Acromegaly has a negative influence on trabecular bone, but not on cortical bone, as assessed by high-resolution peripheral quantitative computed tomography

Influence of disease activity and gonadal status on bone mineral density and turnover in acromegaly

INTRODUCTION

The purpose of this study was to evaluate the impact of disease activity and gonadal status on bone mineral density (BMD) and turnover markers (BTMs) in individuals with acromegaly.

MATERIALS AND METHODS

Subjects underwent laboratory tests for PTH, 25-hydroxyvitamin D, calcium, phosphorus, osteocalcin (OC) and C-telopeptide (CTX-1) and bone densitometry at the lumbar spine (LS), femoral neck (FN) and total hip (TH).

RESULTS

Sixty participants (48.6 ± 11.0 years; 66,7% female) were included in this cross-sectional study. Phosphorus, OC, CTX-1, and LS BMD were greater in the active disease group than in the controlled/cured disease group (P = 0.025, P < 0.001, P = 0.007, and P = 0.016, respectively). When analyzing gonadal status, phosphorus, OC and CTX-1 were greater in the hypogonadal group than in the eugonadal group (P = 0.017, P = 0.015, and P = 0.033, respectively). Patients with hypogonadism had a higher prevalence of reduced bone mass compared to eugonadal patients (44 vs. 17%, P = 0.023).

CONCLUSION

This study revealed increased levels of phosphorus and BTMs in patients with active acromegaly. In this group, the greater LS BMD values are likely due to the anabolic effects of GH and IGF-1 and/or to the influence of LS arthropathy. Moreover, hypogonadism negatively impacts bone metabolism in acromegaly, leading to elevated BTMs and a higher prevalence of reduced bone mass in individuals affected by both conditions.

Association of trabecular bone score corrected for tissue thickness with glucose metabolism in acromegaly

Introduction

Acromegaly is associated with increased vertebral fracture (VF) risk regardless of bone mineral density (BMD). However, the vertebral trabecular compartment is still low; a possible contributor to this may be impaired glucose metabolism (GM) which frequently complicates acromegaly. Additionally, soft tissue thickness may confound bone imaging in acromegaly patients.

Objective

This study aims to assess the association of GM with BMD, trabecular bone score adjusted for BMI (TBSBMI), and trabecular bone score adjusted for tissue thickness (TBSTT) among acromegaly subjects.

Patients and methods

A cross-sectional study was performed among 70 consecutive acromegaly patients (24 male/46 female, aged 55.1 years) divided in two subgroups: abnormal GM (n = 35) and normal GM (n = 35). Using DXA, BMD, TBSBMI, TBSTT, and VF screening were performed.

Results

In all subjects, TBSTT was higher (mean 9.5%) than TBSBMI. Abnormal GM subjects had lower TBSBMI (1.166 ± 0.15) than normal GM subjects (1.232 ± 0.12; p < 0.05). No between-group difference in TBSTT or BMD was observed. In a multiple regression model, the best predictor of TBSTT was HbA1c (p = 0.002). None of the DXA measures or GM parameters was a significant predictor of VF (n = 7).

Conclusion

The abnormal GM acromegaly subjects had lower TBSBMI than those with normal GM. TBSTT was higher than TBSBMI, and no between-group difference based on GM status was observed. TBSTT was significantly associated with GM parameters, notably HbA1c. The relationship of TBSTT with GM parameters may imply an effect of GM on trabecular bone microstructure in patients with acromegaly; a further study is indicated.

Skeletal fragility in pituitary disease: how can we predict fracture risk?

Pituitary hormones play a crucial role in regulating skeletal physiology, and skeletal fragility is a frequent complication of pituitary diseases. The ability to predict the risk of fracture events is crucial for guiding therapeutic decisions; however, in patients with pituitary diseases, fracture risk estimation is particularly challenging. Compared to primary osteoporosis, the evaluation of bone mineral density by dual X-ray absorptiometry is much less informative about fracture risk. Moreover, the reliability of standard fracture risk calculators does not have strong validations in this setting. Morphometric vertebral assessment is currently the cornerstone in the assessment of skeletal fragility in patients with pituitary diseases, as prevalent fractures remain the strongest predictor of future fracture events. In recent years, new tools for evaluating bone quality have shown promising results in assessing bone impairment in patients with pituitary diseases, but most available data are cross-sectional, and evidence regarding the prediction of incident fractures is still scarce. Of note, apart from measures of bone density and bone quality, the estimation of fracture risk in the context of pituitary hyperfunction or hypofunction cannot ignore the evaluation of factors related to the underlying disease, such as its severity and duration, as well as the specific therapies implemented for its treatment. Aim of this review is to provide an up-to-date overview of all major evidence regarding fracture risk prediction in patients with pituitary disease, highlighting the need for a tailored approach that critically integrates all clinical, biochemical, and instrumental data according to the specificities of each disease.

Impact of medical therapy for hormone-secreting Pituitary tumors on bone

PURPOSE

Bone health is often impaired in patients with hormone-secreting pituitary tumors. Since medical therapy is central to their care, understanding how its use impacts on this is highly important.

METHODS

This review summarizes a systemmatic review of the literature on the effects of medical therapies for hormone-secreting pituitary tumors on bone.

RESULTS

In acromegaly, medical therapy lowers bone turnover marker (BTM) levels, consistent with correction of the high bone turnover of active disease, and overall, areal bone mineral density (aBMD) does not change or increases. Somatostatin-receptor ligand (SRL) and pegvisomant-treated acromegaly patients have persistently reduced volumetric BMD and microarchitectural abnormalities of the peripheral skeleton, deficits that are similar to those in surgically-treated patients. Fracture risk remains elevated in medically-treated acromegaly patients but in conjunction with biochemical control the risk is lessened. Treatment of prolactin-secreting tumors with dopamine agonists is associated with improvements in aBMD, but this does not always fully normalize despite effective medical treatment of the prolactinoma. In one cross-sectional study, prolactinoma patients had lower total volumetric BMD and impaired microarchitecture suggesting that bone microstructure does not fully normalize despite dopamine agonist therapy. Cross-sectional studies show a high rate of VF in patients with prolactin-secreting tumors that is lowered on cabergoline therapy, but still the fracture rate of men and postmenopausal women is higher than that of controls in some studies. Studies on the effects of modern-day medical therapy for Cushing's disease on bone are lacking.

CONCLUSION

More research is needed on the effectsof medical therapies for hormone secreting pituitary tumors on bone health.

Vitamin D in pituitary driven osteopathies

The evidence that pituitary hormones may bypass peripheral endocrine glands to exert remarkable effects on the skeleton is gaining ground. Both hormonal excess and deficit may determine impairment in bone structure, and they commonly result in bone loss in patients affected by pituitary and neuroendocrine disorders. Vertebral fractures are the most common skeletal alterations and may occur independently of bone mass. Use of vitamin D (VD) supplementation is still debated in this setting. This review will focus on the interactions between different metabolites of VD and pituitary hormones, and the effects of VD supplementation on bone metabolism in patients with pituitary diseases.

Novel approach to bone comorbidity in resistant acromegaly

Active acromegaly may lead to irreversible complications. Among them, acromegaly osteopathy and fragility (vertebral and hip) fractures have emerged as frequent and precocious events in the natural history of the disease, being correlated with longer disease duration and higher growth hormone (GH) levels, accounting for patients' reported poor quality of life, physical performance and other life-impacting complications. Differently from primary osteoporosis, bone mineral density is not a reliable tool to predict fracture risk in this clinical setting, as patients with active disease frequently have normal or slightly reduced bone mass; whereas bone quality is particularly compromised, as determined by low trabecular bone score (TBS) in patients with active disease as compared to healthy controls or patients with cured/controlled disease. The evidence of impaired bone microstructure has been profoundly investigated with different computed tomography (CT) techniques, reporting low trabecular number and thickness as well as wide but more porous cortical bone, providing an explanation for such a high prevalence of vertebral fractures (up to 40-50% in selected cohorts). Since data on bone-active drugs are scanty, disease control remains a cornerstone to prevent fractures. Nonetheless, some potential protective effects may derive from vitamin D supplementation and pasireotide therapies, independently from disease status. Aim of this manuscript is to review the current and emerging evidence on skeletal fragility in patients with active and resistant acromegaly.

The Value of Mandibular Indices on Cone Beam Computed Tomography in Secondary Causes of Low Bone Mass

Background: As implant treatment cases increase, many cases of failure/side effects also occur. Generally, dental clinics determine the density of the jawbone using cone beam CT (CBCT). Considering the known potential role of this tool for bone assessment in primary osteoporosis, this study evaluated patients with secondary endocrine causes of low bone mass. Methods: The study included 83 patients with endocrine causes of osteoporosis who were evaluated by dual-energy X-ray absorptiometry (DXA), trabecular bone score (TBS), and mental foramen (MF) region CBCT. The following CBCT indices were measured: anterior (A)-thickness of inferior mandibular cortex 10 mm anterior from MF; molar (M)-thickness of inferior mandibular cortex 10 mm posterior from MF; posterior (P)-thickness of inferior mandibular cortex 25 mm posterior from MF; symphysis (S)-thickness of inferior mandibular cortex equidistant from the centers of right and left MF. Results: The highest correlation coefficient in the secondary causes group was between the A index and the lumbar BMD (r = 0.375, p = 0.001) and the P index and the femoral neck BMD (r = 0.38, p = 0.001). Hypercortisolism seems to be the most predictable cause of secondary osteoporosis using the A, M, and P indices. The A, M, and P indices showed predictive values of the bone micro-architecture that was evaluated using TBS score, and were statistically significant. The symphysis index does not significantly predict osteoporosis or impaired bone micro-architecture. Conclusions: These findings support the potential usefulness of A, M, and P CBCT-derived radiomorphometric mandibular indices in secondary osteoporosis, underlining the well-known effects of these pathologies on bone micro-architecture rather than bone quantity.

Long-term Pegvisomant Therapy of Acromegaly: Effects on Bone Density, Turnover and Microstructure Using HRpQCT

Context

Fracture rate is increased in patients with active acromegaly and those in remission. Abnormalities of bone microstructure are present in patients with active disease and persist despite biochemical control after surgery. Effects of treatment with the GH receptor antagonist pegvisomant on bone microstructure were unknown.

Methods

We studied 25 patients with acromegaly (15 men, 10 women). In 20, we evaluated areal bone mineral density (BMD) by dual-energy X-ray absorptiometry and bone turnover markers (BTMs) longitudinally, before and during pegvisomant treatment. After long-term pegvisomant in 17, we cross-sectionally assessed volumetric BMD, microarchitecture, stiffness, and failure load of the distal radius and tibia using high-resolution peripheral quantitative computed tomography (HRpQCT) and compared these results to those of healthy controls and 2 comparison groups of nonpegvisomant-treated acromegaly patients, remission, and active disease, matched for other therapies and characteristics.

Results

In the longitudinal study, areal BMD improved at the lumbar spine but decreased at the hip in men after a median ∼7 years of pegvisomant. In the cross-sectional study, patients on a median ∼9 years of pegvisomant had significantly larger bones, lower trabecular and cortical volumetric density, and disrupted trabecular microarchitecture compared to healthy controls. Microstructure was similar in the pegvisomant and acromegaly comparison groups. BTMs were lowered, then stable over time.

Conclusion

In this, the first study to examine bone microstructure in pegvisomant-treated acromegaly, we found deficits in volumetric BMD and microarchitecture of the peripheral skeleton. BTM levels remained stable with long-term therapy. Deficits in bone quality identified by HRpQCT may play a role in the pathogenesis of fragility in treated acromegaly.

Changes in acromegaly comorbidities, treatment, and outcome over three decades: a nationwide cohort study

Objective

To study the time-dependent changes in disease features of Danish patients with acromegaly, including treatment modalities, biochemical outcome, and comorbidities, with a particular focus on cancer and mortality.

Methods

Pertinent acromegaly-related variables were collected from 739 patients diagnosed since 1990. Data are presented across three decades (1990-1999, 2000-2009, and 2010-2021) based on the year of diagnosis or treatment initiation.

Results

Adenoma size and insulin-like growth factor I (IGF-I) levels at diagnosis did not differ significantly between study periods. The risk of being diagnosed with diabetes, heart disease, sleep apnea, joint disease, and osteoporosis increased from the 1990s to the later decades, while the mortality risk declined to nearly half. The risk of cancer did not significantly change. Treatment changed toward the use of more medical therapy, and fewer patients underwent repeat surgeries or pituitary irradiation. A statistically significant increase in the proportion of patients achieving IGF-I normalization within 3-5 years was observed over time (69%, 83%, and 88%). The proportion of patients with three or more deficient pituitary hormones decreased significantly over time.

Conclusion

Modern medical treatment regimens of acromegaly as well as increased awareness and improved diagnostics for its comorbidities have led to better disease control, fewer patients with severe hypopituitarism, and declining mortality in the Danish cohort of acromegaly patients. The risk of cancer did not increase over the study period.

Differences between bone health parameters in adults with acromegaly and growth hormone deficiency: A systematic review

Preserving bone health is an important goal of care of patients with acromegaly and growth hormone deficiency (GHD). Both disorders are associated with compromised bone health and an increased risk of fracture. However, parameters of bone health that are routinely used to predict fractures in other populations, such as aBMD measured by DXA, are unreliable for this in acromegaly and GHD. Additional methodologies need to be employed to assess bone health in these patients. This review summarizes available data on the effects of acromegaly and GHD on parameters of bone health such as aBMD, volumetric bone mineral density (vBMD) and microarchitecture assessed by HRpQCT and other techniques, trabecular bone score (TBS) and fracture assessment. More research is needed to identify reliable predictors of fracture risk and to determine how best to screen for and treat those patients at risk so that bone health is optimized in these patients.

Acromegaly versus hypogonadism: Bone fragility and evaluation

INTRODUCTION

Osteopathy in patients with acromegaly is characterized by increased prevalence of vertebral fragility fractures (VF). However, the diagnostic criteria for osteoporosis are seldomly met in terms of bone mineral density (BMD), as patients with acromegaly frequently present normal BMD for age and gender.

METHODOLOGY

We performed a cross-sectional study on 71 patients with acromegaly and 75 patients with hypogonadism. Turnover markers comprised alkaline phosphatase, osteocalcin, the C-terminal telopeptide of type I collagen and total procollagen type-1 amino-terminal propeptide; imaging comprised dual x-ray absorptiometry for BMD, T and Z scores of the lumbar spine, femoral neck and total hip, trabecular bone score (TBS), and x-ray scans of the thoracic and lumbar spine.

RESULTS

Vertebral fractures (VF) in subjects with acromegaly were significantly more frequent than in subjects with hypogonadism, with a prevalence of 29.6% compared to 9.3%. Patients with acromegaly had significantly higher BMD at all skeletal sites but lower TBS than hypogonadal subjects. This difference remained statistically significant after grouping patients with acromegaly according to gonadal status and comparing them with patients with hypogonadism. However, presence of hypogonadism in patients with acromegaly did not influence BMD, TBS or VF prevalence. Moreover, patients with active acromegaly did not have significantly different BMD, TBS and VF prevalence compared to patients with controlled disease. Patients with acromegaly with VF had significantly lower BMD at all skeletal sites than those without VF, but no difference in TBS.

CONCLUSIONS

Vertebral fractures are frequent in acromegaly, and are associated with lower BMD but not with TBS. Patients with acromegaly, regardless of gonadal status, have significantly higher BMD but lower TBS than hypogonadal patients. Moreover, disease activity and hypogonadism do not influence BMD, TBS or VF in acromegaly.

Acromegaly and the long-term fracture risk of the vertebra and hip: a national cohort study

In this national cohort study, the patients with acromegaly had significantly higher risks of clinical vertebral (HR 2.09 [1.58-2.78]) and hip (HR 2.52 [1.61-3.95]) fractures than the controls. The increased fracture risk in patients with acromegaly was time-dependent and was observed even during the early period of follow-up.

PURPOSE

Acromegaly is characterized by the overproduction of growth hormone (GH) and insulin-like growth factor-1 (IGF-1), both play important roles in regulating bone metabolism. We investigated the risk of vertebral and hip fractures in patients with acromegaly compared to age- and sex-matched controls.

METHODS

This nationwide population-based cohort study included 1,777 patients with acromegaly aged 40 years or older in 2006-2016 and 8,885 age- and sex-matched controls. A Cox proportional hazards model was used to estimate the adjusted hazard ratio (HR) [95% confidence interval].

RESULTS

The mean age was 54.3 years and 58.9% were female. For approximately 8.5 years of follow-up, the patients with acromegaly had significantly higher risks of clinical vertebral (HR 2.09 [1.58-2.78]) and hip (HR 2.52 [1.61-3.95]) fractures than the controls in the multivariate analyses. There were significant differences in the risks of clinical vertebral (P < 0.0001) and hip (P < 0.0001) fractures between the patients with acromegaly and the controls in the Kaplan-Meier survival analysis. The multivariable-adjusted HRs for clinical vertebral fractures comparing the patients with acromegaly with controls during and excluding the first 7 years of observation were 1.69 [1.15-2.49] and 2.70 [1.75-4.17], respectively. The HRs for hip fractures during and excluding the first 7 years of observation were 2.29 [1.25-4.18] and 3.36 [1.63-6.92], respectively.

CONCLUSIONS

The patients with acromegaly had a higher risk of hip fractures as well as clinical vertebral fractures than the controls. The increased fracture risk in patients with acromegaly was time-dependent and was observed even during the early period of follow-up.

Persistent Deficits in Bone Quality in Treated Acromegaly: Evidence From Assessments of Microstructure

Purpose

Fractures are increased in patients with acromegaly, both before and after successful acromegaly treatment. Abnormalities of bone microstructure, which may underlie this fragility, are present in active acromegaly but to what extent these improve with acromegaly treatment or persist despite biochemical remission remains unclear. To examine these questions, we studied the effects of acromegaly treatment and remission on bone quality.

Methods

Sixty-five women and men with acromegaly were studied. Subgroups underwent assessments of areal bone mineral density by dual x-ray absorptiometry, trabecular bone score (TBS), and volumetric bone mineral density, microarchitecture, stiffness and failure load of the distal radius and tibia by high-resolution peripheral quantitative tomography in a longitudinal study before and after acromegaly treatment and in a cross-sectional study in which patients were compared to sex-, age-, and body mass index-matched healthy controls.

Results

In the longitudinal study, significant increases in total, cortical, and trabecular densities at the radius and tibia and increased stiffness and failure load of the tibia occurred with acromegaly treatment. In the cross-sectional study, patients in biochemical remission after surgery had larger bones, lower trabecular and cortical volumetric density, and disrupted trabecular microarchitecture compared to controls. TBS did not change with acromegaly treatment but correlated with some microstructural parameters.

Conclusion

We show, for the first time, that volumetric bone mineral density and microarchitecture of the peripheral skeleton improve with acromegaly treatment but remain abnormal in patients in remission after surgery compared to controls. These abnormalities, known to be associated with fractures in other populations, may play a role in the pathogenesis of persistent fragility in treated acromegaly.

Age, body composition parameters and glycaemic control contribute to trabecular bone score deterioration in acromegaly more than disease activity

Introduction

Impairment of bone structure in patients with acromegaly (AP) varies independently of bone mineral density (BMD). Body composition parameters, which are altered in patients with acromegaly, are important determinants of bone strength.

Purpose

The aim of this study was to examine BMD and lumbar trabecular bone score (TBS) by dual-energy X-ray absorptiometry (DXA) and to assess its relationship with disease activity, age, glucose metabolism, and body composition parameters.

Methods

This cross-sectional prospective study involved 115 patients with acromegaly (70 F, 45 M) and 78 healthy controls (CON) (53 F, 25 M) matched for age, gender, and BMI. Bone mineral density, TBS and body composition parameters were measured using DXA.

Results

AP presented with lower TBS compared to CON (1.2 ± 0.1 v 1.31 ± 0.1, P< 0.001). No significant correlation was observed between IGF-1/GH levels and TBS. Age, glycated haemoglobin, BMI, waist circumference, fat mass, and lean mass negatively correlated with TBS in both sexes. Multiple linear regression analysis of all these parameters revealed age and waist circumference as independent significant predictors of TBS in AP. We did not find difference in BMD (lumbar and femoral sites) between AP and CON nor between active and controlled AP. We observed negative correlation between age and BMD of the femoral neck and total hip (P < 0.001). Testosterone levels in males, BMI, waist circumference, fat mass, and lean mass positively correlated with BMD in AP, with stronger correlation between lean mass and BMD compared to fat mass.

Conclusion

Patients with acromegaly have lower TBS than controls, confirming impaired bone microarchitecture in acromegaly regardless of BMD. Age, body composition parameters and glucose metabolism contribute to TBS deterioration in AP more than disease activity itself.

Bone quality in endocrine diseases: determinants and clinical relevance

PURPOSE

Bone is one of the main targets of hormones and endocrine diseases are frequent causes of secondary osteoporosis and fractures in real-world clinical practice. However, diagnosis of skeletal fragility and prediction of fractures in this setting could be a challenge, since the skeletal alterations induced by endocrine disorders are not generally captured by dual-energy X-ray absorptiometry (DXA) measurement of bone mineral density (BMD), that is the gold standard for diagnosis of osteoporosis in the general population. The aim of this paper is to review the existing evidence related to bone quality features in endocrine diseases, proposing assessment with new techniques in the future.

METHODS

A comprehensive search within electronic databases was performed to collect reports of bone quality in primary hyperparathyroidism, hypoparathyroidism, hyperthyroidism, hypercortisolism, growth hormone deficiency, acromegaly, male hypogonadism and diabetes mellitus.

RESULTS

Using invasive and non-invasive techniques, such as high-resolution peripheral quantitative computed tomography or DXA measurement of trabecular bone score (TBS), several studies consistently reported altered bone quality as predominant determinant of fragility fractures in subjects affected by chronic endocrine disorders.

CONCLUSIONS

Assessment of skeletal fragility in endocrine diseases might take advantage from the use of techniques to detect perturbation in bone architecture with the aim of best identifying patients at high risk of fractures.

New tools for bone health assessment in secreting pituitary adenomas

Pituitary hormones regulate skeletal physiology, and excess levels affect bone remodeling and alter bone microstructure. Vertebral fractures (VFs) are an early phenomenon of impaired bone health in secreting pituitary adenomas. However, they are not accurately predicted by areal bone mineral density (BMD). Emerging data demonstrate that a morphometric approach is essential for evaluating bone health in this clinical setting and is considered to be the gold standard method in acromegaly. Several novel tools have been proposed as alternative or additional methods for the prediction of fractures, particularly in pituitary-driven osteopathies. This review highlights the novel potential biomarkers and diagnostic methods for bone fragility, including their pathophysiological, clinical, radiological, and therapeutic implications in acromegaly, prolactinomas, and Cushing's disease.

Vertebral Fractures in Acromegaly: A Systematic Review

INTRODUCTION

Acromegaly is characterized by a very particular alteration of bone microarchitecture, leading to increased vertebral fragility. However, due to inconsistent and insufficient evidence, no guidelines are available for the evaluation of this osteopathy.

METHODS

We performed a literature review of studies published between 1968 and January 2022 on the PubMed and SCOPUS databases using the terms "acromegaly" and "vertebral fractures". Twenty-four studies were found eligible for inclusion, published between June 2005 and November 2021. Included studies evaluated acromegaly patients, who were assessed for the presence of vertebral fractures. We excluded case reports, reviews, meta-analyses, letters to the editor, articles not written in English, and research performed on the same set of patients without significant differences in study design. Risk of bias was avoided by following the ROBIS risk of bias recommendations. We executed rigorous data collection, and the results are depicted as a narrative overview, but also, as statistical synthesis. Limitations of the evidence presented in the study include study heterogeneity, small sample sizes, and a small number of prospective studies with short follow-up.

FINDINGS

Data regarding vertebral fractures (VFs) in acromegaly and their influencing factors are variable. Twenty-four studies were included, nine out of which had a prospective design. The smallest group of acromegaly patients had 18 subjects and the largest included 248 patients. Prevalence ranges between 6.5% and 87.1%, although most studies agree that it is significantly higher than in controls. VFs also have a higher incidence (between 5.6% and 42%) and are more frequently multiple (between 46.15% and 71%). Evidence shows that disease activity and active disease duration are influencing factors for the prevalence and incidence of VFs. Nonetheless, hypogonadism does not seem to influence the frequency of VFs. While reports are conflicting regarding the use of bone mineral density in acromegaly, evidence seems to be slightly in favor of it not being associated with VFs. However, trabecular bone score is significantly lower in fractured patients, although no prospective studies are available.

INTERPRETATION

Vertebral fractures evaluation should be performed with regularity in all acromegalic patients, especially in the presence of active disease. Disease activity is an important determinant of vertebral fracture incidence and prevalence, although hypogonadism is less so. To clarify the predictive value of both BMD and TBS for vertebral fractures, additional, larger, prospective studies are necessary.

Determinants of skeletal fragility in acromegaly: a systematic review and meta-analysis

PURPOSE

Vertebral fractures (VFs) are a potential complication in acromegaly. However, the etiology of this skeletal fragility is unknown. This review aimed to evaluate the effect of acromegaly on VFs, bone turnover, areal bone mineral density (aBMD), and bone quality/microarchitecture. The effect of disease activity and gonadal status in these determinants of skeletal fragility was also evaluated.

METHODS

Articles published in English until September 6, 2020 on PubMed and Embase that reported at least one determinant of skeletal fragility in acromegalic patients, were included. Odds ratio (OR) to evaluate the risk of VFs and the standardized mean difference (SMD) to evaluate bone turnover, aBMD and bone quality/microarchitecture were calculated.

RESULTS

Fifty-eight studies met eligibility criteria, assembling a total of 2412 acromegalic patients. Of these, 49 studies were included in the meta-analysis. Acromegalic patients, when compared to non-acromegalic patients, had higher risk of VFs [OR 7.00; 95% confidence interval (CI) 2.80-17.52; p < 0.0001], higher bone formation (SMD 1.14; 95% CI 0.69-1.59; p < 0.00001), higher bone resorption (SMD 0.60; 95% CI 0.09-1.10; p = 0.02) and higher aBMD at the femoral neck (SMD 0.36; 95% CI 0.15-0.57; p = 0.0009). No significant differences were found regarding aBMD at lumbar spine. Considering the results of the different techniques evaluating bone quality/microarchitecture, the main reported alterations were a decrease in trabecular bone thickness and density, and an increase in trabecular separation. The presence of active disease and/or hypogonadism were associated with worst results.

CONCLUSION

Patients with acromegaly are at increased risk of VFs, mainly because of deterioration in bone microarchitecture.

Fracture Healing in the Setting of Endocrine Diseases, Aging, and Cellular Senescence

More than 2.1 million age-related fractures occur in the United States annually, resulting in an immense socioeconomic burden. Importantly, the age-related deterioration of bone structure is associated with impaired bone healing. Fracture healing is a dynamic process which can be divided into four stages. While the initial hematoma generates an inflammatory environment in which mesenchymal stem cells and macrophages orchestrate the framework for repair, angiogenesis and cartilage formation mark the second healing period. In the central region, endochondral ossification favors soft callus development while next to the fractured bony ends, intramembranous ossification directly forms woven bone. The third stage is characterized by removal and calcification of the endochondral cartilage. Finally, the chronic remodeling phase concludes the healing process. Impaired fracture healing due to aging is related to detrimental changes at the cellular level. Macrophages, osteocytes, and chondrocytes express markers of senescence, leading to reduced self-renewal and proliferative capacity. A prolonged phase of "inflammaging" results in an extended remodeling phase, characterized by a senescent microenvironment and deteriorating healing capacity. Although there is evidence that in the setting of injury, at least in some tissues, senescent cells may play a beneficial role in facilitating tissue repair, recent data demonstrate that clearing senescent cells enhances fracture repair. In this review, we summarize the physiological as well as pathological processes during fracture healing in endocrine disease and aging in order to establish a broad understanding of the biomechanical as well as molecular mechanisms involved in bone repair.

Trabecular Bone Score as a Reliable Measure of Lumbar Spine Bone Microarchitecture in Acromegalic Patients

Although GH and IGF-1 excess has a controversial impact on bone mineral density (BMD), acromegalic patients display variable degrees of bone structure impairment. In this study, we aim to investigate the usefulness of trabecular bone score (TBS), compared to BMD, in identifying acromegalic patients with impaired lumbar spine trabecular microarchitecture. Forty-four acromegalic patients were investigated for disease control, metabolic and gonadal status, bone metabolism parameters, and the presence of vertebral fractures (VFs). Patients and matched healthy controls underwent BMD and TBS examination. Mean TBS values were lower in patients than in controls (p < 0.001), without significant differences in mean lumbar and femoral BMD. TBS values were significantly higher in controlled patients compared to the uncontrolled ones (p = 0.012). No significant differences were found in bone markers with respect to disease control. Mean TBS or lumbar BMD did not significantly differ in patients with or without VFs (prevalence 11.4%). TBS and BMD levels were lower in hypogonadal patients compared to the eugonadal ones (p = 0.030 and p < 0.001, respectively). In conclusion, TBS values are significantly lower in patients than in controls, confirming the presence of impaired lumbar spine trabecular bone in acromegaly. Both uncontrolled disease and hypogonadism contribute to TBS deterioration in acromegaly.

High Prevalence of Vertebral Fractures Associated With Preoperative GH Levels in Patients With Recent Diagnosis of Acromegaly

CONTEXT

Osteopathy and morphometric vertebral fractures (VFs) are emerging complications in acromegaly. However, the prediction of VFs in this clinical setting is still a matter of uncertainty, and it is debated whether they are an early event in the natural history of the disease.

OBJECTIVE

We aimed to evaluate the prevalence and determinants of morphometric VFs in patients with recently diagnosed acromegaly.

METHODS

We enrolled 92 patients (43 men/49 women) on admission to the neurosurgery unit before transsphenoidal surgery, and compared them with control individuals without secondary forms of osteoporosis and pituitary disorders. We performed a VF assessment on preoperative chest x-ray images and collected biochemical, demographic, and clinical data.

RESULTS

We detected a significantly higher prevalence of VFs (33.7%) in patients with acromegaly than in controls (P = .001). Among the patients with acromegaly and VFs, 12 (38.7%) showed multiple VFs, and 5 (16.1%) showed moderate/severe VFs. Patients with VFs had higher random serum growth hormone (GH) levels than those with no VFs (P = .03), but there was no difference in insulin-like growth factor-1 (IGF-1) (P = .07) and IGF-1/Upper Normal Limit ratio (P = .08). Free 3,5,3'-triiodothyronine was slightly lower in patients with acromegaly and VFs than in those without VFs (P = .05). In multiple logistic analysis, GH was independently associated with risk for VFs (P = .003). The preoperative serum GH cutoff value that predicted VFs was 12 ng/mL.

CONCLUSION

For the first time, high prevalence of radiological VFs is reported in patients with recent diagnosis of acromegaly. Therefore, we can hypothesize that VFs are an early phenomenon of acromegaly and related to GH levels. VF assessment should be included in the workup at the diagnosis of acromegaly.

Skeletal disorders associated with the growth hormone-insulin-like growth factor 1 axis

Growth hormone (GH) and insulin-like growth factor 1 (IGF1) are important regulators of bone remodelling and metabolism and have an essential role in the achievement and maintenance of bone mass throughout life. Evidence from animal models and human diseases shows that both GH deficiency (GHD) and excess are associated with changes in bone remodelling and cause profound alterations in bone microstructure. The consequence is an increased risk of fractures in individuals with GHD or acromegaly, a condition of GH excess. In addition, functional perturbations of the GH-IGF1 axis, encountered in individuals with anorexia nervosa and during ageing, result in skeletal fragility and osteoporosis. The effect of interventions used to treat GHD and acromegaly on the skeleton is variable and dependent on the duration of the disease, the pre-existing skeletal state, coexistent hormone alterations (such as those occurring in hypogonadism) and length of therapy. This variability could also reflect the irreversibility of the skeletal structural defect occurring during alterations of the GH-IGF1 axis. Moreover, the effects of the treatment of GHD and acromegaly on locally produced IGF1 and IGF binding proteins are uncertain and in need of further study. This Review highlights the pathophysiological, clinical and therapeutic aspects of skeletal fragility associated with perturbations in the GH-IGF1 axis.

Low sclerostin levels after long-term remission of acromegaly

PURPOSE

Bone health is compromised in acromegaly resulting in vertebral fractures (VFs), regardless of biochemical remission. Sclerostin is a negative inhibitor of bone formation and is associated with increased fracture risk in the general population. Therefore, we compared sclerostin concentrations between well-controlled acromegaly patients and healthy controls, and assessed its relationship with bone mineral density (BMD), and VFs in acromegaly.

METHODS

Seventy-nine patients (mean age 58.9 ± 11.4 years, 49% women) with controlled acromegaly, and 91 healthy controls (mean age 51.1 ± 16.9 years, 59% women) were included. Plasma sclerostin levels (pg/mL) in patients were measured with an ELISA assay, whereas in controls, serum levels were converted to plasma levels by multiplication with 3.6. In patients, VFs were radiographically assessed, and BMD was assessed using dual X-ray absorptiometry.

RESULTS

Median sclerostin concentration in controlled acromegaly patients was significantly lower than in healthy controls (104.5 pg/mL (range 45.7-234.7 pg/mL) vs 140.0 pg/mL (range 44.8-401.6 pg/mL), p < 0.001). Plasma sclerostin levels were not related to age, current growth hormone (GH) or insulin-like factor-1 (IGF-1) levels, gonadal state, treatment modality, remission duration, or BMD, VF presence, severity or progression.

CONCLUSION

Patients with long-term controlled acromegaly have lower plasma sclerostin levels than healthy controls, as a reflection of decreased osteocyte activity. Further longitudinal studies are needed to establish the course of sclerostin during different phases of disease and its exact effects in acromegalic osteopathy.

Trabecular Bone Score and Osteoprotegerin as Useful Tools in the Assessment of Bone Deterioration in Acromegaly

PURPOSE

This study aimed to assess bone mineral density (BMD) and trabecular bone score (TBS) in 61 patients from the acromegaly group (AG) with regard to the activity of the disease in comparison to 42 patients-control group (CG). We also analyzed selected bone markers and their association with BMD and TBS.

MATERIALS AND METHODS

Lumbar spine and femoral neck BMD measurements were performed. TBS values were obtained. Serum concentrations of selected bone markers, including osteoprotegerin (OPG), were measured.

RESULTS

We revealed a difference in TBS values between the AG and CG as well as between the TCA (treatment-controlled acromegaly) vs. CG and TCA+CA (cured acromegaly) vs. CG. We did not observe any statistically significant difference in BMD. OPG had a lower concentration in the CG compared to the AG. TBS correlated negatively with OPG in the AG (r = -0.31, p = 0.01) and in the TCA+ CA group (r = -0.3, p = 0.01).

CONCLUSIONS

The acromegalic patients have altered bone microstructure as indicated by the decreased TBS regardless of the activity of the disease and BMD. OPG could be a marker of the destruction of the bone microstructure, but further studies are needed.

Vertebral Fractures Occur Despite Control of Acromegaly and Are Predicted by Cortical Volumetric Bone Mineral Density

CONTEXT

Recent studies suggest that cortical bone could also play a role in vertebral fracture (VF) development in acromegaly.

OBJECTIVE

Evaluate the occurrence of VFs and their relationship to dual energy x-ray absorptiometry-derived bone parameters.

METHODS

A single-center 2-year prospective study of acromegaly patients was conducted. Each subject had L1-4 spine, femoral neck and total hip (TH) areal BMD measured using DXA, and trabecular bone score (TBS) measurement performed. 3D Shaper™ was used to assess proximal femur trabecular and cortical volumetric (v)BMD, cortical surface (s)BMD, and cortical thickness (Cth). VF assessment was performed using the lateral spine imaging IVA™ mode with a Hologic Horizon® densitometer using a semiquantitative approach. Study outcomes were assessed at 2 time points: baseline and month 24.

RESULTS

70 acromegaly patients (34 M/36F; average 55.1 years) were studied, including 26 with active disease. In 13 patients, 9 with controlled disease, VF was observed. A decrease in TBS, sBMD, neck trabecular vBMD, TH, and neck cortical vBMD in VF compared with non-VF subjects was observed (P < .05). Multivariate analysis of fracture prediction showed TH cortical vBMD as the best fracture prediction parameter with area under the curve of 0.774. TBS was negatively associated with fasting plasma glucose and glycated hemoglobin (HBA1c) at each time point during the follow-up.

CONCLUSION

From the total number of 13 VF subjects, 9 were in the controlled disease group. The most sensitive and specific predictor of incident VF was TH cortical vBMD, suggesting that cortical bone is involved in fracture development.

Trabecular bone score and bone mineral density in acromegalic osteopathy assessment: a cross-sectional study

PURPOSE

The evaluation of acromegalic osteopathy is a subject of current interest as there is a lack of evidence concerning proper evaluation techniques and clear diagnostic criteria. The aim of this study was to evaluate lumbar spine trabecular bone score (TBS) and bone mineral density (BMD) in acromegaly patients compared to healthy controls.

METHODS

We conducted a cross-sectional study on 43 acromegaly patients recruited between 2018 and 2020 and a healthy control group matched 1:1 for age, gender, and body mass index (BMI). All subjects underwent DXA, lumbar spine TBS, and bone turnover markers measurement.

RESULTS

Acromegaly patients showed significantly decreased lumbar spine TBS (1.244 ± 0.117 vs. 1.343 ± 0.124, p < 0.001) and no difference regarding BMD compared to control patients. In the subgroup analysis, TBS was significantly lower in both males and females (1.282 ± 0.075 vs. 1.366 ± 0.113, p = 0.01 and 1.222 ± 0.132 vs. 1.329 ± 0.130, p = 0.005) and, also, in hypogonadal and eugonadal acromegaly subjects compared to their healthy controls (1.231 ± 0.130 vs. 1.306 ± 0.125, p = 0.04 and 1.280 ± 0.065 vs. 1.381 ± 0.113, p = 0.008). Femoral neck BMD was higher in acromegalic hypogonadal patients [1.027 (IQR: 0.939-1.135) vs. 0.876 (IQR: 0.737-1.014), p = 0.004].

CONCLUSION

Our study indicates that TBS, but not BMD, is significantly decreased in acromegaly patients, regardless of gender and gonadal status. This data suggests that TBS could be a valuable tool in the assessment of acromegalic osteopathy.

Impaired Bone Microarchitecture in Premenopausal Women With Acromegaly: The Possible Role of Wnt Signaling

CONTEXT

Acromegaly can impair bone integrity, increasing the risk of vertebral fractures (VFs).

OBJECTIVE

To evaluate the impact of isolated GH/IGF-I hypersecretion on bone turnover markers, Wnt inhibitors, bone mineral density (BMD), microarchitecture, bone strength and vertebral fractures in female patients with acromegaly (Acro), compared with healthy control group (HC).

DESIGN, SETTING, AND PATIENTS

Cross-sectional study including 83 premenopausal women without any pituitary deficiency:18 acromegaly in remission (AcroR), 12 in group with active acromegaly (AcroA), and 53 HC. Serum procollagen type 1 N-terminal propeptide, β-carboxy-terminal crosslinked telopeptide of type 1 collagen, osteocalcin, sclerostin, and DKK1 were measured in blood samples. dual-energy X-ray absorptiometry, high-resolution peripheral quantitative computed tomography (HR-pQCT) and vertebral fractures evaluation were also assessed simultaneously.

MAIN OUTCOME AND RESULTS

AcroA showed significantly lower sclerostin and higher DKK1 compared with HC. On HR-pQCT of tibia and radius, Acro showed impairment of trabecular (area and trabecular number), increased cortical porosity, and increased cortical area and cortical thickness compared with HC. The only significant correlation found with HR-pQCT parameters was a positive correlation between cortical porosity and serum DKK1 (R = 0.45, P = 0.044). Mild VFs were present in approximately 30% of patients.

CONCLUSIONS

Eugonadal women with acromegaly without any pituitary deficiency showed increased cortical BMD, impairment of trabecular bone microstructure, and increased VF. Sclerostin was not correlated with any HR-pQCT parameters; however, DKK1 was correlated with cortical porosity in tibia (P = 0.027). Additional studies are needed to clarify the role of Wnt inhibitors on bone microarchitecture impairment in acromegaly.

Trabecular bone score and bone mineral density in patients with long-term controlled acromegaly

OBJECTIVE

Acromegaly is associated with increased vertebral fracture (VFs) risk not correlated to bone mineral density (BMD). Trabecular bone score (TBS), related to bone microarchitecture, provides information on bone strength. This cross-sectional study considered the usefulness of TBS and BMD to assess bone status in long-term controlled acromegalic patients.

DESIGN, PATIENTS, MEASUREMENTS

26 acromegaly patients (14 female and 12 males) were included in the study. A further 117 subjects were recruited as controls (58 females and 57 males). BMD was measured using dual-energy X-ray absorptiometry (DXA), TBS was obtained applying Medimaps software 2.0. Biochemical parameters were determined by standardized techniques.

RESULTS

73% of patients with acromegaly exhibited normal lumbar spine (LS) BMD. TBS was normal in 38% of acromegalic patients and partially degraded or degraded in 31% of patients, respectively. No differences were found in LS BMD between acromegalic patients and controls. TBS values were significantly lower in patients with acromegaly (1.27 ± 0.13 vs. 1.35 ± 0.17, p = .01). Postsurgical remission was associated with higher TBS values (1.35 ± 0.10 vs. 1.23 ± 0.13, p = .02) and pituitary radiotherapy treatment with lower TBS values (1.18 ± 0.12 vs. 1.31 ± 0.12, p = .004). On multivariate analysis, age, BMI and LS BMD were predictors of TBS changes in patients with acromegaly (p < .05).

CONCLUSIONS

Patients with long-term controlled acromegaly can exhibit deterioration of bone microstructure measured with TBS, despite BMD measurement not showing bone loss. Our study suggests that TBS is useful for monitoring the bone status changes in acromegalic patients.

3D DXA Hip Differences in Patients with Acromegaly or Adult Growth Hormone Deficiency

The skeleton is regulated by and responds to pituitary hormones, especially when the circulating levels are perturbed in disease. This study aims to analyse the between-group differences in 3D dual-energy X-ray absorptiometry (DXA) parameters at the hip site among patients with acromegaly or adult growth hormone deficiency (AGHD) and a healthy control group. The current cross-sectional study includes data for 67 adults, 20 with acromegaly, 14 with AGHD and 33 healthy controls. We obtained the areal bone mineral density (aBMD) outcomes using DXA and cortical and trabecular parameters using 3D-DXA software (3D-SHAPER). The mean-adjusted 3D-DXA parameters did not differ between acromegaly patients and the controls (p > 0.05); however, we found cortical bone impairment (−7.3% to −8.4%; effect size (ES) = 0.78) in AGHD patients (p < 0.05). Differences in the cortical bone parameters were more evident when comparing AGHD patients (−8.5% to −16.2%; ES = 1.22 to 1.24) with acromegaly patients (p < 0.05). In brief, the 3D mapping highlighted the trochanter as the site with greater cortical bone differences between acromegaly patients and the controls. Overall, AGHD patients displayed lower cortical parameters at the trochanter, femoral neck and intertrochanter compared to the controls and acromegaly patients. To sum up, 3D-DXA provided useful information about the characteristics of bone involvement in growth hormone (GH)-related disorders. Patients with AGHD showed distinct involvement of the cortical structure.

The Negative Impacts of Acromegaly on Bone Microstructure Not Fully Reversible

PURPOSE

This study aimed to evaluate the bone turnover markers and bone microarchitecture parameters derived from high-resolution peripheral quantitative computed tomography (HR-pQCT) in active and controlled acromegaly patients.

METHODS

This cross-sectional study involved 55 acromegaly patients from a tertiary hospital (23 males and 32 females, aged 45.0 ± 11.6 years). Firstly, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and markers for bone turnover were assessed. Next, we derived peripheral bone microstructure parameters and volumetric bone mineral density (vBMD) through HR-pQCT. These parameters were compared between acromegaly patients and 110 healthy controls, as well as between 27 active and 28 controlled acromegaly patients. Moreover, the relationship between GH/IGF-1 and bone microstructure parameters was analyzed through multiple linear regression.

RESULTS

As compared with healthy controls, acromegaly patients exhibited elevated cortical vBMD, reduced trabecular vBMD, and increased trabecular inhomogeneity in the distal radius and tibia. While controlled acromegaly patients had slower bone turnover, they did not necessarily have better bone microstructure relative to active patients in intergroup comparison. Nevertheless, multiple regression indicated that higher IGF-1 was associated with lower tibial stiffness and failure load. Additionally, males with higher IGF-1 typically had larger trabecular separation, lower trabecular number, and larger cortical pores in the radius. Moreover, patients with elevated GH typically had more porous cortical bone in the radius and fewer trabeculae in the tibia. However, the compromised bone strength in active patients was partially compensated by increased bone thickness. Furthermore, no significant linkage was observed between elevated GH/IGF-1 and the most important HR-pQCT parameters such as trabecular volumetric bone density.

CONCLUSION

Acromegaly adversely affected bone quality, even in controlled patients. As the deterioration in bone microstructure due to prolonged GH/IGF-1 exposure was not fully reversible, clinicians should be aware of the bone fragility of acromegaly patients even after they had achieved biochemical remission.

Entropy and uniformity as additional parameters to optimize the effectiveness of bone CT in the evaluation of acromegalic patients

PURPOSE

Acromegaly is considered an important cause of secondary osteoporosis. However, studies on bone mineral density (BMD) have yielded conflicting results and there are few studies that evaluate an accurate imaging method for early diagnosis of osteoporosis in these patients. The objective of this study was to assess whether entropy and uniformity on computed tomography (CT) scans are useful parameters for optimization of assessment of bone fragility in patients with acromegaly.

METHODS

We included 34 patients and 36 controls matched for age and sex in a cross-sectional study. Patients and controls underwent CT scan of the lumbosacral spine, dual-energy x-ray absorptiometry (DXA) and blood tests. A software was developed to calculate the entropy and uniformity by a region of interest (ROI) of the trabecular bone of the first lumbar vertebra (L1).

RESULTS

The acromegalic group presented higher mean bone entropy (6.87 ± 0.98 vs. 6.03 ± 1.68, p = 0.013) and lower mean bone uniformity (0.035 ± 0.704 vs. 0.113 ± 0.205, p = 0.035) than control group. Analyzing only acromegalics, mean bone entropy was higher and bone uniformity was lower in patients with hypogonadism than patients without hypogonadism (7.28 ± 0.36 vs. 6.74 ± 1.08, p = 0.038 and 0.008 ± 0.002 vs. 0.043 ± 0.079, p = 0.031) respectively. Patients with acromegaly presented higher BMD and Z-score in the femoral neck than control group (1.156 ± 0.108 vs. 0.925 ± 0.326 g/cm², p = 0.043 and 0.6 ± 0.6 vs. -0.05 ± 0.8, p = 0.041, respectively). Entropy was negatively correlated with T-score of the lumbar spine (r_p = -0.357, p = 0.033) in control group and uniformity was positively correlated with T-score of the lumbar spine, neck, and total hip, respectively (r_p = 0.371, p = 0.031; r_p = 0.348, p = 0.043 and r_p = 0.341, p = 0.049) in acromegalic group.

CONCLUSIONS

The study identified that entropy and uniformity are a relevant parameters data in bone fragility assessment in acromegalic patients.

Bone Evaluation by High-Resolution Peripheral Quantitative Computed Tomography in Patients With Adrenal Incidentaloma

CONTEXT

Data regarding high-resolution peripheral quantitative computed tomography (HR-pQCT) in patients with adrenal incidentaloma (AI) are unknown.

PURPOSE

To evaluate the areal bone mineral density (aBMD), microstructure, and fractures in patients with nonfunctioning AI (NFAI) and autonomous cortisol secretion (ACS).

METHODS

We evaluated 45 patients with NFAI (1 mg dexamethasone suppression test [DST] ≤1.8 µg/dL) and 30 patients with ACS (1 mg DST 1.9-5.0 µg/dL). aBMD was measured using dual-energy X-ray absorptiometry; vertebral fracture by spine X-ray; and bone geometry, volumetric bone mineral density (vBMD), and microstructure by HR-pQCT.

RESULTS

Patients with ACS showed lower aBMD values at the spine, femoral neck, and radius 33% than those with NFAI. Osteoporosis was frequent in both groups: NFAI (64.9%) and ACS (75%). Parameters at the distal radius by HR-pQCT were decreased in patients with ACS compared to those with NFAI: trabecular vBMD (Tb.vBMD, P = 0.03), inner zone of the trabecular region (Inn.Tb.vBMD, P = 0.01), the bone volume/tissue volume ratio (BV/TV, P = 0.03) and trabecular thickness (P = 0.04). As consequence, a higher ratio of the outer zone of the trabecular region/inner zone vBMD (Meta/Inn.vBMD, P = 0.003) was observed. A correlation between the cortisol levels after 1 mg DST and Meta/Inn.vBMD ratio was found (r = 0.29; P = 0.01). The fracture frequency was 73.7% in patients with ACS vs 55.6% in patients with NFAI (P = 0.24).

CONCLUSION

Our findings point to an association between trabecular bone microarchitectural derangement at the distal radius and ACS. Our data suggest that AI have a negative impact on bone when assessed by HR-pQCT, probably associated to subclinical hypercortisolism.

Bone Augmentation Procedures in a Patient with Acromegaly

The objective of this clinical case is to evaluate if bone augmentation procedures can be successful in a patient with altered bone metabolism due to a systemic disease: acromegaly. Two guided bone regeneration procedures were made on the same patient: horizontal ridge augmentation with lateral wall approach sinus graft of the left maxilla and horizontal ridge augmentation of the front left maxilla. CBCT assessment of the new formed bone was made after a minimum of nine months and dental implants were placed. The results show that bone augmentation procedures can be successful in a patient with acromegaly, after pituitary adenoma removal, when autologous bone is not included in the grafting procedure.

Drug treatment strategies for secondary diabetes in patients with acromegaly

INTRODUCTION

Acromegaly is a rare disease due to oversecretion of growth hormone (GH). Even though the disease is often portrayed by its most apparent clinical features, given the abundance of GH receptors throughout the body, it truly is a systemic disease leading to numerous complications and comorbidities. A distinct medical issue in the context of acromegaly is diabetes: It can be a complication as a consequence of GH excess and its mediators, but it can also result from treatment of acromegaly.

AREAS COVERED

This review provides an overview of the effects of acromegaly pathophysiology on glucose homeostasis. Furthermore, it devotes an extensive section on the influence that acromegaly treatment has on glucose metabolism, including approved as well as currently investigated drugs. It also summarizes observations from the use of anti-diabetic medication in patients with acromegaly.

EXPERT OPINION

Glucose imbalance is an important aspect of acromegaly comorbidity and deserves more attention. Even though numerous studies have investigated glucose homeostasis in acromegaly, there is still a clear need for more basic, translational, and also clinical research to advance the understanding of the underlying mechanisms and how to best address them.

Effects of Pegvisomant and Pasireotide LAR on Vertebral Fractures in Acromegaly Resistant to First-generation SRLs

PURPOSE

Osteopathy is an emerging complication of acromegaly. In somatostatin receptor ligands (SRL)-resistant patients, pegvisomant (PegV) and pasireotide LAR (Pasi) are used for acromegaly treatment, but their effect on skeletal health is still not defined.

METHODS

In a longitudinal retrospective international study, we evaluated incidence of radiological vertebral fractures (VFs) in 55 patients with acromegaly resistant to first-generation SRL.

RESULTS

At study entry, prevalent VFs occurred in 23 patients (41.8%). Biochemical acromegaly control was reached in 66.7% of patients on PegV and in 66.7% of patients on Pasi. During the follow-up, incident VFs (iVFs) were detected in 16 patients (29.1%). Occurrence of iVFs was associated with prevalent VFs (P = .002), persistence of active acromegaly (P = .01) and higher value of insulin-like growth factor 1 (IGF-1) during follow-up (P = .03). Among patients with active disease at last visit, iVFs occurred less frequently in patients on treatment with Pasi (25%) compared to PegV (77.8% P = .04), independently of the IGF-1 values (P = .90). In patients who reached biochemical control, 22.7% on PegV and 12.5% on Pasi had iVFs (P = .40). Among both treatment groups, the presence of pre-existent VFs was the main determinant for iVFs.

CONCLUSION

Our data show for the first time that patients with biochemically active disease treated with Pasi had lower risk of iVFs versus those treated with PegV. It also confirms that the presence of pre-existent VFs was the main determinant for iVFs. Additional studies on larger populations and with longer follow-up are needed to confirm our data and disclose the mechanisms underlying our findings.

Exon 3-deleted growth hormone receptor isoform is not related to worse bone mineral density or microarchitecture or to increased fracture risk in acromegaly

PURPOSE

Acromegaly is a cause of secondary osteoporosis and is associated with increased risk of vertebral fractures (VFs). The influence of exon 3-deleted isoform of growth hormone receptor (d3-GHR) on bone microarchitecture has not been studied in acromegaly.

AIM

The aim of this study was to analyze the associations between d3-GHR isoform and bone mineral density (BMD), bone microarchitecture, and VFs in acromegaly patients.

METHODS

Consecutive acromegaly patients treated at a single reference center were included. BMD was analyzed using dual-energy X-ray absorptiometry (DXA) and bone microarchitecture was analyzed by high-resolution peripheral quantitative computed tomography (HR-pQCT). The presence of moderate to severe VFs was assessed by thoracic and lumbar X-ray. GHR genotyping was analyzed by PCR, and full-length isoform of GHR (fl-GHR) was represented by a 935-bp fragment and d3-GHR by a 532-bp fragment.

RESULTS

Eighty-nine patients were included [56 females; median age at diagnosis: 43 years (17-78)]. Disease was uncontrolled in 63% of patients. At least one d3-GHR allele was present in 60% of patients. Frequency of active disease (p = 0.276) and hypogonadism (p = 1.000) was not different between patients with fl-GHR and those with at least one d3-GHR. There was no difference in any DXA or HR-pQCT parameters between patients with fl-GHR and those with d3-GHR. Significant VFs were observed in 14% of patients, but there was no difference in frequency between patients with fl-GHR and those with at least one d3-GHR allele (p = 0.578).

CONCLUSIONS

Presence of d3-GHR was not associated with worse BMD or bone microarchitecture or with higher frequency of significant VFs.

Exosomal hsa-miR-21-5p derived from growth hormone-secreting pituitary adenoma promotes abnormal bone formation in acromegaly

Growth hormone-secreting pituitary adenoma (GHPA), a benign endocrine tumor located in the base of the skull, results in acromegaly. In addition to the mass effect of the tumor itself in the sellar region, GHPA can lead to the overgrowth of almost every organ. Previous findings indicated that the processes underlying acromegaly were partly attributable to hyperactivity of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis. However, the mechanisms driving this syndrome remains largely unknown. Additionally, the roles of GHPA-derived exosomes, which contain functional microRNAs and proteins that manipulate target cell proliferation and differentiation in distal extremities, are also unknown. In this study, we demonstrated that GHPA exosomes promote bone formation in vitro and trabecula number in vivo. The mechanism of increased trabecula formation may be attributable to GHPA exosome-induced osteoblast proliferation via increased cell viability and DNA replication. We further discovered that exosomal hsa-miR-21-5p plays a distinct role from the GH/IGF-1 axis in these processes. Accordingly, the results of this study provide a novel mechanism whereby GHPA influences distal extremities and a new perspective for treating GHPA.

Hip Structure Analyses in Acromegaly: Decrease of Cortical Bone Thickness After Treatment: A Longitudinal Cohort Study

Long‐standing growth hormone (GH) excess causes the skeletal clinical signs of acromegaly with typical changes in bone geometry, including increased cortical bone thickness (CBT). However, a high prevalence and incidence of vertebral fractures has been reported. The aim of this study was to assess the course of cortical bone dimensions in the hip by comparing patients with acromegaly and clinically nonfunctioning pituitary adenomas (NFPAs) at baseline and 1 year after pituitary surgery (1‐year PO) in a longitudinal cohort study. DXA was performed in patients with acromegaly (n = 56) and NFPA (n = 47). CBT in the femoral neck (CBTneck), calcar (CBTcalcar), and shaft (CBTshaft) were determined by hip structural analysis (HSA). CBT at baseline and the change to 1‐year PO were compared. Test results were adjusted for differences in gender distribution, age, and gonadal status. Cortical thickness analyses showed higher values [mm] at baseline in patients with acromegaly compared with NFPA: CBTneck median [25th; 75th] 6.2 [4.7; 8.0] versus 5.1 [4.1; 6.4] (p = 0.006), CBTcalcar 4.8 [4.2, 5.7] versus 4.0 [3.2, 4.5] (p < 0.001), CBTshaft 6.2 [5.1, 7.2] versus 5.2 [4.6, 6.0], (p = 0.003). In acromegaly, GH was correlated with CBTneck (r = 0.31, p = 0.020), whereas IGF‐1 was correlated with CBTcalcar (r = 0.39, p = 0.003) at baseline. In acromegaly, CBTneck decreased by 11.2%, p = 0.002 during follow‐up. Finally, the decrease in CBTneck and CBTcalcar in acromegaly was significant compared with NFPA (p = 0.023 and p = 0.017, respectively). Previous observations of increased CBT in acromegaly were confirmed with DXA‐derived HSA in a large, well‐defined cohort. The decline in CBT in acromegaly could contribute to the increased fracture risk in acromegaly despite increased bone dimensions and disease control. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

The acromegalic spine: fractures, deformities and spinopelvic balance

INTRODUCTION

Axial skeleton arthropathy and osteoporotic vertebral fractures are common findings in acromegalic patients and can result in severe spinal deformity.

OBJECTIVE

To investigate the presence of spinal fractures and deformities, sagittal imbalances, and spinopelvic compensatory mechanisms in acromegalics.

PATIENTS AND METHODS

58 patients with acromegaly from a referral neuroendocrinology center were prospectively evaluated by panoramic spine radiographs to detect the presence of fractures and scoliosis, to measure thoracic kyphosis, lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sagittal vertical axis (SVA). Sagittal imbalance criteria were considered: thoracic kyphosis > 50°, PI-LL > 10°, PT > 20° and SVA > 5 cm. Their medical records were analyzed for clinical and laboratorial data.

RESULTS

The prevalence of fractures was 13.8%, predominantly in the thoracic spine, with mild and anterior wedge compressions. Scoliosis was present in 34.5% of the cases, all with degenerative lumbar curve apex. Thoracic kyphosis > 50º occurred in 36.8% of patients, PI-LL > 10° in 48.3%, PT > 20° in 41.4% and SVA > 5 cm in 12.1%.

CONCLUSION

Increased number of vertebral fractures and high prevalence of spinal deformities related to sagittal imbalance were detected, indicating the importance of monitoring bone comorbidities in acromegaly, with radiological evaluation of the spine as part of the follow up.

Determinants of morbidities and mortality in acromegaly

Acromegaly is a systemic disease associated with increased morbidity, presenting cardiovascular, metabolic, respiratory, neoplastic, endocrine, articular and bone complications. Most of these comorbidities can be prevented or delayed with adequate disease treatment and, more recent studies with the use of modern treatments of acromegaly, have shown a change in the severity and prevalence of these complications. In addition, acromegaly is associated with increased mortality, but recent studies (especially those published in the last decade) have shown a different scenario than older studies, with mortality no longer being increased in adequately controlled patients and a change in the main cause of death from cardiovascular disease to malignancy. In this review, we discuss this changing face of acromegaly summarizing current knowledge and evidence on morbimortality of the disease. Arch Endocrinol Metab. 2019;63(6):630-7.

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Acromegaly is characterized by increased release of growth hormone (GH) and, consequently, Insulin-Like Growth Factor I (IGF-I), most often by a pituitary adenoma. Prolonged exposure to excess hormone leads to progressive somatic disfigurement and a wide range of systemic manifestations that are associated with increased mortality. Transsphenoidal adenomectomy is the treatment of choice of GH-secreting pituitary tumors but surgical cure is not achieved in around 50% of patients, then adjuvant treatment is necessary. Mortality in acromegaly is normalized with biochemical control and has decreased in the last decade with the increased use of adjuvant therapy. Both GH and IGF-I are currently biomarkers for assessing disease activity in patients with acromegaly. However, discordance between GH and IGF-I results is encountered in a quarter of treated patients. The impacts of such a discrepancy over mortality and morbidity and the risk of biochemical and/or clinical recurrence are unclear. Moreover, despite a good biochemical control, some symptoms persist, leading to a decreased quality of life. Back pain due to vertebral fractures seem to be frequent in these patients and underdiagnosed. In patients with acromegaly, bone mineral density is not a reliable predictor of fracture risk. A more accurate evaluation of bone microstructural alterations associated with GH hypersecretion and vertebral fractures may be provided by new radiological devices analyzing alteration of trabecular microarchitecture, leading to a better prevention. © 2019 Published by Elsevier Masson SAS. All rights reserved. Cet article fait partie du numéro supplément Les Must de l'Endocrinologie 2019 réalisé avec le soutien institutionnel de Ipsen-Pharma.

DIAGNOSIS OF ENDOCRINE DISEASE: Evaluation of bone fragility in endocrine disorders

An underlying disease affecting bone health is present in up to 40% and 60% of osteoporotic post-menopausal women and men respectively. Among the disorders leading to a secondary form of osteoporosis, the endocrine diseases are highly represented. A frequent finding in patients affected with an endocrine-related forms of bone disease is that the skeletal fragility is partially independent of the bone density, since the fracture risk in these patients is related more to a reduction of bone quality than to a decrease of bone mass. As a consequence, bone mineral density evaluation by dual-X-ray Absorptiometry may be inadequate for establishing the risk of fracture in the setting of the endocrine-related forms of osteoporosis. In the recent years several attempts to non-invasively estimating bone quality have been done. Nowadys, some new tools are available in the clinical practice for optimizing the fracture risk estimation in patients with endocrine disorders. The aim of this review is to summarise the evidences regarding the role of the different imaging tools for evaluating bone density and bone quality in the most frequent forms of endocrine-related osteoporosis, such as obesity, diabetes, acromegaly, thyrotoxicosis, primary hyperparathyroidism, hypercortisolism and hypogonadism. For each of these disorders, data regarding both the current available tools and the future possible new techniques for assessing bone fragility in patients with endocrine diseases are reported.

Systemic Complications of Acromegaly and the Impact of the Current Treatment Landscape: An Update

Acromegaly is a chronic systemic disease with many complications and is associated with increased mortality when not adequately treated. Substantial advances in acromegaly treatment, as well as in the treatment of many of its complications, mainly diabetes mellitus, heart failure, and arterial hypertension, were achieved in the last decades. These developments allowed change in both prevalence and severity of some acromegaly complications and furthermore resulted in a reduction of mortality. Currently, mortality seems to be similar to the general population in adequately treated patients with acromegaly. In this review, we update the knowledge in complications of acromegaly and detail the effects of different acromegaly treatment options on these complications. Incidence of mortality, its correlation with GH (cumulative exposure vs last value), and IGF-I levels and the shift in the main cause of mortality in patients with acromegaly are also addressed.

Circulating miR-103a-3p and miR-660-5p are associated with bone parameters in patients with controlled acromegaly

Background Biochemical control of GH/IGF-I excess in acromegaly (ACRO) is associated with persistent impairment of trabecular microstructure leading to increased risk of vertebral fractures. Circulating miRNAs modulate the activity of osteoblasts and osteoclasts, and may be potential biomarkers of osteoporosis. Aims Identify differentially expressed miRNAs in the serum of patients with controlled ACRO vs controls and correlate miRNA levels with both biochemical and structural bone parameters. Patients and methods Twenty-seven patients with controlled ACRO (11 males, 16 females; mean age, 48 ± 5 years; BMI, 28 ± 4 kg/m2) and 27 age-, gender- and BMI-matched controls were recruited. Areal BMD at lumbar spine and femur, and trabecular bone score were assessed; volumetric BMD was measured by quantitative computed tomography QCT-Pro (Mindways). Twenty miRNAs, chosen by their putative role in bone, were quantified in serum using real-time qPCR. Results In ACRO patients, miR-103a-3p and miR-191-5p were found overexpressed, whereas miR-660-5p was underexpressed (P < 0.001). miR-103a-3p levels were negatively associated with both trabecular vBMD at trochanter and serum osteoprotegerin concentrations (P < 0.05) and positively with vitamin D concentrations (P < 0.01) and total cross-sectional area of the femoral neck (P < 0.05). miR-660-5p levels were correlated with both trabecular vBMD at trochanter and OPG concentrations (P < 0.05), but were negatively associated with vitamin D levels (P < 0.05). A negative correlation between miR-103-a-3p and miR-660-5p was found in both groups (P < 0.001). Conclusions Circulating miR-103a-3p and miR-660-5p are differentially expressed in controlled ACRO patients and associated with bone structural parameters. miRNAs may be one of the mechanisms involved in the pathogenesis of bone disease and could be used as biomarkers in ACRO patients.

Preoperative and Postoperative Bone Mineral Density Change and Risk Factor Analysis in Patients with a GH-Secreting Pituitary Adenoma

PURPOSE

This study analysed changes in bone mineral density (BMD) at different sites in patients with acromegaly and postoperative BMD changes and explored risk factors associated with BMD.

METHODS

Clinical data of 39 patients with growth hormone- (GH-) secreting pituitary adenomas and 29 patients with nonfunctioning pituitary adenomas who were newly diagnosed in neurosurgery from January 2016 to December 2018 were retrospectively analysed, including measurements of preoperative and postoperative BMD, serum GH glucose inhibition, random GH and IGF-1, and other anterior pituitary hormones.

RESULTS

The average patient age and disease duration were 43.74 (33.41-54.07) years and 72.15 (22.82-121.48) months, respectively. Compared with patients with nonfunctioning adenomas, patients with GH-secreting pituitary adenomas had significantly higher BMDs at L1, L2, femoral neck, Ward triangle, trochanter, femoral shaft, and total hip sites (p < 0.05). The BMD Z score at L1 and femoral neck sites significantly increased (p < 0.05). Thirteen patients underwent re-examination of BMD 1 year postsurgery, and the BMD Z score was reduced to normal levels at L1, L2, L3, L4, L1-L4, and L2-L4 compared with preoperative levels (p < 0.05). Postoperative BMD Z scores in the femoral neck and total hip were significantly increased (p < 0.05). Disease duration was negatively correlated with the lumbar-spine BMD Z score. IGF-1 burden was negatively correlated with the BMD Z score at L1 and L1-L4. Multiple regression analysis showed that IGF-1 burden was a risk factor for a BMD Z score decrease at L1 and L1-L4.

CONCLUSION

BMD in patients with GH-secreting pituitary adenomas (compared with nonfunctional adenomas) increased at L1, L2, femoral neck, Ward triangle, trochanter, femoral shaft, and total hip sites. Lumbar-spine BMD Z score recovered to normal levels postsurgically when GH and IGF-1 levels were controlled. BMD Z score was negatively correlated with disease duration and IGF-1 burden in patients with GH-secreting pituitary adenomas, and IGF-1 burden was an independent risk factor for reduced lumbar-spine BMD Z score.

Pituitary Diseases and Bone

Neuroendocrinology of bone is a new area of research based on the evidence that pituitary hormones may directly modulate bone remodeling and metabolism. Skeletal fragility associated with high risk of fractures is a common complication of several pituitary diseases such as hypopituitarism, Cushing disease, acromegaly, and hyperprolactinemia. As in other forms of secondary osteoporosis, pituitary diseases generally affect bone quality more than bone quantity, and fractures may occur even in the presence of normal or low-normal bone mineral density as measured by dual-energy X-ray absorptiometry, making difficult the prediction of fractures in these clinical settings. Treatment of pituitary hormone excess and deficiency generally improves skeletal health, although some patients remain at high risk of fractures, and treatment with bone-active drugs may become mandatory. The aim of this review is to discuss the physiological, pathophysiological, and clinical insights of bone involvement in pituitary diseases.

Effects of pegvisomant and somatostatin receptor ligands on incidence of vertebral fractures in patients with acromegaly

PURPOSE

Acromegalic osteopathy is an emerging complication of acromegaly characterized by increase in bone turnover, deterioration in bone microarchitecture and high risk of vertebral fractures (VFs). Somatostatin receptor ligands (SRLs) and pegvisomant (PegV) are used for treatment of acromegaly and there is evidence that both drugs may exert direct effects on peripheral targets regardless of biochemical control of disease. However, whether or not SRLs and PegV may directly influence skeletal health its is unknown.

METHODS

In this longitudinal study, we evaluated the incidence of radiological VFs in 83 patients (48 females, 35 males; median age 47 years, range 18-80 years) who were treated with SRLs alone (42 cases), PegV alone (6 cases) or in combination with SRLs (35 cases) for median period of 82 months (range 36-126). PegV was given when acromegaly was not controlled by SRLs alone.

RESULTS

During the follow-up, 29 patients (34.9%) developed incident VFs. In patients receiving PegV due to active disease during SRL therapy, incidence of VFs decreased significantly from 43.9 to 26.8% (p = 0.039). When acromegaly was controlled by PegV, the incidence of VFs was slightly but not significantly lower as compared to that observed in patients with biochemical control of disease by SRLs (10.0 vs. 26.7%; p = 0.09). In the multivariate logistic regression analysis, incident VFs were independently predicted by pre-existing VFs (odds ratio 61.0; p = 0.009), duration of active acromegaly (odds ratio 1.01; p = 0.05) and mean serum IGF-I during the follow-up (odds ratio 5.26; p = 0.03), regardless of the therapeutic regimen (odds ratio 1.05; p = 0.94).

CONCLUSIONS

PegV and SRLs had comparable effects on VF risk in acromegaly. The activity of disease was the main determinant of VFs independently of the drug used to control acromegaly.

Bone histomorphometry in acromegaly patients with fragility vertebral fractures

CONTEXT

The high risk of vertebral fractures (VFs) in acromegaly patients despite normal bone mineral density (BMD) is well known. The reasons for this paradoxical finding of skeleton fragility are poorly understood due to the limited data on bone histomorphometry in acromegaly.

OBJECTIVE

This study aimed to analyze histomorphometric parameters including bone microarchitecture in acromegaly patients with VFs and normal BMD compared to normal subjects, and also to evaluate the differences between active and controlled acromegaly patients.

PATIENTS AND METHODS

Forty-seven acromegaly patients (17 active, 30 controlled), median (range) age 57 years (30-88) were evaluated for bone turnover, morphometric VFs and BMD by dual-energy X-ray absorptiometry at lumbar spine and hip; 12 patients with VFs and normal BMD underwent iliac crest bone biopsy; 12 biopsies were taken at the autopsy in healthy sex and age-matched control subjects.

RESULTS

The histomorphometric evaluation of acromegaly fractured patients was compared with that of normal controls and showed significantly reduced median (range) levels of bone volume/tissue volume (BV/TV: 15.37% (7.93-26.75) vs. 18.61% (11.75-27.31), p = 0.036), trabecular thickness (TbTh: 77.6 µm (61.7-88.3) vs. 82.7 µm (72.3-92.0) p = 0.045), with increased trabecular separation (TbSp: 536.4 µm (356.2-900.6) vs. 370.3 µm (377.1-546.3) p = 0.038) and increased cortical thickness (1268 μm (752-2521) vs. 1065 μm (851-1205) p = 0.025) and porosity (11.9% (10.2-13.3) vs. 4.8% (1.6-8.8) p = 0.0008). While active acromegaly patients showed histomophometric features of increased bone turnover, patients with controlled disease presented normal bone turnover with significantly lower osteoblastic activity, expressed as osteoblast number (p = 0.001), active osteoblasts and vigor (p = 0.014) in the presence of reduced osteocyte number (p = 0.008) compared to active disease.

CONCLUSIONS

The apparent paradox of bone fragility in acromegaly patients with a normal BMD can be explained by increased cortical thickness and porosity and reduced trabecular thickness with increased trabecular separation. These structural and microarchitectural abnormalities persist in the controlled phase of acromegaly despite bone turnover normalization. The main determinant of bone disease after hormonal control is severe osteoblastic dysfunction.

Bone microarchitecture and estimated bone strength in men with active acromegaly

CONTEXT

Both acromegaly and adult growth hormone deficiency (GHD) are associated with increased fracture risk. Sufficient data are lacking regarding cortical bone microarchitecture and bone strength, as assessed by microfinite element analysis (µFEA).

OBJECTIVE

To elucidate both cortical and trabecular bone microarchitecture and estimated bone strength in men with active acromegaly or GHD compared to healthy controls.

DESIGN AND SUBJECTS

Cross-sectional study at a clinical research center, including 48 men (16 with acromegaly, 16 with GHD and 16 healthy controls).

OUTCOME MEASURES

Areal bone mineral density (aBMD), cortical and trabecular bone microarchitecture and estimated bone strength (µFEA) at the radius and tibia.

RESULTS

aBMD was not different between the 3 groups at any skeletal site. At the radius, patients with acromegaly had greater cortical area (P < 0.0001), cortical thickness (P = 0.0038), cortical pore volume (P < 0.0001) and cortical porosity (P = 0.0008), but lower trabecular bone density (P = 0.0010) compared to controls. At the tibia, patients with acromegaly had lower trabecular bone density (P = 0.0082), but no differences in cortical bone microstructure. Compressive strength and failure load did not significantly differ between groups. These findings persisted after excluding patients with hypogonadism. Bone microarchitecture was not deficient in patients with GHD.

CONCLUSIONS

Both cortical and trabecular microarchitecture are altered in men with acromegaly. Our data indicate that GH excess is associated with distinct effects in cortical vs trabecular bone compartments. Our observations also affirm the limitations of aBMD testing in the evaluation of patients with acromegaly.