Factors associated with vertebral fracture risk in patients with primary hyperparathyroidism

Factors influencing serum calcium levels and the incidence of hypocalcemia after parathyroidectomy in primary hyperparathyroidism patients

Background

Parathyroidectomy (PTX) is an effective treatment for primary hyperparathyroidism (PHPT) patients. Postoperative hypocalcemia is a common complication after PTX. This study aimed to analyze the factors influencing serum calcium levels and the incidence of hypocalcemia after parathyroidectomy in primary hyperparathyroidism patients.

Methods

The retrospective study included 270 PHPT patients treated with PTX and collected their demographic and clinical information and their laboratory indices. Factors influencing serum calcium levels and hypocalcemia after PTX in PHPT patients were analyzed using univariate and multifactorial analyses.

Results

First, in patients with normal preoperative serum calcium levels (2.20-2.74 mmol/L), the higher the preoperative alkaline phosphatase and serum phosphorus levels, the lower the postoperative serum calcium levels. Furthermore, the higher the preoperative serum calcium levels and the accompanying clinical symptoms, the higher the postoperative serum calcium levels. Low preoperative serum calcium levels were shown to be a risk factor for postoperative hypocalcemia (OR=0.022), and the optimal preoperative serum calcium threshold was 2.625 mmol/L (sensitivity and specificity were 0.587 and 0.712, respectively). Second, in the mild preoperative hypercalcemia group (2.75-3.00 mmol/L), the older the patient, the higher the preoperative and postoperative serum calcium levels, the higher the postoperative serum calcium; the lower the alkaline phosphatase and calcitonin levels, the higher the postoperative serum calcium levels. On the other hand, the younger the patient was, the more likely hypocalcemia blood was (OR=0.947), with an optimal age threshold of 47.5 years (sensitivity and specificity were 0.543 and 0.754, respectively). Third, in the preoperative moderate to severe hypercalcemia group (>3.0mmol/L), patients undergoing a combined contralateral thyroidectomy and a total thyroidectomy had low postoperative serum calcium levels.

Conclusion

Patients with different preoperative serum calcium levels had various factors influencing their postoperative serum calcium levels and postoperative hypocalcemia, which facilitated the assessment of their prognosis.

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.

Degraded Bone Microarchitecture in Women with PHPT-Significant Predictor of Fracture Probability

Introduction

Patients with primary hyperparathyroidism (PHPT) experience bone mineral density (BMD) loss and trabecular bone score (TBS) alteration, which current guidelines recommend assessing. Considering TBS alongside BMD for a 10-year fracture risk assessment (FRAX) may improve PHPT management.

Design

Retrospective, cross-sectional study composed of 49 Caucasian females (62 ± 10.6 years, 27.7 ± 0.87 kg/m²) with PHPT and 132 matched control subjects (61.3 ± 10.5 years, 27.5 ± 0.49 kg/m²) evaluated in 3 years. We assessed lumbar spine (LS) and femoral neck (FN) BMD, T and Z scores (GE Healthcare Lunar Osteodensitometer) and TBS (iNsight 1.8), major osteoporotic fracture (MOF), and hip FRAX.

Results

Patients with PHPT had statistically lower mean values for lumbar spine bone mineral density (LS BMD) (0.95 ± 0.25 vs 1.01 ± 0.14 g/cm², P = .01), LS T-scores (-2 ± 0.2 vs -1.4 ± 0.1 SD, P = .009), LS Z scores (-0.9 ± 0.19 vs -0.1 ± 0.11 SD, P = .009), femoral neck bone mineral density (FN BMD) (0.79 ± 0.02 vs 0.83 ± 0.01 g/cm², P = .02), FN T-scores (-1.8 ± 0.13 vs -1.5 ± 0.07 SD, P = .017), FN Z scores (-0.51 ± 0.87 vs -0.1 ± 0.82 SD, P = .006), and TBS (0.95 ± 0.25 vs 1.01 ± 0.14 g/cm², P = .01) compared with control subjects. 22.4% of patients with PHPT had degraded microarchitecture (TBS < 1.2) vs. 7.6% in control group (χ² = 0.008). PHPT proved to be a covariate with unique contribution (P = .031) alongside LS BMD (P = .040) in a linear regression model [R ² = 0.532, F(4,16) = 4.543] for TBS < 1.2. TBS adjustment elevated MOF FRAX both for PHPT (4.35  ± 0.6% vs 5.25% ± 0.73%, P < .001) and control groups (4.5  ± 0.24% vs 4.7% ± 0.26%, P < .001) compared with BMD-bases FRAX, but also increased differently between the 2 study groups (1.1-folds for PHPT patients and 1.04 for control subjects, P = .034).

Conclusion

Compared with control, TBS-adjusted FRAX provides significantly higher MOF risk than BMD-based FRAX in PHPT women.

Epidemiology, Pathophysiology, and Genetics of Primary Hyperparathyroidism

In this narrative review, we present data gathered over four decades (1980-2020) on the epidemiology, pathophysiology and genetics of primary hyperparathyroidism (PHPT). PHPT is typically a disease of postmenopausal women, but its prevalence and incidence vary globally and depend on a number of factors, the most important being the availability to measure serum calcium and parathyroid hormone levels for screening. In the Western world, the change in presentation to asymptomatic PHPT is likely to occur, over time also, in Eastern regions. The selection of the population to be screened will, of course, affect the epidemiological data (ie, general practice as opposed to tertiary center). Parathyroid hormone has a pivotal role in regulating calcium homeostasis; small changes in extracellular Ca++ concentrations are detected by parathyroid cells, which express calcium-sensing receptors (CaSRs). Clonally dysregulated overgrowth of one or more parathyroid glands together with reduced expression of CaSRs is the most important pathophysiologic basis of PHPT. The spectrum of skeletal disease reflects different degrees of dysregulated bone remodeling. Intestinal calcium hyperabsorption together with increased bone resorption lead to increased filtered load of calcium that, in addition to other metabolic factors, predispose to the appearance of calcium-containing kidney stones. A genetic basis of PHPT can be identified in about 10% of all cases. These may occur as a part of multiple endocrine neoplasia syndromes (MEN1-MEN4), or the hyperparathyroidism jaw-tumor syndrome, or it may be caused by nonsyndromic isolated endocrinopathy, such as familial isolated PHPT and neonatal severe hyperparathyroidism. DNA testing may have value in: confirming the clinical diagnosis in a proband; eg, by distinguishing PHPT from familial hypocalciuric hypercalcemia (FHH). Mutation-specific carrier testing can be performed on a proband's relatives and identify where the proband is a mutation carrier, ruling out phenocopies that may confound the diagnosis; and potentially prevention via prenatal/preimplantation diagnosis. © 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).

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.

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.

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.

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.

Epigenetics of human parathyroid tumors

Parathyroid tumors are common endocrine neoplasia associated with primary hyperparathyroidism, a metabolic disorder sustained by parathormone hypersecretion. The epigenetic scenario in parathyroid tumors is beginning to be decoded. Here, main findings are reviewed: hypermethylation of specific DNA CpG islands has been described, despite global DNA promoter hypomethylation was not detectable; embryonic-related miRNAs, belonging to the C19MC and miR‐371-373 clusters, and miR‐296, are deregulated; expression of histone H1.2 and H2B is increased; expression of histone methyltransferase EZH2, BMI1 and RIZ1 is impaired; the tumor suppressor HIC1, MEN1 and CDC73 gene products, key molecules in parathyroid tumorigenesis, may be involved in epigenetic aberrant changes. Epigenetic changes are more frequent and more consistent in parathyroid malignancies, and positively correlated with severity of primary hyperparathyroidism.

Osteoporotic Vertebral Fractures as Part of Systemic Disease

Our understanding of the genetic control of skeletogenesis and bone remodeling is expanding, and normally, bone resorption and bone formation are well balanced through regulation by hormones, growth factors, and cytokines. Osteoporosis is considered a systemic disease characterized by low bone mass and microarchitectural deterioration of bone tissue. Consequent increased bone fragility results in higher fracture risk. The most common osteoporotic fractures are located in the spine, and they form a significant health issue. A large variety of systemic diseases are associated with risk of osteoporotic vertebral fractures, illustrating its multifactorial etiology. Prevalences of these conditions vary from common to extremely rare, and incidence peaks differ according to etiology. This review appreciates different aspects of osteoporotic vertebral fractures as part of systemic disease, including genetic, immunologic, inflammatory, metabolic, and endocrine pathways. It seems impossible to be all-comprehensive on this topic; nevertheless, we hope to provide a reasonably thorough overview. Plenty remains to be elucidated in this field, identifying even more associated diseases and further exposing pathophysiological mechanisms underlying osteoporotic vertebral fractures.

The calcium-sensing receptor in bone--mechanistic and therapeutic insights

The extracellular calcium-sensing receptor, CaSR, is a member of the G protein-coupled receptor superfamily and has a critical role in modulating Ca(2+) homeostasis via its role in the parathyroid glands and kidneys. New evidence suggests that CaSR expression in cartilage and bone also directly regulates skeletal homeostasis. This Review discusses the role of CaSR in chondrocytes, through which CaSR contributes to the development of the cartilaginous growth plate, as well as in osteoblasts and osteoclasts, through which CaSR has effects on skeletal development and bone turnover in young and mature animals. The interaction of skeletal CaSR activation with parathyroid hormone (PTH), which is secreted by the parathyroid gland, can lead to net bone formation in trabecular bone or net bone resorption in cortical bone. Allosteric modulators of CaSR are beneficial in some clinical conditions, with effects that are mediated by the ability of these agents to alter levels of PTH and improve Ca(2+) homeostasis. However, further insights into the action of CaSR in bone cells might lead to CaSR-based drugs that maximize not only the effects of the receptor on the parathyroid glands and kidneys but also on bone.