Prevalence of fractures among the Thalassemia syndromes in North America

REPIN1 regulates iron metabolism and osteoblast apoptosis in osteoporosis

Osteoporosis is not well treated due to the difficulty of finding commonalities between the various types of it. Iron homeostasis is a vital component in supporting biochemical functions, and iron overload is recognized as a common risk factor for osteoporosis. In this research, we found that there is indeed evidence of iron accumulation in the bone tissue of patients with osteoporosis and REPIN1, as an origin specific DNA binding protein, may play a key role in this process. We revealed that sh-Repin1 therapy can rescue bone loss in an iron-overload-induced osteoporosis mouse model. Knockdown of Repin1 can inhibit apoptosis and enhance the resistance of osteoblasts to iron overload toxicity. REPIN1 promoted apoptosis by regulating iron metabolism in osteoblasts. Mechanistically, knockdown of Repin1 decreased the expression of Lcn2, which ameliorated the toxic effects of intracellular iron overload. The anti-iron effect of lentivirus sh-Repin1 was partially reversed or replicated by changing LCN2 expression level via si-RNA or plasmid, which indirectly verified the key regulatory role of LCN2 as a downstream target. Furthermore, the levels of BCL2 and BAX, which play a key role in the mitochondrial apoptosis pathway, were affected. In summary, based on the results of clinical specimens, animal models and in vitro experiments, for the first time, we proved the key role of REPIN1 in iron metabolism-related osteoporosis.

Bone Mineral Density and Dickkopf-1 in Adolescents with Non-Deletional Hemoglobin H Disease

BACKGROUND

Low bone mineral density (BMD) is prevalent in individuals with β-thalassemia and is associated with increased circulating dickkopf-1 concentration. These data are limited in α-thalassemia. Therefore, we aimed to determine the prevalence of low BMD and the association between BMD and serum dickkopf-1 in adolescents with non-deletional hemoglobin H disease, a form of α-thalassemia whose severity is comparable to β-thalassemia intermedia.

METHODOLOGY

The lumbar spine and total body BMD were measured and converted into height-adjusted z-scores. Low BMD was defined as BMD z-score ≤ -2. Participant blood was drawn for measurement of dickkopf-1 and bone turnover marker concentrations.

RESULTS

Thirty-seven participants with non-deletional hemoglobin H disease (59% female, mean age 14.6 ± 3.2 years, 86% Tanner stage ≥2, 95% regularly transfused, 16% taking prednisolone) were included. Over one year prior to the study, mean average pretransfusion hemoglobin, ferritin and 25-hydroxyvitamin D concentrations were 8.8 ± 1.0 g/dL, and 958 ± 513 and 26 ± 6 ng/mL, respectively. When participants taking prednisolone were excluded, the prevalence of low BMD at the lumbar spine and total body was 42% and 17%, respectively. BMD at both sites was correlated positively with body mass index z-score, and negatively with dickkopf-1 (all p-values <0.05). There were no correlations among dickkopf-1, 25-hydroxyvitamin D, osteocalcin and C-telopeptide of type-I collagen. Multiple regression analysis showed dickkopf-1 inversely associated with total body BMD z-score adjusting for sex, bone age, body mass index, pre-transfusion hemoglobin, 25-hydroxyvitamin D, history of delayed puberty, type of iron chelator and prednisolone use (p-value = 0.009).

CONCLUSIONS

We demonstrated a high prevalence of low BMD in adolescents with non-deletional hemoglobin H disease. Moreover, dickkopf-1 inversely associated with total body BMD suggesting it may serve as a bone biomarker in this patient population.

Treatment for osteoporosis in people with beta-thalassaemia

BACKGROUND

Osteoporosis is characterized by low bone mass and micro-architectural deterioration of bone tissue leading to increased bone fragility. In people with beta-thalassaemia, osteoporosis represents an important cause of morbidity and is due to a number of factors. First, ineffective erythropoiesis causes bone marrow expansion, leading to reduced trabecular bone tissue with cortical thinning. Second, excessive iron loading causes endocrine dysfunction, leading to increased bone turnover. Lastly, disease complications can result in physical inactivity, with a subsequent reduction in optimal bone mineralization. Treatments for osteoporosis in people with beta-thalassaemia include bisphosphonates (e.g. clodronate, pamidronate, alendronate; with or without hormone replacement therapy (HRT)), calcitonin, calcium, zinc supplementation, hydroxyurea, and HRT alone (for preventing hypogonadism). Denosumab, a fully human monoclonal antibody, inhibits bone resorption and increases bone mineral density (BMD). Finally, strontium ranelate simultaneously promotes bone formation and inhibits bone resorption, thus contributing to a net gain in BMD, increased bone strength, and reduced fracture risk. This is an update of a previously published Cochrane Review.

OBJECTIVES

To review the evidence on the efficacy and safety of treatment for osteoporosis in people with beta-thalassaemia.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, which includes references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. We also searched online trial registries. Date of most recent search: 4 August 2022.

SELECTION CRITERIA

Randomized controlled trials (RCTs) in people with beta-thalassaemia with: a BMD Z score below -2 standard deviations (SDs) for children aged under 15 years, adult males (aged 15 to 50 years) and premenopausal females aged over 15 years; or a BMD T score below -2.5 SDs for postmenopausal females and males aged over 50 years.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the eligibility and risk of bias of the included RCTs, and extracted and analysed data. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included six RCTs (298 participants). Active interventions included bisphosphonates (3 trials, 169 participants), zinc supplementation (1 trial, 42 participants), denosumab (1 trial, 63 participants), and strontium ranelate (1 trial, 24 participants). The certainty of the evidence ranged from moderate to very low and was downgraded mainly due to concerns surrounding imprecision (low participant numbers), but also risk of bias issues related to randomization, allocation concealment, and blinding. Bisphosphonates versus placebo or no treatment Two RCTs compared bisphosphonates to placebo or no treatment. After two years, one trial (25 participants) found that alendronate and clodronate may increase BMD Z score compared to placebo at the femoral neck (mean difference (MD) 0.40, 95% confidence interval (CI) 0.22 to 0.58) and the lumbar spine (MD 0.14, 95% CI 0.05 to 0.23). One trial (118 participants) reported that neridronate compared to no treatment may increase BMD at the lumbar spine and total hip at six and 12 months; for the femoral neck, the study found increased BMD in the neridronate group at 12 months only. All results were of very low-certainty. There were no major adverse effects of treatment. Participants in the neridronate group reported less back pain; we considered this representative of improved quality of life (QoL), though the certainty of the evidence was very low. One participant in the neridronate trial (116 participants) sustained multiple fractures as a result of a traffic accident. No trials reported BMD at the wrist or mobility. Different doses of bisphosphonate compared One 12-month trial (26 participants) assessed different doses of pamidronate (60 mg versus 30 mg) and found a difference in BMD Z score favouring the 60 mg dose at the lumbar spine (MD 0.43, 95% CI 0.10 to 0.76) and forearm (MD 0.87, 95% CI 0.23 to 1.51), but no difference at the femoral neck (very low-certainty evidence). This trial did not report fracture incidence, mobility, QoL, or adverse effects of treatment. Zinc versus placebo One trial (42 participants) showed zinc supplementation probably increased BMD Z score compared to placebo at the lumbar spine after 12 months (MD 0.15, 95% CI 0.10 to 0.20; 37 participants) and 18 months (MD 0.34, 95% CI 0.28 to 0.40; 32 participants); the same was true for BMD at the hip after 12 months (MD 0.15, 95% CI 0.11 to 0.19; 37 participants) and 18 months (MD 0.26, 95% CI 0.21 to 0.31; 32 participants). The evidence for these results was of moderate certainty. The trial did not report BMD at the wrist, fracture incidence, mobility, QoL, or adverse effects of treatment. Denosumab versus placebo Based on one trial (63 participants), we are unsure about the effect of denosumab on BMD Z score at the lumbar spine, femoral neck, and wrist joint after 12 months compared to placebo (low-certainty evidence). This trial did not report fracture incidence, mobility, QoL, or adverse effects of treatment, but the investigators reported a reduction in bone pain measured on a visual analogue scale in the denosumab group after 12 months of treatment compared to placebo (MD -2.40 cm, 95% CI -3.80 to -1.00). Strontium ranelate One trial (24 participants) only narratively reported an increase in BMD Z score at the lumbar spine in the intervention group and no corresponding change in the control group (very low-certainty evidence). This trial also found a reduction in back pain measured on a visual analogue scale after 24 months in the strontium ranelate group compared to the placebo group (MD -0.70 cm (95% CI -1.30 to -0.10); we considered this measure representative of improved quality of life.

AUTHORS' CONCLUSIONS

Bisphosphonates may increase BMD at the femoral neck, lumbar spine, and forearm compared to placebo after two years' therapy. Zinc supplementation probably increases BMD at the lumbar spine and hip after 12 months. Denosumab may make little or no difference to BMD, and we are uncertain about the effect of strontium on BMD. We recommend further long-term RCTs on different bisphosphonates and zinc supplementation therapies in people with beta-thalassaemia-associated osteoporosis.

Prevalence and risk factors of fractures in transfusion dependent thalassemia - A Hong Kong Chinese population cohort

Objective

To delineate the prevalence and associated risk factors of low BMD, osteoporosis/bone fragility and fracture in transfusion‐dependent thalassemia (TDT) in the Chinese population in Hong Kong.

Design, Patients and Measurements

A retrospective cohort study design was employed. Patients of TDT who had serial Hologic dual‐energy X‐ray absorptiometry (DXA) from 2010 to 2016 and received regular transfusion for at least 5 years were recruited. Clinical and biochemical data, from 5 years before the first DXA scan, were retrieved from the electronic record system of the Hospital Authority, till 30 June 2020. Low bone mineral density and osteoporosis/bone fragility are defined by the ISCD 2019 position guidelines.

Results

Seventy‐seven patients were included in the analysis. The fracture prevalence of TDT among the Chinese population in Hong Kong was 15.58%. Up to 55.84% of patients had low bone mineral density, and 5.19% patients had osteoporosis/bone fragility state. The median age at first fracture was 31.73 years (range 24.06–44.18 years). In the regression analysis, a higher log(10) transformation of average ferritin levels over 5 years before the first DXA scan was significantly associated with fracture occurrence regardless of bisphosphonate treatment (OR 310.73, 95% CI 3.99–24183.89, p = .010). Mean average ferritin level over 5 years was 6695.5 ± 2365.7 pmol/L (fracture group) versus 4350.7 ± 3103.2 pmol/L (non‐fracture group), p = .016. Hip and spine BMD Z‐score did not have statistically significant association with fracture occurrence.

Conclusion

Iron overloading plays an important role in adverse bone health in TDT. Dual X‐ray densitometry is insufficient in predicting fracture risk.

Genotypic and Clinical Analysis of a Thalassemia Major Cohort: An Observational Study

Thalassemia major (TM) is a hereditary disease caused by defective globin synthesis. Because of the significant increase in life expectancy, these patients are suffering from various health conditions, including endocrinopathies and low bone mineral density. The aim of the present study was to investigate the correlation between clinical and biochemical parameters as well as to identify possible relations in a genotype to phenotype pattern. Sixty-four patients with TM (32 men and 32 women) participated in a cross-sectional study design. The patients were recruited from "Aghia Sofia" Children's Hospital. Clinical and biochemical parameters were evaluated as well as specific mutations were identified. We have found significant correlations between biochemical parameters and iron chelation, hormone replacement treatment as well as TM genotype and hematocrit and T-score. To conclude, the current study showed that clinical parameters of TM patients correlate significantly with both biochemical factors and genotypical patient parameters. Our present study showed that there is a connection between genotype and phenotype as, for example, the identified relation between hematocrit and T-scores and TM-specific mutations. This connection indicates that there is still much more to learn about the role of mutations not only in the disease itself but also in the underlying comorbidities.

Fracture prevalence in thalassemia: a systematic review and meta-analysis

BACKGROUND

Multiple observational studies have reported high prevalence of fracture in patients with thalassemia. However, most of these studies have included limited number of patients, and only few of them have reported prevalence of fracture among patients with different types and severity of thalassemia.

OBJECTIVE

This systematic review and meta-analysis was conducted to summarize all available data of fracture prevalence among patients with thalassemia.

METHODS

A systematic review was conducted using EMBASE and MEDLINE databases from inception to June 2021 to determine studies that reported prevalence of fracture in thalassemia patients. The pooled prevalence with 95% confidence interval (95%CI) of fracture across studies was determined using a random-effect, generic inverse variance method.

RESULTS

After two rounds of systematic review, a total of 25 studies with 4934 patients were included in the meta-analysis. The pooled prevalence of fracture among patients with thalassemia was 16% (95%CI, 15-17%, I² = 94.3%). The subgroup analyses showed that the pooled prevalence of fracture was 4% (95%CI, 2-6%; I² = 70.4%) among patients with alpha thalassemia, 17% (95%CI, 16-19%; I² = 93.2%) among patients with beta thalassemia, 18% (95%CI, 16-19%; I² = 89.0%) among patients with transfusion-dependent thalassemia, and 7% (95%CI, 4-10%; I² = 94.2%) among patients with non-transfusion-dependent thalassemia.

CONCLUSION

Fracture is common in patients with thalassemia, and may be more prevalent in beta thalassemia and transfusion-dependent thalassemia than in alpha thalassemia and non-transfusion-dependent thalassemia.

The Polygenic and Monogenic Basis of Paediatric Fractures

PURPOSE OF REVIEW

Fractures are frequently encountered in paediatric practice. Although recurrent fractures in children usually unveil a monogenic syndrome, paediatric fracture risk could be shaped by the individual genetic background influencing the acquisition of bone mineral density, and therefore, the skeletal fragility as shown in adults. Here, we examine paediatric fractures from the perspective of monogenic and complex trait genetics.

RECENT FINDINGS

Large-scale genome-wide studies in children have identified ~44 genetic loci associated with fracture or bone traits whereas ~35 monogenic diseases characterized by paediatric fractures have been described. Genetic variation can predispose to paediatric fractures through monogenic risk variants with a large effect and polygenic risk involving many variants of small effects. Studying genetic factors influencing peak bone attainment might help in identifying individuals at higher risk of developing early-onset osteoporosis and discovering drug targets to be used as bone restorative pharmacotherapies to prevent, or even reverse, bone loss later in life.

Musculoskeletal imaging manifestations of beta-thalassemia

Beta-thalassemia is a heterogeneous group of anemic disorders caused by the absence or defective production of beta-globin chains. Their clinical manifestations vary from asymptomatic to severe symptoms leading to a transfusion-dependent anemic state. The genes that cause thalassemia are prevalent in Asian and African populations, particularly concentrated in the Middle East, Mediterranean region, parts of India, and South East Asia. Over time, the disease causes various musculoskeletal abnormalities with complex pathophysiology secondary to chronic anemia. The compensatory mechanisms result in diffuse marrow hyperplasia, yellow to red marrow reconversion, osteopenia, and pathologic fractures. Inability to remove excess iron and inevitable iron overload as a result of multiple blood transfusions in patients with thalassemia major and intermedia is another face of the disease. Musculoskeletal manifestations include osteopenia, coarse trabeculae, bone expansion, synovitis, joint effusion, and metaphyseal dysplasia. These complications have long-lasting effects on the skeletal growth pattern resulting in bone deformity, short stature, premature closure of physes, and predisposition to infection. Additionally, there are radiologic features of iron-chelator therapy, which are unique and unrelated to the disease process itself. Familiarity of radiologists with the imaging features of beta-thalassemia is crucial in both diagnosis and timely management of the disease and its complications.

The hepcidin regulator erythroferrone is a new member of the erythropoiesis-iron-bone circuitry

Background

Erythroblast erythroferrone (ERFE) secretion inhibits hepcidin expression by sequestering several bone morphogenetic protein (BMP) family members to increase iron availability for erythropoiesis.

Methods

To address whether ERFE functions also in bone and whether the mechanism of ERFE action in bone involves BMPs, we utilize the Erfe-/- mouse model as well as β-thalassemic (Hbbth3/+) mice with systemic loss of ERFE expression. In additional, we employ comprehensive skeletal phenotyping analyses as well as functional assays in vitro to address mechanistically the function of ERFE in bone.

Results

We report that ERFE expression in osteoblasts is higher compared with erythroblasts, is independent of erythropoietin, and functional in suppressing hepatocyte hepcidin expression. Erfe-/- mice display low-bone-mass arising from increased bone resorption despite a concomitant increase in bone formation. Consistently, Erfe-/- osteoblasts exhibit enhanced mineralization, Sost and Rankl expression, and BMP-mediated signaling ex vivo. The ERFE effect on osteoclasts is mediated through increased osteoblastic RANKL and sclerostin expression, increasing osteoclastogenesis in Erfe-/- mice. Importantly, Erfe loss in Hbbth3/+mice, a disease model with increased ERFE expression, triggers profound osteoclastic bone resorption and bone loss.

Conclusions

Together, ERFE exerts an osteoprotective effect by modulating BMP signaling in osteoblasts, decreasing RANKL production to limit osteoclastogenesis, and prevents excessive bone loss during expanded erythropoiesis in β-thalassemia.

Funding

YZG acknowledges the support of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (R01 DK107670 to YZG and DK095112 to RF, SR, and YZG). MZ acknowledges the support of the National Institute on Aging (U19 AG60917) and NIDDK (R01 DK113627). TY acknowledges the support of the National Institute on Aging (R01 AG71870). SR acknowledges the support of NIDDK (R01 DK090554) and Commonwealth Universal Research Enhancement (CURE) Program Pennsylvania.

Chronic Hemolysis May Adversely Affect Skeletal Health. A Cross-Sectional Study of a Pediatric Population

Hereditary hemolytic disorders cause ineffective erythropoiesis and bone marrow hyperplasia. Little is known about their effect on growth and skeletal health. The aim of this study was to evaluate growth, bone and body composition of non transfusion-dependent (NTD) pediatric patients with chronic hemolysis. A detailed history and clinical examination, dual-energy X-ray absorptiometry (DXA) of the lumbar spine (LS) and total body less head (TBLH) and bone turnover markers were performed. Thirty-nine patients (22 males and 17 females, 20 prepubertal), aged 11.4 ± 3.6 years [14 had β-thalassemia intermedia (β-TI), 17 α-thalassemia (α-thal) and eight hereditary spherocytosis (HS)] were evaluated. Fifty-seven previously studied controls were used for statistical analysis. The patients had lower weight and body mass index (BMI) (Z-scores -0.2 and -0.3, respectively, p < 0.05). Post-traumatic fractures were reported by 28.0% of the patients. Compared to controls, they had lower lumbar and subcranial bone mineral density (BMD), as well as reduced fat mass (FM), whereas muscle mass was not affected. One in three patients had low vitamin D and there was increased bone resorption and reduced bone formation. Correlations between different parameters revealed a potential role of osteocalcin, hemoglobin (Hb) and lactate dehydrogenase (LDH) as prognostic markers for bone health, in the setting of chronic hemolysis. Hereditary spherocytosis (HS) patients were the least affected in terms of growth and bone profile. Chronic hemolysis may lead to impaired growth and bone health, even in young, NTD patients. The degree of hemolysis determines bone health risk. Regular surveillance of bone health is justifiable.

Increased prevalence of fractures in inadequately transfused and chelated Indian children and young adults with beta thalassemia major

INTRODUCTION

In patients with beta thalassemia major, inadequate transfusion and chelation may compromise bone health and increase risk of fractures. The objective of this study was to describe the prevalence of fractures in Indian inadequately transfused and chelated children, adolescents and young adults with beta thalassemia major.

METHODS

We studied 179 patients with beta thalassemia (3.6-28.3 years; 105 boys). Medical, transfusion, chelation and fracture history were recorded. Vertebral fracture assessment (VFA) was performed using lateral spine images acquired using the GE Lunar iDXA (Wisconsin, MD). Fractures were classified according to an adapted semi-quantitative method.

RESULTS

History of non-traumatic long bone fractures was observed in 21% patients (n = 37); there were significantly greater (p < 0.05) number of males (n = 30) than females (n = 15). The 21% fracture prevalence in the present study is higher than the reported fractures of 9% in healthy Indian children and adolescents. The prevalence of vertebral fractures was 4.5% (n = 8) in the study group. Of those with fractures, four patients had both long bone and vertebral fractures, and (any, long bone or vertebral fractures) sixteen patients had more than 1 fracture; eleven patients had 2 fractures, four patients had 3 fractures and one patient had 5 fractures. Thus, in 179 patients, there were a total of 68 single fractures which translates to 307 fractures per 10,000 patient years.

CONCLUSION

This study found increased prevalence of non-traumatic long bone and vertebral fractures in children and adolescents with thalassemia major.

DXA and pQCT derived parameters in Indian children with beta thalassemia major - A case controlled study

Children with beta thalassemia major (BTM) are known to have reduced bone mass which increases incidence of non-traumatic fractures. Few studies have assessed prevalence of fractures and bone health in underprivileged children with BTM. Our objectives were to 1) determine prevalence of fractures in underprivileged Indian children with BTM, 2) assess size corrected bone density and bone geometry using Dual x-ray absorptiometry (DXA) and peripheral quantitative computerized tomography (pQCT) in these children and healthy controls 3) determine predictors of fractures in children with BTM 4) compare differences in bone density between children with BMT with and without fractures. Bone mineral content and areal bone mineral density (aBMD) of lumbar spine and whole body and vertebral fracture assessment (VFA) was performed by DXA in 334 children (3-18 years, 167 BTM + 167 controls). Volumetric BMD (vBMD) and bone geometry were assessed by pQCT (subset, 70 BTM, 70 healthy) at distal radius. Children with BTM had higher prevalence of vertebral and long bone fractures (p < 0.05). DXA aBMD was lower in children with BTM (p < 0.05), whereas, lumbar spine bone mineral apparent density (LSBMAD) was higher (p > 0.05). Children with BTM had lower total distal radial vBMD, cortical vBMD and strength strain index (SSI) at 66% site whereas, distal radial trabecular vBMD at 4% was higher (p < 0.05). On height adjustment, children with BTM had lower muscle area and cortical thickness and higher marrow area (p < 0.05) at 66% site. Age, body size, total body less head (TBLH) aBMD and strength strain index (SSI) were important predictors of fractures in children with BTM. Thus, children with BTM had higher prevalence of non-traumatic fractures. Despite lower areal and volumetric densities, they had higher LSBMAD and trabecular densities which may be attributed to erythroid hyperplasia and iron deposition due to inadequate transfusion and chelation. As LSBMAD is raised in these children, it is unlikely to identify BTM subjects at risk of fracture; VFA thus maybe useful in identifying asymptomatic vertebral fractures.

The Effect of Treatment and Bone Metabolic Factors on Fracture Incidence in Patients with Thalassemia-Induced Osteoporosis: An Observational Study

Aim:

The aim of the present study was to evaluate the fracture incidence regarding the markers of bone metabolism, bone mineral density and treatment of osteoporosis as well as treatment of comorbidities.

Methods:

Sixty-four patients with TM (32 men and 32 women) participated in a cross-sectional study design. The patients were recruited from “Aghia Sofia” Children’s Hospital and evaluated using dual-energy X-ray absorptiometry (DXA) of the lumbar spine and femoral neck and with markers of bone remodeling including receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), C-terminal telopeptide (CTX), and sclerostin.

Results:

The statistical analysis of markers of bone metabolism in relation to fractures revealed no statistical significance. However, statistical analysis of bone mineral density and markers of bone metabolism in relation to fractures was also not significant.

Conclusions:

In TM patients, fractures are not related to bone mineral density. Maybe some other conditions are the cause, haemosidirosis, drugs, comorbid conditions.

Bone mineral density in transfusion-dependent thalassemia patients and its associated factors in Southern Iran

Despite the significant improvements in the management of thalassemia, there are growing concerns regarding their long-term complications. We showed that low bone mass is one of the most prevalent complications among these patients. Insufficient physical activity and hypogonadism are the main possible associated factors followed by DM and insufficient sun exposure.

PURPOSE

Despite the significant improvements in the management of transfusion-dependent thalassemia (TDT), there are growing concerns regarding their long-term complications.

METHODS

This cross-sectional study included 615 TDT patients who were registered and followed in a comprehensive thalassemia clinic in Southern Iran. We measured serum biochemical tests and bone mineral density in all patients. We recorded physical activity and sun exposure subjectively, and an endocrinologist visited and examined all the patients. A group of age- and gender-matched healthy volunteers participated in the study as the control group.

RESULTS

The mean age of the studied population was 28.4 ± 7.7 years, and 55.8% were female. The prevalence of vitamin D deficiency was 45.6% and 54.4% in TDT patients and the control group. A portion of TDT patients suffered from different endocrinopathies, which included hypogonadism (49.8%), diabetes mellitus (17.2%), hypoparathyroidism (14.6%), and hypothyroidism (6.3%). The prevalence of low bone mass in patients with TDT was 48.3 and 74.6% in the femoral and lumbar bones, respectively. Low physical activity, insufficient sun exposure, diabetes mellitus, and hypogonadism were associated with low bone mass.

CONCLUSION

Low bone mass is highly prevalent among TDT patients in Southern Iran. Insufficient physical activity and hypogonadism are the main possible associated factors, followed by DM and insufficient sun exposure.

The Trabecular Bone Score as a Predictor for Thalassemia-Induced Vertebral Fractures in Northeastern Thailand

Introduction

Thalassemia bone disease is one of the disease-related complications in patients with thalassemia. Prevalence of fractures and the role of a trabecular bone score (TBS) as a predictive factor for fractures were evaluated in patients with thalassemia.

Methods

A cross-sectional study was conducted in patients with thalassemia aged ≥18 years at Srinagarind Hospital, Khon Kaen University, Thailand. A lateral thoracolumbar radiograph and bone mineral density (BMD) at the lumbar spine and hip, as well as the TBS measured by dual-energy X-ray absorptiometry (DXA), were evaluated in all patients.

Results

Among 86 patients, 14 patients were found to have radiographic vertebral fracture yielding a prevalence of 16.3%. All patients who had fractures were β-thalassemia/Hb E. Combined low BMD and TBS at lumbar spines and a presence of endocrinopathies were significantly associated with vertebral fractures.

Conclusions

The prevalence of vertebral fractures in patients with thalassemia was not uncommon. A combined low BMD and TBS and a presence of endocrinopathies were associated with vertebral fractures. These findings suggested that BMD testing and TBS measurement have a clinical implication as a screening tool for evaluating the risk of vertebral fractures in thalassemic patients, particularly in β-thalassemia/Hb E who have endocrinopathies.

Hematological Diseases and Osteoporosis

Secondary osteoporosis is a common clinical problem faced by bone specialists, with a higher frequency in men than in women. One of several causes of secondary osteoporosis is hematological disease. There are numerous hematological diseases that can have a deleterious impact on bone health. In the literature, there is an abundance of evidence of bone involvement in patients affected by multiple myeloma, systemic mastocytosis, thalassemia, and hemophilia; some skeletal disorders are also reported in sickle cell disease. Recently, monoclonal gammopathy of undetermined significance appears to increase fracture risk, predominantly in male subjects. The pathogenetic mechanisms responsible for these bone loss effects have not yet been completely clarified. Many soluble factors, in particular cytokines that regulate bone metabolism, appear to play an important role. An integrated approach to these hematological diseases, with the help of a bone specialist, could reduce the bone fracture rate and improve the quality of life of these patients.

Impaired Bone Microarchitecture in Patients with Hereditary Hemochromatosis and Skeletal Complications

Hereditary hemochromatosis (HHC) is characterized by excessive intestinal iron absorption resulting in a pathological increase of iron levels. Parenchyma damage may be a consequence of iron deposition in affected organs (e.g., liver, pancreas, gonads) as well as bones and joints, leading to osteoporosis with increased fracture risk and arthropathy. Up to date, it is not known whether HHC can also be considered as a risk factor for osteonecrosis. Likewise, the underlying skeletal changes are unknown regarding, e.g., microstructural properties of bone. We aimed to study the spectrum of skeletal complications in HHC and the possible underlying microarchitectural changes. Therefore, we retrospectively analyzed all patients with HHC (n = 10) presenting in our outpatient clinic for bone diseases. In addition to dual-energy X-ray absorptiometry (DXA), high-resolution peripheral quantitative computed tomography (HR-pQCT) was performed and bone turnover markers, 25-OH-D3, ferritin and transferrin saturation were measured. Cortical volumetric bone mineral density (Ct.BMD) and cortical thickness (Ct.Th) were reduced, whereas trabecular microstructure (Tb.Th) and volumetric bone mineral density (Tb.BMD) were preserved compared to age- and gender-adjusted reference values from the literature. Interestingly, the occurrence of bone complications was age dependent; while younger patients presented with osteonecroses or transient bone marrow edema, patients older than 65 years presented with fractures. Our study provides first insights into altered bone microarchitecture in HHC and sheds new light on the occurrence of osteonecrosis. If available, HR-pQCT is a useful complement to fracture risk assessment and to determine microstructural deterioration and volumetric bone mineralization deficits.

Iron Overload Associated Endocrine Dysfunction Leading to Lower Bone Mineral Density in Thalassemia Major

CONTEXT

Patients with thalassemia major (TM) have a lower bone mineral density (BMD) and higher risk of fracture than the general population. The possible mechanisms include anemia, iron overload, malnutrition, and hormonal deficiency, but these have not been thoroughly investigated.

OBJECTIVE

To identify major mineral and hormonal factors related to BMD in adult TM patients to provide human evidence for the proposed mechanisms.

DESIGN

Retrospective study.

SETTING

Referral center.

PATIENTS

Twenty-nine patients with β-TM, aged 23 to 44 years who were followed-up during 2017 to 2018 were enrolled.

OUTCOME MEASUREMENTS

Endocrine profiles, including thyroid, parathyroid, and pituitary function, glucose, vitamin D, calcium, phosphate, and fibroblast growth factor 23 (FGF23) were obtained. The relationships among the above parameters, body height, fractures, and BMD were analyzed.

RESULTS

Abnormal BMD was observed in 42.9% of women and 23.1% of men. The mean final heights of women and men were 3.7 cm and 7.3 cm lower than the mean expected values, respectively. Fracture history was recorded in 26.7% of women and 35.7% of men. BMD was negatively correlated with parathyroid hormone, FGF23, thyrotropin, and glycated hemoglobin (HbA1c) levels, and positively correlated with testosterone, IGF-1, and corticotropin levels (all P < .05). Moreover, hypothyroidism was associated with lower BMD in both the lumbar spine (P = .024) and the femoral neck (P = .004). Patients with hypothyroidism had a higher percentage of abnormal BMD (P = .016).

CONCLUSION

Hypothyroidism, higher HbA1c, and lower adrenocorticotropin were predictors of abnormal BMD in patients with β-TM. Whether the correction of these factors improves BMD warrants further research.

Dual-energy X-ray absorptiometry pitfalls in Thalassemia Major

BACKGROUND

Low mineral mass and reduced bone strength with increased fracture risk are the main causes of morbidity in Thalassemia Major (TM). The pathogenesis is multifactorial and includes ineffective erythropoiesis with medullary expansion, multiple endocrine dysfunctions, direct iron bone deposition, deferoxamine-induced bone dysplasia, and reduced physical activity associated with disease complications. Dual-energy X-ray absorptiometry (DXA) is the "gold standard" for bone mineral density (BMD) assessment and for bone strength and quality evaluation. This method identifies patients at greater risk of fragility fractures, guiding treatment and monitoring response to therapy. In TM, DXA shows limitations concerning BMD calculation accuracy and fracture risk prediction. One of the main challenges in the assessment of bone health in patients with TM is the accurate interpretation of densitometric results.

PURPOSE

This review investigates the major pitfalls in DXA implementation and interpretation in TM.

METHODS

Available literature has been assessed.

CONCLUSIONS

DXA shows limitations in assessing bone mineral "status" in TM, especially in the paediatric population, due to the peculiar characteristics of bone architecture and deformities associated with the disease. A radiological technique adjustment in this population is mandatory.

Pathogenesis of Thalassemia Major-associated Osteoporosis: A Review with Insights from Clinical Experience

Due to increasing life expectancy in thalassemia major (TM), osteoporosis is emerging as a significant problem. Its aetiology is multifactorial, culminating in increased bone resorption and impaired remodelling. Hypogonadism and marrow expansion seem to play an important role, but iron overload, deferoxamine toxicity, a defective growth hormone-insulin-like growth factor-1 axis and multiple endocrinopathies may represent additional causes of bone damage. Many of these patients, though under appropriate treatment programs, do not achieve normal peak bone mass. The receptor activator of nuclear factor kappa-ß (RANK)/RANK ligand/osteoprotegerin and the Wnt/β-catenin systems work as major mediators of imbalanced bone turnover and bone loss. Additional genetic factors, such as collagen type 1 alpha 1 and vitamin D receptor gene polymorphisms, may exert some influence on the enhanced fracture risk observed in TM. To date, in spite of adequate hormone replacement, chelating therapy and acceptable haemoglobin levels, subjects with TM display impaired bone density and imbalanced bone turnover, thus the puzzle of the pathogenesis of TM-induced osteoporosis remains far from being solved.

Influence of Iron on Bone Homeostasis

Bone homeostasis is a complex process, wherein osteoclasts resorb bone and osteoblasts produce new bone tissue. For the maintenance of skeletal integrity, this sequence has to be tightly regulated and orchestrated. Iron overload as well as iron deficiency disrupt the delicate balance between bone destruction and production, via influencing osteoclast and osteoblast differentiation as well as activity. Iron overload as well as iron deficiency are accompanied by weakened bones, suggesting that balanced bone homeostasis requires optimal-not too low, not too high-iron levels. The goal of this review is to summarize our current knowledge about how imbalanced iron influence skeletal health. Better understanding of this complex process may help the development of novel therapeutic approaches to deal with the pathologic effects of altered iron levels on bone.

Deletion of ferroportin in murine myeloid cells increases iron accumulation and stimulates osteoclastogenesis in vitro and in vivo

Osteoporosis, osteopenia, and pathological bone fractures are frequent complications of iron-overload conditions such as hereditary hemochromatosis, thalassemia, and sickle cell disease. Moreover, animal models of iron overload have revealed increased bone resorption and decreased bone formation. Although systemic iron overload affects multiple organs and tissues, leading to significant changes on bone modeling and remodeling, the cell autonomous effects of excessive iron on bone cells remain unknown. Here, to elucidate the role of cellular iron homeostasis in osteoclasts, we generated two mouse strains in which solute carrier family 40 member 1 (Slc40a1), a gene encoding ferroportin (FPN), the sole iron exporter in mammalian cells, was specifically deleted in myeloid osteoclast precursors or mature cells. The FPN deletion mildly increased iron levels in both precursor and mature osteoclasts, and its loss in precursors, but not in mature cells, increased osteoclastogenesis and decreased bone mass in vivo Of note, these phenotypes were more pronounced in female than in male mice. In vitro studies revealed that the elevated intracellular iron promoted macrophage proliferation and amplified expression of nuclear factor of activated T cells 1 (Nfatc1) and PPARG coactivator 1β (Pgc-1β), two transcription factors critical for osteoclast differentiation. However, the iron excess did not affect osteoclast survival. While increased iron stimulated global mitochondrial metabolism in osteoclast precursors, it had little influence on mitochondrial mass and reactive oxygen species production. These results indicate that FPN-regulated intracellular iron levels are critical for mitochondrial metabolism, osteoclastogenesis, and skeletal homeostasis in mice.

Intestinal calcium transport and its regulation in thalassemia: interaction between calcium and iron metabolism

Osteoporosis and derangement of calcium homeostasis are common complications of thalassemia. Despite being an important process for bone and calcium metabolism, little is known about intestinal calcium transport in thalassemia. Recent reports of decreases in both intestinal calcium transport and bone mineral density in thalassemic patients and animal models suggested that defective calcium absorption might be a cause of thalassemic bone disorder. Herein, the possible mechanisms associated with intestinal calcium malabsorption in thalassemia are discussed. This includes alterations in the calcium transporters and hormonal controls of the transcellular and paracellular intestinal transport systems in thalassemia. In addition, the effects of iron overload on intestinal calcium absorption, and the reciprocal interaction between iron and calcium transport in thalassemia are elaborated. Understanding the mechanisms underlining calcium malabsorption in thalassemia would lead to development of therapeutic agents and mineral supplements that restore calcium absorption as well as prevent osteoporosis in thalassemic patients.

A contemporary therapeutic approach to bone disease in beta-thalassemia - a review

Homozygous beta-thalassemia represents a serious hemoglobinopathy, in which an amazing prolongation in the survival rate of patients has been achieved over recent decades. A result of this otherwise positive evolution is the fact that bone problems have become a major issue in this group of patients. Through an in-depth review of the related literature, the purpose of this study is to present and comment on the totality of the data that have been published to date pertaining to the prevention and treatment of thalassemia bone-disease, focusing on: the contribution of diet and lifestyle, the treatment of hematologic disease and its complications, the management of hypercalciuria, the role of vitamins and minerals and the implementation of anti-osteoporosis medical regimen. In order to comprehensively gather the above information, we mainly reviewed the international literature through the PubMed database, searching for the preventive and therapeutic data that have been published pertaining to thalassemia bone-disease over the last twenty-nine years. There is no doubt that thalassemia bone-disease is a complication of a multi-factorial etiopathology, which does not follow the rules of classical postmenopausal osteoporosis. Bisphosphonates have been the first line of treatment for many years now, with varied and usually satisfactory results. In addition, over the last few years, more data have arisen for the use of denosumab, teriparatide, and other molecules that are in the clinical trial phase, in beta-thalassemia.

β-Thalassemia intermedia: a comprehensive overview and novel approaches

β-Thalassemia intermedia is a clinical condition of intermediate gravity between β-thalassemia minor, the asymptomatic carrier, and β-thalassemia major, the transfusion-dependent severe anemia. It is characterized by a significant clinical polymorphism, which is attributable to its genetic heterogeneity. Ineffective erythropoiesis, chronic anemia, and iron overload contribute to the clinical complications of thalassemia intermedia through stepwise pathophysiological mechanisms. These complications, including splenomegaly, extramedullary erythropoiesis, iron accumulation, leg ulcers, thrombophilia, and bone abnormalities can be managed via fetal hemoglobin induction, occasional transfusions, chelation, and in some cases, stem cell transplantation. Given its clinical diversity, thalassemia intermedia patients require tailored approaches to therapy. Here we present an overview and novel approaches to the genetic basis, pathophysiological mechanisms, clinical complications, and optimal management of thalassemia intermedia.

Risk of fracture in transfusion-naïve thalassemia population: A nationwide population-based retrospective cohort study

In thalassemia major or transfusion-dependent thalassemia patients, osteoporosis-related bone complications such as fracture events are common. However, no studies have investigated the risk of fracture in transfusion-naïve thalassemia population. Therefore, we conducted a longitudinal nationwide cohort study to determine whether this population has an increased risk of fracture. This nationwide, population-based cohort study analyzed data from 1998 to 2010 obtained from the Taiwanese National Health Insurance Research Database, with a follow-up period extending until the end of 2011. We identified cases with transfusion-naïve thalassemia and selected a comparison cohort that was frequency-matched according to age and year of diagnosis of thalassemia at a ratio of one subject with thalassemia to four subjects in the control group. We analyzed the risk of fracture events to occur in transfusion-naïve thalassemia cases by using Cox proportional hazards regression models. Totally, the study recruited 1369 transfusion-naïve thalassemia subjects and 5416 controls. We identified a total of 71 cases with fracture events within the thalassemia group and 204 within the control group. The overall risks for developing fracture events were 1.35-fold higher in transfusion-naïve thalassemia individuals than the comparison cohort after adjusting for age, sex and comorbidities. Most fracture events were observed in male transfusion-naïve thalassemia individuals rather than the normal population. In subgroup analysis, there was a 1.46-fold higher risk to develop upper-limb fracture in the thalassemia group than in the control groups. In conclusion, our long-term, cohort study results showed that there was a higher risk for the development of fractures in transfusion-naïve thalassemia individuals, particularly in male cases.

Rheumatological complications of beta-thalassaemia: an overview

Beta-thalassaemia, an autosomal recessive haemoglobinopathy, ranks among the most frequent monogenetic diseases globally. The severe form of the disease, beta-thalassaemia major, is accompanied by progressive involvement of multiple organ systems as a result of the disease pathophysiology as well as iron overload from blood transfusions on a regular basis. Some of the manifestations might also be caused by medications used to manage iron overload. The purpose of this review is to highlight the rheumatological complications of beta-thalassaemia, which include musculoskeletal manifestations, such as arthritis and arthropathies, joint effusions, osteoporosis, bone fractures and myalgias, in addition to CTDs, such as pseudoxanthoma elasticum. Rheumatologists are strongly encouraged to take part in a multidisciplinary approach to the management of this debilitating disease.

Bone quality in beta-thalassemia intermedia: relationships with bone quantity and endocrine and hematologic variables

We report the first evaluation of bone quality in 70 thalassemia intermedia (TI) patients (37 males, 33 females, age 41 ± 12 years). Thirty-three patients (47%) had been transfused, 34 (49%) had been splenectomized, 39 (56%) were on iron chelation therapy, and 11 (16%) were on hydroxyurea. Mean hemoglobin was 9.2 ± 1.5 g/dl, median ferritin 537 ng/dl (range 14-4893), and mean liver iron concentration 7.6 ± 6.4 mg Fe/g dw. Fifteen patients (21%) had endocrinopathies, and 29 (41%) had vitamin D deficiency. Bone quantity (bone mineral density, BMD) and bone quality (trabecular bone score, TBS) were evaluated by densitometry. In 53/70 patients (76%), osteopathy was found (osteoporosis in 26/53, osteopenia in 27/53). BMD values were higher in the never-transfused patients and in the not-chelated group. A highly significant correlation was found between splenectomy and BMD at all the sites, with lower values in the splenectomized patients. TBS values were significantly lower in TI patients than in 65 non-thalassemic controls (1.22 vs 1.36, p < 0.01), mainly in those splenectomized and in the transfused and chelated groups (p < 0.01). TBS did not correlate with liver iron concentration values. Our data disclose the major role of non-invasive bone quality evaluation in TI patients, especially those with the worst health state, to obtain a comprehensive assessment of fracture risk. Splenectomy seems to play a major part in bone complications.

Clinical Impact and Cellular Mechanisms of Iron Overload-Associated Bone Loss

Diseases/conditions with diverse etiology, such as hemoglobinopathies, hereditary hemochromatosis and menopause, could lead to chronic iron accumulation. This condition is frequently associated with a bone phenotype; characterized by low bone mass, osteoporosis/osteopenia, altered microarchitecture and biomechanics, and increased incidence of fractures. Osteoporotic bone phenotype constitutes a major complication in patients with iron overload. The purpose of this review is to summarize what we have learnt about iron overload-associated bone loss from clinical studies and animal models. Bone is a metabolically active tissue that undergoes continuous remodeling with the involvement of osteoclasts that resorb mineralized bone, and osteoblasts that form new bone. Growing evidence suggests that both increased bone resorption and decreased bone formation are involved in the pathological bone-loss in iron overload conditions. We will discuss the cellular and molecular mechanisms that are involved in this detrimental process. Fuller understanding of this complex mechanism may lead to the development of improved therapeutics meant to interrupt the pathologic effects of excess iron on bone.

Thalassemia-associated osteoporosis: a systematic review on treatment and brief overview of the disease

Thalassemia-associated osteoporosis constitutes a major complication in patients with thalassemia. This review presents the existing studies on the treatment of thalassemia-associated osteoporosis and discusses the management of this debilitating complication. A brief presentation of the disease characteristics and pathogenetic mechanisms is also provided. The life expectancy of patients with thalassemia has increased markedly in recent years resulting in the aging of the population and the emergence of new comorbidities. The majority of patients with thalassemia have low bone mineral density and experience lifelong fracture rates as high as 71 %. The pathogenesis of thalassemia-associated osteoporosis (TAO) is multifactorial with anemia and iron overload playing crucial role in its development. Data concerning the prevention and treatment of TAO are extremely limited. We performed a literature research in Pubmed and Scopus to identify interventional studies evaluating the effects of various agents on TAO. Seventeen studies were retrieved. We present the results of these studies as well as a brief overview of TAO including presentation, pathogenesis, and management. Most of the studies identified are of poor quality, are not randomized controlled, and include small number of participants. There are no data concerning effects on fracture rates. Bisphosphonates are the most widely studied agents and among them zoledronic acid is the most well studied. Hormone replacement treatment (HRT) shows beneficial but small effects. Denosumab and strontium ranelate have each been evaluated in only a single study, while there are no data about the effects of anabolic agents. Given the increased life expectancy and the increase in fracture rates with age, more data about the management of TAO are warranted. Moreover, due to the need for lifelong management starting at young age, careful treatment plans which may include sequential treatment may often be required. However, currently, there are no relevant data available.

Iron overload induced death of osteoblasts in vitro: involvement of the mitochondrial apoptotic pathway

BACKGROUND

Iron overload is recognized as a new pathogenfor osteoporosis. Various studies demonstrated that iron overload could induce apoptosis in osteoblasts and osteoporosis in vivo. However, the exact molecular mechanisms involved in the iron overload-mediated induction of apoptosis in osteoblasts has not been explored.

PURPOSE

In this study, we attempted to determine whether the mitochondrial apoptotic pathway is involved in iron-induced osteoblastic cell death and to investigate the beneficial effect of N-acetyl-cysteine (NAC) in iron-induced cytotoxicity.

METHODS

The MC3T3-E1 osteoblastic cell line was treated with various concentrations of ferric ion in the absence or presence of NAC, and intracellular iron, cell viability, reactive oxygen species, functionand morphology changes of mitochondria and mitochondrial apoptosis related key indicators were detected by commercial kits. In addition, to further explain potential mechanisms underlying iron overload-related osteoporosis, we also assessed cell viability, apoptosis, and osteogenic differentiation potential in bone marrow-derived mesenchymal stemcells(MSCs) by commercial kits.

RESULTS

Ferric ion demonstrated concentration-dependent cytotoxic effects on osteoblasts. After incubation with iron, an elevation of intracelluar labile iron levels and a concomitant over-generation of reactive oxygen species (ROS) were detected by flow cytometry in osteoblasts. Nox4 (NADPH oxidase 4), an important ROS producer, was also evaluated by western blot. Apoptosis, which was evaluated by Annexin V/propidium iodide staining, Hoechst 33258 staining, and the activation of caspase-3, was detected after exposure to iron. Iron contributed to the permeabilizatio of mitochondria, leading to the release of cytochrome C (cyto C), which, in turn, induced mitochondrial apoptosis in osteoblasts via activation of Caspase-3, up-regulation of Bax, and down-regulation of Bcl-2. NAC could reverse iron-mediated mitochondrial dysfunction and blocked the apoptotic events through inhibit the generation of ROS. In addition, iron could significantly promote apoptosis and suppress osteogenic differentiation and mineralization in bone marrow-derived MSCs.

CONCLUSIONS

These findings firstly demonstrate that the mitochondrial apoptotic pathway involved in iron-induced osteoblast apoptosis. NAC could relieved the oxidative stress and shielded osteoblasts from apoptosis casused by iron-overload. We also reveal that iron overload in bone marrow-derived MSCs results in increased apoptosis and the impairment of osteogenesis and mineralization.

Management of beta-thalassemia-associated osteoporosis

Beta-Thalassemia-associated osteoporosis is a multifactorial and complex condition. Different acquired and genetic factors are involved in its pathogenesis. These factors produce an imbalance in bone remodeling by inhibiting osteoblast activity and increasing osteoclast function, leading to bone loss and increased fracture risk. The management of patients presenting with thalassemia-associated osteoporosis should consist of the implementation of general measures and the prescription of a specific pharmacological agent, with the aim of reducing fracture risk and preventing disability and deterioration of quality of life. General measures include control of anemia, adequate chelation therapy, healthy nutrition and lifestyle, regular exercise, adequate management of comorbid conditions, hormone replacement therapy in patients with hypogonadism, and vitamin D supplementation/therapy. Among the pharmacological agents currently available for the management of osteoporosis in postmenopausal women and men, bisphosphonates have been shown to improve bone mineral density, to reduce bone turnover, and to decrease bone/back pain in patients with thalassemia-associated osteoporosis, with a good profile of safety and tolerability. On the other hand, there are limited experiences with other pharmacological agents (e.g., denosumab or teriparatide). The complexity of this condition presents diagnostic and therapeutic challenges and underscores the importance of a comprehensive and multidisciplinary approach.

Polycythemia is associated with bone loss and reduced osteoblast activity in mice

Increased fragility has been described in humans with polycythemia vera (PV). Herein, we describe an osteoporotic phenotype associated with decreased osteoblast activity in a mouse model of PV and another mouse of polycythemia and elevated circulating erythropoietin (EPO). Our results are important for patients with PV or those treated with recombinant EPO (rEPO).

INTRODUCTION

PV and other myeloproliferative syndromes have been recently associated with an increased risk for fractures. However, the presence of osteoporosis in these patients has not been well documented. EPO, a hormone primarily known to stimulate erythropoiesis, has been shown recently to regulate bone homeostasis in mice. The aim of this study was to examine the bone phenotype of a mouse model of PV and compare it to that of animals with polycythemia caused by elevated circulating EPO.

METHODS

Bone mass and remodeling were evaluated by micro-computed tomography and histomorphometry. The JAK2(V617F) knock-in mouse, a model of human PV, manifests polycythemia and low circulating EPO levels. Results from this mouse were compared to wild type (wt) controls and the tg6 transgenic mouse that shows polycythemia caused by increased constitutive expression of EPO.

RESULTS

Compared to wt, both JAK2(V617F) and tg6 mice had a decrease in trabecular bone mass. Tg6 mice showed an additional modest decrease in cortical thickness and cortical bone volume per tissue volume (P < 0.01) suggesting a more severe bone phenotype than JAK2(V617F). Decreased osteoblast numbers and bone formation along with normal osteoclast numbers and activity were found in both mice.

CONCLUSIONS

This study indicates that PV is associated with low bone mass and decreased osteoblast activity in mice. Our results support future studies of osteoporosis in affected humans. Polycythemia caused by chronically elevated circulating EPO also results in bone loss, and implications on patients treated with rEPO should be evaluated.

Treatment for osteoporosis in people with ß-thalassaemia

BACKGROUND

Osteoporosis is a systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. Osteoporosis represents an important cause of morbidity in people with beta-thalassaemia and its pathogenesis is multifactorial. Factors include bone marrow expansion due to ineffective erythropoiesis, resulting in reduced trabecular bone tissue with cortical thinning; endocrine dysfunction secondary to excessive iron loading, leading to increased bone turnover; and lastly, a predisposition to physical inactivity due to disease complications with a subsequent reduction in optimal bone mineralization.A number of therapeutic strategies have been applied to treat osteoporosis in people with beta-thalassaemia, which include bisphosphonates, with or without, hormone replacement therapy. There are various forms of bisphosphonates, such as clodronate, pamidronate, alendronate and zoledronic acid. Other treatments include calcitonin, calcium, zinc supplementation, hydroxyurea and hormone replacement therapy for preventing hypogonadism.

OBJECTIVES

To review the evidence on the efficacy and safety of treatment for osteoporosis in people with beta-thalassaemia.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Date of most recent search: 04 February 2016.

SELECTION CRITERIA

Randomised, placebo-controlled trials in people with thalassaemia with a bone mineral density z score of less than -2 standard deviations for: children less than 15 years old; adult males (15 to 50 years old); and all pre-menopausal females above 15 years and a bone mineral density t score of less than -2.5 standard deviations for post-menopausal females and males above 50 years old.

DATA COLLECTION AND ANALYSIS

Two review authors assessed the eligibility and risk of bias of the included trials, extracted and analysed data and completed the review. We summarised results using risk ratios or rate ratios for dichotomous data and mean differences for continuous data. We combined trial results where appropriate.

MAIN RESULTS

Four trials (with 211 participants) were included; three trials investigated the effect of bisphosphonate therapies and one trial investigated the effect of zinc supplementation. Only one trial was judged to be of good quality (low risk of bias); the remaining trials had a high or unclear risk of bias in at least one key domain.One trial (data not available for analysis) assessing the effect of neridronate (118 participants) reported significant increases in favour of the bisphosphonate group for bone mineral density at the lumbar spine and hip at both six and 12 months. For the femoral neck, a significant difference was noted at 12 months only. A further trial (25 participants) assessed the effect of alendronate and clodronate and found that after two years, bone mineral density increased significantly in the alendronate and clodronate groups as compared to placebo at the lumbar spine, mean difference 0.14 g/cm(2) (95% confidence interval 0.05 to 0.22) and at the femoral neck, mean difference 0.40 g/cm(2) (95% confidence interval 0.22 to 0.57). One 12-month trial (26 participants) assessed the effects of different doses of pamidronate (30 mg versus 60 mg) and found a significant difference in bone mineral density in favour of the 60 mg dose at the lumbar spine and forearm, mean difference 0.43 g/cm(2) (95% CI 0.10 to 0.76), mean difference 0.87 g/cm(2) (95% CI 0.23 to 1.51), respectively, but not at the femoral neck.In a zinc sulphate supplementation trial (42 participants), bone mineral density increased significantly compared to placebo at the lumbar spine after 12 months (37 participants), mean difference 0.15 g/cm(2) (95% confidence interval 0.10 to 0.20) and after 18 months (32 participants), mean difference 0.34 g/cm(2) (95% confidence interval 0.28 to 0.40). The same was true for bone mineral density at the hip after 12 months, mean difference 0.15 g/cm(2) (95% confidence interval 0.11 to 0.19) and after 18 months, mean difference 0.26 g/cm(2) (95% confidence interval 0.21 to 0.31).Fractures were not observed in one trial and not reported in three trials. There were no major adverse effects reported in two of the bisphosphonate trials; in the neridronate trial there was a reduction noted in the use of analgesic drugs and in the reported back pain score in favour of bisphosphonate treatment. Adverse effects were not reported in the trial of different doses of pamidronate or the zinc supplementation trial.

AUTHORS' CONCLUSIONS

There is evidence to indicate an increase in bone mineral density at the femoral neck, lumbar spine and forearm after administration of bisphosphonates and at the lumbar spine and hip after zinc sulphate supplementation. The authors recommend that further long-term randomised control trials on different bisphosphonates and zinc supplementation therapies in people with beta-thalassaemia and osteoporosis are undertaken.

Decreased Bone Formation Explains Osteoporosis in a Genetic Mouse Model of Hemochromatosiss

Osteoporosis may complicate iron overload diseases such as genetic hemochromatosis. However, molecular mechanisms involved in the iron-related osteoporosis remains poorly understood. Recent in vitro studies support a role of osteoblast impairment in iron-related osteoporosis. Our aim was to analyse the impact of excess iron in Hfe-/- mice on osteoblast activity and on bone microarchitecture. We studied the bone formation rate, a dynamic parameter reflecting osteoblast activity, and the bone phenotype of Hfe-/- male mice, a mouse model of human hemochromatosis, by using histomorphometry. Hfe-/- animals were sacrificed at 6 months and compared to controls. We found that bone contains excess iron associated with increased hepatic iron concentration in Hfe-/- mice. We have shown that animals with iron overload have decreased bone formation rate, suggesting a direct impact of iron excess on active osteoblasts number. For bone mass parameters, we showed that iron deposition was associated with bone loss by producing microarchitectural impairment with a decreased tendency in bone trabecular volume and trabecular number. A disorganization of trabecular network was found with marrow spaces increased, which was confirmed by enhanced trabecular separation and star volume of marrow spaces. These microarchitectural changes led to a loss of connectivity and complexity in the trabecular network, which was confirmed by decreased interconnectivity index and increased Minkowski's fractal dimension. Our results suggest for the first time in a genetic hemochromatosis mouse model, that iron overload decreases bone formation and leads to alterations in bone mass and microarchitecture. These observations support a negative effect of iron on osteoblast recruitment and/or function, which may contribute to iron-related osteoporosis.

Documentation of renal glomerular and tubular impairment and glomerular hyperfiltration in multitransfused patients with beta thalassemia

Urinary albumin to creatinine (ACR) and beta2 microglobulin to creatinine ratios (BCR) are the surrogate and robust markers of renal glomerulopathy and tubulopathy, respectively. These markers predict short-term renal deterioration and mortality in various conditions. We aimed to assess the frequency and predictors of glomerular and tubular defects, renal impairment, and hyperfiltration in 96 adult patients with beta thalassemia intermedia and major. ACR > 300 mg/g creatinine and BCR > 300 μg/g creatinine were used to define the renal glomerular and tubular damages, respectively. Glomerular filtration rate (eGFRcreat) was estimated according to 2009 the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Decreased eGFRcreat was defined as less than 60 mL/min per 1.73 m(2). Renal glomerular and/or tubular defects were observed in about 68.8 % of all patients. Forty percent of patients had glomerular hyperfiltration. None of the patients had a decreased eGFRcreat. T2* value ≤20 msec on cardiac magnetic resonance (cMR) was the only independent predictor of glomerular damage (p = 0.013). Use of alendronate was associated with less renal tubular damage (p = 0.007). Female gender and previous history of splenectomy were the independent predictors of glomerular hyperfiltration in multivariate analysis (p < 0.001 and p = 0.040, respectively). Renal tubular and glomerular damage is frequent in adult patients with thalassemia intermedia and major. T2* value on cMR was the only independent predictor of glomerular damage. However, since we did not explore all the parameters of iron, it is not possible to draw a definite conclusion about the association of cMR and glomerular damage. There is no association with cardiac iron overload/accumulation and tubular damage or hyperfiltration.

Iron overload increases osteoclastogenesis and aggravates the effects of ovariectomy on bone mass

Postmenopausal osteoporosis is a metabolic disease associated with estrogen deficiency. The results of numerous studies have revealed the positive correlation between iron accumulation and postmenopausal osteoporotic status. Although the results of previous studies have indicated that estrogen or iron alone have an effect on bone metabolism, their combined effects are not well defined. Using an in vivo mouse model, we found that bone mass was minimally affected by an excess of iron in the presence of estrogen. Once the source of estrogen was removed (ovariectomy), iron accumulation significantly decreased bone mass. These effects were accompanied by fluctuations in the level of oxidative stress. To determine whether these effects were related to bone formation or bone resorption, primary osteoblasts (OBs), RAW264.7 cells, and bone-marrow-derived macrophages were used for in vitro experiments. We found that iron accumulation did inhibit the activity of OBs. However, estrogen had little effect on this inhibition. In contrast, iron promoted osteoclast differentiation through the production of reactive oxygen species. Estrogen, a powerful reactive oxygen scavenger, suppressed this effect in osteoclasts. Our data provided direct evidence that iron affected the bone mass only in the absence of estrogen. The inhibitory effect of estrogen on iron-induced osteopenia was particularly relevant to bone resorption rather than bone formation.

Chronic iron deficiency as an emerging risk factor for osteoporosis: a hypothesis

Iron is essential in oxygen transport and participates in many enzymatic systems in the body, with important roles in collagen synthesis and vitamin D metabolism. The relationship between iron and bone health comes from clinical observations in iron overload patients who suffered bone loss. The opposite scenario—whether iron deficiency, with or without anemia, affects bone metabolism—has not been fully addressed. This is of great interest, as this nutrient deficiency is a worldwide public health problem and at the same time osteoporosis and bone alterations are highly prevalent. This review presents current knowledge on nutritional iron deficiency and bone remodeling, the biomarkers to evaluate iron status and bone formation and resorption, and the link between iron and bone metabolism. Finally, it is hypothesized that chronic iron deficiency induces bone resorption and risk of osteoporosis, thus complete recovery from anemia and its prevention should be promoted in order to improve quality of life including bone health. Several mechanisms are suggested; hence, further investigation on the possible impact of chronic iron deficiency on the development of osteoporosis is needed.

Endocrine and bone complications in β-thalassemia intermedia: current understanding and treatment

Thalassemia intermedia (TI), also known as nontransfusion dependent thalassemia (NTDT), is a type of thalassemia where affected patients do not require lifelong regular transfusions for survival but may require occasional or even frequent transfusions in certain clinical settings and for defined periods of time. NTDT encompasses three distinct clinical forms: β-thalassemia intermedia (β-TI), Hb E/β-thalassemia, and α-thalassemia intermedia (Hb H disease). Over the past decade, our understanding of the molecular features, pathophysiology, and complications of NTDT particularly β-TI has increased tremendously but data on optimal treatment of disease and its various complications are still lacking. In this paper, we shall review a group of commonly encountered complications in β-TI, mainly endocrine and bone complications.

Bisphosphonates in the management of thalassemia-associated osteoporosis: a systematic review of randomised controlled trials

Bisphosphonates are potent inhibitors of bone resorption, widely used for the management of osteoporosis and fracture prevention. Recent evidence suggests that bisphosphonates may have beneficial effects in the treatment of thalassemia-associated osteoporosis, a complex and multifactorial condition. Here we summarise available data about the efficacy and tolerability of bisphosphonates in beta--thalassemic patients. Randomised controlled trials (RCTs) of bisphosphonates in beta-thalassemia were identified searching PubMed. Studies were reviewed to retrieve relevant clinical information. The following variables were considered to assess the safety and efficacy of bisphosphonates-bone mineral density (BMD), markers of bone turnover, incidence of fragility fracture, bone pain, back pain, and clinical adverse events. Five RCTs were identified, investigating alendronate, clodronate, zoledronic acid and neridronate. All bisphosphonates produced a significant decrease of the markers of bone turnover. Alendronate, neridronate, and zoledronic acid significantly improved BMD at the lumbar spine, femoral neck and total hip. Zoledronic acid and neridronate were also shown to reduce bone and back pain. Probably due to the small sample sizes and to the short duration of the trials, it was not possible to establish the anti-fracture efficacy of bisphosphonates; however, they were well tolerated and adverse events were rare but expected on the basis of previous studies. Sufficient evidence exists to support the use of bisphosphonates in the management of thalassemia-associated osteoporosis (to prevent bone loss and improve the BMD). Further research is warranted to establish their anti-fracture efficacy and long-term safety.

Thalassemia major and sickle cell disease in adolescents and young adults

The increased longevity of patients with thalassemia and sickle cell disease (SCD) introduces new clinical challenges due to the accumulation of disease-related morbidity, psychosocial issues and health care adjustments. Patients with thalassemia major now live into adulthood without suffering heart failure but must confront delayed puberty, impaired fertility and progressive bone disease. The increased survival in SCD brings to the front previously unrecognized complications including pulmonary hypertension, silent cerebral infarcts and also reproductive dysfunction. Adolescents and young adults (AYAs) have age-related psychosocial needs in their transition from the pediatric health care environment to the adult system. In this review we present the uniquely age-related medical issues facing the AYA thalassemia and SCD cohort in their transition into adulthood.

Bone disease in adult patients with β-thalassaemia major: a case-control study

Despite the extraordinary improvements carried out in diagnostic and therapeutic management of thalassaemia major over the past few decades, bone demineralization is still a common finding, even in optimally treated patients. The relationships between bone density and several clinical characteristics or hematological markers have been described, and many factors contributing to demineralization have been identified; among them endocrine complications seem to play an important role. Nevertheless, the complex etiological mechanisms of this heterogeneous osteopathy still remains incompletely clarified. While previous studies focused on the characteristics of thalassaemic patients affected from bone demineralization, we conducted a case-control study focused on thalassaemic patients free from bone disease, aimed to detect the distinctive characteristics and any possible protective feature. Among a large cohort of 150 adult patients with β-thalassaemia major, we enrolled 20 patients with normal bone mineralization and 20 patients with osteoporosis matched for gender, BMI, age at first transfusion, serum ferritin and pre-transfusional hemoglobin (Hb) levels. The differences in demographic, clinical and endocrinological profiles were investigated, correcting for physical and hematological features known as confounding variables. The comparison of the two groups for biochemical parameters and endocrine function showed a protective role of normal gonadic function and IGF-1 levels against osteoporosis, and a similar influence of hypoparathyroidism. Treatment-corrected hypothyroidism and diabetes seemed not to affect bone mineralization. In conclusion, from a different perspective our results corroborate the role of endocrinopathies in thalassaemic osteopathy, and once again underline the crucial importance of an early and multi-disciplinary intervention in preventing bone complications in thalassaemic patients.

Children with hemoglobin E/β-thalassemia have a high risk of being vitamin D deficient even if they get abundant sun exposure: a study from Thailand

BACKGROUND

Vitamin D is a key component in calcium homeostasis, bone mineralization and immune function, and people with a vitamin D deficiency may therefore be at higher risk of osteoporosis, osteopenia, delayed growth and fractures. Vitamin D deficiency is a known clinical complication of patients with β-thalassemia major; however, as yet there are limited data on the vitamin D status of patients with Hb E/β-thalassemia. Hb E/β-thalassemia is characterized by a wide clinical heterogeneity ranging from non-transfusion dependency to transfusion dependency. Because patients with Hb E/β-thalassemia are so clinically diverse, the prevalence of vitamin D deficiency might differ among Hb E/β-thalassemia patients.

PROCEDURE

We investigated the vitamin D status of 109 children with Hb E/β-thalassemia who attended the Pediatric Hematology Clinic at the Siriraj Hospital in Bangkok, Thailand, from April 2009 to March 2010.

RESULTS

Forty-nine of the children were classified as transfusion-dependent (TD) and the remainder (n = 60) as non-transfusion-dependent (NTD). Only 10.1% of the children in our study had normal vitamin D levels, despite Thailand's geographic position 15° N and 100° E and climate, which provides abundant sunlight exposure and therefore efficient vitamin D synthesis. In addition, NTD children were significantly more likely to be vitamin D deficient than TD children (P = 0.01).

CONCLUSIONS

Our results highlight the importance of monitoring serum vitamin D levels in children with Hb E/β-thalassemia regardless of their clinical severity or the amount of sunlight they are exposed to.

Thalassemia bone disease: the association between nephrolithiasis, bone mineral density and fractures

Thalassemia bone disease is well described, but the prevalence of nephrolithiasis has not been characterized. The association between nephrolithiasis, reduced bone density, and increased fractures has been demonstrated through this retrospective study of 166 participants with transfusion-dependent thalassemia. The findings support the need for increased vigilance of kidney and bone disease in this cohort.

INTRODUCTION

Previous studies have revealed that thalassemia is associated with reduced bone mineral density (BMD) and fractures. Many causes are implicated including hypogonadism, growth hormone deficiency, marrow expansion, and iron overload. Nephrolithiasis is associated with reduced BMD and increased fractures in the general population. However, the prevalence of nephrolithiasis and its association with bone density and fractures have not been characterized in thalassemia.

METHODS

We have addressed this question by performing a retrospective cohort study of 166 participants with transfusion-dependent thalassemia who had undergone dual-energy X-ray absorptiometry between 2009 and 2011. Logistic regression modeling was used to adjust for potential confounders.

RESULTS

We found a high prevalence of kidney stones (18.1 %) which was greater in males compared to females (28.7 vs 9.7 %, respectively). Renal stones were associated with reduced femoral neck Z-score and fractures in men after adjusting for potential confounders. These results indicate that nephrolithiasis is highly prevalent in patients with transfusion-dependent thalassemia and is significantly associated with reduced BMD and increased fractures.

CONCLUSIONS

The findings from this study strongly support the need for ongoing surveillance of BMD, fractures, and nephrolithiasis in the management of transfusion-dependent thalassemia.