activities of osteoblasts and osteoclasts, and perhaps prolonged exposure to high extracellular glucose. Herein, we determined the rate of duodenal calcium transport in hemizygous β-globin knockout thalassemic (BKO) mice. Their bones were collected for primary osteoblast and osteoclast culture. We found that BKO mice had lower calcium absorption than their wild-type (WT) littermates. Osteoblasts from BKO mice showed aberrant expression of osteoblast-specific genes, e.g., Runx2, alkaline phosphatase and osteocalcin, which could be partially restored by 1,25(OH)₂D₃ treatment. However, the mRNA expression levels of RANK, calcitonin receptor (Calcr), c-Fos, NFATc1, cathepsin K and DMT1 were similar in both BKO and WT groups. Exposure to high extracellular glucose modestly but significantly affected the expression of osteoclast-specific markers in WT osteoclasts with no significant effect on osteoblast-specific genes in WT osteoblasts. Thus, high glucose alone was unable to convert WT bone cells to BKO-like bone cells. In conclusion, the impaired calcium absorption and mutation-related aberrant bone cell function rather than exposure to high blood glucose were likely to be the principal causes of thalassemic bone loss.

Dysregulation of the RANKL/RANK/OPG axis in thalassemia intermedia patients

Objective

Thalassemia intermedia (TI) describes a disease ranging in severity between β thalassemia major (TM) and β thalassemia trait. Osteoporosis is observed in TI and TM. The exact reason of osteoporosis in TI could be hypogonadism and/or an increase in erythropoietin (EPO) levels. The carboxy-terminal collagen cross links (CTX), a marker of bone resorption, and the N-terminal propeptide of type 1 collagen (P1NP), a marker of bone formation are serum markers of osteoporosis. The receptor activator of NF-kappaB ligand (RANKL)/receptor activator of NF-kappaB (RANK)/osteoprotegerin (OPG) axis plays an important role in metabolic bone diseases. Herein, we tested the relationship between the RANKL/RANK/OPG axis and the bone-turnover markers CTX and P1NP in TI.

Results

We recruited 44 TI patients and 33 non-thalassemic controls and measured the serum levels of hemoglobin, sex steroid hormones, CTX, P1NP, RANKL and OPG. We then used a general linear model to test the association of the above variables with CTX and P1NP as outcome variables. We showed that EPO levels were the strongest predictor of CTX change (P < 0.000), followed by RANKL (P = 0.017). On the other hand, RANKL was the strongest predictor of P1NP change (P < 0.000), followed by OPG (P = 0.009) and EPO (P = 0.024).

Hematological and biochemical evaluation of β-thalassemia major (βTM) patients in Gaza Strip: A cross-sectional study

OBJECTIVES

In Gaza Strip, Palestine, β-thalassemia is a major public health problem where more than 300 β-thalassemia major (βTM) patients are currently being managed at governmental hospitals. We set up to evaluate the hematological and biochemical aspects of our βTM patients at the Gaza European hospital and their correlation with iron overload.

METHODS

Our study included 65 transfusion-dependent βTM, as well as 37 apparently healthy subjects as control group. The hematological and biochemical evaluations included complete blood count, coagulation profile liver and kidney function tests, fasting blood sugar, lipid profile, and serum ferritin.

RESULTS

Deteriorated hematological and biochemical statuses were reported in both males and females of βTM patients as compared to the control group. Statistical comparisons showed no significant differences between males and females βTM patients in all parameters except for total cholesterol. The results concerning the splenectomized versus non-splenectomized patients revealed significantly higher values in splenectomized patients for white blood cell (WBC), platelet, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, albumin, total protein, cholesterol, and potassium concentration compared to the non-splenectomized patients. Patients infected with hepatitis C virus and/or hepatitis B virus showed significant decrease in WBC count as compared to infection free patients, while for serum urea and creatinine, the virally infected βTM patients revealed significantly higher values compared to infection free patients.

CONCLUSION

This study justified the necessity for strengthening the efforts for regular evaluation and follow-up of the βTM patients which could be used to improve or modify the management protocols and thus ameliorating their deteriorated hematological and biochemical status.

Influence of body weight on bone mass, architecture and turnover

Weight-dependent loading of the skeleton plays an important role in establishing and maintaining bone mass and strength. This review focuses on mechanical signaling induced by body weight as an essential mechanism for maintaining bone health. In addition, the skeletal effects of deviation from normal weight are discussed. The magnitude of mechanical strain experienced by bone during normal activities is remarkably similar among vertebrates, regardless of size, supporting the existence of a conserved regulatory mechanism, or mechanostat, that senses mechanical strain. The mechanostat functions as an adaptive mechanism to optimize bone mass and architecture based on prevailing mechanical strain. Changes in weight, due to altered mass, weightlessness (spaceflight), and hypergravity (modeled by centrifugation), induce an adaptive skeletal response. However, the precise mechanisms governing the skeletal response are incompletely understood. Furthermore, establishing whether the adaptive response maintains the mechanical competence of the skeleton has proven difficult, necessitating the development of surrogate measures of bone quality. The mechanostat is influenced by regulatory inputs to facilitate non-mechanical functions of the skeleton, such as mineral homeostasis, as well as hormones and energy/nutrient availability that support bone metabolism. Although the skeleton is very capable of adapting to changes in weight, the mechanostat has limits. At the limits, extreme deviations from normal weight and body composition are associated with impaired optimization of bone strength to prevailing body size.

Osteoclasts Are Required for Hematopoietic Stem and Progenitor Cell Mobilization but Not for Stress Erythropoiesis in Plasmodium chabaudi adami Murine Malaria

The anemia and inflammation concurrent with blood stage malaria trigger stress haematopoiesis and erythropoiesis. The activity of osteoclasts seems required for the mobilization of hematopoietic stem and progenitor cells (HSPC) from the bone marrow to the periphery. Knowing that BALB/c mice with acute Plasmodium chabaudi adami malaria have profound alterations in bone remodelling cells, we evaluated the extent to which osteoclasts influence their hematopoietic response to infection. For this, mice were treated with osteoclast inhibiting hormone calcitonin prior to parasite inoculation, and infection as well as hematological parameters was studied. In agreement with osteoclast-dependent HSPC mobilization, administration of calcitonin led to milder splenomegaly, reduced numbers of HSPC in the spleen, and their retention in the bone marrow. Although C-terminal telopeptide (CTX) levels, indicative of bone resorption, were lower in calcitonin-treated infected mice, they remained comparable in naive and control infected mice. Calcitonin-treated infected mice conveniently responded to anemia but generated less numbers of splenic macrophages and suffered from exacerbated infection; interestingly, calcitonin also decreased the number of macrophages generated in vitro. Globally, our results indicate that although osteoclast-dependent HSC mobilization from bone marrow to spleen is triggered in murine blood stage malaria, this activity is not essential for stress erythropoiesis.

Impairment of bone health in pediatric patients with hemolytic anemia

Introduction

Sickle cell anemia and thalassemia result in impaired bone health in both adults and youths. Children with other types of chronic hemolytic anemia may also display impaired bone health.

Study Design

To assess bone health in pediatric patients with chronic hemolytic anemia, a cross-sectional study was conducted involving 45 patients with different forms of hemolytic anemia (i.e., 17 homozygous sickle cell disease and 14 hereditary spherocytosis patients). Biochemical, radiographic and anamnestic parameters of bone health were assessed.

Results

Vitamin D deficiency with 25 OH-vitamin D serum levels below 20 ng/ml was a common finding (80.5%) in this cohort. Bone pain was present in 31% of patients. Analysis of RANKL, osteoprotegerin (OPG) and osteocalcin levels indicated an alteration in bone modeling with significantly elevated RANKL/OPG ratios (control: 0.08+0.07; patients: 0.26+0.2, P = 0.0007). Osteocalcin levels were found to be lower in patients compared with healthy controls (68.5+39.0 ng/ml vs. 118.0+36.6 ng/ml, P = 0.0001). Multiple stepwise regression analysis revealed a significant (P<0.025) influence of LDH (partial r² = 0.29), diagnosis of hemolytic anemia (partial r² = 0.05) and age (partial r² = 0.03) on osteocalcin levels. Patients with homozygous sickle cell anemia were more frequently and more severely affected by impaired bone health than patients with hereditary spherocytosis.

Conclusion

Bone health is impaired in pediatric patients with hemolytic anemia. In addition to endocrine alterations, an imbalance in the RANKL/OPG system and low levels of osteocalcin may contribute to this impairment.

Modified activin receptor IIB ligand trap mitigates ineffective erythropoiesis and disease complications in murine β-thalassemia

In β-thalassemia, unequal production of α- and β-globin chains in erythroid precursors causes apoptosis and inhibition of late-stage erythroid differentiation, leading to anemia, ineffective erythropoiesis (IE), and dysregulated iron homeostasis. Here we used a murine model of β-thalassemia intermedia (Hbb(th1/th1) mice) to investigate effects of a modified activin receptor type IIB (ActRIIB) ligand trap (RAP-536) that inhibits Smad2/3 signaling. In Hbb(th1/th1) mice, treatment with RAP-536 reduced overactivation of Smad2/3 in splenic erythroid precursors. In addition, treatment of Hbb(th1/th1) mice with RAP-536 reduced α-globin aggregates in peripheral red cells, decreased the elevated reactive oxygen species present in erythroid precursors and peripheral red cells, and alleviated anemia by promoting differentiation of late-stage erythroid precursors and reducing hemolysis. Notably, RAP-536 treatment mitigated disease complications of IE, including iron overload, splenomegaly, and bone pathology, while reducing erythropoietin levels, improving erythrocyte morphology, and extending erythrocyte life span. These results implicate signaling by the transforming growth factor-β superfamily in late-stage erythropoiesis and reveal potential of a modified ActRIIB ligand trap as a novel therapeutic agent for thalassemia syndrome and other red cell disorders characterized by IE.

Thalassemias

The thalassemia syndromes are hemoglobin disorders that result from significantly reduced or absent synthesis of either the α- or β-globin chains. The result is a chronic hemolytic anemia with ineffective erythropoiesis and bone marrow overstimulation. This article reviews current diagnostic approaches, complications, and disease management of thalassemia.

Alterations in bone and erythropoiesis in hemolytic anemia: comparative study in bled, phenylhydrazine-treated and Plasmodium-infected mice

Sustained erythropoiesis and concurrent bone marrow hyperplasia are proposed to be responsible for low bone mass density (BMD) in chronic hemolytic pathologies. As impaired erythropoiesis is also frequent in these conditions, we hypothesized that free heme may alter marrow and bone physiology in these disorders. Bone status and bone marrow erythropoiesis were studied in mice with hemolytic anemia (HA) induced by phenylhydrazine (PHZ) or Plasmodium infection and in bled mice. All treatments resulted in lower hemoglobin concentrations, enhanced erythropoiesis in the spleen and reticulocytosis. The anemia was severe in mice with acute hemolysis, which also had elevated levels of free heme and ROS. No major changes in cellularity and erythroid cell numbers occurred in the bone marrow of bled mice, which generated higher numbers of erythroid blast forming units (BFU-E) in response to erythropoietin. In contrast, low numbers of bone marrow erythroid precursors and BFU-E and low concentrations of bone remodelling markers were measured in mice with HA, which also had blunted osteoclastogenesis, in opposition to its enhancement in bled mice. The alterations in bone metabolism were accompanied by reduced trabecular bone volume, enhanced trabecular spacing and lower trabecular numbers in mice with HA. Taken together our data suggests that hemolysis exerts distinct effects to bleeding in the marrow and bone and may contribute to osteoporosis through a mechanism independent of the erythropoietic stress.