Changes in bone mass and metabolism after surgery for primary hyperparathyroidism

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.

Changes in Bone Metabolism and Structure in Primary Hyperparathyroidism

Parathyroid hormone (PTH) is a key regulator of bone turnover. Depending on the duration of action, the hormone causes catabolic and anabolic effects by binding with specific receptors (PTHR1) in the bone. Various cells expressing PTHR1 on their surface are involved in the process – osteoblasts, osteocytes, bone marrow stromal cells, T-lymphocytes and macrophages. In physiological conditions PTH balances the bone metabolism. Intermittent pharmacological doses of PTH lead to the prevalence of bone formation and are used in the treatment of osteoporosis. Persistently elevated levels of PTH stimulate bone resorption by impacting mainly the cortical bone. New imaging and analysis techniques show that high PTH levels can also have an adverse effect on trabecular microarchitecture. Primary hyperparathyroidism (PHPT) is a disease characterized by increased bone metabolism, decreased bone mineral density (BMD), inadequate osteoid mineralization and an increased risk of fractures. Prolonged overproduction of PTH leads to stimulation of bone resorption and defects in bone formation, mainly causing loss of cortical bone mass, while in the trabecular bone predominate demineralization processes. One explanation of these findings is the enhanced stimulation of RANKL expression by osteoblasts with decreased OPG expression and bone formation at the same time.

Biochemical bone turnover markers in hormonal disorders in adults: a narrative review

BACKGROUND

Hormonal disorders are often associated with abnormal levels of bone turnover markers (BTMs). N-terminal propeptide of type I procollagen (PINP) and serum C-terminal cross-linking telopeptide of type I collagen (CTX-I) are the reference markers of bone formation and bone resorption, respectively.

METHODS

A comprehensive literature search within the MEDLINE and Web of Science databases was performed.

RESULTS

Acromegaly is associated with higher BTM levels, which decrease during the remission after treatment. Adult-onset growth hormone deficiency is often associated with decreased BTM levels. Growth hormone replacement therapy stimulates bone turnover and increases BTM levels. Hypothyroidism is characterized by general slowing of bone metabolism which is reflected by lower BTM levels. The replacement thyroid hormone therapy increases the bone turnover rate and BTM levels increase. Patients with thyroid cancer receive a suppressive dose of thyroid hormones and may have slightly elevated BTM levels. Patients with overt hyperthyroidism had higher BTM levels and anti-thyroid therapy induces a rapid decrease in the BTM levels. Patients with overt primary hyperparathyroidism have higher BTM levels, whereas those with asymptomatic and normocalcemic hyperparathyroidism usually have normal BTM levels. Hypoparathyroidism is characterized by slightly decreased BTM levels. Cushing's syndrome is characterized consistently by markedly decreased osteocalcin concentration, whereas data on other BTMs are discordant.

CONCLUSIONS

BTMs help us to better understand mechanisms of the impact of hormonal disorders and their treatment on bone metabolism. However, it is unknown whether BTMs may be used to monitor the effect of their treatments on bone in the clinical practice.

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.

A Controversial Problem: Is There a Relationship between Parathyroid Hormone Level and Parathyroid Size in Primary Hyperparathyroidism?

The current study was undertaken with the aim of studying the relationship between parathyroid hormone and hyperfunctioning parathyroids by a sophisticated method of analysis. Our clinical study included 25 patients undergoing surgery for primary hyperparathyroidism. The measurement of basal circulating intact PTH (pg/ml) and the volume (mm3) of the removed gland(s) were recorded. It was essential for the distribution of the sample values to be normal before Pearson's correlation and regression analysis were performed. The Kolmogorov-Smirnov test showed sufficient sample data agreement (p>20%) with normal distribution after their transformation into natural logarithm (ln) and so statistical analysis was performed utilizing ln transformed data. The regression line between basal ln of iPTH levels (x) and ln of tumor volume (y) was highly significant (y=2.3828+1.0424 x, r=.72504, p<.0001). In our opinion, the above is a correct statistical procedure with reliable results.

Bone turnover markers in primary hyperparathyroidism

Primary hyperparathyroidism is an endocrine disorder characterized by elevated or inappropriate normal levels of parathyroid hormone in a setting of hypercalcemia. The inclusion of calcium on the basic metabolic bone panel has allowed this disorder to be diagnosed even in the absence of symptoms. Nevertheless, the skeleton can be a target of excess parathyroid hormone activity even during its asymptomatic presentation. Bone turnover markers a surrogate index of the process of the remodeling process at the level of bone, and thus can be useful to monitor skeleton involvement in primary hyperparathyroidism.

The usefulness of high pre-operative levels of serum type I collagen bone markers for the prediction of changes in bone mineral density after parathyroidectomy

BACKGROUND

Amino-terminal procollagen propeptide of type I collagen (P1NP) and cross-linked C-terminal telopeptide of type I collagen (βCTX) are two of the more sensitive bone markers for reflecting and monitoring patients with an increased bone turnover as observed in primary hyperparathyroidism (PHPT) patients.

AIM

The present study was performed to evaluate the trend of type I collagen markers one year after parathyroidectomy (PTX) and to examine the relationships between serum P1NP and βCTX levels and bone mineral density (BMD) change after PTX in PHPT Spanish patients.

MATERIALS AND METHODS

Fifty-three PHPT patients were enroled and were followed for one year by measuring lumbar BMD, lumbar t-score, lumbar z-score, PTH, calcium, phosphorus, P1NP and βCTX.

RESULTS

Pre-surgery concentrations of both markers were elevated (P1NP: 90.71±5.03; βCTX: 1.52±0.44). A significant decrease was observed in mean post-operative βCTX and P1NP concentrations (p<0.0001). Levels of BMD, t-score and z-score at lumbar spine were relatively low (BMD: 0.75±0.16; z-score -0.90±0.23; t-score -2.51±0.32); after PTX a significant increase was observed in the levels of these three parameters. P1NP and βCTX were correlated with lumbar BMD change one year after PTX (P1NP: r=0.79, p=0.016; βCTX: r=0.89, p=0.003).

CONCLUSIONS

Pre-surgery concentrations of both bone markers were elevated and a significant decrease after PTX was found. Serum βCTX and P1NP levels were potently related to lumbar BMD changes over one year after PTX. The measurement of βCTX and P1NP would be useful to predict long-term changes in lumbar BMD after PTX.

Potential utility of high preoperative levels of serum type I collagen markers in postmenopausal women with primary hyperparathyroidism with respect to their short-term variations after parathyroidectomy

We evaluated short-term changes in serum amino-terminal procollagen propeptide (P1NP) and cross-linked C-terminal telopeptide (betaCTX) of type I collagen after parathyroidectomy (PTX) in 41 postmenopausal women with primary hyperparathyroidism (PHPT). Serum levels of 25-hydroxyvitamin D, intact PTH, calcium, phosphate, albumin, creatinine, P1NP, and betaCTX were measured before and 2 days after PTX. Their P1NP and betaCTX levels were compared with those measured in 41 normally menstruating and 30 postmenopausal controls. Fifteen of these 41 women had both pre-surgery P1NP and betaCTX concentrations above the upper limit noted in our postmenopausal controls [high turnover (HT) subgroup], while betaCTX levels were solely above the upper limit lastly mentioned in 11 women [high bone resorption (HBR) subgroup]. In addition, these two markers were within the postmenopausal control range in 12 of them [normal turnover (NT) subgroup]. A more significant decrease in postoperative betaCTX levels was observed in the 15 HT compared with the 12 NT PHPT women. The significant postoperative increase in P1NP levels observed in the 15 HT as well as in the 11 HBR was no longer significant in the 12 NT women. In conclusion, higher pre-surgery P1NP and betaCTX levels in post-menopausal PHPT women are associated with a preferential activation of bone formation over bone resorption after PTX.

Asymptomatic hyperparathyroidism--need for multicentre studies

Long-term follow-up is initially considered appropriate for the majority of patients with primary hyperparathyroidism (PHPT) having small increases in calcium levels (< 2.8 mmol/l) and lacking the 'classical' symptoms of PHPT. The supportive reasoning is that many such patients never progress to more severe biochemical or clinical disease. There are, however, arguments in favour of early surgical treatment of such patients but adequately powered studies have not been carried out in this subgroup of patients to asses the impact of PHPT on their quality of life, cardiovascular risk and bone density. Progressive loss in bone mineral density and an increased risk of bone fracture become increasingly significant in an ageing population. Left ventricular hypertrophy, an increased risk of arrhythmia and/or myocardial infarction in addition to changes in atherogenic lipid profile and impaired glucose tolerance may translate into an increased risk of premature death in this group of patients. Changes in the quality of life identified using standardized questionnaires are sometimes recognized by patients only in retrospect (i.e. after resolution of symptoms following successful parathyroidectomy). In addition, many series fail to assess and record accurately such symptoms. Multicentre cohort studies of patients with asymptomatic PHPT randomized to immediate or delayed surgical treatment could address some of the debated issues highlighted in this review. Until such studies are set up, most surgeons would consider that parathyroid surgery should represent the first choice of treatment for all patients, but many physicians would favour a long-term follow-up. Nevertheless, the threshold for referral for surgical treatment has been lowered since the introduction of scan-directed minimally invasive parathyroidectomy, which enables the experienced parathyroid surgeon to successfully treat patients with PHPT with a minimum of complications as a day-case operation. In the context of improved surgical treatment, we need more data on the benefits or otherwise in so-called asymptomatic patients with a thorough assessment of their bone quality, cardiovascular risk and quality of life.

Ultrasound of the skeleton: review of its clinical applications and pitfalls

Quantitative ultrasound (QUS) is receiving considerable attention in the assessment of osteoporosis because of its ease of use, lack of radiation exposure, region of interest, and relatively low costs. These features have made the technique appealing for screening adult and pediatric patients. This article discusses some of the clinical applications, limitations, and strengths of QUS.

Quantitative ultrasound of the hand phalanges and calcaneus revealed skeletal abnormalities due to primary hyperparathyroidism: a case report

Primary hyperparathyroidism (PHPT) is a common disease causing bone loss in elderly patients. We report a case study of a 36-year-old woman with PHPT. Quantitative ultrasound (QUS) assessment of the phalanges and calcaneus revealed significantly lower than normal values for age. This observation was confirmed by measuring bone mineral density in different skeletal sites using dual-energy X-ray absorptiometry (DXA). Subsequent parathyroid adenoma surgery normalized calcium metabolism, resulting in a progressive increase of BMD and ultrasound (US) parameters. This report has shown an ability of peripheral QUS examinations (phalanges and calcaneus) in early detection of bone alterations caused by PHPT in a young woman. Skeletal changes after surgery could be evaluated by QUS in a similar manner to that used in DXA.

Effect of metabolic control on parathyroid hormone secretion in diabetic patients

The metabolic derangement caused by diabetes mellitus may potentially affect bone mineral metabolism. In the present study we evaluated the effect of diabetes metabolic control on parathyroid hormone (PTH) secretion during stimulation with EDTA infusion. The study was conducted on 24 individuals, 8 of them normal subjects (group N: glycated hemoglobin - HbA1C = 4.2 +/- 0.2%; range = 3.5-5.0%), 8 patients with good and regular metabolic control (group G-R: HbA1C = 7.3 +/- 0.4%; range = 6.0-8.5%), and 8 patients with poor metabolic control (group P: HbA1C = 12.5 +/- 1.0%; range: 10.0-18.8%). Blood samples were collected at 10-min intervals throughout the study (a basal period of 30 min and a 2-h period of EDTA infusion, 30 mg/kg body weight) and used for the determination of ionized calcium, magnesium, glucose and intact PTH. Basal ionized calcium levels were slightly lower in group P (1.19 +/- 0.01 mmol/l) than in group N (1.21 +/- 0.01 mmol/l) and group G-R (1.22 +/- 0.01 mmol/l). After EDTA infusion, the three groups presented a significant fall in calcium, but with no significant difference among them at any time. Basal magnesium levels and levels determined during EDTA infusion were significantly lower (P<0.01) in group P than in group N. The induction of hypocalcemia caused an elevation in PTH which was similar in groups N and G-R but significantly higher than in group P throughout the infusion period (+110 min, N = 11.9 +/- 2.1 vs G-R = 13.7 +/- 1.6 vs P = 7.5 +/- 0.7 pmol/l; P<0.05 for P vs N and G-R). The present results show that PTH secretion is impaired in patients with poorly controlled diabetes.

Bone status in primary hyperparathyroidism

Traditional bone involvement, such as osteoitis fibrosa, has become very rare (< 1%) in primary hyperparathyroidism (PHPT); nevertheless, fractures seem more frequent than in controls, with a predilection for fractures of the distal extremity of the radius, pelvis, ribs and vertebrae, and a relative modest incidence of fractures of the upper extremity of the femur. Histo-morphometric studies have stressed a discrepancy between cortical and trabecular bone with an increase of bone remodeling. The cortical width is constantly diminished and the cortical porosity is increased whereas trabecular volume is normal and micro-architecture preserved. Bone mineral density (BMD) allows an early diagnosis of bone disease and takes a growing place in the management of patients. Since the consensus conference in 1991, the measurement of BMD has been incorporated in the surgical decision with a threshold: Z-score < -2. The demineralisation predominates on sites rich in cortical bone (1/3 proximal of the distal radius); the radius, which was the first site evaluated for technical reasons, is also the most discriminating one. Spine demineralisation is met in more severe forms and BMD measurement of the whole body is promising but requires more studies. In the absence of a radical processing, moderate forms remain stable, whereas more severe forms have a tendency to deteriorate. The evaluation of spine and femoral BMD is useful for the follow-up because the bone gain after parathyroidectomy is significant early on at these sites (rich in trabecular bone with high bone turnover), whereas the BMD of radius is relatively stable.

Role of surgery in mild primary hyperparathyroidism in the elderly

BACKGROUND

The appropriate management of elderly patients with mild hyperparathyroidism is the subject of much debate.

METHODS

A Medline literature search was conducted using the keywords 'hyperparathyroidism', 'asymptomatic' and 'elderly'. The references of the primary sources were examined for further citations. Personally collected cullings from journals and abstracts from journals were used as an additional source of data.

RESULTS AND CONCLUSION

No prospective randomized controlled trial comparing parathyroidectomy with conservative management for patients with mild or asymptomatic hyperparathyroidism has been published. There are a number of longitudinal studies that attempt to characterize the natural history of hyperparathyroidism, but most do not stratify patients according to age when assessing outcome. None the less, it is clear that elderly patients present with a different spectrum of problems, particularly indistinct neuropsychiatric and musculoskeletal symptoms, and these are likely to be improved by surgery. The evidence allows the conclusion that the truly asymptomatic elderly patient can be successfully managed conservatively; there is a good prospect of benefit from surgery for those with symptomatic disease, and such patients should not be denied an operative option.

[Usefulness of bone densitometry in the evaluation of primary hyperparathyroidism]

BACKGROUND

In recent years, the clinical profile of primary hyperparathyroidism (PH) is predominantly characterized by mild or asymptomatic forms. In this context, the effects of the PH on bone metabolism reach a growing importance in the adoption of therapeutic decisions.

PATIENTS AND METHODS

116 patients with PH were studied, 95 women (25 premenopausal, 70 postmenopausal) and 21 males. In all cases parathyroidectomy criteria were evaluated. Bone mineral density (BMD) was determined in 71 patients in lumbar spine (LS) and femoral neck by dual-X-Ray absorptiometry (DXA) and the influence of this measurement in the decision of surgical treatment was analyzed.

RESULTS

The patients with PH showed a significant reduction of BMD at all sites (p < 0.001) and 71.8% met osteoporosis densitometric criteria. The most frequent parathyroidectomy criteria was the presence of specific clinical manifestations (51.7%) followed by decrease of the BMD in LS (49.3%). The probability of meeting criteria for surgical treatment was significantly higher in patients in which BMD was measured (odds ratio: 3.09 [1.03-9.22]; p = 0.036).

CONCLUSIONS

In its current presentation, PH presents a significant decrease of bone mass. The systematic performance of bone densitometry has a decisive influence in its appropriate management.

Primary hyperparathyroidism: whole-body bone mineral density in surgically treated Danish patients: a three-year follow-up study

Whole-body bone mineral density (BMD) and body composition were measured before surgery in 25 patients (20 women and 5 men, aged 53 +/- 13 years, range 26-73 years) with mild to moderate primary hyperparathyroidism (PHPT) and compared with 25 controls exactly matched with respect to age, gender, and menopausal status. Fifteen pairs of matched patients and controls were reexamined 3 years later (5 men and 10 women, aged 53 +/- 12 years in both groups). In the untreated PHPT patients, whole-body BMD was 95.4% +/- 10.5% (SD) of control BMD (p < 0.05). Body weight and height, body mass index, whole-body fat mass, and lean body mass did not differ significantly between the groups. Relative to values in matched controls, whole-body bone mineral content (BMC) and BMD increased by 4.4% and 3.0%, respectively, in PHPT patients (p < 0.005) during the 3-year follow-up. Neither whole-body BMC nor BMD differed between patients and controls after the 3-year follow-up. A positive correlation was observed between initial serum calcium levels and the 3-year increase in whole-body BMD (r(s) = 0.645, p < 0.01). Baseline serum osteocalcin, serum pyridinoline crosslinked telopeptide of Type I collagen and several histomorphometric indices of trabecular bone turnover (eroded and labeled surfaces, bone formation rate, and activation frequency) also correlated positively with the subsequent increase in whole-body BMD. Six patients disclosed transient postoperative secondary hyperparathyroidism, probably due to hungry bones. Four of these patients completed 3 years of follow-up and had higher increases in whole-body BMD than the remaining normo-parathyroid patients (7.9% +/- 4.5%, range 4.3-14.3% versus 1.9% +/- 2.1%, p < 0.01). It is concluded that Danish patients with mild to moderate PHPT only reveal small reductions in whole-body mineral density. Furthermore, within 3 years after parathyroid surgery, most of the lost bone mineral is regained even in patients with initial high bone turnover. Finally, PHPT in these patients is not associated with substantial changes in body compositions.

Primary hyperparathyroidism: short-term changes in bone remodeling and bone mineral density following parathyroidectomy

Changes in bone remodeling and bone mineral density were observed during a period of 6 months after surgery in 24 patients with primary hyperparathyroidism (20 women and 4 men; age 54+/-12 years, range 26-69 years). All bone markers declined significantly within the 6 month follow-up period, but the time course for changes in renal N-terminal telopeptide of type 1 collagen (NTx) excretion differed from those of the other markers by a steep and significant reduction (p < 0.05) after less than 1 month. During the 6 month period, bone mineral density (BMD) increased significantly at all sites measured (p < 0.05) apart from the femoral neck and the proximal and midforearm. The greatest increase of 4.2% was observed in the trochanteric region (p < 0.001). The increase in BMD in spine, trochanteric, and intertrochanteric regions of the hip correlated inversely with baseline forearm BMD values (p < 0.05). Baseline bone markers (serum alkaline phosphatase [AP], serum bone AP, serum pyridinoline crosslinked telopeptide of type 1 collagen, urinary hydroxyproline, urinary osteocalcin), as well as baseline histomorphometric indices of bone turnover (eroded and labeled surface, bone formation rate, activation frequency, and cortical porosity) were positively correlated with changes in spinal BMD over 6 months (p < 0.05). It was concluded that, within 6 months after parathyroidectomy, patients with primary hyperparathyroidism obtain normalization of bone remodeling and a substantial increase in bone mineral density in regions rich in cancellous bone but no significant changes in regions with predominantly cortical bone.

Longitudinal changes in bone density in hyperparathyroidism

Primary hyperparathyroidism (HPTH) is a known risk factor for cortical bone loss. The primary objective of this study was to examine the time course and location of changes in bone mass within the first year after parathyroidectomy (PAX). The secondary goal was to evaluate the efficacy of combined estrogen therapy and parathyroidectomy in postmenopausal women. Thirty-two subjects with primary HPTH participated in a prospective, longitudinal study for at least 1 yr. Twenty-seven subjects underwent PTX, while five received no therapy (control). Among the PTX patients, 21 were postmenopausal women, and 8 of these women also received estrogen. Subjects had serial measurements of parathyroid hormone levels, serum chemistries, and bone density at multiple sites. Among all PTX patients, lumbar spine, hip, and whole body bone mineral content increased significantly (3.8-6%; p < 0.005) at 12 mo, with most of the increments observed by 3 mo. In postmenopausal women, estrogen treatment resulted in higher increments in the femoral neck (8.6 +/- 2% vs 4.9 +/- 1.2%, respectively; p = 0.07) and the whole body (6 +/- 2% vs 2.4 +/- 1.6%, respectively; p = 0.07). In HPTH, early and generalized increments in bone mass follow PTX, and the combination of surgery with estrogen therapy may be superior to surgery without estrogen treatment. A randomized, controlled trial including PTX, estrogen, and a combination of the two is needed to determine the optimal therapy in postmenopausal women.

Increased biochemical markers of bone formation and resorption in primary hyperparathyroidism with special reference to patients with mild disease

OBJECTIVES

To evaluate the impact on bone turnover of primary hyperparathyroidism (pHPT) with special reference to patients with mild pHPT, using biochemical markers of bone formation and resorption.

DESIGN

A longitudinal study of patients with pHPT before and one year after surgical treatment.

SETTING

The Departments of Internal Medicine and Surgery, Lund University Hospital.

SUBJECTS

Forty consecutive patients with pHPT. Thirty of these patients had mild pHPT and are reported separately. Data on bone mineral was also compared to a reference population.

INTERVENTION

All patients were operated upon and restudied one year later.

MAIN OUTCOME MEASURES

Bone resorption and formation was studied by means of the serum concentrations of the telopeptide of the carboxyterminal region of type 1 collagen (ICTP) and of alkaline phosphatase (ALP), osteocalcin and the carboxyterminal propeptide of type 1 procollagen (PICP), respectively. Bone density was measured at the distal radius by single photon absorptiometry (SPA).

RESULTS

Bone formation markers consistently decreased after parathyroid surgery: ALP from 3.51 +/- 0.23 to 2.94 +/- 0.21 microkat L(-1) (P < 0.05), osteocalcin from 6.15 +/- 0.53 to 2.89 +/- 0.23 microg L(-1) (P < 0.001) and PICP from 126.4 +/- 10.9 to 96.0 +/- 6.5 microg L(-1) (P < 0.001). In parallel, the ICTP concentration, reflecting bone resorption, decreased from 5.10 +/- 0.54 to 3.94 +/- 0.34 microg L(-1) (P < 0.001). There was not any significant change in distal radius bone mineral 1 one year after surgery. In the subgroup of patients classified as mild pHPT, a significant decrease was noted for osteocalcin, PICP and for ICTP but not for ALP, without significant changes in variables reflecting distal radius bone mineral content. Glomerular filtration rate was inversely correlated to serum levels of intact PTH, ionized calcium, alkaline phosphatase, osteocalcin and ICTP and directly correlated to the 1.25-dihydroxy-vitamin D concentrations.

CONCLUSIONS

pHPT is associated with substantial changes in circulating levels of biochemical markers of bone formation and resorption. These findings are also present in patients with mild pHPT. Renal function should be considered in the evaluation of the impact of pHPT on bone turnover.

Changes in bone mass and serum markers of bone metabolism after parathyroidectomy

BACKGROUND

Primary hyperparathyroidism (PHPT) is associated with an increased bone turnover. The simultaneous use of biochemical and bone mass measurements before and after parathyroidectomy is sparsely reported. This study was carried out to evaluate changes in bone mass and markers of bone metabolism in postmenopausal women with PHPT after parathyroidectomy.

METHODS

Twelve women, mean age of 63 years, were investigated. Measurements of bone mineral density (total body, spine, hip, and forearm bone mineral density) with dual-energy x-ray absorptiometry were performed before operation and at follow-up at a median of 23 months. Concomitantly, changes in serum intact parathyroid hormone, bone-specific alkaline phosphatase (B-ALP), osteocalcin, carboxyterminal propeptide of type I procollagen, and the immunoactive carboxyterminal telopeptide of type I collagen were recorded.

RESULTS

At follow-up a significant increase in bone mineral density of the spine (p < 0.05), femoral neck (p < 0.05), Ward's triangle (p < 0.05), and trochanter (p < 0.01) was observed. No significant changes in the forearm were registered. Levels of parathyroid hormone, B-ALP, and osteocalcin were elevated and intercorrelated before operation. The serum levels of these parameters decreased significantly after operation. Serum levels of carboxyterminal propeptide of type I procollagen and the immunoactive carboxyterminal telopeptide of type I collagen did not significantly differ from a reference population, and no major changes were observed at follow-up.

CONCLUSIONS

Bone mineral density in the spine and hip is improved after parathyroidectomy in postmenopausal women with primary hyperparathyrodism. Serum levels of B-ALP and osteocalcin are elevated in PHPT and decrease after operation. The clinical usefulness of serum markers of collagen metabolism in investigating bone metabolism in PHPT seems limited.

SOME CHARACTERISTICS OF PRIMARY HYPERPARATHYROIDISM IN VIETNAMESE IMMIGRANTS LIVING IN SOUTHERN CALIFORNIA

OBJECTIVE

To characterize primary hyperparathyroidism (PHP) in Vietnamese immigrants living in southern California and to summarize the results of treatment.

METHODS

We describe 11 patients (8 women and 3 men) with a mean age of 57.91 years who underwent follow-up from 1991 to 1995 after PHP was diagnosed. The patients had no specific complaints. Four patients had a history of kidney stones, and five had chronic hypertension. Only five patients had high levels of total serum calcium; the other six patients had normal or fluctuating levels of total serum calcium. All patients, however, had high levels of intact parathyroid hormone (PTH) and ionized calcium. Preoperatively, parathyroid imaging with technetium-99m sestamibi demonstrated persistently increased parathyroid gland uptake.

RESULTS

In all nine patients who underwent surgical treatment, an adenoma was found in the parathyroid glands; two patients refused operative intervention. The mean serum phosphate was in the low-normal range and increased postoperatively (2.70 versus 3.52 mg/dL; P<0.001). The mean serum chloride level also decreased postoperatively (104.62 versus 100.78 mEq/L; P<0.001). The ratio of chloride/phosphate decreased significantly after adenoma removal (39.44 versus 29.21; P<0.001). Six patients received calcium gluconate either alone or in combination with vitamin D supplements for hypocalcemia postoperatively. The other three patients, however--who did not receive calcium supplements postoperatively--had persistently high levels of intact PTH but normal serum Ca++ levels and subsequently were treated effectively with calcium gluconate and vitamin D.

CONCLUSION

The presence of hypercalcemia, especially Ca++, and an increased level of intact PTH establishes the diagnosis of PHP. After parathyroidectomy, the persistence of high levels of intact PTH in association with normal serum Ca++ suggested the presence of secondary hyperparathyroidism, which was treated effectively with calcium gluconate and vitamin D. These patients had the same clinical picture as other ethnic groups with PHP, but they needed either calcium alone or calcium and vitamin D supplements after parathyroidectomy because of their bone loss from prolonged PHP.

The skeletal effects of primary hyperparathyroidism

Primary hyperparathyroidism (PHPT) is a common endocrine disorder which occurs most frequently in post-menopausal women and is characterized by mild, stable, and often asymptomatic hypercalcaemia. Chronic parathyroid hormone excess stimulates bone remodelling by inducing production by osteoblasts of soluble factors which stimulate both bone formation and osteoclastic bone resorption. Studies of bone mineral density (BMD) in PHPT suggest that bone loss is accelerated, leading to osteopenia, particularly at sites of cortical bone. Studies of fracture incidence in PHPT have produced conflicting results. Interventional studies have demonstrated that both parathyroid adenomectomy and estrogen replacement therapy increase BMD in patients with PHPT. Patients with PHPT should undergo BMD measurement, and receive treatment designed to stabilize bone mass if there is evidence of either osteopenia or accelerated bone loss.

Vitamin D receptor polymorphism, bone mineral density, and osteoporotic vertebral fracture: studies in a UK population

Bone mineral density is under strong genetic control and polymorphisms of the vitamin D receptor (VDR) have been suggested to account for some of the genetic variation in bone mass. However, the relationship between VDR polymorphisms and bone density is controversial and has not been confirmed by all workers. Since there is little information on the association between VDR genotype and bone mass in the UK, we studied VDR genotype, bone mineral density, and osteoporotic fracture in a cohort or pre- and postmenopausal women from the Northeast of Scotland. We found a highly significant "inverse" association between the VDR genotype and bone mineral density at the hip such that individuals of "bb" genotype had a femoral neck bone density of 0.79 standard deviation lower than individuals of BB genotype (p < 0.02). This contrasts with most previous studies in which the "bb" genotype has been associated with high bone density. A similar, but nonsignificant trend was seen for lumbar spine BMD. To study the clinical significance of this observation, we examined the distribution of VDR genotypes in a subgroup of patients with severe osteoporosis who had vertebral compression fractures (n = 44) as compared with with age-and gender-matched controls (n = 44). Despite the differences in BMD between genotypes, there was no significant excess of any specific VDR genotype in osteoporotic fracture patients, indicating that VDR genotyping may be of limited practical value in identifying patients at risk of vertebral fracture. This study confirms that there is a significant association between VDR genotype and bone mass in our population. The "inverse" relationship between VDR genotype noted in this, as compared with previous studies, would be consistent with a model whereby VDR polymorphisms are not the cause of reduced BMD, but rather, are in linkage disequilibrium with a disease-causing locus nearby.