Biochemical Markers of Bone Turnover in Patients with β-Thalassemia Major: A Single Center Study from Southern Pakistan

Factors associated with phosphate homeostasis in children with beta-thalassemia major: An analytical cross sectional study from Pakistan

INTRODUCTION

Children with beta-thalassemia major (β-TM) commonly experience metabolic bone diseases. Understanding fibroblast growth factor 23 (FGF-23) levels in these children can shed light on phosphate dysregulation. This study aimed to assess changes in phosphate homeostasis and associated factors, including FGF-23 and explore relationships between iron overload, FGF23 levels, and phosphorus regulation for clinical management of phosphate disorders, in children with β-TM.

METHODS

143 β-TM patients (57.3% male, median age 12 years) were recruited from Fatimid Foundation Karachi, a blood transfusion facility from January to October 2022. Clinical and biochemical evaluations were conducted at Aga Khan University Hospital, including serum ferritin, calcium (Ca), phosphate (P), vitamin D levels, and FGF-23. Descriptive and inferential statistics including multivariable analysis were applied.

RESULTS

This study enrolled 143 patients, with 57.3% males. The median age was 12 years, with 53% underweight. Blood transfusion rates varied, with 66.4% receiving 2/month. Bone/joint pain was reported by 76.2%, with 60.8% requiring analgesics. Median serum ferritin was 2768.3 ng/mL. Hypophosphatemia and hyperphosphatemia were observed in 5.6% and 3.5% of participants, respectively. Vitamin D deficiency/insufficiency affected 92.3%. Plasma c-FGF23 was elevated in 60.8%, while i-FGF23 was high in 14%. A low TMP-GFR (glomerular filtration rate) was associated with high c-FGF23 and low i-FGF23. Multivariable regression revealed c-FGF23, TMP:GFR, Corrected Ca, iPTH, and an interaction term between corrected Ca and iPTH as predictors of serum P variability (~75%).

CONCLUSION

The study identified contributors to the variations observed in serum P levels in individuals with β-TM and recommends multidisciplinary care and prospective future studies to form targeted interventions for this population.

Assessment of Serum Vitamin D and Parathyroid Hormone in Children With Beta Thalassemia Major: A Case-Control Study

BACKGROUND

A defective synthesis of vitamin D contributes to alterations in calcium homeostasis due to chronic endocrinopathies, leading to metabolic bone diseases. This study aimed to ascertain the levels of calcium, vitamin D, and parathyroid hormone (PTH) in children with β-thalassemia.

METHODS

In this case-control study, 36 children with major β-thalassemia receiving iron chelation therapy were included. For the control group, 36 cases matched for age and sex were selected. The packed cell volume (PCV) requirements varied among the thalassemic children, with an average PCV requirement of 78.57±49.07. The study was conducted for six months in the Department of Pediatrics at the Government Medical College, Nagpur, India. Serum PTH levels were determined by immunoassay, and serum vitamin D levels were assessed using electrochemiluminescence technique. Additional tests looked at liver function, serum ferritin, calcium, phosphorus, and complete blood count. The student's t-test, Mann-Whitney, and chi-square tests were used for statistical analysis.

RESULT

In comparison to the control group (10.4±1.21 g/dL), the case group's mean hemoglobin level was considerably lower (5.62±1.9 g/dL) (p<0.001). The mean serum ferritin level in the cases was notably higher (3073±1262.24 ng/mL) compared to the control group's level (58.37±29.67 ng/mL) (p<0.001). A total of 80.6% of cases compared to 5.6% of controls had vitamin D deficiency, and 72.2% of cases compared to 2.8% of controls had PTH deficit, both of which showed statistically significant differences (p<0.001). Significant differences were observed between the case and control groups for the mean levels of total serum calcium (8.51±0.84 mg/dL), vitamin D (15.23±10.07 ng/mL), and PTH (14.66±19.86 pg/mL) (9.13±0.6 mg/dL, p=0.05; 34.94±9.57 ng/mL, p<0.001; 32.08±12.42 pg/mL, p<0.001; respectively).

CONCLUSION

Growth failure may result from the markedly reduced serum calcium, vitamin D, and PTH levels in children with β-thalassemia. The relevance of treatment approaches is highlighted by the possibility that these anomalies are caused by excessive iron and inadequate nutritional support.

Identification of osteopenia and osteoporotic changes in pediatric thalassemia patients at thalassemia center, Misan city, Iraq; An intervention study

Background: Thalassemia syndrome is a heterogeneous group of hereditary disorders affecting the synthesis of globin chains of adult hemoglobin's, leading to ineffective erythropoiesis, hemolysis, and moderate to severe anemia. To identify the incidence of osteopenia and osteoporosis and it is relation to some of the probable risk factors of decreasing BMD among thalassemia patients attended Misan thalassemia center in Misan city in Iraq. Methods: A randomized cross-sectional study, applied through a period from September 2020 to September 2021, on 50 thalassemia patients attended thalassemia Center Amarah, Misan, Iraq. 24 were males and 26 were females, we divided them in to two groups according to age (10-14) years, (>14-18) years. They were scanned for bone mineral density (BMD) at lumbar spine. Results: 90% of patients had reduction in BMD patients mostly among THM patients. 40% had positive family history of thalassemia, Vitamin D3 level were low in (80%) of patients & DEXA studies were mostly between [(-1) -(-2.5)] before treatment that slightly improved after therapy in ranges of osteopenia but not in osteoporosis which increase severity as well. Conclusions:  Most thalassemia patient had severe anemia, corrected by frequent blood transfusion are complicated by increasing serum ferritin level and decreasing level of vitamin D3 in association with reduction in bone density mass in ranges of osteopenia and osteoporosis which correlates positively with increasing ages, early age at diagnosis and female gender  this altered bone mass density  require family awareness for better nutrition and optimum medical therapy and compliance to improve outcomes.     

Assessment of serum vitamin D levels in Egyptian children with beta-thalassemia major

Background

Beta-thalassemia major patients are at increased risk of complications including endocrinopathies and bone disease due to iron overload. So, this study aimed to assess the growth parameters, serum levels of 25-OH-vitamin D, calcium, and phosphorous in children with beta-thalassemia major. This was a case-control study that included 55 children with beta-thalassemia major compared with 30 sex- and age-matched healthy children that served as a control group. All enrolled children were subjected to full history taking, clinical examination including anthropometric measurements, and laboratory investigations including complete blood count, serum ferritin, levels of serum calcium, phosphorus, and 25-OH-vitamin D.

Results

Body mass index was statistically significantly lower in the thalassemic group (P < 0.001). It was observed that vitamin D levels were significantly lower in thalassemic patients than in controls (P value < .0001). The mean serum 25-OH-vitamin D levels were 19.84 ± 5.79 ng/ml and 44.98 ± 5.77 ng/ml, respectively; 22 cases (40%) had insufficient vitamin D, and 5 cases (9%) had deficient vitamin D. Regarding serum calcium and phosphorous, there was no significant difference between the thalassemic and control groups.

Conclusion

Children with beta-thalassemia major had low body mass index and metabolic abnormality in the form of lower serum levels of vitamin D that signify the importance of therapeutic interventions.

Increased zinc and albumin but lowered copper in children with transfusion-dependent thalassemia

BACKGROUND

Measurements of copper and zinc in transfusion-dependent thalassemia (TDT) show contradictory results.

AIM OF THE STUDY

To examine serum levels of these minerals in TDT in relation to iron overload indices and erythron variables.

METHODS

This study recruited 60 children with TDT and 30 healthy controls aged 3-12 years old.

RESULTS

Zinc was significantly higher in TDT children than in controls, while copper and the copper to zinc ratio were significantly lowered in TDT. Serum zinc was significantly associated with the number of blood transfusions and iron overload variables (including serum iron and TS%) and negatively with erythron variables (including hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin). Serum copper was significantly and negatively associated with the same iron overload and erythron variables. The copper to zinc ratio was significantly correlated with iron, TS%, ferritin, hemoglobin, mean corpuscular volume, and mean corpuscular hemoglobin. Albumin levels were significantly higher in TDT children than in control children.

CONCLUSION

Our results suggest that the increase in zinc in children with TDT may be explained by iron loading anemia and hemolysis and the consequent shedding of high amounts of intracellular zinc into the plasma. Increased albumin levels and treatment with Desferral may further contribute towards higher zinc levels in TDT. We suggest that the elevations in zinc in TDT are a compensatory mechanism protecting against infection, inflammation, and oxidative stress. Previous proposals for prophylactic use of zinc supplements in TDT may not be warranted.

An Evaluation of Bone Health Parameters in Regularly Transfused Beta-Thalassemia Major Patients

As beta-thalassemia major patients need regular blood transfusions due to the severe hemoglobin deficiency, the occurrence of related bone defects with simultaneous fluctuations in the biochemical and hematologic parameters is seen. The hospital-based cross-sectional observational study was done to determine and correlate the bone mineral density (BMD) with biochemical parameters and hematologic parameters in 50 regularly transfused beta-thalassemia major patients of older than 6 years of age. Descriptive statistics were analyzed with SPSS version 20.0 software. A P<0.05 was considered as statistically significant. The prevalence of suboptimal BMD at lumbar spine was 86% and at femur neck was 74%. A statistically significant correlation of BMD was found with mean pretransfusion hemoglobin values, serum calcium levels, and serum vitamin D levels (P<0.05). It was concluded that continuous monitoring of the BMD, biochemical, and hematologic parameters in regularly transfused beta-thalassemia major patients may help assess the ongoing deficiencies; helping to maintain timely and regular blood transfusions with supplementation of calcium, vitamin D to ensure good bone health.

Association of VDBP rs4701 Variant, but not VDR/RXR-α Over-Expression with Bone Mineral Density in Pediatric Well-Chelated β-Thalassemia Patients

BACKGROUND

The reduced rate of bone formation despite the availability of vitamin D has been reported in β-thalassemia. Genetic factors, together with environmental ones, could be implicated in this condition. Since vitamin D binding protein (VDBP) maintains bioavailability of vitamin D which binds to vitamin D receptor (VDR)-retinoid X receptor alpha (RXRA) heterodimer to exert its molecular actions, we speculated that vitamin D metabolic-axis expression signature and variants could be potential molecular candidates for bone turnover/disease in thalassemia. To this end, this study aims to analyze VDR/RXRA expression signature, and two VDBP variants in a pilot sample of Egyptian β-thalassemia children in correlation with bone mineral density (BMD).

PATIENTS AND METHODS

Forty-four well-chelated β-thalassemia children and 40 unrelated controls were enrolled. The serum bone chemistry profile was measured. Peripheral blood mononuclear cells (PBMN) VDR/RXRA expression levels were quantified by Real-Time quantitative reverse transcription-polymerase chain reaction (qRT-PCR). VDBP rs7041 and rs4588 variants were identified by Real-Time allelic discrimination assay. All patients were subjected to lumbar-spine Dual-energy X-ray absorptiometry (DEXA).

RESULTS

VDR/RXRA expressions were significantly higher in β-thalassemia children compared to controls (P = 0.001 and <0.001, respectively) and showed higher values in β-thalassemia major relative to β-thalassemia intermedia. Expression levels of both genes were not associated with sex or BMD. However, VDBP rs4701 genotyping revealed lower BMD-L4 and a higher frequency of osteoporosis.

CONCLUSIONS

β-Thalassemia children had higher expression levels of PBMN VDR/RXRA. VDBP rs4701 variant was associated with osteoporosis in our β-thalassemia patients on vitamin D supplementation. Further large-scale studies in other ethnic populations are warranted.

Differential effects of Fe2+ and Fe3+ on osteoblasts and the effects of 1,25(OH)2D3, deferiprone and extracellular calcium on osteoblast viability under iron-overloaded conditions

One of the potential contributing factors for iron overload-induced osteoporosis is the iron toxicity on bone forming cells, osteoblasts. In this study, the comparative effects of Fe³⁺ and Fe²⁺ on osteoblast differentiation and mineralization were studied in UMR-106 osteoblast cells by using ferric ammonium citrate and ferrous ammonium sulfate as Fe³⁺ and Fe²⁺ donors, respectively. Effects of 1,25 dihydroxyvitamin D₃ [1,25(OH)₂D₃] and iron chelator deferiprone on iron uptake ability of osteoblasts were examined, and the potential protective ability of 1,25(OH)₂D₃, deferiprone and extracellular calcium treatment in osteoblast cell survival under iron overload was also elucidated. The differential effects of Fe³⁺ and Fe²⁺ on reactive oxygen species (ROS) production in osteoblasts were also compared. Our results showed that both iron species suppressed alkaline phosphatase gene expression and mineralization with the stronger effects from Fe³⁺ than Fe²⁺. 1,25(OH)₂D₃ significantly increased the intracellular iron but minimally affected osteoblast cell survival under iron overload. Deferiprone markedly decreased intracellular iron in osteoblasts, but it could not recover iron-induced osteoblast cell death. Interestingly, extracellular calcium was able to rescue osteoblasts from iron-induced osteoblast cell death. Additionally, both iron species could induce ROS production and G0/G1 cell cycle arrest in osteoblasts with the stronger effects from Fe³⁺. In conclusions, Fe³⁺ and Fe²⁺ differentially compromised the osteoblast functions and viability, which can be alleviated by an increase in extracellular ionized calcium, but not 1,25(OH)₂D₃ or iron chelator deferiprone. This study has provided the invaluable information for therapeutic design targeting specific iron specie(s) in iron overload-induced osteoporosis. Moreover, an increase in extracellular calcium could be beneficial for this group of patients.

Effect of serum fibroblast growth factor receptor 2 and CAPS proteins on calcium status in β-thalassaemia major patients who are free from overt inflammation

Bone disorders and disturbed calcium (Ca) homeostasis are common disorders in β-thalassaemia major (β-TM). In the present study, two bone related markers are studied in β-TM patients with negative C-reactive protein for the first time; fibroblast growth factor receptor 2 (FGFR2) and CAPS protein. Another goal is to estimate the correlation between the recent parameters and bone biomaterials as a function of iron status parameters in β-TM patients. The results revealed that, in patients with β-TM serum FGFR2, CAPS, alkaline phosphatase (ALP) and Mg significantly increased while serum Ca levels were low as compared with controls. Ca status is correlated with iron overload in β-TM. A significant correlation was present between CAPS and FGFR2. In conclusion, FGFR2 and CAPS associated with Ca status and subsequent bone disturbances in β-TM patients. Their level can be predicted from the equation: CAPS =0.001ALP +0.48FGFR2-1.26Ca - 3.95Pi +12.76 with acceptable applicability.

Hypothyroidism and Hypoparathyroidism in Thalassemia Major Patients: A Study in Sistan and Baluchestan Province, Iran

BACKGROUND

Hypothyroidism (HT) and hypoparathyroidism (HPT) are common endocrine complications in thalassemia major (TM) patients.

OBJECTIVES

In the present study, we assessed the frequency of HT and HPT in a population of TM patients in Southeast of Iran.

METHODS

This cross sectional study was performed on 194 TM patients in Zabol, Sistan and Baluchestan Province, Iran, during February - July 2016. The demographic, clinical, and laboratory data were collected via interviews and history - taking. For hormone measurements, specific ELISA kits were used. Statistical analysis was performed in SPSS version 16.

RESULTS

A total of 103 (53.1%) and 91 (46.9%) females and males were recruited in this study, respectively. The mean age of the patients was 15 ± 7.5 years. HT and HPT showed overall frequencies of 8.2% (18/194) and 18% (35/194), respectively. Subclinical and overt HT were observed in 13 (6.7%) and 5 (2.6%) patients, respectively. There was no significant association between HT and age, while patients with HPT were significantly older than those without HPT (20.1 ± 5.8 vs. 13.9 ± 6.2 years; P < 0.001). HPT was significantly associated with the mean received blood per transfusion (P = 0.009), total transfused blood per year (P = 0.01), splenomegaly (P < 0.001), splenectomy (P < 0.001), hepatomegaly (P = 0.01), and chelation regimen (P < 0.001). The ferritin level was correlated with neither HT nor HPT. Also, no significant difference was observed between patients with or without HT or HPT regarding the cooccurrence of either diabetes or hepatitis C virus (HCV) infection. In the multivariate analysis, splenectomy remained an independent risk factor for HPT after correction for potential covariates (OR, 6.5; 95% CI, 1 - 39.2; P = 0.04).

CONCLUSIONS

In patients with TM, HT was a complication with a relatively low frequency, while HPT was more common. Based on the findings, HPT was more frequent in older patients receiving regular blood transfusions, thereby necessitating close monitoring of these patients.

Minerals in thalassaemia major patients: An overview

Thalassaemia major (TM) is a hereditary blood disease characterised by reduced or absent production of beta globin chains. Erythrocyte transfusions are given to raise the haemoglobin level in patients with thalassaemia major. However, transfusions have been related to increased risk of iron overload and tissue damage related to excess iron. Both elevated oxidative stress due to iron overload and increased hemolysis lead to over utilisation of minerals required for antioxidant enzymes activities. Iron chelators have been used to prevent iron overload in thalassaemia major patients, but these chelators have the possibility of removing minerals from the body. Thalassaemia patients are more at risk for mineral deficiency because of increased oxidative stress and iron chelation therapies. Growth and maturational delay, cardiomyopathy, endocrinopathies and osteoporosis are the complications of thalassaemia. Minerals may play a particular role to prevent these complications. In the current review, we provide an overview of minerals including zinc (Zn), copper (Cu), selenium (Se), magnesium (Mg) and calcium (Ca) in thalassaemia major patients. We, also, underline that some complications of thalassaemia can be caused by an increased need for minerals or lack of the minerals.