Prospective study of histomorphometry, biochemical bone markers and bone densitometric response to pamidronate in β-thalassaemia presenting with osteopenia-osteoporosis syndrome

Bone Health Impairment in Patients with Hemoglobinopathies: From Biological Bases to New Possible Therapeutic Strategies

Hemoglobinopathies are monogenic disorders affecting hemoglobin synthesis. Thalassemia and sickle cell disease (SCD) are considered the two major hemoglobinopathies. Thalassemia is a genetic disorder and one of the major hemoglobinopathies determined by an impairment of globin chain production, which causes an alteration of erythropoiesis, an improvement in hemolysis, and an alteration of iron homoeostasis. In SCD, the mutations are on the β-globin chain of hemoglobin which results in a substitution of glutamic acid by valine with consequent formation of Hemoglobin S (HbS). Several factors are involved in bone metabolism alteration in patients with hemoglobinopathies, among them hormonal deficiency, bone marrow hyperplasia, iron overload, inflammation, and increased bone turnover. Bone metabolism is the result of balance maintenance between bone deposition and bone resorption, by osteoblasts (OBs) and osteoclasts (OCs). An impairment of this balance is responsible for the onset of bone diseases, such as osteoporosis (OP). Therefore, here we will discuss the alteration of bone metabolism in patients with hemoglobinopathies and the possible therapeutic strategies to contain and/or counteract bone health impairment in these patients, taking into consideration not only the pharmacological treatments already used in the clinical armamentarium, but also the new possible therapeutic strategies.

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.

Impact of iron overload on bone remodeling in thalassemia

INTRODUCTION

Iron overload, a state with excessive iron storage in the body, is a common complication in thalassemia patients which leads to multiple organ dysfunctions including the bone. Iron overload-induced bone disease is one of the most common and severe complications of thalassemia including osteoporosis. Currently, osteoporosis is still frequently found in thalassemia even with widely available iron chelation therapy.

STUDY SELECTION

Relevant publications published before December 2019 in PubMed database were reviewed. Both pre-clinical studies and clinical trials were obtained using iron overload, thalassemia, osteoporosis, osteoblast, and osteoclast as keywords.

RESULTS

Increased ROS production is a hallmark of iron overload-induced impaired bone remodeling. At the cellular level, oxidative stress affects bone remodeling by both osteoblast inhibition and osteoclast activation via many signaling pathways. In thalassemia patients, it has been shown that bone resorption was increased while bone formation was concurrently reduced.

CONCLUSION

In this review, reports on the cellular mechanisms of iron overload-associated bone remodeling are comprehensively summarized and presented to provide current understanding this pathological condition. Moreover, current treatments and potential interventions for attenuating bone remodeling in iron overload are also summarized to pave ways for the future discoveries of novel agents that alleviate this condition.

Hepatic Hemosiderosis Contributes to Abnormal Vitamin D-PTH Axis in Thalassemia Major

OBJECTIVE

The aim of this study was to evaluate the vitamin D-PTH axis in thalassemia major (TM) in relation to hepatic siderosis liver iron content.

DESIGN AND PARTICIPANTS

In this case-controlled observational study, vitamin D-PTH axis was studied in 158 TM and 84 age and ethnicity-matched healthy nonthalassemic controls attending University College Hospital, London. Patients were classified as 25-hydroxy vitamin D (25-OHD) insufficient and sufficient if the value was less than or greater than 50 nmol/L, respectively. 25-OHD data were evaluated in relation to markers of iron load in TM.

RESULTS

In TM, 25-OHD insufficiency was 8-fold higher than the control group (odds ratio [OR], 8.1; 95% confidence interval [CI], 4.3-15.0; P<0.001). Similarly, serum PTH (P<0.001), calcium (P<0.001), and phosphate levels (P<0.05) were also significantly lower in TM compared with the controls. In TM, serum ferritin of >2500 μg/L (OR, 5.3; 95% CI, 2.3-12.3; P<0.01), liver iron of >7 mg/g dry weight (OR, 8.8; 95% CI, 3.5-10.3; P<0.001), and serum alanine aminotransferase of >50 IU/L (OR, 9.7; 95% CI, 4.0-23.5; P<0.001) were independent risk factors for low 25-OHD levels.

CONCLUSIONS

Our results suggest that TM had a 8-fold higher risk of 25-OHD insufficiency compared with the controls. This was likely to be associated with hepatic hemosiderosis.

Congenital disorders of bone and blood

Bone and marrow are the two facets of the same organ, in which bone and hematopoietic cells coexist and interact. Marrow and skeletal tissue influence each-other and a variety of genetic disorders directly targets both of them, which may result in combined hematopoietic failure and skeletal malformations. Other conditions primarily affect one organ with secondary influences on the other. For instance, various forms of congenital anemias reduce bone mass and induce osteoporosis, while osteoclast failure in osteopetrosis prevents marrow development reducing medullary cavities and causing anemia and pancytopenia. Understanding the pathophysiology of these conditions may facilitate diagnosis and management, although many disorders are presently incurable. This article describes several congenital bone diseases and their relationship to hematopoietic tissue.

Dual-Energy X-ray Absorptiometry Predictors of Vertebral Deformities in Beta-Thalassemia Major

Vertebral fractures in beta-thalassemia major are increasingly found because of the longer life expectancy of patients, with a major negative impact on their quality of life. We performed a retrospective cross-sectional study to investigate the prevalence of vertebral deformities in thalassemic patients and to identify their best dual-energy X-ray absorptiometry (DXA) predictor among trabecular bone score (TBS), bone mineral density (BMD), and Z-score. Eighty-two outpatients with beta-thalassemia major on regular conventional treatment were studied at a single academic center. All patients underwent plain thoracic-lumbar spine X-rays and lumbar DXA to assess the number and the severity of vertebral deformities (Genant's method), the spinal deformity index, lumbar spine DXA parameters (BMD, TBS, and Z-score), and the presence of platyspondyly. Twenty-nine patients (35%) had vertebral deformities and showed significantly lower TBSs than the remainders (1.141 ± 0.083 vs 1.254 ± 0.072, p < 0.0001). The analysis of variance of the TBS between the group of patients without vertebral deformities (spinal deformity index = 0) and the remaining groups showed a significant difference (p < 0.001). The TBS had better sensitivity (86.2%), specificity (75.5%), and diagnostic accuracy (79.3%) than BMD and Z-score in discriminating patients with and without vertebral deformities. Combining the TBS with the BMD or the Z-score showed that the diagnostic accuracy of the first in discriminating patients with and without vertebral deformities improved from 79.3% to 85.4% and 87.8%, respectively. The presence of platyspondyly was a significant predictor of vertebral deformities in the multivariate model. Vertebral deformities in well-treated patients with beta-thalassemia major are common and are often unrecognized. In our hands, the TBS was better than the BMD and the Z-score in predicting vertebral deformities. Plain X-rays of the spine should be performed also in asymptomatic patients, especially when the TBS is low.

The role of biphosphonates in the management of thalassemia-induced osteoporosis: a systematic review and meta-analysis

Thalassemia Major (TM) is a clinical entity with a high prevalence of low bone mass. The aim of the present study was to perform a meta-analysis of all available data on the role of bisphosphonates (BPs) in the therapy of thalassemia major-induced osteoporosis. The PRISMA recommendations for reporting systematic reviews and meta-analyses were used to guide the present study. We searched PubMed and the Cochrane Central Register of Controlled Trials (CENTRAL) through March 31, 2017 for articles related to thalassemia and BPs. To meta-analytically synthesize the primary endpoint, we used the standardized mean difference (SMD) after Hedges's g transformation under the scenario of a random effects model. Heterogeneity across studies was examined using the I² statistic. Nine randomized controlled trials (RCTs) containing original data were included in this review. Three studies were performed in Italy, one in Australia, three in Greece, one in Cyprus, and one in China. The BPs investigated included zoledronate, alendronate, pamidronate, clodronate, and neridronate. Zoledronate and alendronate showed a tendency to perform best as compared to neridronate and the placebo effect with respect to femoral neck, lumbar spine, total hip, and total body in terms of bone mass density (g/cm²). BPs and in particular, zolendronate, were quite effective in the treatment of osteoporosis. These findings suggested that bisphosphonates are still a front-line treatment of osteoporosis in TM. However, to draw more meaningful and significant conclusions for the use and efficacy of BP in TM, larger and more complete RCTs should be conducted.

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.

Bone disease in β thalassemia patients: past, present and future perspectives

Bone disorders in patients with thalassemia major (TM) and intermedia (TI) constitute complex conditions that result from various factors affecting the growing skeleton. Although much progress has been made in our understanding of the natural history, pathogenesis and clinical manifestations of β- and δβ-thalassemia, bone manifestations remain a puzzle for the clinician. In this review, we outline the key points in the current literature on the pathogenesis and management of bone disease in patients with TM and TI who were conventionally treated in recent decades with frequent blood transfusions and iron chelation. Prevention, early recognition and treatment are the most effective strategies for the management of bone disease in these patients. However, further studies are required to maintain optimal bone health for both TM and TI patients. Studying bone disease in patients with non-transfusion dependent TI, which seems to worsen considerably with age, is important to delineate the effect of the disease itself on bone health without the intervening factors of transfusions, iron intoxication and chelation.

Impact of bone disease and pain in thalassemia

Conventional treatment of thalassemia, namely regular blood transfusion and iron chelation, improves perspectives and quality of life; however, successful treatment leads to more time in which long-term complications such as bone disease can develop. Thalassemia bone disease (TBD) is unique: all aspects, from bone anatomy and bone quality to mineral density, may be affected, with important morbidity including osteoporosis, fractures, spinal deformities, nerve compression, and pain. Clinical presentations include growth impairment, rickets-like features, back pain, spinal deformities, any sign of nerve compression, severe osteoporosis, and fragility fractures. Age, history, physical examination, and diagnostic tests support orientation on risk factors. These include bone marrow expansion, toxicity from iron overload and iron chelation, endocrine dysfunctions (hypogonadism, hypohyperparathyroidism, hypothyroidism, growth hormone deficiency, diabetes), and vitamin (D, C, K) and zinc deficiencies. Several of these may coexist in an individual for a long time and at different degrees, making clarification of the relative contribution and selection of the best therapeutic options a challenge. Milestones for prevention of TBD are early and full inhibition of bone marrow hyperplasia and iron toxicity. Empowering patients' positive resources is key for achieving long-term healthy habits with regard to diet, physical activity, sunlight exposure, and lifestyle. Pain, related or unrelated to bone disease, is frequent in thalassemia. The most important targets for the hematologist include having an expert orientation on disease-related causes of pain, driving differential diagnosis, providing effective pain relief and, where feasible, removing the cause.

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.

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.

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.

Spine bone texture assessed by trabecular bone score (TBS) to evaluate bone health in thalassemia major

Due to the increasing survival of thalassemic patients, osteopathy is a mounting clinical problem. Low bone mass alone cannot account for the high fracture risk described; impaired bone quality has been speculated but so far it cannot be demonstrated noninvasively. We studied bone quality in thalassemia major using trabecular bone score (TBS), a novel texture measurement extracted from spine dual-energy X-ray absorptiometry (DXA), proposed in postmenopausal and secondary osteoporosis as an indirect index of microarchitecture. TBS was evaluated in 124 adult thalassemics (age range 19-56 years), followed-up with optimal transfusional and therapeutical regimens, and in 65 non-thalassemic patients (22-52 years) undergoing DXA for different bone diseases. TBS was lower in thalassemic patients (1.04 ± 0.12 [range 0.80-1.30]) versus controls (1.34 ± 0.11 [1.06-1.52]) (p < 0.001), and correlated with BMD. TBS and BMD values correlated with age, indicating that thalassemia negatively affects both bone quality and quantity, especially as the patient gets older. TBS was 1.02 ± 0.11 [0.80-1.28] in the osteoporotic thalassemic patients, 1.08 ± 0.12 [0.82-1.30] in the osteopenic ones and 1.15 ± 0.10 [0.96-1.26] in those with normal BMD. No gender differences were found (males: 1.02 ± 0.13 [0.80-1.30], females 1.05 ± 0.11 [0.80-1.30]), nor between patients with and without endocrine-metabolic disorders affecting bone metabolism. Our findings from a large population with thalassemia major show that TBS is a valuable tool to assess noninvasively bone quality, and it may be related to fragility fracture risk in thalassemic osteopathy.

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.

Iron overload causes osteoporosis in thalassemia major patients through interaction with transient receptor potential vanilloid type 1 (TRPV1) channels

The pathogenesis of bone resorption in β-thalassemia major is multifactorial and our understanding of the underlying molecular and cellular mechanisms remains incomplete. Considering the emerging importance of the endocannabinoid/endovanilloid system in bone metabolism, it may be instructive to examine a potential role for this system in the development of osteoporosis in patients with β-thalassemia major and its relationship with iron overload and iron chelation therapy. This study demonstrates that, in thalassemic-derived osteoclasts, tartrate-resistant acid phosphatase expression inversely correlates with femoral and lumbar bone mineral density, and directly correlates with ferritin levels and liver iron concentration. The vanilloid agonist resiniferatoxin dramatically reduces cathepsin K levels and osteoclast numbers in vitro, without affecting tartrate-resistant acid phosphatase expression. The iron chelators deferoxamine, deferiprone and deferasirox decrease both tartrate-resistant acid phosphatase and cathepsin K expression, as well as osteoclast activity. Taken together, these data show that transient receptor potential vanilloid type 1 activation/desensitization influences tartrate-resistant acid phosphatase expression and activity, and this effect is dependent on iron, suggesting a pivotal role for iron overload in the dysregulation of bone metabolism in patients with thalassemia major. Our applied pharmacology provides evidence for the potential of iron chelators to abrogate these effects by reducing osteoclast activity. Whether iron chelation therapy is capable of restoring bone health in humans requires further study, but the potential to provide dual benefits for patients with β-thalassemia major -preventing iron-overload and alleviating associated osteoporotic changes - is exciting.

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.