Bone turnover markers in primary hyperparathyroidism

Changes in bone turnover markers and bone mineral density after radiofrequency ablation for mild primary hyperparathyroidism: a prospective cohort study

Background

The application of radiofrequency ablation (RFA) is becoming increasingly widespread in the treatment of primary hyperparathyroidism (PHPT). However, the effect of RFA treatment on the skeleton in mild PHPT remains unclear. Therefore, the aim of this study was to investigate the change in bone turnover markers and bone mineral density (BMD) before and 2 years after RFA in patients with mild PHPT.

Methods

In this open-label, prospective study, 81 patients with mild PHPT including 36 treated with RFA and 45 observed without intervention (OBS), along with 81 age-matched healthy controls, were enrolled from November 2018 to September 2021 at Gansu Provincial Hospital. The main outcome measures were levels of serum calcium, serum intact parathyroid hormone (iPTH), and bone turnover markers, including bone-specific alkaline phosphatase (ALP), C-terminal cross-linking telopeptides of type I collagen (β-CTx), and osteocalcin (OC). BMD (femoral neck and lumbar spine) was measured with dual-energy X-ray absorptiometry, and spine radiographs were obtained for vertebral fracture assessment. Paired and unpaired two-tailed t-tests and Spearman rank correlation coefficient were used for statistical analyses.

Results

Normalized outcomes for both iPTH and calcium levels were achieved in 32 of 36 (88.9%) patients with mild PHPT treated with RFA. There was a significant treatment effect of RFA on bone turnover biomarkers compared with OBS before the treatment (P=0.04) and at the end of follow-up or (P=0.03). BMD of the lumbar spine increased by 1.8% (P=0.03) and remained stable in the femoral neck (P=0.17) after RFA. However, there was an obvious treatment effect of RFA on BMD compared with OBS (P 0.04). The only compartment with a T-score increase in the RFA group was the lumbar spine in (P<0.001). There was no difference in fracture frequency between groups during the follow-up period.

Conclusions

RFA can improve serum bone turnover markers in patients with mild PHPT and can be expected to increase BMD in the L1-L4 vertebrae and preserve BMD in the femoral neck. Whether RFA can reduce fracture risk in the long-term is a clinical concern for patients with mild PHPT.

Alkaline Phosphatases: Biochemistry, Functions, and Measurement

Alkaline phosphatases (ALPs) are a group of isoenzymes, situated on the external layer of the cell membrane; they catalyze the hydrolysis of organic phosphate esters present in the extracellular space. Zinc and magnesium are significant co-factors for the biological activity of these enzymes. Although ALPs are available in various body tissues and have distinct physiochemical properties, they are true isoenzymes since they catalyze a similar reaction. In the liver, ALP is cytosolic and present in the canalicular membrane of the hepatocytes. ALPs are available in placenta, ileal mucosa, kidney, bone, and liver. However, most of the ALPs in serum (over 80%) are delivered from liver and bone and in more modest quantities from the intestines. Despite the fact that alkaline phosphatases are found in numerous tissues all through the body, their exact physiological function remains largely unknown.

Efficacy of antiresorptive agents bisphosphonates and denosumab in mitigating hypercalcemia and bone loss in primary hyperparathyroidism: A systematic review and meta-analysis

PURPOSE

Primary hyperparathyroidism (PHPT) is characterized by increased bone remodeling and hypercalcemia. Parathyroidectomy (PTX), the current standard of care, is recommended in all symptomatic and some groups of asymptomatic patients. Anti-resorptive therapies (bisphosphonates and denosumab) have been used in patients where PTX is refused or contraindicated. In this meta-analysis, we investigated the effectiveness of anti-resorptives in preventing/treating PHPT-induced bone loss and mitigating hypercalcemia.

METHOD

PubMed, Scopus, and Cochrane Library databases were searched for articles with keywords containing PHPT, bisphosphonates, and denosumab in various combinations. We extracted and tabulated areal BMD (aBMD), serum mineral, and bone turnover parameters from the qualified studies and used comprehensive meta-analysis software for analysis.

RESULTS

Of the 1,914 articles screened, 13 were eligible for meta-analysis. In the pooled analysis, 12 months of anti-resoptives (bisphosphonates and denosumab) therapy significantly increased aBMD at the lumbar spine (Standard difference in means (SDM)=0.447, 95% CI=0.230 to 0.664, p=0.0001), femoral neck (SDM=0.270, 95% CI=0.049 to 0.491, p=0.017) and increased serum PTH (SDM=0.489, 95% CI=0.139 to 0.839, p=0.006), and decreased serum calcium (SDM=-0.545, 95% CI=-0.937 to -0.154, p=0.006) compared with baseline. 12 months of bisphosphonate use significantly increased aBMD only at the lumbar spine (SDM=0.330, 95% CI=0.088 to 0.571, p=0.007) with a significant increased in serum PTH levels (SDM=0.546, 95% CI= 0.162 to 0.930, p=0.005), and a decreased in serum calcium (SDM=-0.608, 95% CI=-1.048 to -0.169, p=0.007) and bone-turnover markers (BTMs) compared with baseline. Denosumab use for 12 months significantly increased aBMD at both the lumbar spine (SDM=0.828, 95% CI=0.378 to 1.278, p=0.0001) and femur neck (SDM=0.575, 95% CI=0.135 to 1.015, p=0.010) compared with baseline. Mean lumbar spine aBMD (SDM=0.350, 95% CI=0.041 to 0.659, p=0.027) and serum PTH (SDM=0.602, 95% CI= 0.145 to 1.059, p=0.010) were significantly increased after 12 months of alendronate use compared with placebo. When compared with baseline, alendronate significantly decreased BTMs after 12 months and increased aBMD without altering the PTH and calcium levels after 24 months.

CONCLUSION

Anti-resorptives are effective in mitigating bone loss and hypercalcemia in PHPT while maintaining or increasing aBMD. PTX reversed all changes in PHPT and normalized PTH levels.

Changes in Bone Mineral Density After Parathyroidectomy and Their Relations With Biochemical Markers of Bone Metabolism

BACKGROUND

To measure total type 1 serum amino-terminal propeptide procollagen (t-P1NP), β- type 1 cross-linked C-terminal telopeptide collagen (β-CTX), N-terminal osteocalcin (OC), and 25-(OH)-VD3 levels before parathyroidectomy (PTX) in patients with PHPT, and correlate these measurements with bone mineral density (BMD) changes at 1-year post-PTX.

METHODS

Patients with primary hyperparathyroidism (PHPT) were followed from diagnosis to 12 months after surgery. Serum levels of calcium, parathyroid hormone (PTH), vitamin 25-(OH)-VD3, OC, β-CTX, t-P1NP, and BMD were measured before and 1 year after surgery.

RESULTS

One year after PTX, mean BMD increased by 25.7, 27.7, and 33.5% in the lumbar spine (L1-L4), femoral neck (FN), and greater trochanter (GT), respectively. Percent BMD change 1-year post-PTX was significant correlated with preoperative levels of β-CTX (L1-L4: r = 0.41, P < 0.0001; FN: r = 0.54, P = 0.0003; GT: r = 0.46, P = 0.0029), t-P1NP (L1-L4: r = 0.58, P < 0.0001; FN: r = 0.73, P < 0.0001; GT: r = 0.65, P < 0.0001), 25-(OH)-VD3 (L1-L4: r = -0.33, P = 0.034; FN: r = -0.48, P = 0.002; GT: r = -0.52, P = 0.0007), and OC (L1-L4: r = 0.49, P = 0.0013; FN: r = 0.55, P = 0.0002; GT: r = 0.47, P = 0.002).

CONCLUSIONS

Preoperative levels of turnover markers and BMD improvements were significantly correlated in patients with PHPT 1 year after PTX.

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.

What happens to the bone structure after normocalcemic primary hyperparathyroidism surgery?

BACKGROUND

Bone disease in primary hyperparathyroidism is a clear indication for surgical treatment. However, it is not known whether surgery benefits hypercalcemic primary hyperparathyroidism and normocalcemic primary hyperparathyroidism equally. The aim of our study was to evaluate the bone changes in patients undergoing parathyroidectomy based on the biochemical profile 1 and 2 years after surgery.

METHODS

This prospective study included 87 consecutive patients diagnosed with primary hyperparathyroidism who underwent surgery between 2016 and 2018. Bone densitometry (1/3 distal radius, lumbar, and femur) and bone remodeling markers (osteocalcin, type 1 procollagen [P1NP], β-cross-linked telopeptide of type I collagen [BCTX]) were performed preoperatively and postoperatively. Postoperative changes in bone mineral density and bone markers were compared and evaluated according to the clinical characteristics and the individual biochemical profile.

RESULTS

One year after surgery, all patients showed an increase in bone mineral density at the lumbar site (mean, 0.029 g/cm²; range, 0.017-0.04; P < .001) and femur neck (mean, 0.025 g/cm²; range, 0.002-0.05; P < .001); however, there were no changes in the distal third of the radius (mean, -0.003 g/cm²; range, -0.008 to 0.002; P = NS). There were no significant differences when comparing normocalcemic primary hyperparathyroidism and hypercalcemic primary hyperparathyroidism. Serum osteocalcin (37 ± 17.41), P1NP (67.53 ± 31.81) and BCTX (0.64 ± 0.37) levels were elevated before surgery. One year after the surgery, we observed a significant decrease in P1NP (33.05 ± 13.16, P = .001), osteocalcin (15.80 ± 6.19, P = .001), and BCTX (0.26 ± 0.32, P < .001) levels.

CONCLUSION

Our findings indicate that parathyroidectomy has similar benefits for normocalcemic primary hyperparathyroidism and hypercalcemic primary hyperparathyroidism in terms of bone improvement. Although the most substantial improvement occurred during the first postoperative year in both groups, we consider that studies with longer follow-up are warranted.

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.

Bone Turnover Markers in Response to Ultrasound-Guided Microwave Ablation for Primary Hyperparathyroidism

OBJECTIVE

To assess the efficacy and safety of ultrasound-guided microwave ablation (MWA) in the treatment of primary hyperparathyroidism (PHPT), and to investigate whether MWA can improve the bone turnover and renal function.

METHODS

A total of 20 consecutive PHPT patients with 21 parathyroid lesions treated with MWA in our center from May 2019 to March 2021 were recruited in this study. Serum parathyroid hormone (PTH), calcium and phosphorus levels before MWA and at 20 minutes, 4 hours, 1 day, 3 months, 6 months and 12 months after MWA were measured. Bone turnover biomarkers, renal function and lesion volume with volume reduction rate (VRR) before MWA and at the last follow-up were compared. Any complication related with MWA was evaluated. The technical and clinical success rates of MWA in the treatment of PHPT were calculated. Clinical success was defined as normal serum PTH and calcium without PHPT-associated manifestations at more than 6 months after ablation. Technical success was defined as complete ablation indicated by immediate postoperative contrast-enhanced ultrasound.

RESULTS

The serum PTH, calcium and phosphorus levels at their respective follow-up time points dropped significantly after MWA (P <0.05). The volume of parathyroid lesions at the final examination was significantly reduced, compared with pre-ablation volume (P <0.001), with a median VRR reaching 89%. The technical and clinical success rates were 100% and 63.6%, respectively. Substantial changes of bone turnover biomarkers were observed before and after MWA (P <0.05), but the differences in renal function were not statistically significant. No major complications were reported in all cases. Pre-MWA serum PTH, lesion volume, maximum diameter of lesion and ablation time were significantly different between patients with successful and failed MWA.

CONCLUSIONS

PHPT can be effectively and safely treated by ultrasound-guided MWA, as proven by drop in serum PTH and reduction in the volume of parathyroid adenomas. Besides, MWA can impede bone remodeling to suppress hyperparathyroidism in the condition of PHPT.

Gender differences in the presentation, course and outcomes of primary hyperparathyroidism

OBJECTIVE

To investigate gender-associated differences in the presentation, course, and outcomes of primary hyperparathyroidism (PHPT).

STUDY DESIGN

A retrospective institutional cohort.

METHODS

The database of a tertiary endocrine institute was retrospectively screened for patients treated for PHPT in 2010-2018. Clinical, biochemical, and imaging data were collected. Presentation, management, and outcome variables were compared by gender and by age at diagnosis (<50/≥50 years).

RESULTS

The cohort included 182 women and 161 men diagnosed with PHPT at age 57.6 ± 12.8 and followed for 6.3 ± 5.5 years. There were no gender differences in age at detection of hypercalcemia and basal levels of serum and urinary calcium, serum PTH, and serum 25-hydroxyvitamin D. Men had a higher prevalence of nephrolithiasis (33 % vs 21 %, p = 0.01). Women had a higher frequency of osteoporosis (65 % vs 45 %, p < 0.001), and a lower mean lumbar spine T-score at PHPT diagnosis. At last follow-up, women had worse bone mineral density (BMD) results in all measured sites (lumbar spine, femoral neck, distal radius) and more fractures (34 % vs 20 %, p = 0.004), despite more frequent and longer pharmacological treatment of osteoporosis. On analysis by age, all these gender-associated differences were statistically significant only in patients diagnosed at age ≥50 years. Parathyroidectomy was performed in 52 % of women and 42 % of men (p = 0.06).

CONCLUSION

The main differences between male and female patients with PHPT are the higher prevalence, more intensive pharmacological treatment, and worse outcomes of osteoporosis in women. Tailoring the optimal medical and/or surgical treatment for fracture prevention in patients with PHPT remains a major challenge, especially in older women.

Parathyroid Pathology

Proliferative pathologic lesions of parathyroid glands encompass a spectrum of entities ranging from benign hyperplastic processes to malignant neoplasia. This review article outlines the pathophysiologic classification of parathyroid disorders and describes histologic, immunohistochemical, and molecular features that can be assessed to render accurate diagnoses.

Prediction of bone mass changes after successful parathyroidectomy using biochemical markers of bone metabolism in primary hyperparathyroidism: is it clinically useful?

OBJECTIVE

To measure type 1 serum amino-terminal propeptide procollagen (P1NP) and type 1 cross-linked C-terminal telopeptide collagen (CTX) before parathyroidectomy (PTX) in PHPT patients, correlating these measurements with bone mineral density (BMD) changes.

SUBJECTS AND METHODS

31 primary hyperparathyroidism (HPTP) were followed from diagnosis up to 12-18 months after surgery. Serum levels of calcium, parathyroid hormone (PTH) vitamin D, CTX, P1NP, and BMD were measured before and 1 year after surgery.

RESULTS

One year after PTX, the mean BMD increased by 8.6%, 5.5%, 5.5%, and 2.2% in the lumbar spine, femoral neck (FN), total hip (TH), and distal third of the nondominant radius (R33%), respectively. There was a significant correlation between BMD change 1 year after the PTX and CTX (L1-L4: r = 0.614, p < 0.0003; FN: r = 0.497, p < 0.0051; TH: r = 0.595, p < 0.0005; R33%: r = 0.364, p < 0.043) and P1NP (L1-L4: r = 0,687, p < 0,0001; FN: r = 0,533, p < 0,0024; TH: r = 0,642, p < 0,0001; R33%: r = 0,467, p < 0,0079) preoperative levels. The increase in 25(OH)D levels has no correlation with BMD increase (r = -0.135; p = 0.4816). On linear regression, a minimum preoperative CTX value of 0.331 ng/mL or P1NP of 37.9 ng/mL was associated with a minimum 4% increase in L1-L4 BMD. In TH, minimum preoperative values of 0.684 ng/mL for CTX and 76.0 ng/mL for P1NP were associated with a ≥ 4% increase in BMD.

CONCLUSION

PHPT patients presented a significant correlation between preoperative levels of turnover markers and BMD improvement 1 year after PTX.

Bone turnover and bone mineral density in old persons with type 2 diabetes

AIMS

To understand the paradox of an increased fracture risk despite increased bone mineral density (BMD) in persons with type 2 diabetes (DM2).

PATIENTS AND METHODS

We studied 80 old persons with DM2. Mineral metabolism, parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), bone turnover - osteocalcin, procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide of type 1 collagen (CTX) - were measured and BMD was assessed at the lumbar spine (LS) and femoral neck (FN). Data was analyzed with the Statistical Package for the Social Sciences Program.

RESULTS

Low levels of 25OHD (84%) and high values of PTH (20%) were found. Osteocalcin was directly related to CTX, p < 0.001, with increased bone formation and increased BMD (z-score) at LS and FN. PTH was directly related to osteocalcin and CTX and inversely related to BMD at the FN, p < 0.05. Patients with dyslipidemia presented higher P1NP, p < 0.05 and patients with hypertension presented higher BMD at LS and FN, p < 0.01.

CONCLUSION

Old type 2 diabetics present increased bone formation, PTH-driven. Low grade secondary hyperparathyroidism may explain the paradox of an increased fracture risk despite increased BMD.

Clinical utility of bone markers in various diseases

Measurements of bone markers (BMs) in peripheral blood or urine are a pivotal part of bone research within modern clinical medicine. In recent years the use of BMs increased substantially as they can be useful either to diagnose bone (related) disease and to follow its natural history, but also to monitor the effects of interventions. However, the use of BMs is still complicated mainly due to (pre)analytical variability of these substances, limited accessibility of assays, variable cut-off values in different countries and laboratories and heterogeneous results with regard to clinical implications of measuring BMs in several studies. This review will provide the clinician with a practical guide, based on current evidence, in which circumstances to test which bone markers for optimal diagnostic purposes, in order to improve patient care in different areas of bone diseases including Paget's disease, primary osteoporosis, tumor induced osteomalacia, hypophosphatemic rickets, van Buchem disease, chronic kidney disease, rheumatoid arthritis, neoplasma/multiple myeloma, type 2 diabetes mellitus and primary hyperparathyroidism. The clinician should consider fasting state, recent fractures, aging, menopausal status, concomitant liver and kidney disease when ordering and interpreting BM measurements as these factors might result in misleading BM concentrations. We found that BMs are clearly useful in the current diagnosis of tumor induced osteomalacia, van Buchem disease, Paget's disease and hypophosphatemic rickets. In addition, BMs are useful to monitor disease activity in chronic kidney disease, Paget's disease and are useful to monitor treatment adherence in osteoporosis.

Laboratory aspects and clinical utility of bone turnover markers

With an aging population, there is a marked increase in prevalence of metabolic bone diseases, especially osteoporosis. Perhaps the most dreaded complication of metabolic bone disease, fractures typically impose a huge burden on the ailing body and are associated with high co-morbidity and mortality. The consequent public health and socioeconomic burden warrant timely diagnosis, treatment and follow-up of these disorders. Knowing the limitations of radiological techniques, biochemical markers of bone turnover measurements come handy since the changes in their levels readily reflect bone physiology. Bone biomarkers typically analyzed in high throughput automated routine laboratories are collagen degradation products, reflecting osteoclast activity, and the collagenous or non-collagenous proteins produced by the osteoblasts. Since bone biomarker levels vary considerably due to quite a few endogenous and exogenous pre-analytical factors, knowledge of these limitations is mandatory prior to clinical utilization since these variabilities complicate test result interpretation. Standardization to harmonize different assay methodologies is desired, and the primary aims of the IFCC/IOF bone marker standards working group are also presented. Current literature data advocate bone markers as best used in monitoring anti-osteoporosis therapy efficacy and compliance, nonetheless, there is abundant data supporting their role in predicting bone loss and fracture risk. Furthermore, they have widespread clinical utility in osteoporosis, renal osteodystrophy, and certain oncological conditions and rheumatic diseases.

Increased Risk of Osteoporosis in Gastric Cancer Survivors Compared to General Population Control: A Study with Representative Korean Population

Purpose

Although several studies have suggested that osteoporosis is common in survivors of gastric cancer (GC), no study to date has directly assessed the risk for osteoporosis in GC survivors compared to matched controls. Thus, we aimed to investigate the relative risk for osteoporosis in survivors of GC compared to general population.

Materials and Methods

We used the Korea National Health and Nutrition Examination Survey data (2008-2011). Patients with a history of GC (n=94) were defined as case among 8,142 individuals over 50 years old who were evaluated by dual-energy X-ray absorptiometry. Controls (n=470) were matched to cases by age and sex in a 1:5 ratio. Osteopenia (–2.5 < T-score < –1.0) and osteoporosis (T-score ≤ –2.5) were defined.

Results

The prevalence of osteoporosis in GC survivors was 30.2%, which was significantly greater than that of controls (19.7%). In total, GC survivors had a 3.7-fold increased risk for osteoporosis compared to controls (p=0.021). In addition, the risk for osteoporosis of the total proximal femur total (TF) and femur neck (FN) was significantly increased among GC survivors compared to controls (adjusted relative risk, 4.64; 95% confidence interval, 1.16 to 18.6 in TF and adjusted relative risk, 3.58; 95% confidence interval, 1.19 to 10.8 in FN). Furthermore, we found sub-optimal daily calcium intake and mean serum levels of 25-hydroxy-vitamin D in both groups.

Conclusion

GC survivors are at significantly increased risk for osteoporosis, especially in the femur. Clinically, our finding supports the importance of screening bone health and adequate nutrient supplementation in survivors of GC.

Changes in bone turnover markers in primary hyperparathyroidism and response to surgery

Introduction Involvement of the bone is common in primary hyperparathyroidism. The aim of the study was to assess bone turnover markers in response to surgery for primary hyperparathyroidism. Methods This was a retrospective study of patients diagnosed and treated for parathyroid disease between 2005 and 2012. Interventions studied were surgery and medical treatment. The main outcome measures studied were serum levels of calcium, intact parathyroid hormone (iPTH), bone-specific alkaline phosphatase, N-terminal cross-linking propeptide of type 1 procollagen (P1NP) and C-terminal cross-linking telopeptides of type I collagen (CTX), both pre- and postoperatively at 6 months and 1 year; bone mineral density (at the spine and hip assessed by dual-energy x-ray absorptiometry after 1 year of treatment. Results A total of 122 (110 female, 12 male) patients (age range 25-91 years) underwent treatment for parathyroid disease during the study period; 30 patients were treated conservatively and 92 proceeded to surgery following localisation studies. Following surgical intervention, P1NP dropped significantly from a mean of 64.68 ng/ml (standard deviation, SD ± 68.07 ng/ml) preoperatively to 26.37 ng/ml (SD ± 20.94 ng/ml) and CTX from 0.69 pg/ml (SD ± 0.44 pg/ml) to 0.15 pg/ml (SD ± 0.16 pg/ml) at 6-12 months (P < 0.0001). This change was reflected in improvement in bone mineral density (T scores) of the hip and spine by 43% (P < 0.03) and 38% (P < 0.01), respectively, following surgery. In patients treated conservatively (n = 30), there was no improvement either in the bone turnover markers or bone densitometry scans. Conclusions Surgery improves bone density in patients with parathyroid disease. Improvement in serum bone turnover markers is seen following parathyroidectomy. The association with bone density needs further evaluation in larger studies.

Establishment of a normal reference value of parathyroid hormone in a large healthy Chinese population and evaluation of its relation to bone turnover and bone mineral density

A normal reference value of parathyroid hormone (PTH) was established for the first time in a large sample of healthy Chinese subjects by completely excluding interference of vitamin D deficiency. A high PTH level correlated significantly with an elevated bone turnover and a reduced bone mineral density (BMD).

INTRODUCTION

The aims of this study are to establish a normal reference value for serum PTH and to evaluate the effect of parathyroid gland status on bone turnover and BMD.

METHODS

Our cross-sectional study included 1436 healthy individuals from 5 different Chinese cities. Concentrations of serum PTH, 25-hydroxyvitamin D (25OHD), procollagen I N-terminal peptide (P1NP, a bone formation marker), and carboxyl-terminal telopeptide of type I collagen (β-CTX, a bone resorption marker) were measured by electrochemiluminescence immunoassay. BMD was measured by dual-energy X-ray absorptiometry. The relation of PTH concentration to age, gender, height, and weight was examined. Reference values of PTH were established for all subjects and for subjects categorized by serum 25OHD concentrations. Correlations of PTH levels with bone turnover biomarkers and BMD were statistically analyzed.

RESULTS

Reference values of PTH were 8.84-69.95 pg/mL in all the subjects and 7.48-60.73 and 5.83-56.78 pg/mL in the subjects with serum 25OHD concentrations of ≥20 and ≥30 ng/mL, respectively. Serum PTH showed a negative linear correlation with 25OHD, and the breakpoint was 18.21 ng/mL, below which the PTH level rapidly increased. The increase in PTH levels with age showed a positive linear correlation with P1NP and β-CTX concentrations and a negative linear correlation with BMD at the lumbar spines and the femoral neck.

CONCLUSIONS

A reference value of PTH was established in a large sample of healthy Chinese subjects according to 25OHD status, gender, and age. A high PTH level correlated significantly with an elevated bone turnover and a reduced BMD.

PTH and Vitamin D

PTH and Vitamin D are two major regulators of mineral metabolism. They play critical roles in the maintenance of calcium and phosphate homeostasis as well as the development and maintenance of bone health. PTH and Vitamin D form a tightly controlled feedback cycle, PTH being a major stimulator of vitamin D synthesis in the kidney while vitamin D exerts negative feedback on PTH secretion. The major function of PTH and major physiologic regulator is circulating ionized calcium. The effects of PTH on gut, kidney, and bone serve to maintain serum calcium within a tight range. PTH has a reciprocal effect on phosphate metabolism. In contrast, vitamin D has a stimulatory effect on both calcium and phosphate homeostasis, playing a key role in providing adequate mineral for normal bone formation. Both hormones act in concert with the more recently discovered FGF23 and klotho, hormones involved predominantly in phosphate metabolism, which also participate in this closely knit feedback circuit. Of great interest are recent studies demonstrating effects of both PTH and vitamin D on the cardiovascular system. Hyperparathyroidism and vitamin D deficiency have been implicated in a variety of cardiovascular disorders including hypertension, atherosclerosis, vascular calcification, and kidney failure. Both hormones have direct effects on the endothelium, heart, and other vascular structures. How these effects of PTH and vitamin D interface with the regulation of bone formation are the subject of intense investigation.

Clinicopathological correlates of hyperparathyroidism

Hyperparathyroidism is a common endocrine disorder with potential complications on the skeletal, renal, neurocognitive and cardiovascular systems. While most cases (95%) occur sporadically, about 5% are associated with a hereditary syndrome: multiple endocrine neoplasia syndromes (MEN-1, MEN-2A, MEN-4), hyperparathyroidism-jaw tumour syndrome (HPT-JT), familial hypocalciuric hypercalcaemia (FHH-1, FHH-2, FHH-3), familial hypercalciuric hypercalcaemia, neonatal severe hyperparathyroidism and isolated familial hyperparathyroidism. Recently, molecular mechanisms underlying possible tumour suppressor genes (MEN1, CDC73/HRPT2, CDKIs, APC, SFRPs, GSK3β, RASSF1A, HIC1, RIZ1, WT1, CaSR, GNA11, AP2S1) and proto-oncogenes (CCND1/PRAD1, RET, ZFX, CTNNB1, EZH2) have been uncovered in the pathogenesis of hyperparathyroidism. While bi-allelic inactivation of CDC73/HRPT2 seems unique to parathyroid malignancy, aberrant activation of cyclin D1 and Wnt/β-catenin signalling has been reported in benign and malignant parathyroid tumours. Clinicopathological correlates of primary hyperparathyroidism include parathyroid adenoma (80-85%), hyperplasia (10-15%) and carcinoma (<1-5%). Secondary hyperparathyroidism generally presents with diffuse parathyroid hyperplasia, whereas tertiary hyperparathyroidism reflects the emergence of autonomous parathyroid hormone (PTH)-producing neoplasm(s) from secondary parathyroid hyperplasia. Surgical resection of abnormal parathyroid tissue remains the only curative treatment in primary hyperparathyroidism, and parathyroidectomy specimens are frequently encountered in this setting. Clinical and biochemical features, including intraoperative PTH levels, number, weight and size of the affected parathyroid gland(s), are crucial parameters to consider when rendering an accurate diagnosis of parathyroid proliferations. This review provides an update on the expanding knowledge of hyperparathyroidism and highlights the clinicopathological correlations of this prevalent disease.

Current issues in the presentation of asymptomatic primary hyperparathyroidism: proceedings of the Fourth International Workshop

OBJECTIVE

This report summarizes data on traditional and nontraditional manifestations of primary hyperparathyroidism (PHPT) that have been published since the last International Workshop on PHPT.

PARTICIPANTS

This subgroup was constituted by the Steering Committee to address key questions related to the presentation of PHPT. Consensus was established at a closed meeting of the Expert Panel that followed.

EVIDENCE

Data from the 5-year period between 2008 and 2013 were presented and discussed to determine whether they support changes in recommendations for surgery or nonsurgical follow-up.

CONSENSUS PROCESS

Questions were developed by the International Task Force on PHPT. A comprehensive literature search for relevant studies was undertaken. After extensive review and discussion, the subgroup came to agreement on what changes in the recommendations for surgery or nonsurgical follow-up of asymptomatic PHPT should be made to the Expert Panel.

CONCLUSIONS

1) There are limited new data available on the natural history of asymptomatic PHPT. Although recognition of normocalcemic PHPT (normal serum calcium with elevated PTH concentrations; no secondary cause for hyperparathyroidism) is increasing, data on the clinical presentation and natural history of this phenotype are limited. 2) Although there are geographic differences in the predominant phenotypes of PHPT (symptomatic, asymptomatic, normocalcemic), they do not justify geography-specific management guidelines. 3) Recent data using newer, higher resolution imaging and analytic methods have revealed that in asymptomatic PHPT, both trabecular bone and cortical bone are affected. 4) Clinically silent nephrolithiasis and nephrocalcinosis can be detected by renal imaging and should be listed as a new criterion for surgery. 5) Current data do not support a cardiovascular evaluation or surgery for the purpose of improving cardiovascular markers, anatomical or functional abnormalities. 6) Some patients with mild PHPT have neuropsychological complaints and cognitive abnormalities, and some of these patients may benefit from surgical intervention. However, it is not possible at this time to predict which patients with neuropsychological complaints or cognitive issues will improve after successful parathyroid surgery.

Bone uptake of Tc-99m MIBI in patients with hyperparathyroidism

OBJECTIVE

The study aimed to investigate the incidence of bone uptake of tracer on Tc-99m MIBI imaging and explore its influencing factors and significance for diagnosis of metabolic bone disease (MBD) in patients with hyperparathyroidism (HPT).

METHODS

Seventy-nine consecutive patients with histopathologically confirmed HPT (63 primary and 16 secondary) who had preoperative Tc-99m MIBI imaging were retrospectively evaluated. Serum calcium (Ca), phosphorus (P), and intact parathyroid hormone (iPTH) were measured for all patients, and serum alkaline phosphatase (ALP) was measured for 62 patients. Of the 79 patients, 50 underwent bone mineral density (BMD) examination and 30 underwent bone scintigraphy. The incidence and characteristics of abnormal bone uptake of MIBI were recorded. Mann-Whitney test was performed to determine if serum iPTH, Ca, P, ALP, and BMD were different between the patients with and without MIBI bone uptake. Logistic regression analysis was used to analyze the factors that influence the bone uptake of MIBI. The concordance rate between Tc-99m MIBI imaging and bone scintigraphy in delineating MBD was calculated.

RESULTS

Tc-99m MIBI imaging disclosed the abnormal bone uptake of tracer in 22 (27.8 %) patients. Of them, 19 showed diffusely increased activity in skeleton, 2 showed focal uptake in brown tumors, and one showed both above patterns. Patients with bone uptake MIBI had higher level of serum iPTH (Z = -4.34, P < 0.001) and ALP (Z = -3.50, P < 0.001) than those without bone uptake. Logistic regression analysis also showed that bone uptake of MIBI was correlated with serum iPTH (OR = 4.42, P < 0.001) and ALP (OR = 3.21, P = 0.002). Among the 30 patients that underwent bone scintigraphy, 76.7 % patients showed signs of MBD, and the concordance rate between Tc-99m MIBI imaging and bone scintigraphy was 60 % for detecting MBD.

CONCLUSIONS

Bone uptake of MIBI in patients with HPT is commonly related to a high level of iPTH and ALP; it probably reflects an active stage of MBD, and it should be monitored during the conventional Tc-99m MIBI scintigraphy.