Bone quality, as measured by trabecular bone score, in patients with primary hyperparathyroidism

Secondary hyperparathyroidism: Predictors and relationship with vitamin D status, bone turnover markers and bone mineral density

INTRODUCTION

Secondary hyperparathyroidism (SHPT) has adverse implications for bone health but is relatively understudied. In this study we examine the prevalence and determinants of SHPT and describe the relationship of SHPT with bone turnover markers and bone mineral density (BMD) in older Irish adults.

METHOD

Eligible participants (n = 4139) were identified from the Trinity-Ulster-Department of Agriculture (TUDA) study, a cohort of Irish adults aged ≥60 years. Exclusion criteria included an estimated glomerular filtration rate (eGFR) <30 ml/min and serum calcium >2.5 mmol/l to remove hyperparathyroidism due to advanced chronic kidney disease (CKD) and primary hyperparathyroidism respectively. The relationship between SHPT and bone turnover markers and BMD (measured by densitometry) was examined in a subsample (n = 1488). Vitamin D deficiency was defined as 25-hydroxyvitamin D [25 (OH)D] <30 nmol/l.

RESULTS

Participants had a mean age of 73.6 ± 7.9 years, 65.1 % were female and 19.4 % were found to be vitamin D deficient. The prevalence of SHPT decreased as vitamin D increased, from 30.6 % in those deficient to 9.8 % in those with 25(OH)D ≥ 50 nmol/l and increased with declining kidney function. In non‑calcium supplement users, principal determinants of SHPT were vitamin D deficiency (OR 4.18, CI 3.05-5.73, p < 0.001), eGFR 30-44 ml/min (OR 3.69, CI 2.44-5.57, p < 0.001), loop diuretic use (OR 3.52, CI 2.59-4.79, p < 0.001) and to a lesser extent body mass index (p = 0.001), eGFR 45-59 ml/min (p < 0.001) and 25(OH)D level 30-49 nmol/l (p = 0.002). Similar findings were observed in calcium supplement users, though proton pump inhibitors were also associated with SHPT (OR 1.55, CI 1.08-2.22, p = 0.018) while vitamin D 30-49 nmol/l was not. In participants with SHPT versus those without, bone turnover markers were higher: bone alkaline phosphatase (p = 0.017) and tartrate-resistant acid phosphatase (p = 0.033), whilst there was lower BMD at the neck of femur (0.880 vs. 0.903 g/cm2, p = 0.033) and total hip (0.968 vs. 0.995 g/cm2, P = 0.017).

DISCUSSION

The results show that up to one in six older Irish adults had SHPT and this was associated with lower BMD and higher concentrations of bone turnover markers. Both vitamin D deficiency and 25(OH)D level 30-49 nmol/l were important predictors of SHPT. Loop diuretics and PPIs may also increase the risk of SHPT, and their use may need to be carefully considered in this population. Further studies examining the potential impact of these factors on bone health in similar populations to our study sample are warranted.

Unraveling the relationship between serum parathyroid hormone levels and trabecular bone score: a cross-sectional study

The TBS is a new method for clinicians to assess the bone quality. It is directly related to the mechanical strength of bone and helps predict fracture risk. The present analysis aimed to investigate the associations between serum PTH levels and TBS by analyzing data from the National Health and Nutrition Examination Survey (NHANES). A total of 3516 participants from the NHANES 2005-2006 were included in this cross-sectional study. The independent variable was serum PTH, and the outcome variable was TBS. The associations of serum PTH levels with TBS were examined using multivariable linear regression models. After adjusting for covariates, there was a negative association between serum PTH level and TBS (β = - 0.0034; 95% confidence interval, - 0.0050 to - 0.0017). However, in the subgroup analysis stratified by gender, race, and age, this association became negative only in Non-Hispanic White (β =  - 0.0047, 95% CI:  -  0.0071 to  -  0.0048) and young people (age < 60) (β = - 0.0036, 95% CI: - 0.0057, - 0.0016), regardless of gender. In addition, the association of serum PTH with TBS was an U-shaped curve, with a point of inflection at 6.71 pmol/L. This study showed that serum PTH level was negatively associated with TBS. Maintaining PTH levels in a lower reasonable clinical range may be beneficial to bone health, especially for young non-Hispanic white.

Primary Hyperparathyroidism: Assessment of the Effects of Parathyroidectomy Using Dual X-Ray Absorptiometry, Trabecular Bone Score, and Dual X-Ray Absorptiometry-Based Three-Dimensional Modeling

OBJECTIVE

This study aimed to evaluate the bone microstructure to determine whether curative surgery of primary hyperparathyroidism produces changes in bone mineral density (BMD), trabecular bone score (TBS), and three-dimensional (3D) dual x-ray absorptiometry (DXA) parameters and whether these changes are comparable.

METHODS

We retrospectively studied 85 patients (60 women and 25 men, 60.4 ± 12.5 years) diagnosed with primary hyperparathyroidism and undergoing parathyroidectomy. Mean percent changes in BMD (lumbar spine [LS], femoral neck [FN], total hip [TH], and 1/3 radius), TBS and 3D-DXA parameters (trabecular volumetric BMD (vBMD), cortical vBMD, integral vBMD, cortical surface density (sBMD), and cortical thickness at TH) after surgery (12, 24, and/or 36 months) were calculated and compared, and we sought the determinants of these changes.

RESULTS

After parathyroidectomy, BMD presented statistically significant mean increases in LS, FN, and TH during the first 3 years after surgery (P < .001), accompanied by an improvement in all 3D-DXA parameters, but there were no significant changes in 1/3 radius BMD or TBS. Cortical sBMD, trabecular vBMD, and integral vBMD reached mean increases of similar magnitude to those of FN and TH BMD. Age and preoperative serum levels of parathyroid hormone and carboxy-terminal telopeptide of type 1 collagen were significantly associated with percent changes after surgery.

CONCLUSION

We found a benefit of parathyroidectomy for bone, with significant percent increases in LS, FN, and TH BMD up to the third year after surgery, and a qualitative benefit for the hip in both its trabecular and cortical compartments and bone strength.

Evaluation of Trabecular Bone Microarchitecture and Bone Mineral Density in Young Women, Including Selected Hormonal Parameters

The absence of non-invasive methods for assessing bone material and structural changes is a significant diagnostic challenge. Dual-energy X-ray absorptiometry (DXA) bone mineral density (BMD) testing is the gold standard for osteoporosis diagnosis. BMD and the trabecular bone score (TBS) have facilitated targeted osteoporosis prevention and treatment in clinical settings. The findings from this study indicate that BMD modulation in young women is influenced by various hormones, potentially compromising the diagnostic precision of BMD for subclinical bone demineralization. A total of 205 women aged 19 to 37 underwent anthropometric measurements and hormonal tests. BMD was determined using DXA, and TBS values were computed from the lumbar spine L1-L4 segment. The multivariate analysis findings suggest that BMD might not be determined by hormones. The relationship between TBS and TSH was statistically significant in the univariate analysis, which indicates the efficacy of further studies to determine the link between TBS and specific hormones. Analyzing the strength of the correlation between TBS and hormones in the univariate analysis shows which factors are worth considering in further analyses. This makes it possible to create better techniques that will help identify young women who are at a higher risk of developing osteoporosis.

Trabecular Bone Score as a More Sensitive Tool to Evaluate Bone Involvement in MEN1-related Primary Hyperparathyroidism

CONTEXT

The skeletal involvement of multiple endocrine neoplasia type 1-related primary hyperparathyroidism (MHPT) is not exactly the same as that of sporadic primary hyperparathyroidism (SHPT). Trabecular bone score (TBS) as a texture parameter has been reported to reflect trabecular bone damage.

OBJECTIVE

This study aimed to compare the clinical characteristics, especially the skeletal involvement, between patients with MHPT and SHPT.

METHODS

The clinical characteristics were retrospectively collected in 120 patients with MHPT and compared with 360 patients with SHPT in the same period. Dual-energy X-ray absorptiometry were conducted in some patients with MHPT, in whom bone mineral density (BMD) and calculated TBS derived from lumbar spine dual-energy X-ray absorptiometry images were compared with those of patients with SHPT.

RESULTS

Although the duration of disease in the MHPT group was longer, the age at hospital visit was significantly lower than that in the SHPT group (43.5 [interquartile range, 31.5-52.0] vs 52.0 [interquartile range, 40.5-61.0], P < .001). The proportion of skeletal involvement in the MHPT group was significantly lower. However, in the subgroup of MHPT cases (n = 86) with data of BMD, there was no significant difference in skeletal involvement from SHPT cases matched for gender and age. Although the BMD and TBS in the lumbar spines of patients with MHPT were lower than those of patients with SHPT (BMD: 0.91 ± 0.18 g/cm2 vs 1.01 ± 0.17 g/cm2; TBS: 1.22 ± 0.14 vs 1.29 ± 0.11, P < .001). According to TBS, among 34 patients with MHPT with normal BMD, 15 patients had bone microstructure damage.

CONCLUSION

The cancellous bone microarchitecture was more severely damaged in patients with MHPT according to TBS, which suggested that TBS could be a sensitive supplemental index in addition to BMD to identify bone-involvement risk in patients with MHPT.

Trabecular Bone Score Significantly Influences Treatment Decisions in Secondary Osteoporosis

The trabecular bone score (TBS) can be determined in addition to the Dual Energy X-ray Absorptiometry (DXA) for bone mineral density (BMD) measurement to diagnose, evaluate, and stratify bone loss and decide on appropriate treatment in patients at risk. Especially in patients with secondary osteoporosis, TBS detects restricted bone quality. To investigate the influence of an additional evaluation of TBS on patients' treatment strategy decisions, we enrolled 292 patients, with a high proportion of patients with secondary osteoporosis, from one outpatient unit over one year. Patients eligible for BMD measurement had the option to opt-in for TBS measurement. We analyzed demographic data, leading diagnoses, bone metabolism parameters, and results of BMD and TBS measurements. More than 90% of patients consented to TBS measurement. TBS measurement influenced the decision in approximately 40% of patients with a treatment indication for anti-osteoporotic drugs. We demonstrate that depending on the underlying disease/risk spectrum, 21-25.5% of patients had an unremarkable BMD measurement with poor bone quality shown in the TBS measurement. In patients with secondary osteoporosis, the use of TBS supplementary to DXA seems useful to better assess fracture risk and, thus, to initiate therapy for osteoporosis in these patients in time.

Positive Effect of Parathyroidectomy Compared to Observation on BMD in a Randomized Controlled Trial of Mild Primary Hyperparathyroidism

Mild or asymptomatic disease is now the dominating presentation of primary hyperparathyroidism (PHPT). However, bone involvement with decreased bone mineral density (BMD) and an increased risk of fractures has been demonstrated. Indications for parathyroidectomy (PTX) in mild PHPT have been debated for years. There is a need of long-term randomized studies comparing PTX with observation without intervention (OBS). Here, we present bone health data from the Scandinavian Investigation of Primary Hyperparathyroidism (SIPH), a randomized controlled trial, comparing PTX to OBS. This study included 191 patients (96 OBS/95 PTX), and 129 patients (64 OBS/65 PTX) were followed for 10 years to the end of study (EOS). BMD was measured with dual-energy X-ray absorptiometry (DXA), peripheral fractures were noted, and spine radiographs were obtained for vertebral fracture assessment. There was a significant treatment effect of PTX on BMD compared with OBS for all analyzed compartments, most explicit for the lumbar spine (LS) and femoral neck (FN) (p < 0.001). The mean changes in T-score from baseline to 10 years were from 0.41 for radius 33% (Rad33) to 0.58 for LS greater in the PTX group than in the OBS group. There was a significant decrease in BMD for all compartments in the OBS group, most pronounced for FN, Rad33, and ultradistal radius (UDR) (p < 0.001). Even though there was a significant treatment effect of PTX compared with OBS, there was only a significant increase in BMD over time for LS (p < 0.001). We found no difference between groups in fracture frequency in the 10-year cohort, neither with modified intention-to-treat (mITT) analysis nor per protocol analysis. Because BMD is only a surrogate endpoint of bone health and PTX did not reduce fracture risk, observation could be considered a safe option for many patients with mild PHPT regarding bone health in a 10-year perspective. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

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.

Update on trabecular bone score

Trabecular bone score (TBS) is an indirect and noninvasive measure of bone quality. A low TBS indicates degraded bone microarchitecture, predicts osteoporotic fracture, and is partially independent of clinical risk factors and bone mineral density (BMD). There is substantial evidence supporting the use of TBS to assess vertebral, hip, and major osteoporotic fracture risk in postmenopausal women, as well as to assess hip and major osteoporotic fracture risk in men aged > 50 years. TBS complements BMD information and can be used to adjust the FRAX (Fracture Risk Assessment) score to improve risk stratification. While TBS should not be used to monitor antiresorptive therapy, it may be potentially useful for monitoring anabolic therapy. There is also a growing body of evidence indicating that TBS is particularly useful as an adjunct to BMD for fracture risk assessment in conditions associated with increased fracture risk, such as type-2 diabetes, chronic corticosteroid excess, and other conditions wherein BMD readings are often misleading. The interference of abdominal soft tissue thickness (STT) on TBS should also be considered when interpreting these findings because image noise can impact TBS evaluation. A new TBS software version based on an algorithm that accounts for STT rather than BMI seems to correct this technical limitation and is under development. In this paper, we review the current state of TBS, its technical aspects, and its evolving role in the assessment and management of several clinical conditions.

Management of Primary Hyperparathyroidism

Since the last international guidelines were published in 2014 on the evaluation and management of primary hyperparathyroidism (PHPT), new information has become available with regard to evaluation, diagnosis, epidemiology, genetics, classical and nonclassical manifestations, surgical and nonsurgical approaches, and natural history. To provide the most current summary of these developments, an international group, consisting of over 50 experts in these various aspects of PHPT, was convened. This paper provides the results of the task force that was assigned to review the information on the management of PHPT. For this task force on the management of PHPT, two questions were the subject of systematic reviews using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) methodology. The full report addressing surgical and nonsurgical management of PHPT, utilizing the GRADE methodology, is published separately in this series. In this report, we summarize the results of that methodological review and expand them to encompass a much larger body of new knowledge that did not specifically fit the criteria of the GRADE methodology. Together, both the systematic and narrative reviews of the literature, summarized in this paper, give the most complete information available to date. A panel of experts then considered the last set of international guidelines in light of the newer data and assessed the need for their revision. This report provides the evidentiary background to the guidelines report. In that report, evidence from all task forces is synthesized into a summary statement and revised guidelines for the evaluation and management of PHPT. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Classical and Nonclassical Manifestations of Primary Hyperparathyroidism

This narrative review summarizes data on classical and nonclassical manifestations of primary hyperparathyroidism (PHPT). It is based on a rigorous literature search, inclusive of a Medline search for systematic reviews from 1940 to December 2020, coupled with a targeted search for original publications, covering four databases, from January 2013-December 2020, and relevant articles from authors' libraries. We present the most recent information, identify knowledge gaps, and suggest a research agenda. The shift in the presentation of PHPT from a predominantly symptomatic to an asymptomatic disease, with its varied manifestations, has presented several challenges. Subclinical nephrolithiasis and vertebral fractures are common in patients with asymptomatic disease. The natural history of asymptomatic PHPT with no end organ damage at diagnosis is unclear. Some observational and cross-sectional studies continue to show associations between PHPT and cardiovascular and neuropsychological abnormalities, among the different disease phenotypes. Their causal relationship is uncertain. Limited new data are available on the natural history of skeletal, renal, cardiovascular, neuropsychological, and neuromuscular manifestations and quality of life. Normocalcemic PHPT (NPHPT) is often diagnosed without the fulfillment of rigorous criteria. Randomized clinical trials have not demonstrated a consistent long-term benefit of parathyroidectomy (PTX) versus observation on nonclassical manifestations. We propose further refining the definition of asymptomatic disease, into two phenotypes: one without and one with evidence of target organ involvement, upon the standard evaluation detailed in our recommendations. Each of these phenotypes can present with or without non-classical manifestations. We propose multiple albumin-adjusted serum calcium determinations (albumin-adjusted and ionized) and exclusion of all secondary causes of high parathyroid hormone (PTH) when establishing the diagnosis of NPHPT. Refining the definition of asymptomatic disease into the phenotypes proposed will afford insights into their natural history and response to interventions. This would also pave the way for the development of evidence-based guidance and recommendations. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Evaluation and Management of Primary Hyperparathyroidism: Summary Statement and Guidelines from the Fifth International Workshop

The last international guidelines on the evaluation and management of primary hyperparathyroidism (PHPT) were published in 2014. Research since that time has led to new insights into epidemiology, pathophysiology, diagnosis, measurements, genetics, outcomes, presentations, new imaging modalities, target and other organ systems, pregnancy, evaluation, and management. Advances in all these areas are demonstrated by the reference list in which the majority of listings were published after the last set of guidelines. It was thus, timely to convene an international group of over 50 experts to review these advances in our knowledge. Four Task Forces considered: 1. Epidemiology, Pathophysiology, and Genetics; 2. Classical and Nonclassical Features; 3. Surgical Aspects; and 4. Management. For Task Force 4 on the Management of PHPT, Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) methodology addressed surgical management of asymptomatic PHPT and non-surgical medical management of PHPT. The findings of this systematic review that applied GRADE methods to randomized trials are published as part of this series. Task Force 4 also reviewed a much larger body of new knowledge from observations studies that did not specifically fit the criteria of GRADE methodology. The full reports of these 4 Task Forces immediately follow this summary statement. Distilling the essence of all deliberations of all Task Force reports and Methodological reviews, we offer, in this summary statement, evidence-based recommendations and guidelines for the evaluation and management of PHPT. Different from the conclusions of the last workshop, these deliberations have led to revisions of renal guidelines and more evidence for the other recommendations. The accompanying papers present an in-depth discussion of topics summarized in this report. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

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.

The Bone Strain Index: An Innovative Dual X-ray Absorptiometry Bone Strength Index and Its Helpfulness in Clinical Medicine

Bone strain Index (BSI) is an innovative index of bone strength that provides information about skeletal resistance to loads not considered by existing indexes (Bone Mineral Density, BMD. Trabecular Bone Score, TBS. Hip Structural Analysis, HSA. Hip Axis Length, HAL), and, thus, improves the predictability of fragility fractures in osteoporotic patients. This improved predictability of fracture facilitates the possibility of timely intervention with appropriate therapies to reduce the risk of fracture. The development of the index was the result of combining clinical, radiographical and construction-engineering skills. In fact, from a physical point of view, primary and secondary osteoporosis, leading to bone fracture, are determined by an impairment of the physical properties of bone strength: density, internal structure, deformation and fatigue. Dual X-ray absorptiometry (DXA) is the gold standard for assessing bone properties, and it allows measurement of the BMD, which is reduced mainly in primary osteoporosis, the structural texture TBS, which can be particularly degraded in secondary osteoporosis, and the bone geometry (HSA, HAL). The authors recently conceived and developed a new bone deformation index named Bone Strain Index (BSI) that assesses the resistance of bone to loads. If the skeletal structure is equated to engineering construction, these three indexes are all considered to determine the load resistance of the construct. In particular, BSI allows clinicians to detect critical information that BMD and TBS cannot explain, and this information is essential for an accurate definition of a patient’s fracture risk. The literature demonstrates that both lumbar and femoral BSI discriminate fractured osteoporotic people, that they predict the first fragility fracture, and further fragility fractures, monitor anabolic treatment efficacy and detect patients affected by secondary osteoporosis. BSI is a new diagnostic tool that offers a unique perspective to clinical medicine to identify patients affected by primary and, specially, secondary osteoporosis. This literature review illustrates BSI’s state of the art and its ratio in clinical medicine.

Bone Mineral Density Compared to Trabecular Bone Score in Primary Hyperparathyroidism

Individuals with primary hyperparathyroidism (PHPT) have reduced bone mineral density (BMD) according to dual X-ray absorptiometry at cortical sites, with relative sparing of trabecular BMD. However, fracture risk is increased at all sites. Trabecular bone score (TBS) may more accurately describe their bone quality and fracture risk. This study compared how BMD and TBS describe bone quality in PHPT. We conducted a retrospective cross-sectional study with a longitudinal component, of adults with PHPT, admitted to a tertiary hospital in Australia over ten years. The primary outcome was the TBS at the lumbar spine, compared to BMD, to describe bone quality and predict fractures. Secondary outcomes compared changes in TBS after parathyroidectomy. Of 68 included individuals, the mean age was 65.3 years, and 79% were female. Mean ± SD T-scores were −1.51 ± 1.63 at lumbar spine and mean TBS was 1.19 ± 0.12. Only 20.6% of individuals had lumbar spine BMD indicative of osteoporosis, while 57.4% of TBS were ≤1.20, indicating degraded architecture. There was a trend towards improved fracture prediction using TBS compared to BMD which did not reach statistical significance. Comparison of 15 individuals following parathyroidectomy showed no improvement in TBS.

Skeletal abnormalities in Hypoparathyroidism and in Primary Hyperparathyroidism

Both hypoparathyroidism (HypoPT), as well as its pathological counterpart, primary hyperparathyroidism (PHPT), can lead to skeletal abnormalities. Chronic deficiency of PTH in patients with HypoPT is associated with a profound reduction in bone remodeling, with consequent increases in bone density, and abnormalities in microarchitecture and bone strength. It is still not clear whether there is an increase in fracture risk in HypoPT. While standard therapy with calcium supplements and active vitamin D does not restore bone homeostasis, treatment of HypoPT with PTH appears to correct some of those abnormalities. In PHPT, the continuous exposure to high levels of PTH causes an increase in bone remodeling, in which bone resorption prevails. In the symptomatic form of PHPT, patients can present with fragility fractures, and/or the classical radiological features of osteitis fibrosa cystica. However, even in mild PHPT, catabolic skeletal actions of PTH are evident through reduced BMD, deterioration of bone microarchitecture and increased risk of fragility fractures. Successful parathyroidectomy improves skeletal abnormalities. Medical treatment, such as bisphosphonates and denosumab, can also increase bone density in patients with PHPT who do not undergo surgery. This article reviews skeletal involvement in HypoPT and in PHPT, as assessed by bone remodeling, DXA, trabecular bone score, and quantitative computed tomography, as well as data on bone strength and fracture risk. The effects of PTH replacement on the skeleton in subjects with HypoPT, and the outcome of parathyroidectomy in patients with PHPT, are also reviewed here.

DXA parameters, Trabecular Bone Score (TBS) and Bone Mineral Density (BMD), in fracture risk prediction in endocrine-mediated secondary osteoporosis

Osteoporosis, a disease characterized by low bone mass and alterations of bone microarchitecture, leading to an increased risk for fragility fractures and, eventually, to fracture; is associated with an excess of mortality, a decrease in quality of life, and co-morbidities. Bone mineral density (BMD), measured by dual X-ray absorptiometry (DXA), has been the gold standard for the diagnosis of osteoporosis. Trabecular bone score (TBS), a textural analysis of the lumbar spine DXA images, is an index of bone microarchitecture. TBS has been robustly shown to predict fractures independently of BMD. In this review, while reporting also results on BMD, we mainly focus on the TBS role in the assessment of bone health in endocrine disorders known to be reflected in bone.

The Impact of Observation Versus Parathyroidectomy on Bone Mineral Density and Fracture Risk Determined by FRAX Tool in Patients With Primary Hyperparathyroidism

To study impact of observation (OBV) vs parathyroidectomy (PTX) on biochemistry, bone mineral density (BMD) and fracture risk calculated by Fracture Risk Assessment (FRAX) tool in primary hyperparathyroidism (PHPT). Retrospective study of 60 patients (OBV - 26; PTX - 34 patients). Mean adjusted calcium improved in both groups [OBV - 2.76 ± 0.07 vs 2.51 ± 0.20 mmol/L; p < 0.00001, PTX - 2.87 ± 0.21 vs 2.36 ± 0.12 mmol/L; p < 0.00001]. Mean parathyroid hormone level declined in both but more in PTX group [OBV - 11.4 ± 5.2 vs. 9.7 ± 5.6 pmol/L; p = 0.04, PTX - 14.3 ± 8.2 vs 4.6 ± 2.2 pmol/L; p < 0.00001]. In OBV group, BMD and T scores declined at all sites. Mean percentage change of BMD was -5.8 % at femoral neck (FN), -4.9 % at total hip (TH), -6.2 % at lumbar spine (LS) and -10.0 % at lower 1/3^rd radius (LR). PTX led to stabilization of BMD at FN (3.0 %), TH (-0.6 %) and LS (2.2 %) but significant improvement at LR (13.9 %; p = 0.0005). In OBV group, 10 year risk of hip fracture (HF) (7.5 ± 9.0 % vs. 8.6 ± 9.0; p = 0.01) and major osteoporotic fracture (OF) (16.6 ± 10.9 % vs 18.3 ± 10.8 %; p = 0.002) worsened with time whereas in PTX group, risk of both type of fractures remained stable (HF; p = 0.48 and OF; p = 0.43). Comparison between groups showed greater improvement in median % change of fracture risk for both HF and OF in PTX group. OBV in PHPT lead to greater decline in BMD at all skeletal sites and imparted significant risk of HF and major OF. PTX offered stabilization of BMD at most sites but improvement at LR with unchanged fracture risk. FRAX tool should be used more frequently and universally.

Bone Analysis Using Trabecular Bone Score and Dual-Energy X-Ray Absorptiometry-Based 3-Dimensional Modeling in Postmenopausal Women With Primary Hyperparathyroidism

OBJECTIVE

Predominance of bone loss in cortical sites with relative preservation of trabecular bone, even in postmenopausal women, has been described in primary hyperparathyroidism (PHPT). The aim of this study was to evaluate bone microarchitectural differences using dual-energy x-ray absorptiometry (DXA), trabecular bone score (TBS), and DXA-based 3-dimensional (3D) modeling (3D-DXA) between postmenopausal women diagnosed with PHPT (PM-PHPT) and healthy postmenopausal controls.

METHODS

This retrospective study included 44 women with PM-PHPT (9 of whom had fractures) and 48 healthy women matched by age, body mass index, and years since menopause treated at Hospital Universitario Fundación Jiménez Díaz between 2008 and 2017. The bone mineral density (BMD) of the lumbar spine (LS), femoral neck, total hip (TH), and 1/3 radius was assessed using DXA, and trabecular volumetric BMD (vBMD), cortical vBMD, integral vBMD, cortical thickness, and cortical surface BMD at TH were assessed using a 3D-DXA software and TBS at LS.

RESULTS

The mean adjusted BMD values at LS, the femoral neck, and TH; TBS at LS; and TH 3D-DXA parameters (trabecular vBMD, integral vBMD, cortical thickness, and cortical surface BMD) were significantly reduced in women with PM-PHPT compared with those in the controls. However, differences in mean cortical vBMD were not statistically significant (P = .078). There were no significant differences in mean BMD, TBS, or the 3D-DXA parameters between patients with fractures and those without fractures. The 25-hydroxyvitamin D level appeared to be associated with TBS but not with DXA and 3D-DXA measurements.

CONCLUSION

PM-PHPT has significant involvement of the trabecular and cortical compartments of the bone, as determined by DXA, TBS, and 3D-DXA.

[The clinical practice guidelines for primary hyperparathyroidism, short version]

Primary hyperparathyroidism (PHPT) is an endocrine disorder of parathyroid glands characterized by excessive secretion of parathyroid hormone (PTH) with an upper normal or elevated blood calcium level. Classical PHPT refers to a symptomatic, multi-system disorder, wich can lead to a significant decrease in the quality of life, disability of patients, and even an increased risk of premature death. Hypercalcemia and the catabolic effect of PTH on various cells are considered as the main pathogenetic mechanisms of the PHPT associated complications. In the last two decades, there has been an increase in the incidence of PHPT, mainly due to the mild forms of the disease, primarily due to the routine calcium screening in North America, Western Europe and, Asia. High prevalence of the disease, as well as the variety of clinical manifestations, cause the attention of different specialists - physicians, rheumatologists, urologists, nephrologists, cardiologists and other doctors. This review cover the main issues of Russian guidelines for the management of PHPT, approved in 2020, including laboratory and instrumental methods, differential diagnosis, surgical and conservative approach, short-term and long-term follow-up. This guidelines also include the recommendations for special groups of patients with hereditary forms of PHPT, parathyroid carcinoma, PHPT during pregnancy.

DXA-Based Bone Strain Index: A New Tool to Evaluate Bone Quality in Primary Hyperparathyroidism

CONTEXT

Primary hyperparathyroidism (PHPT) is associated with impaired bone quality and increased fracture risk. Reliable tools for the evaluation of bone quality parameters are not yet clinically available. Bone Strain Index (BSI) is a new metric for bone strength based on Finite Element Analysis from lumbar spine and femoral neck dual-energy x-ray absorptiometry (DXA) images.

OBJECTIVE

To assess the lumbar spine (LS), femoral neck (FN), and total hip (TH) BSI in PHPT patients compared with controls and to investigate the association of BSI with vertebral fractures (VFs) in PHPT.

METHODS

This case-control study enrolled 50 PHPT patients and 100 age- and sex-matched control subjects from an outpatient clinic. The main outcome measures were LS-BSI, FN-BSI, and TH-BSI.

RESULTS

FN bone mineral density (BMD) and one-third distal radius BMD were lower in the PHPT group than in controls (FN 0.633 ± 0.112 vs 0.666 ± 0.081, P = 0.042; radius 0.566 ± 0.07 vs 0.625 ± 0.06, P < 0.001). PHPT group has significant lower TBS score compared with controls (1.24 ± 0.09 vs 1.30 ± 0.10, P < 0.001). BSI was significantly higher at LS (2.28 ± 0.59 vs 2.02 ± 0.43, P = 0.009), FN (1.72 ± 0.41 vs 1.49 ± 0.35, P = 0.001), and TH (1.51 ± 0.33 vs 1.36 ± 0.25, P = 0.002) in PHPT. LS-BSI showed moderate accuracy for discriminating VFs (AUC 0.667; 95% CI, 0.513-0.820). LS-BSI ≥ 2.2 and was a statistically significant independent predictor of VFs, with an adjusted odds ratio ranging from 5.7 to 15.1.

CONCLUSION

BSI, a DXA-derived bone quality index, is impaired in PHPT and may help to identify PHPT subjects at high risk of fractures.

Risk of fractures in primary hyperparathyroidism: a systematic review and meta-analysis

An increased risk of fractures in primary hyperparathyroidism (PHPT) has been reported in a number of relatively small studies. Performing a systematic literature search, we identified available studies and calculated common estimates by pooling results from the individual studies in a meta-analysis. Searching EMBASE and PubMed, we identified published studies reporting the risk of fractures in PHPT compared to a control group. We calculated odds ratio (OR) with 95% confidence interval (CI). A total of 804 studies were identified of which 12 studies were included. Risk of any fracture was increased compared to controls (OR 2.01; 95% CI, 1.61-2.50; I² 46%, 5 studies). Analysis of fracture risk at specific sites showed an increased risk of fracture at the forearm (OR 2.36; 95% CI, 1.64-3.38; I² 0%, 4 studies) and spine (OR 3.00; 95% CI, 1.41, 6.37, I² 88%, 9 studies). Risk estimate for hip fractures was non-significantly increased (OR 1.27; 95% CI, 0.97-1.66; I² 0%, 3 studies). Risk of vertebral fractures (VFx) was also increased if analyses were restricted to only studies with a healthy control group (OR 5.76; 95% CI, 3.86-8.60; I² 29%, 6 studies), studies including patients with mild PHPT (OR 4.22; 95% CI, 2.20-8.12; I² 57%, 4 studies) or studies including postmenopausal women (OR 8.07; 95% CI, 4.79-13.59; I² 0%, 3 studies). PHPT is associated with an increased risk of fractures. Although a number of studies are limited-it seems that the risk is increased across different skeletal sites including patients with mild PHPT and postmenopausal women.

Application of the Trabecular Bone Score in Clinical Practice

The trabecular bone score (TBS) was introduced as an indirect index of trabecular microarchitecture, complementary to bone mineral density (BMD), and is derived using the same dual energy X-ray absorptiometry images. Recently, it has been approved for clinical use in Korea. Therefore, we conducted a comprehensive review to optimize the use of TBS in clinical practice. The TBS is an independent predictor of osteoporotic fractures in postmenopausal women and men aged >50 years. The TBS is potentially useful in monitoring the skeletal effects of anabolic agents but not of antiresorptive agents. In postmenopausal women with type 2 diabetes mellitus, the TBS assesses osteoporotic fracture risk not captured by BMD. However, high body mass index and soft tissue thickness can cause underestimation of the TBS; however, this limitation has been improved in recent versions of the TBS software. However, a high precision error and low reproducibility limit the use of TBS. This review may provide information on the application of the TBS in clinical practice based on reliable evidence.

Bone Quality as Measured by Trabecular Bone Score in Normocalcemic Primary Hyperparathyroidism

OBJECTIVE

The impact of normocalcemic hyperparathyroidism (NHPT) on bone quality remains largely unexplored. We aimed to investigate the usefulness of trabecular bone score (TBS) assessment in NHPT and the accuracy of TBS in predicting vertebral fractures (VFs) in NHPT.

METHODS

In this multicentric cross-sectional study, we assessed the TBS in 47 subjects with NHPT, 41 with primary hyperparathyroidism (PHPT), and 39 age- and sex-matched control subjects.

RESULTS

TBS values did not differ among the 3 groups. The prevalence of low TBS (TBS < 1.2) was 23.4% in NHPT, 26.8% in PHPT, and 15.4% in controls, without statistically significant differences between groups. However, we found a lower lumbar spine Z-score adjusted for TBS (LS Z-score∗TBS) in PHPT participants when compared with controls (-0.48 ± 1.06 vs 0.07 ± 0.93, P = .017). In NHPT group, LS Z-score∗TBS did not detect patients with overall VFs (threshold, -0.15; area under the curve, 0.45; 95% CI, 0.253-0.648; accuracy, 55.3%). Instead, it was useful for moderate-severe VFs (threshold, 0.55; area under the curve, 0.81; 95% CI, 0.62-0.996; accuracy, 83%). In PHPT subjects also, TBS did not predict VFs.

CONCLUSION

In NHPT, TBS is not reduced. When adjusted for TBS, the LS Z-score might predict moderate-to-severe VFs.

Factors associated with degraded trabecular bone score in heart transplant recipients

Trabecular bone score (TBS) is a textural index that provides indirect evaluation of trabecular microarchitecture. It improves fracture risk assessment in several high-risk populations. We aimed to evaluate the role of TBS assessment in heart transplant recipients (HTR). In a cross-sectional study with 87 HTR (69 males and 18 females), we assessed TBS and evaluated potential associations between TBS and factors related to increased fracture risk. We also evaluated the correlations between the presence of vertebral fractures (VF) and degraded TBS. We confirmed degraded TBS in the majority of HTR. 27.6% of HTR had partially degraded, 27.6% had degraded TBS. HTR with degraded TBS were older, had higher body mass index, lower bone mineral density (BMD), and T-score. As opposed to stable BMD over different time points, TBS significantly differed among different post-transplant time periods. TBS did not correlate with current methylprednisolone or past zoledronic acid treatment, presence of hypogonadism or diabetes. TBS did not have additional value over BMD in predicting the presence of VF. Most fractures occurred in patients with osteopenia and in patients with partly degraded TBS. Studies with longitudinal designs and larger sample sizes are warranted to further assess the potential role of TBS in HRT.

The Risk of Fractures in Primary Hyperparathyroidism: A Meta-Analysis

Primary hyperparathyroidism (PHPT) is a common metabolic bone disease affecting 1% of the adult population. Patients with PHPT have reduced BMD, especially at the cortical bone. However, studies evaluating its impact on fracture risk have shown contradictory results. In an effort to further inform fracture risk for this patient population, a meta‐analysis of studies of fracture in patients with PHPT compared with a control population was undertaken. Articles were searched in PubMed/MEDLINE, Excerpta Medica, Cochrane Central Register of Controlled Trials, Latin American and Caribbean Health Sciences Literature, and Web of Science bibliographic databases. The meta‐analysis included 17 studies involving 3807 PHPT cases and 11,908 controls. The primary outcome was to determine the risk of vertebral fracture (VF), nonvertebral fracture, hip fracture, distal radius fracture, and total fracture (TF) among patients with PHPT in comparison with a control population. BMD (lumbar spine, femoral neck, total hip, and distal radius) and serum 25‐hydroxy vitamin D level, as well as possible predictors of VF as secondary outcomes were assessed. From this meta‐analysis, it was found that there was a significantly increased risk of VF (risk ratio [RR], 2.57; 95% CI, 1.3–5.09; p = 0.007) and TF (RR, 1.71; 95% CI, 1.48–1.97; p < 0.00001) in patients with PHPT. There was a significant decrease in BMD in patients with PHPT versus controls at all four sites. Older age, longer duration since menopause, and lower BMD at lumbar spine and distal radius were predictors for VF. To conclude, patients with PHPT had a significantly higher risk for VF and TF in comparison with controls. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

[Asymptomatic primary hyperparathyroidism : Operation or observation?]

BACKGROUND

In many cases primary hyperparathyroidism (PHPT) remains asymptomatic for years and is only detected by abnormalities in routine diagnostics. While symptomatic disease almost always requires surgical treatment, in symptom-free patients the question of whether and in what form treatment should be carried out is particularly important.

OBJECTIVE

The aim of this review is to summarize the current recommendations regarding the diagnostics and treatment of asymptomatic PHPT, taking the existing evidence into account.

RESULTS AND CONCLUSION

The diagnostics of asymptomatic PHPT is the same as for symptomatic disease. The diagnosis is made in the presence of elevated parathyroid hormone and balanced vitamin D levels when a combination of hypercalcemia, hypophosphatemia and hypercalciuria is present. Borderline laboratory findings occur especially in asymptomatic PHPT and the differential diagnosis of familial hypocalciuric hypercalcemia must be considered. Once the diagnosis is made sonography, radiography or computed tomography (CT) is used to search for nephrolithiasis or nephrocalcinosis. Regarding bone mineral density (BMD) measurements, in addition to routine measurements at the lumbar spine and femur, measurement at the distal radius is important as it is the most sensitive site for detecting osteoporosis in PHPT. An indication for parathyroidectomy is confirmed in the case of hypercalcemia > 1.0 mg/dl (>0.25 mmol/l) above the upper limit of normal, hypercalciuria > 400 mg/day (>10 mmol/day), renal insufficiency, proven osteoporosis or age < 50 years. If none of these criteria are fulfilled and surgery is not desired by the patient, annual laboratory check-ups and assessment of BMD every 1-2 years are recommended.

Does Baseline PTH Influence Recovery of Bone Mineral Density, Trabecular Bone Score and Bone Turnover Markers? A Prospective Study Following Curative PArathyroidectomy in Primary Hyperparathyroidism

OBJECTIVE

This prospective study was carried out to assess trabecular bone score, bone mineral density (BMD), and bone biochemistry in Indian subjects with symptomatic primary hyperparathyroidism (PHPT), and to study the influence of baseline parathyroid hormone (PTH) on recovery of these parameters following curative surgery.

METHODS

This was a 2-year prospective study conducted at a tertiary care centre in southern India. Baseline assessment included demographic details, mode of presentation, bone mineral biochemistry, BMD, trabecular bone score (TBS), and bone turnover markers (BTMs). These parameters were reassessed at the end of the first and second years following curative parathyroid surgery.

RESULTS

Fifty-one subjects (32 men and 19 women) with PHPT who had undergone curative parathyroidectomy were included in this study. The mean (SD) age was 44.6 (13.7) years. The TBS, BTMs, and BMD at lumbar spine and forearm were significantly worse at baseline in subjects with higher baseline PTH (≥250 pg/mL) when compared to the group with lower baseline PTH (<250 pg/mL). At the end of 2 years, the difference between high versus low PTH groups (mean ± SD) persisted only for forearm BMD (0.638±0.093 versus 0.698±0.041 g/cm²; P =.01). However, on follow-up visits in the first and second year after curative parathyroidectomy, there was no significant difference in BTMs, BMD at the femoral neck, lumbar spine, and TBS between the 2 groups stratified by baseline PTH.

CONCLUSION

The BMD at the forearm remained significantly worse in individuals with high baseline PTH even at 2 years after surgery, while other parameters including TBS improved significantly from baseline.

ABBREVIATIONS

25(OH)D = 25-hydroxyvitamin D; BMD = bone mineral density; BMI = body mass index; BTMs = Bone turnover markers; CTX = C-terminal telopeptide of type 1 collagen; DXA = dual energy X-ray absorptiometry; P1NP = N-terminal propeptide of type 1 procollagen; PHPT = primary hyperparathyroidism; PTH = parathyroid hormone; TBS = trabecular bone score.

The Potential Role of Preoperative Trabecular Bone Score in Predicting Changes in Bone Mineral Density After Parathyroidectomy

BACKGROUND

The skeletal indication for parathyroidectomy for primary hyperparathyroidism (PHPT) is based on bone mineral density (BMD) T-score <  - 2.5. Whether trabecular bone score (TBS) additionally identifies patients who benefit from parathyroidectomy in terms of bone health is unknown. We aimed to study changes in BMD and TBS among Chinese who underwent curative parathyroidectomy for PHPT, in relation to their preoperative parameters, especially in those with worst site BMD T-score ≥  - 2.5 (non-osteoporotic range).

METHODS

We included consecutive Chinese individuals who underwent curative parathyroidectomy during 2002-2015 for PHPT and completed preoperative and postoperative BMD and TBS measurements in Queen Mary Hospital. Correlations between preoperative parameters and changes in densitometric parameters were studied.

RESULTS

45 Chinese individuals (13 men, 32 women) were included (mean age 62.0 ± 10.0 years and BMI 24.6 ± 4.7 kg/m²). After parathyroidectomy, BMD at lumbar spine (LS) improved by 6.7% (p < 0.001) while TBS did not change. Among women, peak preoperative parathyroid hormone and calcium levels independently predicted LS BMD gain. Among women with BMD in non-osteoporotic range, LS BMD also improved after parathyroidectomy, where preoperative TBS was the only significant variable inversely correlating with percentage change in LS BMD (ρ - 0.775, p = 0.005). Particularly, those with preoperative TBS ≤ 1.25 gained 7.1% LS BMD post-parathyroidectomy (p = 0.003).

CONCLUSIONS

LS BMD, but not TBS, improved after parathyroidectomy. Among non-osteoporotic PHPT women, preoperative TBS inversely correlated with postoperative BMD improvement. Hence, low preoperative TBS may be an additional indication for surgical benefit with parathyroidectomy in non-osteoporotic PHPT women, as those with worse preoperative TBS tend to benefit more from surgery.

Effects of denosumab as compared with parathyroidectomy regarding calcium, renal, and bone involvement in osteoporotic patients with primary hyperparathyroidism

PURPOSE

To evaluate the effects of denosumab (Dmb) on calcium, renal, and bone involvement in osteoporotic patients with primary hyperparathyroidism (PHPT) and compare with those who underwent a parathyroidectomy (PTX) procedure.

METHODS

This retrospective, longitudinal study included patients treated with Dmb (60 mg) once every 6 months (n = 19) and those who successfully underwent a PTX procedure (n = 19) corrected calcium (cCa), eGFR, bone mineral density (BMD) in the lumbar spine (LS), total hip (TH), and femoral neck (FN) and LS-trabecular bone score (TBS) changes at 1 year after beginning Dmb or undergoing PTX were measured.

RESULTS

Dmb group had older age, and showed milder disease activity and lower eGFR as compared with PTX group. In PTX group, cCa and eGFR were significantly decreased following surgery, while those were stable in Dmb group. There were significant increases in LS, TH, and FN-BMD in both Dmb (LS: 6.0 ± 0.8%, TH: 3.7 ± 1.0%, FN: 4.3 ± 1.5%) and PTX (LS: 11.2 ± 1.5%, TH: 7.5 ± 1.5%, FN: 7.9 ± 2.1%) groups. In Dmb group, LS-TBS was significantly improved by 3.0 ± 1.0%, while TBS change in PTX group approached significance (2.8 ± 1.5%). Percent change in TH-BMD was significantly correlated with baseline tartrate-resistant acid phosphatase-5b (TRACP-5b) in both groups.

CONCLUSIONS

Dmb treatment not only increased BMD, dependent on bone turnover status, the same as PTX, but also improved LS-TBS. In addition, it did not decrease the level of eGFR, whereas PTX did. These results suggest that Dmb treatment help in the clinical management of osteoporotic patients with PHPT who do not undergo surgery as alternative to PTX.

Physical Activity-Dependent Regulation of Parathyroid Hormone and Calcium-Phosphorous Metabolism

Exercise perturbs homeostasis, alters the levels of circulating mediators and hormones, and increases the demand by skeletal muscles and other vital organs for energy substrates. Exercise also affects bone and mineral metabolism, particularly calcium and phosphate, both of which are essential for muscle contraction, neuromuscular signaling, biosynthesis of adenosine triphosphate (ATP), and other energy substrates. Parathyroid hormone (PTH) is involved in the regulation of calcium and phosphate homeostasis. Understanding the effects of exercise on PTH secretion is fundamental for appreciating how the body adapts to exercise. Altered PTH metabolism underlies hyperparathyroidism and hypoparathyroidism, the complications of which affect the organs involved in calcium and phosphorous metabolism (bone and kidney) and other body systems as well. Exercise affects PTH expression and secretion by altering the circulating levels of calcium and phosphate. In turn, PTH responds directly to exercise and exercise-induced myokines. Here, we review the main concepts of the regulation of PTH expression and secretion under physiological conditions, in acute and chronic exercise, and in relation to PTH-related disorders.

TSH suppressive therapy and bone

Thyroid hormones stimulate bone turnover in adults by increasing osteoclastic bone resorption. TSH suppressive therapy is usually applied in patients with differentiated thyroid cancer (DTC) to improve the disease outcome. Over the last decades several authors have closely monitored the potential harm suffered by the skeletal system. Several studies and meta-analyses have shown that chronic TSH suppressive therapy is safe in premenopausal women and men. Conversely, in postmenopausal women TSH suppressive therapy is associated with a decrease of bone mineral density, deterioration of bone architecture (quantitative CT, QCT; trabecular bone score, TBS), and, possibly, an increased risk of fractures. The TSH receptor is expressed in bone cells and the results of experimental studies in TSH receptor knockout mice and humans on whether low TSH levels, as opposed to solely high thyroid hormone levels, might contribute to bone loss in endogenous or exogenous thyrotoxicosis remain controversial. Recent guidelines on the use of TSH suppressive therapy in patients with DTC give value not only to its benefit on the outcome of the disease, but also to the risks associated with exogenous thyrotoxicosis, namely menopause, osteopenia or osteoporosis, age >60 years, and history of atrial fibrillation. Bone health (BMD and/or preferably TBS) should be evaluated in postmenopausal women under chronic TSH suppressive therapy or in those patients planning to be treated for several years. Antiresorptive therapy could also be considered in selected cases (increased risk of fracture or significant decline of BMD/TBS during therapy) to prevent bone loss.

Clinical, Biochemical, and Radiological Profile of Normocalcemic Primary Hyperparathyroidism

CONTEXT

The clinical and radiological aspects of normocalcemic hyperparathyroidism (NHPT) are confounded by the differing methods used to rule out secondary hyperparathyroidism and by the small sample size.

OBJECTIVE

To assess the clinical, biochemical, and radiological profile of NHPT compared with primary hyperparathyroidism (PHPT) and control subjects.

DESIGN

Multicentric cross-sectional study.

SETTING

Outpatient clinic.

PATIENTS

47 NHPT, 41 PHPT, and 39 age- and sex-matched control subjects.

MAIN OUTCOME MEASURES

Calcium metabolism and bone turnover markers (BTMs). Lumbar spine, total hip, femoral neck, one-third distal radius bone mineral density (BMD). Morphometric vertebral fracture (VF) assessed by dual-energy X-ray absorptiometry.

RESULTS

NHPT patients had significantly higher parathyroid hormone, 25(OH)-vitamin D levels and lower calcium × phosphorus product than controls (P < .001). Compared with PHPT, the NHPT group had significantly higher 25(OH) vitamin D levels (P = .016). NHPT had BTM levels similar to controls and PHPT. NHPT, PHPT, and controls have similar lumbar spine and femoral neck BMD. NHPT and controls had a similar radial BMD, while patients with PHPT had a lower radial BMD than both patients with NHPT (P = .031) and controls (P < .05). Using the control group as the reference, after adjustment for interacting factors, there was no increase in risk of moderate-severe VF in NHPT (odds ratio [OR] 1.04, 95% confidence interval [CI] 0.25-4.55), while PHPT had an increased risk (OR 3.81,95% CI 1.15-15.12). Seventy-nine percent of NHPT and 59% of PHPT patients fulfilled the criteria for asymptomatic hyperparathyroidism.

CONCLUSIONS

The biochemical phenotype of NHPT is intermediate between PHPT and controls. In contrast, the bone phenotype resembles controls with normal bone turnover, no significant BMD impairment, and no increased risk of VF.

Effects of PTH and PTH Hypersecretion on Bone: a Clinical Perspective

PURPOSE OF REVIEW

Hyperparathyroidism may be due to an autonomous hypersecretion of parathyroid hormone (PTH) or occurs in response to a number of physiological stimuli. A number of recent findings have provided new insights into the importance of the calcium-parathyroid-vitamin D axis to bone in normal physiology and pathological conditions.

RECENT FINDINGS

PTH is known to affect bone microarchitecture with different effects on cortical and trabecular bone compartments. In trabecular bone, PTH may exert anabolic effects, whereas PTH promotes bone resorption in cortical bone. Vertebral fractures are prevalent in primary hyperparathyroidism (PHPT), and patients seem to fracture at higher values of bone mineral density (BMD) than patients with osteoporosis. This may be explained by changes in bone microarchitecture, which cannot be detected by measuring BMD. Even in mild PHPT, bone seems to benefit from parathyroidectomy. In secondary hyperparathyroidism, bone seems much more susceptible to fracture with insufficient levels of vitamin D compared with a replete vitamin status. If elevated PTH levels cannot be explained by conditions known to cause secondary hyperparathyroidism, the condition is termed normocalcemic PHPT, which also has been associated with an increased risk of fractures. Hyperparathyroidism is harmful to bone, which is why it is of importance to normalize PTH levels either by parathyroidectomy in PHPT or by counteracting conditions known to increase PTH in secondary hyperparathyroidism.

A paternally inherited non-sense variant c.424G>T (p.G142*) in the first exon of XLαs in an adult patient with hypophosphatemia and osteopetrosis

XLαs, the extra-large isoform of alpha-subunit of the stimulatory guanine nucleotide-binding protein (Gsα), is paternally expressed. The significance of XLαs in humans remains largely unknown. Here, we report a patient who presented with increased bone mass, hypophosphatemia, and elevated parathyroid hormone (PTH) levels. His serum calcium was in the lower limit of the normal range. Whole exome sequencing of this subject found a novel non-sense variant c.424G>T (p. G142*) in the first exon of XLαs, which was inherited from his father and transmitted to his daughter. This variant was predicted to exclusively influence the expression of XLαs, while possibly having no significant effects on other gene products of this locus. Ellsworth-Howard test revealed normal renal response to PTH in proband. Human SaOS2 cells transfected with mutant XLαs failed to generate cyclic adenosine monophosphate under PTH stimulation, indicating skeletal resistance to this hormone. This subject showed higher circulating sclerostin, dickkopf1, and osteoprotegerin (OPG) levels, while lower receptor activator of nuclear factor kappa-B ligand/OPG ratio, leading to reduced bone resorption. Our findings indicate that XLαs plays a critical role in bone metabolism and GNAS locus should be considered as a candidate gene for high bone mass.

A new finite element based parameter to predict bone fracture

Dual Energy X-Ray Absorptiometry (DXA) is currently the most widely adopted non-invasive clinical technique to assess bone mineral density and bone mineral content in human research and represents the primary tool for the diagnosis of osteoporosis. DXA measures areal bone mineral density, BMD, which does not account for the three-dimensional structure of the vertebrae and for the distribution of bone mass. The result is that longitudinal DXA can only predict about 70% of vertebral fractures. This study proposes a complementary tool, based on Finite Element (FE) models, to improve the DXA accuracy. Bone is simulated as elastic and inhomogeneous material, with stiffness distribution derived from DXA greyscale images of density. The numerical procedure simulates a compressive load on each vertebra to evaluate the local minimum principal strain values. From these values, both the local average and the maximum strains are computed over the cross sections and along the height of the analysed bone region, to provide a parameter, named Strain Index of Bone (SIB), which could be considered as a bone fragility index. The procedure is initially validated on 33 cylindrical trabecular bone samples obtained from porcine lumbar vertebrae, experimentally tested under static compressive loading. Comparing the experimental mechanical parameters with the SIB, we could find a higher correlation of the ultimate stress, σULT, with the SIB values (R2adj = 0.63) than that observed with the conventional DXA-based clinical parameters, i.e. Bone Mineral Density, BMD (R2adj = 0.34) and Trabecular Bone Score, TBS (R2adj = -0.03). The paper finally presents a few case studies of numerical simulations carried out on human lumbar vertebrae. If our results are confirmed in prospective studies, SIB could be used-together with BMD and TBS-to improve the fracture risk assessment and support the clinical decision to assume specific drugs for metabolic bone diseases.

Risk factors for vertebral fracture in primary hyperparathyroidism

PURPOSE

Screening for vertebral fractures (VF) in primary hyperparathyroidism (PHPT) is recommended, but there are limited data regarding which patients are at greatest risk for VF. We evaluated risk factors for VF in PHPT.

METHODS

This is a retrospective cross-sectional analysis of 117 participants with PHPT. We assessed Grades 2 and 3 VF by vertebral fracture assessment (VFA) and the association of VF with the trabecular bone score (TBS), other skeletal parameters and clinical risk factors. VFA was performed only in those who met National Osteoporosis Foundation criteria for VFA screening.

RESULTS

T-scores were in the osteopenic range and TBS was degraded. Overall VF rate based on VFA or other imaging was 12.8%. Serum PTH, calcium and TBS were not associated with VF. Those with VF were older (p = 0.04), had worse renal function (p = 0.04), were more likely to have received osteoporosis treatment (p = 0.03), and tended to have had a prior fracture (p = 0.06). T-scores did not differ by fracture status at any skeletal site. Those with VF had nine times the odds of osteoporosis at the hip (95% CI 2.4-34.5), but this risk factor had low sensitivity (46.7%) for VF. Hip T-score < -2.6, Age > 78.6 years, and GFR < 58.8 ml/min/1.73 m² (thresholds maximizing sensitivity and specificity) had areas under the curve of 0.60-0.67 for VF (all p < 0.05) and low sensitivity. Findings were similar when analyses were limited to women.

CONCLUSIONS

In PHPT, VF risk factors included older age, prior fracture, worse renal function and osteoporosis at the hip, but not osteoporosis at other sites, TBS or biochemical indices of PHPT. Since identified risk factors had low sensitivity and were generally inaccurate for categorizing those with VF, the data do not support limiting screening to PHPT patients with these specific VF risk factors.

Effectiveness of anti-osteoporotic treatment after successful parathyroidectomy for primary hyperparathyroidism: a randomized, double-blind, placebo-controlled trial

PURPOSE

After successful surgery for primary hyperparathyroidism, bone mineral density (BMD) does not improve equally in all patients. As no trial has so far aimed to influence normalization of BMD, it was the goal of this investigation to determine whether pharmacological treatment is effective in improving regain of BMD after successful parathyroidectomy in patients with preoperatively diagnosed osteoporosis or osteopenia and to evaluate when treatment may be indicated.

METHODS

In this randomized, placebo-controlled, double-blind trial, 52 patients were treated with strontium ranelate 2 g daily + 1000 mg calcium + 800 IU vitamin D (strontium group; SG) or with 1000 mg calcium + 800 IU vitamin D alone (placebo group; PG) for 1 year. The main outcome measures were BMD (lumbar spine, femoral neck, radius) and bone turnover markers.

RESULTS

The baseline characteristics were similar in both groups. Absolute BMD (1.007 ± 0.197 vs. 0.897 ± 0.137 g/cm²; p = 0.024) and both relative (9.94 vs. 3.94%; p < 0.001) and absolute (0.09 ± 0.06 vs. 0.03 ± 0.04 g/cm²; p < 0.001) changes in lumbar-spine BMD were significantly higher in the SG than in the PG. Compared to baseline, BMD significantly increased in both groups at the lumbar spine (p < 0.001 and p = 0.001, respectively) and femoral neck (both p < 0.001), whereas radius BMD only changed significantly in the SG. However, the proportion of patients with osteoporosis/osteopenia significantly declined only at the lumbar spine in the SG (from 69.0 to 37.9%; p = 0.034), whereas no decrease was found in the PG. No severe adverse events occurred.

CONCLUSIONS

Postoperative anti-osteoporotic treatment can positively influence regain of BMD mainly in the lumbar spine and should be considered. Without treatment, most patients and especially those with low preoperative markers of bone turnover remained osteoporotic/osteopenic 1 year after surgery.

The utility and limitations of using trabecular bone score with FRAX

PURPOSE OF REVIEW

Trabecular bone score (TBS) is a texture index derived from the lumbar spine dual-energy X-ray absorptiometry which can assess skeletal quality and provide information about fracture risk independent of bone mineral density (BMD). TBS is useful in assessing osteoporotic fracture risk, with lower TBS values associated with increased fracture risk. In this article, we review the current state of TBS, including its utility and limitations in the assessment and management of osteoporosis, with particular emphasis on the recent literature.

RECENT FINDINGS

Ten-year fracture risk assessment using the FRAX tool can be improved through the use of a TBS adjustment. The use of TBS-adjusted FRAX can change management in a modest but significant number of patients, particularly in those close to an intervention threshold. Change in lumbar spine TBS for patients undergoing antiresorptive treatment is not a useful indicator of antifracture effect.

SUMMARY

Lumbar spine TBS provides information complementary to conventional BMD, and has been shown to be clinically useful for enhancing fracture risk prediction.

Effect of Endogenous Parathyroid Hormone on Bone Geometry and Skeletal Microarchitecture

Parathyroid hormone (PTH) has anabolic or catabolic effects on bones; however, the skeletal effect of endogenous PTH on cortical and trabecular bones is not yet clear. Therefore, we aimed to examine the effects of an excess and a deficiency of endogenous PTH on the lumbar spine trabecular bone score (TBS) and bone geometry using dual-energy X-ray absorptiometry. We retrospectively included 70 patients with primary hyperparathyroidism (PHPT), 26 patients with idiopathic or postoperative hypoparathyroidism (HypoPT), and 96 normal controls matched by age, sex, and body mass index. The bone mineral density (BMD) at the lumbar spine, femur neck, and total hip was higher in the HypoPT, followed by the controls and PHPT group (all P < 0.001). The TBS was significantly decreased in the PHPT group compared to the controls (P = 0.021); however, statistical significance disappeared after adjusting for the lumbar BMD (P = 0.653). There were no significant differences in the TBS between the HypoPT group and controls as well as the PHPT and HypoPT group. As for bone geometry parameters, the cross-sectional area, cross-sectional moment of inertia, and section modulus were higher in the HypoPT, followed by the controls and PHPT group (all P < 0.001); statistical significance remained after adjusting for the total hip BMD. We also observed a significantly increased cortical neck width in the HypoPT group compared to the PHPT group (P = 0.009). The buckling ratio was higher in the PHPT than the HypoPT group and controls (P = 0.018 and P = 0.013, respectively). The present study demonstrated that an excess of endogenous PTH had catabolic effects on both cortical and trabecular bones. Under conditions of endogenous PTH deficiency, the effect on cortical bone was pronounced, but that on trabecular bone was modest.

Usefulness of Trabecular Bone Score (TBS) to Identify Bone Fragility in Patients with Primary Hyperparathyroidism

BACKGROUND

Patients with primary hyperparathyroidism usually show decreased bone strength that are often not well diagnosed by conventional Dual-energy X-ray absorptiometry (DXA). Trabecular Bone Score (TBS) is a new technique for assessing bone microarchitecture indirectly. This cross-sectional study evaluates the usefulness of TBS in patients with primary hyperparathyroidism in clinical practice.

METHODOLOGY

Bone mineral density (BMD) by DXA and TBS values by TBS InSight® software were determined in 72 patients with primary hyperparathyroidism to analyze its relationship with fragility fractures. A receiver operating curve was performed to evaluate the usefulness of TBS as predictor of fragility fractures. FRAX index with and without adjustment by TBS was calculated. Additionally, longitudinal data of a subgroup of patients according to the therapeutic management were also evaluated.

RESULTS

A total of 51.4% of the patients showed degraded microarchitecture while only 37.5% of them were diagnosed of osteoporosis by DXA. No significant correlation was found between TBS values and BMD parameters. However, TBS values were lower in osteoporotic patients compared to those classified as normal by BMD (1.16 ± 0.12vs 1.26 ± 0.17; p = 0.043) and in patients with fragility fractures compared to nonfractured patients (1.19 ± 0.03vs 1.24 ± 0.02, p < 0.001). The area under the curve for TBS performed better than the combination of femoral, hip and spine-BMD for prevalent fractures (0.714vs 0.679). TBS-adjusted FRAX was higher than nonadjusted model for both major osteoporotic and hip fracture (4.5% vs 3%; 0.9% vs 0.7%; p < 0.001). At follow-up, an improvement in TBS values was observed in treated patients (medical or surgical) vs nontreated close to significance (1.27 ± 0.10vs 1.24 ± 0.11, p = 0.074).

CONCLUSIONS

TBS could be a useful tool to identify increased fracture risk in patients with primary hyperparathyroidism underdiagnosed by BMD. Moreover, FRAX adjusted by TBS could be a more robust tool for predicting the risk of osteoporotic fracture to help in therapeutic decisions in this population.

Asymptomatic and normocalcemic hyperparathyroidism, the silent attack: a combo-endocrinology overview

Asymptomatic primary hyperparathyroidism (PHPT) and the new variant of PHPT, normocalcemic PHPT, are considered by many physicians as mild, innocuous forms of disease, requiring nothing more than monitoring. Although this may be true in some cases in which the disease does not progress or cause complications, deterioration with more or less severe manifestations may occur. In the present review, we discuss the existing evidence of both the classic (skeletal and renal) and non-classic (cardiovascular, gastrointestinal, and psychiatric) features that have been attributed to asymptomatic and normocalcemic PHPT and the treatment effect on them.

Trabecular Bone Score (TBS) and Bone Metabolism in Patients Affected with Type 1 Neurofibromatosis (NF1)

In patients with neurofibromatosis type 1 (NF1), decreased bone mineral density (BMD) and low levels of 25-hydroxy vitamin D3 (25OHD) have been reported. Recently, the trabecular bone score (TBS) measurement has been proposed as index of bone microarchitecture and fracture risk. In 74 NF1 patients (48 females, 26 males, age 41 ± 12), we measured TBS and investigated clinical stage, lifestyle, vitamin D, serum bone turnover markers, vertebral and femoral BMD. A homogenous cohort of 61 healthy subjects was used as control group. TBS was lower in NF1 patients (1.266 ± 0.113 vs. 1.346 ± 0.105) without differences between sexes. No correlations with 25OHD, low exercise, low calcium intake, reduced sun exposure, and number of skin neurofibromas were observed. As expected, hypovitaminosis D was common (98.6%), as well as BMD reduction in hip and spine sites: In NF1 patients, bone texture evaluated by TBS was low in both sexes without any correlation with clinical or metabolic parameters, suggesting a direct role of the fibromin mutation.

Classical complications of primary hyperparathyroidism

Traditionally, classical complications of primary hyperparathyroidism are mainly represented by skeletal, kidney and gastrointestinal involvement. The old picture of osteitis fibrosa cystica is no longer commonly seen, at least in the western world. However, new imagining techniques have highlighted deterioration of skeletal tissue in patients with primary hyperparathyroidism not captured by traditional DXA measurement. Concerning the kidney, the most common consequences of excessive parathyroid hormone secretion are hypercalciuria and kidney stones; however, the exact pathogenesis of urinary stone formation is still unknown. The 2013 International Congress on the management of Asymptomatic Primary Hyperparathyroidism, emphasized the role of imaging techniques for early discovery of both skeletal and renal complications in asymptomatic patients. Gastrointestinal manifestations include acid-peptic disease, constipation, pancreatitis and gall stone disease. More studies are needed in this area to find the exact pathophysiological mechanism underlying these manifestations and the effect of parathyroid surgery.

Associations between trabecular bone score and biochemistry in surgically vs conservatively treated outpatients with primary hyperparathyroidism: A retrospective cohort study

PURPOSE

Trabecular Bone Score (TBS) is a software-based method for indirect assessment of trabecular bone structure of the spine, based on analysis of pixels in dual energy x-ray absorptiometry (DXA) images. Few studies describe the use of TBS in patients with primary hyperparathyroidism (PHPT). This study aimed at further describing this relationship, investigating possible correlations between biochemistry, body mass index (BMI), fracture incidence and TBS.

METHODS

Cross-sectional study of 195 patients with verified PHPT, surgically (27) or conservatively (168) treated at the Department of Endocrinology, Aalborg University Hospital. TBS was acquired by reanalyzing DXA-images of the included subjects from the outpatient clinic. Biochemical variables were obtained from clinical routine blood samples taken in relation to the DXA-scans. History of fractures and medical history was obtained from radiology reports and medical charts.

RESULTS

Patients with active PHPT had a TBS-score signifying a partly degraded bone structure, whereas surgically treated patients had a normal bone structure as judged by TBS, though the difference in TBS-score was not statistically significant. Use of antiresorptive treatment was negatively associated with BMD but not TBS. No correlations between the biochemical variables and TBS were found. A negative correlation between TBS and BMI in patients with PHPT was present. Patients experiencing a fragility fracture had a significantly lowered TBS, BMD and T-Score.

CONCLUSION

Biochemistry does not seem to predict bone status in terms of TBS in patients with PHPT. TBS is negatively correlated to BMI, which is also seen in patients not suffering from PHPT. The lack of a predictive value for antiresorptive treatment for TBS may raise concern. TBS appears to have a predictive value when assessing risk of fracture in patients with PHPT.

MINI ABSTRACT

This cross-sectional study investigates possible correlations between biochemical variables, body mass index (BMI) and trabecular bone score (TBS) in 195 patients with primary hyperparathyroidism. It finds no correlation between biochemical variables and TBS, but finds a negative correlation between TBS and BMI and a clear association between fracture incidence and low TBS-score.

Prevalence and Risk of Vertebral Fractures in Primary Hyperparathyroidism: A Nested Case-Control Study

Prevalence of vertebral fractures (VFx) in primary hyperparathyroidism (PHPT) remains uncertain. We aimed to estimate the prevalence of VFx, investigate potential risk factors associated with VFx, and whether bone mineral density (BMD) differs between PHPT and osteoporotic patients with VFx. Through the Danish National Patient Register, we identified patients diagnosed with PHPT from 2005 to 2015. The diagnosis was verified by reviewing biochemical findings, and X-ray reports were reviewed by two investigators. Osteoporotic patients with VFx were identified from our outpatient clinic and matched on age and sex with PHPT patients with VFx. We identified 792 PHPT patients among whom spine X-ray was available from 588 patients. VFx were present in 122 (21%) patients and were equally frequent among sexes (77% females). Fractured patients were older (70 versus 63 years) and had lower heights (163 versus 166 cm) compared with nonfractured patients (p all < 0.02). After stratification by age groups, the prevalence of VFx differed significantly between sexes (p < 0.01). Ionized calcium and parathyroid hormone did not differ between groups. BMD at total hip and forearm were lower in fractured compared with nonfractured patients (p < 0.03 for both) after adjusting for age, sex, and body mass index (BMI). Compared with osteoporotic patients with VFx (n = 108), BMD at the lumbar spine was higher in PHPT patients with VFx (n = 108) (p < 0.01). This did not change by excluding patients with lumbar VFx (p < 0.01). The severity of PHPT assessed by biochemistry does not seem to be associated with risk of VFx. Compared with osteoporosis, VFx seems to occur at a higher BMD in PHPT. © 2018 American Society for Bone and Mineral Research.

In which patients does lumbar spine trabecular bone score (TBS) have the largest effect?

BACKGROUND

Lumbar spine TBS, a texture index derived from lumbar spine dual-energy x-ray absorptiometry (DXA) images, enhances fracture prediction. No studies to date have studied a broad range of clinical variables to determine which patients might experience the greatest benefit from the use of TBS.

METHODS

Using the Manitoba BMD Registry, we identified 37,176 subjects with baseline DXA, FRAX®-based fracture probability, lumbar spine TBS, and minimum 5 years of observation. Subgroups considered were based on sex, age, body mass index (BMI), prior fracture, chronic obstructive lung disease (COPD), high alcohol use, rheumatoid arthritis (RA), high glucocorticoid use, osteoporotic femoral neck T-score, number of comorbidities, diabetes, secondary osteoporosis, and prior osteoporosis treatment. Non-traumatic major osteoporotic fractures (MOF, n = 3741) and hip fractures (HF, n = 1008) were identified using population-based health services data. We analyzed baseline TBS using analysis of covariance (ANCOVA). FRAX-adjusted hazard ratios (HR) per SD reduction in TBS were estimated and tested for interactions. Categorical net reclassification improvement (NRI) was estimated using fixed FRAX-based intervention cut-offs.

RESULTS

Adjusted baseline TBS was significantly lower (p ≤ 0.001) for women (-4.2%), osteoporotic hip T-score (-4.0%), COPD (-2.8%), diabetes (-2.6%), high alcohol use (-2.3%), prior fracture (-2.2%), glucocorticoid use (-1.5%), RA (-0.9%) and secondary osteoporosis (-0.8%), whereas recent osteoporosis therapy was associated with greater TBS (+1.5%). HRs per SD reduction in TBS for fracture prediction were larger for age < 65 vs 65+ (MOF p-interaction = 0.004, HF p-interaction < 0.001), without vs with prior fracture (MOF p-interaction = 0.003, HF p-interaction = 0.048), without vs with glucocorticoid use (HF p-interaction = 0.029), lower vs higher comorbidity score (HF p-interaction < 0.001), and without vs with osteoporosis treatment (MOF p-interaction = 0.005). NRI for using the TBS adjustment to FRAX in all subjects was 1.2% for MOF (p = 0.002) and 1.7% for HF (p = 0.016). NRI was greater in subjects age < 65 y (MOF:1.7%, HF:5.6%), no prior fracture (HF: 2.4%), non-osteoporotic T-score (HF: 3.0%), and high glucocorticoid use (MOF: 3.9%).

CONCLUSION

TBS is sensitive to the effects of multiple risk factors for fracture. TBS-adjusted fracture risk assessment resulted in significant improvements for multiple subgroups.

The trabecular bone score is associated with bone mineral density, markers of bone turnover and prevalent fracture in patients with end stage kidney disease

Fracture risk increases in end-stage kidney disease (ESKD), but bone mineral density (BMD) measurement is less predictive of risk than in the general population. In this study of patients with ESKD, a lower trabecular bone score (TBS), indicative of microarchitectural deterioration, was associated with higher bone turnover markers and prevalent non-vertebral fracture.

INTRODUCTION

Declining renal function carries increased fracture risks, but BMD is less predictive of fracture for dialysis patients than the general population. The TBS, obtained from lumbar spine dual-energy X-ray absorptiometry (DXA) images, provides information on microarchitectural integrity not captured by BMD. The aim of this study was to assess associations of the TBS to clinical, DXA, radiological, and laboratory measures in patients with ESKD undergoing kidney and simultaneous pancreas kidney (SPK) transplantation.

METHODS

A total of 147 patients with ESKD underwent pre-transplant laboratory testing, DXA, lateral spine X-ray, and structured history within 4 weeks of transplantation. Associations of the TBS to demographic data, prevalent fracture, BMD, and laboratory variables were assessed.

RESULTS

Of 147 patients (60% male, mean age 48 ± 13 years), 36% had diabetes mellitus (DM) and 54 patients had fractures: 21 prevalent vertebral fractures only, 22 non-vertebral fractures only, and 11 had both. The mean TBS (1.345 ± 0.125) was lower in patients undergoing SPK than kidney-only transplants (1.292 vs. 1.364, p = 0.001). The TBS correlated to spine and total hip BMD, body mass index and inversely to parathyroid hormone, alkaline phosphatase and procollagen 1 N-propeptide. By multivariable logistic regression, lower TBS was significantly associated to prior non-vertebral fracture (p = 0.026).

CONCLUSIONS

A lower TBS, suggestive of increased microarchitectural damage, was associated with type 1 DM, markers of higher bone turnover, and prevalent fracture. These data support the need for prospective studies to evaluate whether TBS inclusion improves fracture prediction in patients with ESKD.

TRABECULAR BONE SCORE (TBS) HAS A POOR DISCRIMINATIVE POWER FOR VERTEBRAL FRACTURES IN 153 ROMANIAN PATIENTS WITH PRIMARY HYPERPARATHYROIDISM

CONTEXT

Trabecular Bone Score (TBS) has been recently proposed as a good tool to investigate secondary osteoporosis.

OBJECTIVE

The aim of this study was to assess TBS from spine DXA images in patients with primary hyperparathyroidism (PHPT) and look at its correlates.

SUBJECTS AND METHODS

153 patients, mean age 59.1 ± 12.1 yrs, females and males (10%), mean BMI 26.2 ± 4.8 kg/m2, mean serum calcium and PTH of 11.3 ± 1.2 mg/dL and 232 ± 329 pg/mL, respectively; 89% had osteoporosis/osteopenia by LS DXA and 46% had renal involvement. There were 7.6% patients with vertebral fractures, 13.2% patients with nonvertebral fractures. TBS indices were derived from LS-DXA images and cutoff points used were those previously reported.

RESULTS

Mean TBS was in the partially degraded range (1.258 ± 0.115); 32% of patients had degraded microarchitecture (TBS ≤ 1.20), 51% had partially degraded microarchitecture (TBS > 1.20 and < 1.35) and 17% had normal TBS. TBS was significantly correlated with areal BMD both at the LS (r=0.544; p<0.001) and FN (r = 0.315; p < 0.001), and negatively with age (r= - 0.354; p < 0.001) and years since menopause - YSM (r = - 0.257, p = 0.005). Patients with vertebral fractures had mean values of TBS in the degraded range, significantly lower than those without vertebral fractures (1.173 ± 0.076 vs. 1.263 ± 0.115; p = 0.006). The presence of vertebral fracture was independently associated only with YSM (OR = 1.131, 95% CI = 0.032 - 0.214, p = 0.008) but not with TBS.

CONCLUSIONS

In a cohort of symptomatic PHPT patients, including postmenopausal, premenopausal and male patients, we have shown that TBS was in the partially degraded range, but it was not independently associated with fractures.

Trabecular Bone Score in Obese and Nonobese Subjects With Primary Hyperparathyroidism Before and After Parathyroidectomy

CONTEXT

Obesity has been shown to be unfavorable to skeletal microarchitecture when assessed by trabecular bone score (TBS). The influence of adiposity on skeletal microstructure in primary hyperparathyroidism (PHPT) has not yet been evaluated.

OBJECTIVE

To investigate the effect of obesity on TBS and bone mineral density (BMD) in subjects with PHPT at baseline and through 2 years after parathyroidectomy.

DESIGN

Prospective observational study.

SETTING

Referral center.

PATIENTS OR OTHER PARTICIPANTS

Thirty men and women with PHPT undergoing parathyroid surgery.

MAIN OUTCOME MEASURES

TBS and BMD by dual-energy X-ray absorptiometry (DXA).

RESULTS

There were notable improvements in lumbar spine and femoral neck BMD in the obese (lumbar spine: 4.3 ± 4.7%, femoral neck: 3.8 ± 6.6%; P < 0.05 for both) and nonobese subjects (lumbar spine: 3.8 ± 5.6%, femoral neck 3.1 ± 5.0%; P < 0.05 for both) but no marked change in TBS in either group at 24 months postparathyroidectomy. Obese subjects had fully degraded TBS values compared with the nonobese subjects, whose TBS values were minimally below normal throughout the study (baseline: 1.199 ± 0.086 vs 1.327 ± 0.099, respectively; P = 0.003; 24 months: 1.181 ± 0.061 vs 1.352 ± 0.114, respectively; P = 0.001), despite improvements in BMD.

CONCLUSIONS

The detrimental effect of obesity on TBS, an index of bone quality, was demonstrated in subjects with PHPT. Obesity was associated with fully degraded skeletal microarchitecture as measured by TBS in PHPT, despite similar values in bone density by DXA compared with nonobese subjects. TBS values did not improve postparathyroidectomy in either obese or nonobese subjects.