**7. Adrenal dysfunction**

Histological and imaging studies have shown that iron deposits in the adrenal cortex of thalassaemic patients are mainly confined to the zona glomerulosa with rare involvement of the zona fascicularis [95]. Most studies have revealed intact pituitary adrenal axis in thalassaemia patients [35, 60, 65, 66, 96]. Prevalence of adrenal insufficiency is variable and depends both on the degree of iron overload, cut off values for cortisol measurement and diagnostic test used [97, 98].

Poggi et al. used a low dose synacthen test with adrenal insufficiency determined by cortisol <500 nmol/L and found a prevalence of 13.7% in the study population [97]. Huang et al. used a glucagon stimulation test, followed by corticotrophin-releasing hormone and found a prevalence of 61% [98].

Raised ACTH levels were found by McIntosh which suggests primary adrenal failure [66], however Costin et al. found suppressed ACTH levels and reduced adrenal reserve despite the lack of clinical signs [5]. The diminished ability of the adrenal cortex to react to further pulses of ACTH may be reflected in the fact that baseline serum and urinary cortisol levels are usually normal [99].

Low serum Dihydroepiandrostenedione (DHEA), Dihydroepiandrostenedione Sulphate (DHEAS), androstenedione and testosterone levels were found to be

caused by the dissociation between androgen, cortisol and aldosterone synthesis. This may be the reason adrenarche is usually absent in these patients [100]. Dysfunctions in ACTH secretion circadian patterns but unaffected cortisol and aldosterone secretory were seen in these patients [101]. In addition to that, falsely low serum cortisol levels may be found in thalassaemic patients with chronic liver disease because cortisol is usually bound to cortisol binding globulin (CBG) which is produced by hepatocytes [102]. Currently, there are no reports on CBG levels in thalassaemic patients. Nonetheless, the role of CBG in adrenal insufficiency is excluded by a normal CBG level in the presence of low cortisol. In female patients, oestrogen may cause a rise in CBG levels resulting in inaccurate cortisol levels.

Current research shows female gender to be a protective factor [97]. Huang et al. have found that there was a significant prevalence of adrenal insufficiency in males when compared to females (92% vs. 29%, p = 0.049) in their study cohort [98]. Imaging studies by Drakonaki et al. using MRI scan have frequently identified adrenal hypointensity without alteration of morphology in thalassaemia patients and verified autopsy findings of correlation between adrenal iron and liver iron [103]. However a study by Guzelbey et al., found that, on the contrary, there was no statistically significant correlation between iron deposition in the adrenal glands and liver [104]. Another study suggests that imaging from Cardiac MRI T2 could be used as a surrogate of adrenal hypofunction, with a sensitivity of 81% and specificity of 78% [105]. However, despite high sensitivity, histology still remains the gold standard for diagnosis of iron deposition.

Currently, routine cortisol monitoring does not form part of the recommended routine investigations to screen for adrenal dysfunction in patients with thalassaemia [30]. However, the UK standards for thalassaemia guidelines acknowledges that annual monitoring of cortisol may allow for trends in decline to be noted, but also stress that normal cortisol levels does not exclude partial adrenal insufficiency when the patient is unwell. While current literature is very contradictory, adrenal dysfunction can be life-threatening in an acutely unwell patient. Therefore, hydrocortisone supplementation should be considered even before formal proof of insufficiency is available, if clinically relevant [30].

## **8. Osteoporosis**

Beta thalassaemia is associated with marrow expansion, osteopaenia with cortical thickening, trabecular coarsening and bone deformity [106]. Osteoporosis defined as a microarchietctual deterioration in bone tissue leading to an increased fracture risk [107]—is the predominant bone disease in beta thalassaemia. The prevalence of osteoporosis in thalassaemia is variably estimated from 13.6–50% [108]. In a cohort of well-treated thalassaemia patients, Baldini and colleagues reported demineralization—.osteoporotic or osteopaenic bone—in 92.7% [109].

Factors implicated in its cause include hypogonadism, diabetes mellitus, hypothyroidism, hypoparathyroidism, iron overload and its treatment [108, 110]. Malnutrition, inadequate exercise and absence of adrenal sex hormones during adrenarche and gonadal hormones during puberty are other contributory factors [111]. Excessive erythropoesis may also impair bone formation [112]. Iron chelation therapy is further linked to hypercalciuria, with consequential nephrolithiasis and reduced bone mineral density (BMD) [113]. Desferrioxamine is also linked to bone dysplasia, independently of osteoporosis [114].

Spine and hip osteoporosis is common in both sexes, with spinal osteoporosis more common in women and the lumbar vertebrae and femoral neck affected more frequently in men [110]. Osteoporosis is characterised by significant decreases

**71**

*Investigation and Management of Endocrinopathies in Thalassaemia Major*

in bone mineral density, both cortical and trabecular. In an Italian case series, pathological fractures were reported in 19.7% of transfusion-dependent patients with thalassaemia major [115]. With regard to putative mechanisms, significantly lower osteoprotegerin/RANKL ratios have been observed in thalassaemia patients. Excessive RANKL activity favours osteoclastic bone resorption, leading to reduced BMD [116]. Sapunarova and colleagues report 10-fold higher serum levels of sclerostin, a secreted glycoprotein with anti-osteoblastic properties, in adults with transfusion-dependent beta thalassaemia compared to controls [117]. Given its correlation with both lumbar spine/femoral neck Z-scores and incidence of fragility fractures, it has been proposed to act as a biomarker of severe osteoporosis in advanced beta thalassaemia. In Tehran, Shamishiraz et al. [1] demonstrated similar prevalence of that osteoporosis and osteopaenia in the lumbar spine (50.7% and 39.4% respectively) of patients with thalassaemia. In the same cohort, osteoporosis and osteopaenia prevalences were 10.8% and 36.9% at the femoral neck. These prevalences have been replicated in other cohorts [118, 119]. Jensen amd colleagued reported "severely low" bone mass in 51% of thalassaemia patients, with "low bone mass" in 45% [110]. Among 31 thalassaemic patients studied by Vogiatzi and colleagues (5 of whom with the milder thalassaemia intermedia phenotype), 22.6% had reduced bone mass (defined as Z score = −1 to −2 on DXA analysis) and 61.3%

Early diagnosis requires accurate estimation of BMD via densitometry. Interpretation of dual-energy X-ray absorptiometry (DXA) may be confounded in thalassaemia due to short stature and spinal deformities caused by medullary expansion, bone dysplasia and the increased rate of degenerative vertebral disc disease in TM patients [120, 121]. Artefact from hepatic iron loading might also derange DXA analysis [122]. Alternative modalities for assessing bone microarchitecture in thalassaemia include trabecular bone structure (TBS) analysis—a textural assessment derived from DXA images—and quantitative computed tomography (QCT). These alternative methods remain limited by the distinctive profile of thalassaemia osteopathy and, in the case of QCT, by the amount of vertebral iron

Prevention, early diagnosis and effective chelation therapy are most effective in arresting the progression of bone disease in thalassaemia. Tight adherence to recommended chelation treatment is required during childhood to prevent desferroximine-asssociated bone pathologies, including "pseudo-rickets" and cartilaginous dysplasia [30]. Diets rich in calcium and Vitamin D and exercise can improve the outcome [69]. The role of lifestyle interventions is particularly prominent during childhood. If deficient, calcium, vitamin D and zinc supplementation are advised, preferably via the oral route [119]. 2016 UKTS guidelines advise that many patients will require maintenance vitamin D3 supplementation [30]. Annual monitoring of vitamin D levels are recommended from age 2 years, aiming for a level of approximately 80 nmol/L. Intramuscular depot injection of vitamin D are not recommended by UKTS, nor are activated vitamin D preparations (for example alfacalcidol) in the absence of proven hypoparathyroidism secondary to iron

In terms of anti-osteoclastic treatments, the human anti-RANKL monoclonal antibody denosumab has shown promise in a Phase 2b RCT, increasing both lumbar spine and wrist BMD in transfusion-dependent TM patients [119]. Data from both Indian and Iranian cohorts suggest a role for zolendronic acid in increasing lumbar spine BMD [124, 125]. Alendronate and vitamin D regimen showed promise in an Italian Phase 2b RCT [126]. Prior to this, Morabito and colleagues showed that daily oral alendronate increased BMD in a two-year study of young adults with thalassaemia [127]. A 2016 Cochrane review of both bisphosphonates and zinc

*DOI: http://dx.doi.org/10.5772/intechopen.93861*

had a low bone mass (Z score ≤ −2) [93].

deposition [121, 123].

deposition [30].

*Investigation and Management of Endocrinopathies in Thalassaemia Major DOI: http://dx.doi.org/10.5772/intechopen.93861*

*Human Blood Group Systems and Haemoglobinopathies*

standard for diagnosis of iron deposition.

insufficiency is available, if clinically relevant [30].

dysplasia, independently of osteoporosis [114].

**8. Osteoporosis**

caused by the dissociation between androgen, cortisol and aldosterone synthesis. This may be the reason adrenarche is usually absent in these patients [100]. Dysfunctions in ACTH secretion circadian patterns but unaffected cortisol and aldosterone secretory were seen in these patients [101]. In addition to that, falsely low serum cortisol levels may be found in thalassaemic patients with chronic liver disease because cortisol is usually bound to cortisol binding globulin (CBG) which is produced by hepatocytes [102]. Currently, there are no reports on CBG levels in thalassaemic patients. Nonetheless, the role of CBG in adrenal insufficiency is excluded by a normal CBG level in the presence of low cortisol. In female patients, oestrogen may cause a rise in CBG levels resulting in inaccurate cortisol levels. Current research shows female gender to be a protective factor [97]. Huang et al. have found that there was a significant prevalence of adrenal insufficiency in males when compared to females (92% vs. 29%, p = 0.049) in their study cohort [98]. Imaging studies by Drakonaki et al. using MRI scan have frequently identified adrenal hypointensity without alteration of morphology in thalassaemia patients and verified autopsy findings of correlation between adrenal iron and liver iron [103]. However a study by Guzelbey et al., found that, on the contrary, there was no statistically significant correlation between iron deposition in the adrenal glands and liver [104]. Another study suggests that imaging from Cardiac MRI T2 could be used as a surrogate of adrenal hypofunction, with a sensitivity of 81% and specificity of 78% [105]. However, despite high sensitivity, histology still remains the gold

Currently, routine cortisol monitoring does not form part of the recommended routine investigations to screen for adrenal dysfunction in patients with thalassaemia [30]. However, the UK standards for thalassaemia guidelines acknowledges that annual monitoring of cortisol may allow for trends in decline to be noted, but also stress that normal cortisol levels does not exclude partial adrenal insufficiency when the patient is unwell. While current literature is very contradictory, adrenal dysfunction can be life-threatening in an acutely unwell patient. Therefore, hydrocortisone supplementation should be considered even before formal proof of

Beta thalassaemia is associated with marrow expansion, osteopaenia with cortical thickening, trabecular coarsening and bone deformity [106]. Osteoporosis defined as a microarchietctual deterioration in bone tissue leading to an increased fracture risk [107]—is the predominant bone disease in beta thalassaemia. The prevalence of osteoporosis in thalassaemia is variably estimated from 13.6–50% [108]. In a cohort of well-treated thalassaemia patients, Baldini and colleagues reported demineralization—.osteoporotic or osteopaenic bone—in 92.7% [109]. Factors implicated in its cause include hypogonadism, diabetes mellitus, hypothyroidism, hypoparathyroidism, iron overload and its treatment [108, 110]. Malnutrition, inadequate exercise and absence of adrenal sex hormones during adrenarche and gonadal hormones during puberty are other contributory factors [111]. Excessive erythropoesis may also impair bone formation [112]. Iron chelation therapy is further linked to hypercalciuria, with consequential nephrolithiasis and reduced bone mineral density (BMD) [113]. Desferrioxamine is also linked to bone

Spine and hip osteoporosis is common in both sexes, with spinal osteoporosis more common in women and the lumbar vertebrae and femoral neck affected more frequently in men [110]. Osteoporosis is characterised by significant decreases

**70**

in bone mineral density, both cortical and trabecular. In an Italian case series, pathological fractures were reported in 19.7% of transfusion-dependent patients with thalassaemia major [115]. With regard to putative mechanisms, significantly lower osteoprotegerin/RANKL ratios have been observed in thalassaemia patients. Excessive RANKL activity favours osteoclastic bone resorption, leading to reduced BMD [116]. Sapunarova and colleagues report 10-fold higher serum levels of sclerostin, a secreted glycoprotein with anti-osteoblastic properties, in adults with transfusion-dependent beta thalassaemia compared to controls [117]. Given its correlation with both lumbar spine/femoral neck Z-scores and incidence of fragility fractures, it has been proposed to act as a biomarker of severe osteoporosis in advanced beta thalassaemia. In Tehran, Shamishiraz et al. [1] demonstrated similar prevalence of that osteoporosis and osteopaenia in the lumbar spine (50.7% and 39.4% respectively) of patients with thalassaemia. In the same cohort, osteoporosis and osteopaenia prevalences were 10.8% and 36.9% at the femoral neck. These prevalences have been replicated in other cohorts [118, 119]. Jensen amd colleagued reported "severely low" bone mass in 51% of thalassaemia patients, with "low bone mass" in 45% [110]. Among 31 thalassaemic patients studied by Vogiatzi and colleagues (5 of whom with the milder thalassaemia intermedia phenotype), 22.6% had reduced bone mass (defined as Z score = −1 to −2 on DXA analysis) and 61.3% had a low bone mass (Z score ≤ −2) [93].

Early diagnosis requires accurate estimation of BMD via densitometry. Interpretation of dual-energy X-ray absorptiometry (DXA) may be confounded in thalassaemia due to short stature and spinal deformities caused by medullary expansion, bone dysplasia and the increased rate of degenerative vertebral disc disease in TM patients [120, 121]. Artefact from hepatic iron loading might also derange DXA analysis [122]. Alternative modalities for assessing bone microarchitecture in thalassaemia include trabecular bone structure (TBS) analysis—a textural assessment derived from DXA images—and quantitative computed tomography (QCT). These alternative methods remain limited by the distinctive profile of thalassaemia osteopathy and, in the case of QCT, by the amount of vertebral iron deposition [121, 123].

Prevention, early diagnosis and effective chelation therapy are most effective in arresting the progression of bone disease in thalassaemia. Tight adherence to recommended chelation treatment is required during childhood to prevent desferroximine-asssociated bone pathologies, including "pseudo-rickets" and cartilaginous dysplasia [30]. Diets rich in calcium and Vitamin D and exercise can improve the outcome [69]. The role of lifestyle interventions is particularly prominent during childhood. If deficient, calcium, vitamin D and zinc supplementation are advised, preferably via the oral route [119]. 2016 UKTS guidelines advise that many patients will require maintenance vitamin D3 supplementation [30]. Annual monitoring of vitamin D levels are recommended from age 2 years, aiming for a level of approximately 80 nmol/L. Intramuscular depot injection of vitamin D are not recommended by UKTS, nor are activated vitamin D preparations (for example alfacalcidol) in the absence of proven hypoparathyroidism secondary to iron deposition [30].

In terms of anti-osteoclastic treatments, the human anti-RANKL monoclonal antibody denosumab has shown promise in a Phase 2b RCT, increasing both lumbar spine and wrist BMD in transfusion-dependent TM patients [119]. Data from both Indian and Iranian cohorts suggest a role for zolendronic acid in increasing lumbar spine BMD [124, 125]. Alendronate and vitamin D regimen showed promise in an Italian Phase 2b RCT [126]. Prior to this, Morabito and colleagues showed that daily oral alendronate increased BMD in a two-year study of young adults with thalassaemia [127]. A 2016 Cochrane review of both bisphosphonates and zinc

supplementation for thalassaemia-associated osteoporosis acknowledges an accretion of evidence in favour of their use, but suggests that further RCT evidence is required [128].

Current UKTS guidelines advocate consideration of anti-osteoclastic agents for individuals with low age-adjusted BMD or in whom fragility fractures have occurred despite appropriate vitamin D/calcium or hormone supplementation. Bisphosphonate initiation should occur following consultation with a specialist in osteoporosis, given that no definite evidence exists for fracture reductions with bisphosphonates in thalassaemia patients, despite the evidence for improved BMD. Burden of adverse effects, including atypical femoral fractures and osteonecrosis of the jaw, are significant [30].

Hormone replacement therapy is beneficial in patients with concomitant osteoporosis and hypogonadism but may not offer complete resolution, due to the multifactorial nature of bone pathology in thalassaemia [129, 130]. Patients with concomitant hypogonadism require hormone replacement therapy [108].
