Thalassemic osteopathy: A new marker of bone deposition

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.

The efficacy of alendronate for the treatment of thalassemia-associated osteoporosis: a randomized controlled trial

Background

With adequate blood transfusion and iron chelation, thalassemia patients have a longer life expectancy and experience long-term metabolic complications, including osteoporosis, fractures, and bone pain. Alendronate, an oral bisphosphonate, is currently used to treat various types of osteoporosis. However, the efficacy for the treatment of thalassemia-associated osteoporosis remains unclear.

Methods

We conducted a randomized controlled trial to evaluate the efficacy of alendronate for the treatment of osteoporosis in thalassemia patients. Patients were included if they were males (18-50 years) or premenopausal females with low bone mineral density (BMD) (Z-score < -2.0 SD) or positive vertebral deformities from vertebral fracture analysis (VFA). Stratified randomization was performed according to sex and transfusion status. Patients were 1:1 allocated to receive once weekly alendronate 70 mg orally or placebo for a total duration of 12 months. BMD and VFA were re-evaluated at 12 months. Markers of bone resorption (C-terminal crosslinking telopeptide of type I collagen; CTX) and bone formation (Procollagen type I N-terminal propeptide; P1NP), and pain scores were measured at baseline, 6 months, and 12 months. The primary outcome was the change of BMD. The secondary endpoints were changes in bone turnover markers (BTM) and pain scores.

Results

A total of 51 patients received the study drug, 28 patients were assigned to receive alendronate and 23 patients to receive placebo. At 12 months, patients in the alendronate group had significant improvement of BMD at L1-L4 compared to their baseline (0.72 ± 0.11 vs 0.69 ± 0.11 g/cm², p = 0.004), while there was no change in the placebo group (0.69 ± 0.09 vs 0.70 ± 0.06 g/cm², p = 0.814). There was no significant change of BMD at femoral neck in both groups. Serum BTMs were significantly decreased among patients receiving alendronate at 6 and 12 months. The mean back pain score was significantly reduced compared to the baseline in both groups (p = 0.003). Side effects were rarely found and led to a discontinuation of the study drug in 1 patient (grade 3 fatigue).

Conclusion

Alendronate 70 mg orally once weekly for 12 months effectively improves BMD at L-spine, reduces serum BTMs, and alleviates back pain in thalassemia patients with osteoporosis. The treatment was well tolerated and had a good safety profile.

Bone mineral density among Palestinian patients suffering from hemoglobinopathy disorders

This study aimed to investigate the correlation between bone mineral density (BMD) with hemoglobin and ferritin levels in Palestinian patients suffering from various types of hemoglobinopathies. The study revealed the thresholds of hemoglobin and ferritin to protect against low BMD in these patients.

PURPOSE

Iron overload is the main cause of low BMD in subjects with hemoglobinopathies. We used iron overload-related parameters like hemoglobin and ferritin to estimate the cutoff values required to maintain bone health and identify subjects with low BMD.

METHODS

Palestinian patients (135) suffering from various types of hemoglobinopathies were recruited from various medical centers including 87 β thalassemia major (TM), 13 thalassemia intermedia (TI), 16 sickle cell anemia (SCA), 17 sickle cell thalassemia (SCT), and 1 thalassemia trait (TT). Most subjects (84%) were below the age of 30 years. BMD was measured and the z score was used to identify subjects with low BMD (z < - 2.0). Receiver operator characteristic (ROC) curve analysis was used to estimate the thresholds of hemoglobin and ferritin levels needed to protect against low BMD in these patients.

RESULTS

No difference in means of age, weight, BMI, hemoglobin, and ferritin levels among the recruited male and female subjects were observed. The results showed that 77% of TM subjects had low BMD levels and femoral neck and total hip BMD were significantly lower among female compared to male subjects. Thalassemia patients (TM, TI, and SCT combined) had significantly low BMD and lower hemoglobin mean values compared to normal BMD subjects (8.54 vs. 9.25 g/dL, p = 0.01). Pearson's correlation analysis showed positive correlation between hemoglobin levels and BMD at the three sites, being higher with lumbar spine (r = 0.444) compared to femoral neck (r = 0.291) and total hip (r = 0.224). Ferritin levels in TM patients (4800 ng/ml) and TI subjects (1500 ng/ml) were abnormally high. ROC curve analysis showed that hemoglobin threshold ≤ 9.3 g/dL represents a risk for developing low BMD with an area under the ROC curve (AUC) 0.699 and sensitivity and specificity were 87.9% and 47.7%, respectively. Similar analysis revealed that Ferritin threshold to protect against low BMD should be maintained below 2300 ng/ml with AUC 0.619 and sensitivity and specificity were 55.0% and 71.4%, respectively.

CONCLUSIONS

The results of this study strongly recommend to maintain hemoglobin levels above 9.3 g/dL and ferritin below 2300 ng/ml to protects against low BMD in TM subjects and patients suffering from the other related hemoglobinopathies.

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.

Consumption of Greek yogurt during 12 weeks of high-impact loading exercise increases bone formation in young, adult males – a secondary analysis from a randomized trial

Exercise combined with protein and calcium has been shown to benefit bone turnover and bone metabolism. Greek yogurt (GY) contains important nutrients that support bone but has yet to be studied with exercise for this purpose. Thirty untrained, university-aged, males were randomized to 2 groups (n = 15/group): GY (20 g protein, 208 mg calcium/dose) or placebo pudding (PP; 0 g protein, 0 g calcium/dose) consumed 3×/day on training days and 2×/day on nontraining days. Both groups underwent a resistance/plyometric training program for 12 weeks. Blood was obtained at weeks 0, 1, and 12 to measure procollagen-type-I-N-terminal-propeptide (P1NP) and C-terminal-telopeptide (CTX). After outlier treatment, P1NP increased more over time in GY versus PP (p = 0.002; interaction). Both groups decreased CTX over time (p = 0.046; time effect). Following 1 week of training, there was a trend towards a significant increase in CTX in PP with no change in GY (p = 0.062; interaction). P1NP changed more in GY than PP (baseline to week 12; p = 0.029) as did the P1NP/CTX ratio (p = 0.015) indicating a greater increase in formation with GY. Thus, GY added to a high-load, high-impact exercise program positively shifted bone turnover towards increased formation while attenuating resorption. GY could be a plausible postexercise food to support bone health in young adult males.

Novelty Greek yogurt, with exercise, increased bone formation in young adult males over 12 weeks. After 1 week of an osteogenic exercise program, Greek yogurt tended to blunt a rise in bone resorption seen with the placebo. Greek yogurt is a plausible postexercise food that supports bone.

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.

Site-Specific Onset of Low Bone Density and Correlation of Bone Turnover Markers in Exclusive Breastfeeding Mothers

PURPOSE

Lactation often affects calcium metabolism and induces bone loss. Calcium supplementation and a high calcium diet are recommended to prevent bone loss, especially during inadequate calcium intake. Our study aimed at determining bone loss in breastfeeding mothers, and if it occurred, whether it was site specific and there were correlations between serum bone turnover markers.

MATERIALS AND METHODS

Since the 6-month exclusive breastfeeding is usually recommended in several countries, our study examined bone mineral density (BMD) in early (1-2 month), mid (3-4 month)-, and late (5-6 month) lactation compared with nonpregnant, nonlactating control women. Site-specific bone loss was monitored in lumbar vertebrae and femora. Bone turnover markers, that is, C-terminal telopeptide of type 1 collagen and N-terminal propeptide of type 1 collagen (P1NP), were determined by electrochemiluminescence immunoassays.

RESULTS

The onset of bone loss in exclusive breastfeeding mothers was site specific, for example, in the lumbar bone at mid-lactation and in the femoral bone in late lactation. Serum ionized calcium levels in late lactation were lower than the normal levels. In addition, a correlation was found between bone turnover marker, P1NP, and femoral BMD.

CONCLUSIONS

The onset of bone loss in exclusive breastfeeding mothers was site specific, and the lumbar bone was a vulnerable and perhaps better representative site for bone loss detection. It was suggested that the optimal starting time for calcium supplementation should be before the mid-lactation when the bone loss was observed. In addition, the biochemical marker that best predicted the onset of bone loss in lactating women was P1NP.