Bone mineral changes in primary hyperparathyroidism

Mutations of calcium-sensing receptor gene: two novel mutations and overview of impact on calcium homeostasis

OBJECTIVE

Genetic disorders of calcium metabolism arise in a familial or sporadic setting. The calcium-sensing receptor (CASR) plays a key role in maintaining calcium homeostasis and study of the CASR gene can be clinically useful in determining etiology and appropriate therapeutic approaches. We report two cases of novel CASR gene mutations that illustrate the varying clinical presentations and discuss these in terms of the current understanding of CASR function.

PATIENTS AND METHODS

A 16-year-old patient had mild hypercalcemia associated with low-normal urinary calcium excretion and normal-to-high parathyroid hormone (PTH) levels. Because of negative family history, familial hypocalciuric hypercalcemia was originally excluded. The second patient was a 54-year-old man with symptomatic hypocalcemia, hyperphosphatemia, low PTH, and mild hypercalciuria. Familial investigation revealed the same phenotype in the patient's sister. The coding region of the CASR gene was sequenced in both probands and their available first-degree relatives.

RESULTS

The first patient had a novel heterozygous inactivating CASR mutation in exon 4, which predicted a p.A423K change; genetic analysis was negative in the parents. The second patient had a novel heterozygous activating CASR mutation in exon 6, which predicted a p.E556K change; the affected sister of the proband was also positive.

CONCLUSIONS

We reported two novel heterozygous mutations of the CASR gene, an inactivating mutation in exon 4 and the first activating mutation reported to date in exon 6. These cases illustrate the importance of genetic testing of CASR gene to aid correct diagnosis and to assist in clinical management.

Diagnostic value of micro-CT in comparison with histology in the qualitative assessment of historical human skull bone pathologies

Cases of pathologically changed bone might constitute a diagnostic pitfall and frequently need histological methods to be etiologically properly evaluated. With micro-computed tomography (microCT), a new epoch of 2D and 3D imaging has been launched. We evaluated the diagnostic investigation of this analytical method versus well established histological investigations of historical human bone. Pathological changes due to various etiologies (infectious, traumatic, endocrinological, neoplasia) observed in autopsy-based macerated human skulls (Galler Collection, Natural History Museum Basel, Switzerland) were investigated by microCT and compared with histological thin ground sections using polarized light. Micro-CT images visualize the architecture of the bone with high spatial resolution without preparation or destruction of the sample in the area to be sectioned. Changes in the bone surfaces as well as alterations of the diploë can be assessed. However, morphological patterns caused by reactive response, such as typical arrangements of collagen fibers, can only be visualized by the microscopic investigation of thin ground sections using polarized light. A great advantage of microCT is the high number of slices obtained so that spatial differences within the areas of the specimen become visible. Micro-CT is a valuable tool for the diagnosis of vestiges of skull bone diseases. Its advantages over histology are the fast, automated image acquisition and the fact that the specimen is not completely destroyed. Only excision of the area to be scanned is necessary, if the specimen is too large to be scanned as a whole. Further, the 3D visualization of the micro-architecture allows an easy orientation within the sample, for example, for the choice of the location of the histological slices. However, the need to differentiate woven from lamellar bone still makes histology an indispensable method.

The management of primary hyperparathyroidism

Recent improvements in parathyroid imaging have led to renewed interest in the criteria for, and the surgical approach to, parathyroidectomy. It therefore seemed appropriate to review current evidence relating to the evaluation and management of primary hyperparathyroidism for those working within a general endocrine service. The recommendations are based on an electronic search spanning the past decade using the search terms hyperparathyroidism, management and parathyroidectomy/surgery, but we have also included key publications outside this period. The findings have been graded systematically (Appendix), according to the quality of the information available, to indicate the level of evidence on which they are based.

Separate assessment of forearm cortical and trabecular bone density from standard densitometry data

BACKGROUND

Cortical and trabecular bone are different bone components. Their mineral density cannot be measured directly by areal bone densitometry.

AIM

To introduce a method for assessment of pure radial cortical and trabecular bone density based on standard densitometry data.

METHOD

The study included 418 healthy females (aged 20-83 years, body mass index between 19 and 30) free of previous fractures and conditions or drugs affecting bone metabolism; as well as a group of 64 age-matched females with early menopause. Forearm bone density was measured by single X-ray absorptiometry and calculated separately for cortical and trabecular bone. Age-adjusted bone density curves were built.

RESULTS

Peak bone density was found to occur between 30 and 34 years of age and was 0.561 g/cm2 for cortical and 0.281 g/cm2 for trabecular bone. In comparison, lowest values were registered between 70 and 74 years of age; cortical bone density reduced by 26% and trabecular density by 44%. Both bone density profiles through life reflected the earlier peri- and postmenopausal (mainly trabecular) and later senile (cortical bone also involved) changes in bone mass. A step-wise pattern of trabecular bone reduction was registered with acceleration around 45, 55 and 65 years. The effects of early menopause on trabecular and cortical bone were tested in the prematurely menopausal women.

CONCLUSIONS

The ability of our model to discriminate between natural and premature menopause was moderate. Although hypothetical (based on calculations from integral densitometry data rather than on direct measurements), our method could differentiate between cortical and trabecular osteopenia and may prove helpful in assessing the type of osteoporosis, in making therapy choices and monitoring response to therapy based on forearm bone density.

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.

Primary hyperparathyroidism: bone structure, balance, and remodeling before and 3 years after surgical treatment

In 19 patients with primary hyperparathyroidism (PHPT) (14 women and 5 men; age 53 +/- 11 years, range 29-69 years), bone densitometry, biochemical markers of bone turnover, and iliac crest bone biopsies were obtained before and 3 years after successful surgical treatment. A significant increase in bone mineral content (BMC) was observed in both the lumbar spine (p < 0.001) and the proximal part of the distal forearm (p < 0.001), whereas the increase in BMC in the femoral neck was insignificant. Biochemical markers of bone formation (serum alkaline phosphatase, serum bone alkaline phosphatase and serum osteocalcin) and resorption (serum pyridinoline cross-linked telopeptide of type I collagen and urine N-telopeptide of type I collagen) all decreased following treatment. In cortical bone, relative cortical width increased following surgery (p < 0.05) and cortical porosity decreased (p < 0.01). No changes were observed in core width or cortical width. In cancellous bone, no significant changes were observed in any of the measured structural parameters. However, significant reductions in the extent of osteoid- (p < 0.01) and tetracycline-labeled surfaces (p < 0.001), and in bone formation rate (p < 0.001) and activation frequency (p < 0.001), were found. The numerical decrease in the extent of eroded surfaces did not reach significance (p = 0.057). No changes were observed in mineral appositional rate and adjusted appositional rate. The amount of bone resorbed (expressed as the resorption depth) and the amount of bone reformed (expressed as wall thickness) per remodeling cycle seemed unaffected by the treatment. Consequently, no effect on bone balance per remodeling cycle could be detected. The present study of PHPT patients showed that, within 3 years after surgery, BMC of both cancellous and cortical bone areas had increased. At the same time, bone turnover decreased markedly, as judged from biochemical as well as histomorphometric data, but no changes were seen in trabecular bone structure. In cortical bone, the relative cortical width increased and the cortical porosity decreased.

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: effect of parathyroidectomy on regional bone mineral density in Danish patients: a three-year follow-up study

Changes in skeletal remodeling (biochemical bone markers) and regional bone mineral density (spine, hip, and forearm bone mineral density [BMD]) were observed for 3 years in 20 patients (15 women and 5 men; age 54 +/- 11 years, range 29-69 years) after successful surgery for primary hyperparathyroidism (PHPT). Fifteen PHPT patients were compared with 15 normal controls who were exactly matched with respect to age, gender, and menopausal status (10 women and 5 men; age 53 +/- 12 years, range 29-65 years [PHPT] and 29-66 years [controls]). All bone markers (serum osteocalcin, bone alkaline phosphatase, and type I collagen telopeptide [ICTP], and urinary hydroxyproline and NTx/creatinine ratio) declined significantly and reached normal levels within 6 months. No major changes took place during the remaining 2.5 years, apart from urine hydroxyproline, which disclosed a small peak around 12 months with a further decline towards study end (p < 0.05). Bone mineral density increased significantly in all regions (p < 0.001). At all locations, except the intertrochanteric region of the hip, the increase continued from 6 months until study end (p < 0.05). The increase in BMD was unequally distributed among regions (p < 0.001). The increase at the proximal forearm was less than in the spine (p < 0.05), the trochanteric region of the hip (p < 0.05), and the distal forearm (p < 0.05). No difference in BMD increase was observed between men, and pre- and postmenopausal women. Compared with the matched control group, PHPT patients had significantly lower BMD at baseline in the proximal (p < 0.02) and distal (p < 0.05) forearm. Furthermore, during the 3-year follow-up period, the PHPT patients showed a significant increase in BMD compared with controls in the spine (p < 0.005), the trochanteric and intertrochanteric regions of the hip (p < 0.005 and p < 0.05, respectively), and the distal forearm (p < 0.005). In conclusion, bone remodeling is normalized within the first 6 months after successful parathyroid surgery, with no major changes during the following 2.5 years. Bone mineral density increases at both cancellous and cortical sites, but in predominantly cortical bone, the recovery in BMD is less than in cancellous bone-rich areas.

Bone mineral recovery after parathyroidectomy in patients with primary and renal hyperparathyroidism

Patients with hyperparathyroidism (HPT) generally display reduced bone mass due to excessive PTH activity. The effect of parathyroidectomy on bone mass changes in different types of HPT, however, is not well understood. Bone mineral density (BMD) was measured in the distal radius, total body, femoral neck, and lumbar spine by dual energy x-ray absorptiometry in four groups of patients with different hyperparathyroid conditions: primary symptomatic HPT (n = 54), primary asymptomatic (mild) HPT (n = 24), HPT associated with hemodialysis (n = 20), and HPT associated with renal transplant (n = 30). Subsets of patients with primary symptomatic HPT (n = 52), HPT associated with hemodialysis (n = 19), and HPT associated with renal transplant (n = 15) underwent parathyroidectomy, and bone density was measured longitudinally for 3 yr. Patients with primary asymptomatic (mild) HPT did not undergo surgery and were followed prospectively. Before surgery, all groups showed a greater reduction of bone mineral density in cortical bone (distal radius) than in predominantly trabecular bone (lumbar spine). In primary symptomatic HPT, the BMD z-score of the distal radius was -1.80 +/- 0.21 (+/-SEM), and the corresponding figures for the total body, femoral neck, and lumbar spine were -0.60 +/- 0.15, -0.54 +/- 0.14, and -0.53 +/- 0.18 compared with those of an age- and sex-matched reference group. In renal HPT BMD z-scores were -2.51 +/- 0.38 (hemodialysis patients) and -2.83 +/- 0.43 (renal transplant patients) for the distal radius and between -0.81 and -1.46 for the other measured sites. After parathyroidectomy, BMD increased by 1-8% at all sites in patients with primary symptomatic HPT and HPT associated with renal transplant. The largest increase in bone mass was observed in patients with HPT associated with hemodialysis, in whom the improvement amounted to 7-23%. In patients with primary HPT and HPT associated with hemodialysis, this increase in bone density resulted in virtual recovery from their preoperative bone loss. The majority of patients with asymptomatic primary HPT disease (n = 21) maintained their bone density during the follow-up period and have not shown evidence of increases in serum calcium or PTH levels, but three patients followed conservatively underwent parathyroidectomy due to progressive deterioration of BMD. We conclude that, regardless of the etiology, a large proportion of HPT patients show reduced bone density. In patients with primary symptomatic HPT and patients with HPT associated with hemodialysis, bone density increases after parathyroidectomy to an extent that largely restores the preoperative bone loss. However, no anabolic effect of parathyroidectomy on bone mass was observed in patients with HPT associated with renal transplant, probably because of their immunosuppressive therapy.

Bone mineral density and circulating cytokines in patients with acromegaly

Acromegalic patients present an increase of osteoblastic and osteoclastic activity, showing a different effect on the axial and appendicular skeletal structures. At this regard controversial data about bone mineral density (BMD) have been published in literature. In fact an increase of BMD levels in femoral neck and Ward's triangle without any difference in lumbar spine has been described. On the other hand normal BMD levels at forearm and reduced BMD levels at lumbar spine were found. These patients seem to have a reduction of trabecular BMD similar to postmenopausal osteoporotic patients despite normal or slightly elevated cortical BMD. Recently, it has been described that cytokines, in particular tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1), are implicated in the pathogenetic mechanism of postmenopausal osteoporosis. Taking into account that growth hormone (GH) can increase TNF-alpha and IL-1 secretion by mononuclear blood cells, the evaluation of possible relationship between the reduced BMD at lumbar spine and circulating cytokines levels was carried out in acromegalic patients. In addition we evaluated the effect of acute octreotide administration on serum TNF-alpha and IL-I concentrations. Eleven patients with active acromegaly and eleven healthy age-, sex-, weight- and heightmatched subjects were enrolled in this study. BMD was significantly reduced at lumbar spine (0.80 +/- 0.29 g/cm2 vs 1.02 +/- 0.11 g/cm2; p < 0.01), but not at femoral neck level or at Ward's triangle level (0.92 + 0.15 g/cm2 vs 0.97 + 0.11 g/cm2, p = NS; and 0.74 +/- 0.16 g/cm2 vs 0.85 +/- 0.1 g/cm2, p = NS) when compared to controls. Baseline serum levels of TNF-alpha and IL-1 were in the normal range both in patients and controls. After acute octreotide administration, no differences in circulating TNF-alpha and IL-1 levels were found. In conclusion, acromegalic patients present a reduced BMD at lumbar spine but not at femoral neck level and Ward's triangle. Circulating cytokines such as TNF-alpha and IL-1 are in the normal range. These data suggest that cytokines are not involved in the pathogenesis of GH-excess induced osteoporosis. The possibility that the GH excess might affect bone turnover inducing an increase of cytokines acting by a paracrine/autocrine mechanism cannot be ruled out.

Primary hyperparathyroidism and osteoporosis

Primary hyperparathyroidism (PHPT) is considered a cause of secondary osteoporosis as a consequence of its known catabolic effect promoting osteoclast activity and bone resorption. However, recent in vitro and in vivo studies have shown that parathyroid hormone (PTH) may also have an anabolic effect on the mammalian skeleton. These two paradoxical effects of parathyroid hormone are discussed in the light of recent results of basic research, and of bone densitometric and histomorphometric data collected in patients affected by PHPT. Review of the literature leads to the conclusion that in PHPT skeletal damage involves prevalently cortical bone, while the mineral content of trabecular bone is preserved or even increased. On the basis of bone mineral density (BMD) measurements, osteoporosis prevalence in the early postmenopausal period seems to be significantly higher in women affected by PHPT than in the general population. As age progresses, osteoporosis prevalence seems to decrease in PHPT, while it increases exponentially with age in the general population. Similarly in PHPT, vertebral and appendicular fractures occur prevalently in the earlier decades of life with a higher frequency than in normal subjects, while with advancing age the fracture incidence becomes equal to that of the general population. When bone density is measured in lateral projection at lumbar level, BMD values in patients with mild asymptomatic PHPT are significantly higher than in controls. We conclude that PTH hypersecretion may represent a risk factor for osteoporosis and fractures in the young and in the early postmenopausal period, while it may have a protective effect on trabecular bone in elderly postmenopausal women.

Primary hyperparathyroidism: biochemical markers and bone mineral density at multiple skeletal sites in Danish patients

Biochemical bone markers and bone mineral density (BMD) in spine, hip, and forearm were measured, before surgery, in 30 patients with mild to moderate primary hyperparathyroidism (PHP) (25 women and 5 men; mean age 54 +/- 12 years, range 26-73 years) and compared with normal controls. A group of 291 healthy adults (181 women and 110 men) served as controls for BMD. A smaller group of 30 normal individuals (25 women and 5 men; mean age 54 +/- 12 years; range 26-74 years) were used as matched normal controls. Parameters of bone formation (s-osteocalcin, s-alkaline phosphatase activity, and s-bone isoenzyme alkaline phosphatase activity) and bone resorption (s-type-1 collagen telopeptide) were considerably increased in patients with PHP compared with normal controls (p < 0.01 for all parameters). BMD was found to be reduced in the hip (trochanteric: 95.1 +/- 14.7% of expected, p < 0.05; intertrochanteric: 95.2 +/- 13.8% of expected, p < 0.05), and the forearm (proximal: 93.3 +/- 12.2% of expected, p < 0.05; mid: 91.8 +/- 11.6% of expected, p < 0.001; distal: 90.7 +/- 13.1% of expected, p < 0.001). Spine BMD was found significantly reduced in premenopausal (87.8 +/- 7.6% of expected, p < 0.05) but not in postmenopausal patients, and although normal women showed a decrease in spinal BMD with increasing age this was not found in the PHP women. Forearm BMD was reduced in both pre- and postmenopausal patients (distal forearm: 86.7 +/- 12.2% of expected, p < 0.05; 87.6 +/- 12.1% of expected, p < 0.01, respectively). It was concluded that Danish patients with mild or moderate PHP have only small reductions in BMD. The bone loss is mainly found in the appendicular skeleton.

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.

An earlier fracture as a risk factor for new fracture and its association with smoking and menopausal age in women

OBJECTIVES

The purpose of this study was to investigate whether a previous fracture is a risk factor for fracture later in life and its association with tobacco smoking, menopausal age and the use of oral contraceptives. This is an epidemiological population study based on a questionnaire. A sample of 10000 women from seven birth cohorts between 1900-1940 was obtained at random from the population register. The overall response rate was 74.6%. The responders (n = 7459) represented 53% of the total population.

METHODS

The women from all these birth cohorts were questioned regarding a possible history of fractures and the year in which they were sustained. The questionnaire also included questions about menopausal age, use of oral contraceptives, previous gynaecological operations and possible oestrogen medication. The women from the 1900-1920 birth cohorts were questioned in detail about urogenital disorders, while tobacco smoking data were recorded only for the 1930 and 1940 birth cohorts.

RESULTS

The relative risk of sustaining a further fracture was significantly related to fracture premenopausally before 40 years of age and later fracture postmenopausally after 60 years of age (1.29; 0.97-1.70) compared to controls (0.78; 0.59-1.03)(P = 0.03). Both an early menopause and tobacco smoking were associated significantly with repeated fractures, while use of oral contraceptives had a protective effect against repeated fractures in the 1940 birth cohort. Logistic multiple regression showed that a fracture was a significant independent risk factor for further fracture in both cohorts 1900-1920 (P < 0.01) and 1930-1940 (P < 0.05).

CONCLUSIONS

This study suggests poorer protective resources against new fractures among women with previous fractures, and that lack of oestrogen menopausally can partly explain the enhanced risk of fracture, not only during the menopause but also later in life when a hip fracture may have immense consequences. The results should draw our attention to emphasise the need for active treatment of patients with established osteoporosis because of the increased risk of new fractures later in life.

Decreased cortical and increased cancellous bone in two children with primary hyperparathyroidism

The basis for this study is two children with primary hyperparathyroidism (PHPT) who radiographically manifested both marked subperiosteal resorption and prominent osteosclerosis. We hypothesize that the parathyroid hormone (PTH) elevation not only increased osteoclastic resorption of cortical bone but also simultaneously enhanced cancellous bone formation, giving rise to osteosclerosis. In this report, we describe the changes in trabecular and cortical bone density, as measured by quantitative computed tomography (QCT), in these two young patients with severe PHPT, before and after removal of a parathyroid adenoma. Before surgery, the radiographic findings of subperiosteal resorption and osteosclerosis were associated with low cortical and high cancellous bone density values in both children. Within 1 week of surgery, both cortical and cancellous bone density values increased and serum concentrations of calcium and, to a lesser degree, phosphorus decreased due to the "hungry bone syndrome." Twelve weeks after parathyroidectomy, QCT bone density values and skeletal radiographs were normal in both patients. The findings suggest that in patients with severe PHPT, the catabolic effect of PTH on cortical bone may be associated with a simultaneous anabolic effect on cancellous bone, and PTH may cause a significant redistribution of bone mineral from cortical to cancellous bone.

Bone structure in postmenopausal hyperparathyroid, osteoporotic, and normal women

The purpose of this study was to test the hypothesis that patients with mild primary hyperparathyroidism are protected against postmenopausal (PM) loss of cancellous bone architecture. To achieve this, we compared bone structure and turnover in iliac bone biopsies from three groups: 16 women with mild primary hyperparathyroidism (PHPT; 58.2 +/- 2.2 years, 11.5 +/- 1.7 years PM), 17 women with untreated primary osteoporosis (OP; 65.1 +/- 2.0 years, 17.2 +/- 2.3 years PM), and 31 healthy women (N; 59.8 +/- 1.4 years, 13.4 +/- 1.5 years PM). The bone formation rate was significantly higher in PHPT than in either OP or N, and not different between OP and N. Cancellous bone volume, total strut length, and indices of connectivity (node number, node to node strut length, and node to terminus ratio) were significantly lower in OP than in either PHPT or N but were the same or higher in PHPT than in N. Indices of disconnectivity were significantly lower in PHPT than in N, whereas they were the same or higher in OP than N. The data were also analyzed in subgroups matched by years PM with no changes in the results. These findings indicate that osteoporotic patients with normal bone turnover have low bone volume and microarchitectural deterioration, while patients with mild PHPT have normal bone volume and normal or greater trabecular connectivity despite higher bone turnover. These findings suggest that mild PHPT protects against the loss of cancellous bone structure that normally follows menopause.

Effects of oral calcitriol on bone mineral density in patients with end-stage renal failure

Evolution of bone mineral density (BMD) at various skeletal sites and the influence of calcitriol on BMD are still poorly documented in patients with terminal renal failure. Using dual photon absorptiometry, we investigated the changes in BMD at the levels of lumbar spine, femoral neck and midfemoral shaft in 21 patients with end-stage renal failure (ESRF) treated with calcitriol (mean dosage +/- SEM: 0.21 +/- 0.02 microgram/day) and compared them to 25 patients with ESRF but not treated with calcitriol (control group) over a period of 20.3 +/- 1.5 and 17.2 +/- 1.2 months, respectively. Lumbar spine BMD increased by 7.7 +/- 3.2%/year in the treated group and decreased by 2.5 +/- 1.3%/year in the control group (P < 0.005). Femoral shaft BMD increased more in treated than in control group (+ 6.7 +/- 2.3 vs. + 1.4 +/- 2.0%/year; P < 0.05) and femoral neck BMD remained stable. PTH levels increased by 92 +/- 121 and 1033 +/- 254 pmol/year (P < 0.01) in the treated group and the controls, respectively. Osteocalcin changes were -2.7 +/- 3.7 and +20.1 +/- 11.7 micrograms/liter (P < 0.05) per year in the same groups. These results indicate that low doses of oral calcitriol in patients with end-stage renal failure were associated with an increase in BMD at the levels of lumbar spine and femoral shaft, and with a stabilization of serum PTH and osteocalcin concentrations.

The risk of hip fractures in patients with primary hyperparathyroidism: a population-based cohort study with a follow-up of 19 years

OBJECTIVE

To evaluate primary hyperparathyroidism (HPT) as a risk factor for hip fractures.

DESIGN

A population-based, record-linked, prospective study with a mean observation time of 17 years (women) and 16.5 years (men).

SETTING

A cohort obtained from a register of hospital admissions in the Uppsala Health Care Region, Sweden, 1965-1983.

PARTICIPANTS

All patients (1373 women and 551 men) who were admitted to hospital with the diagnosis of HPT during the period. Comparisons were made with the entire background population.

MEASUREMENTS

Cohort subjects were followed with regard to a first instance of hip fracture prior to or after the diagnosis of HPT. The observed number of cases was compared with that expected on the basis of person-years of observation and incidence rates in the background population. Analyses were made for cervical and trochanteric fractures, and for patients operated and not operated for HPT.

MAIN RESULTS

(i) Women. During 23,341 person-years of observation, 67 cases of first hip fractures occurred, yielding a relative risk (RR) of 0.93 (95% confidence interval [CI] 0.72-1.19). The RR for cervical fractures was 0.77 (CI 0.54-1.06), and for trochanteric fractures 1.33 (CI 0.88-1.93). Operation for HPT did not influence the risk of hip fracture. (ii) Men. The total person-years was 9091. Eleven fractures were observed--compared with the expected 7.90 (RR 1.39; CI 0.69-2.50). Men operated for HPT had an increased risk for cervical hip fractures (RR 2.73; CI 1.18-5.39). Owing to the few fractures in this group (n = 8) the relevance of this is uncertain.

CONCLUSIONS

This study indicates that HPT is not a risk factor for hip fractures in women.

Primary hyperparathyroidism: iliac crest cortical thickness, structure, and remodeling evaluated by histomorphometric methods

Iliac crest bone biopsies from 62 patients (42 women, 20 men; median age 59 years; range 17-79 years) with primary hyperparathyroidism (PHP) were examined. Static and structural parameters were compared with 30 age- and sex-matched normal controls. Eighteen sex-matched younger controls were used for evaluation of the dynamic controls. On the endocortical surface increase in extension of eroded (p < 0.01) and formative (p < 0.01) surfaces was found in PHPs compared with normals. Endocortical bone formation rate was increased in PHPs (p < 0.05), but mineral appositional rate and adjusted appositional rate were normal. On the periosteal surface very little remodeling activity was found. Although bone formation rate was found increased in PHPs (p < 0.05), more than half of the labeled biopsies were without periosteal tetracycline in patients, and only 2 of 18 biopsies from normals contained periosteal tetracycline labels. No significant decreases in cortical width or relative cortical width were found in PHPs. In both patients and controls an age-related decrease in relative cortical width cortical width were found in PHPs. In both patients and controls an age-related decrease in relative cortical width was noted for women (PHPs: r = -0.52, p < 0.01; controls: r = -0.59, p < 0.001), but not for men. Cortical porosity was about 30% increased in PHPs (p < 0.02). Only normal women showed a positive age-related increase in porosity (r = 0.61, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Trabecular bone mineral density in primary hyperparathyroidism: relationship to clinical presentation and biomarkers of skeletal turnover

This study was carried out in order to investigate the entity of trabecular bone involvement in 62 patients with primary hyperparathyroidism (PHPT). Bone mineral density (BMD) was measured in all patients at the ultradistal radius (UDR) of the non-dominant arm by a dual photon densitometer and also at the lumbar spine (L) in 40 of the patients by means of quantitative dual energy radiography. Mean Z score values of UDR-BMD (-2.4 +/- 0.4) and L-BMD (-3.5 +/- 0.2) in patients with the skeletal variety of the disease (n = 6) were significantly reduced in respect to values of both asymptomatic (n = 31) and kidney stone patients (n = 25). As far as the comparison between the two sites of trabecular bone mass measurement in each hyperparathyroid subgroup of patients was concerned, a significant difference (P < 0.05) was found in patients with skeletal manifestations of the disease. Either serum total alkaline phosphatase activity, or osteocalcin and the 24-h hydroxyproline/creatinine ratio were significantly inversely related to the entity of bone mass evaluated at these two sites. Z score changes following surgery in 14 patients showed a positive trend in 13 of them at L compared to 7 out of 14 at UDR (P < 0.036 by chi square analysis). There was a very good inverse correlation between basal Z score values and the changes following surgery at the L (r = -0.851; P < 0.001) but not at the UDR. Our results demonstrate firstly that, in PHPT skeletal sites with almost similar composition of trabecular bone are differently involved in patients with more severe skeletal damage and that different skeletal sites may be divergently affected by the cessation of parathyroid gland hyperfunction.

Maintenance of cancellous bone connectivity in primary hyperparathyroidism: trabecular strut analysis

We previously demonstrated an increase in cancellous bone volume and trabecular number in patients with mild primary hyperparathyroidism (PHPT). To test the hypothesis that this increase is due to preservation of cancellous bone architecture, we conducted a trabecular strut analysis using a new method that measures trabecular connectivity. Iliac crest biopsies from 37 patients with PHPT, 14 men (28-68 years) and 23 women (26-68 years), were examined histomorphometrically and compared to cadaveric samples from 24 age-matched subjects, 17 men and 7 women. Two-dimensional indices of cancellous structure--node number (N.Nd), terminus number (N.Tm), node to node (Nd.Nd), node to terminus (Nd.Tm), and terminus to terminus (Tm.Tm) strut lengths, and total strut length (TSL)--were measured and the ratio of node number to terminus number (N.Nd/N.Tm) calculated. TSL, N.Nd, and Nd.Nd were significantly higher in patients than in controls. TSL and Nd.Nd, but not N.Nd or Nd/Tm, decreased significantly with age in PHPT, indicating that age-related bone loss in PHPT occurs without significant loss of trabecular connectivity. Two-dimensional indices reflecting connectivity or the amount of bone, that is, N.Nd, Nd.Nd, N.Nd/N.Tm, and TSL, correlated positively with cancellous bone volume (BV/TV) and trabecular number (Tb.N) and negatively with trabecular spacing (Tb.Sp) in both PHPT and controls. Trabecular thickness (Tb.Th) correlated positively with Nd.Nd and Tb.N and negatively with Tm.Tm in PHPT but not in controls. The present data show that in PHPT there is not only greater cancellous bone volume and trabecular number but preserved trabecular connectivity as well. The data further support the hypothesis that in PHPT cancellous bone architecture is maintained.

Clinical spectrum of primary hyperparathyroidism: evolution with changes in medical practice and technology

Over the last 25 years, the perceived clinical spectrum of primary hyperparathyroidism (HPT) has changed dramatically from a disorder characterized by severe bone and renal disease to one typically manifested by few or mild symptoms and little evidence of organ damage. Reasons for this change in spectrum include changing demographics (primary HPT is primarily a disease of the middle-aged and elderly), diffusion of medical knowledge leading to a higher index of suspicion, and improved clinical laboratory technology (especially inexpensive and accurate determination of serum calcium and parathyroid hormone). In the first 343 cases of primary HPT seen at the Massachusetts General Hospital, 57% had renal stones, 23% had hyperparathyroid bone disease, and less than 1% had no symptoms. By contrast, studies dating from the availability of automated serum calcium measurement found renal stones and hyperparathyroid bone disease in less than 5% of cases, and about half of cases had few or no symptoms. Most patients with primary HPT today have mild, nonspecific symptoms, such as weakness, fatigue, and mental depression, and such signs as arterial hypertension and osteopenia, and detection of their hypercalcemia is generally serendipitous. The mildness and slow progression seen in many cases of primary HPT has resulted in much controversy about appropriate management.

Methods of determining bone mass

Bone disease is one of the most important clinical manifestations of primary hyperparathyroidism. Recent studies have shown that the loss of bone in "modern" hyperparathyroidism is not homogeneous throughout the skeleton. Whereas measurements of the spine and the trabecular portion of iliac crest are normal or even slightly increased, the wrist and the cortical bone of the iliac crest are significantly lower than expected. Thus, knowledge of the percentage of trabecular bone at each measurement site is important. These include distal radius, 80%; midradius, 5%; vertebrae, 19-25%; vertebral body, 33-42%; and femoral neck, 43%. Knowledge of the precision and its relationship to ranges and rates of change of bone mass are essential. For an individual, the bone mass should change by 2.8 times the precision before one can determine with 90% confidence that the change was real, not due to measurement error. Noninvasive methods of measuring bone mass that are commercially available include single- and dual-photon absorptiometry, quantitative computed tomography, and dual-energy x-ray absorptiometry. The precision of these techniques varies, with the best values reported using dual-energy x-ray absorptiometry. Research should be done to describe more completely the patterns of bone loss in this disease, including longitudinal studies on rates of loss at different skeletal sites. Studies that relate the bone mass at a particular site to fractures must be done in populations with hyperparathyroidism to see if the risk of fracture is similar to the risk in normal or osteoporotic individuals.

The influence of surgery on the risk of death in patients with primary hyperparathyroidism

The previous finding of an increased risk of premature death in a consecutive series of 896 patients operated on for primary hyperparathyroidism between 1953 and 1982 [1] raised the question of the role that surgery plays in relation to the risk of death. In the present study, undertaken to examine that issue, 3 factors--age, calendar year of surgery, and time passed after surgery--have been found to be significantly related to the risk of death (p less than 0.001), each factor contributing independently. A correlation was found between a late calendar year of surgery and a low degree of hyperparathyroidism as evaluated by serum calcium and creatinine levels. There was an increased risk of premature death in all age groups. The risk was less among patients operated on in later years. The observed normalization of the increased risk of death with time after surgery also took place sooner in patients operated on in later years. Our findings of improved survival following surgical intervention contrasts favorably with the findings of others in studies of subjects with untreated mild hyperparathyroidism. We have also found that preoperative serum calcium levels affect the risk of death, and that there is an additional factor related to the calendar year of surgery affecting the risk of death. Circumstantial evidence indicates that the duration of hyperparathyroidism contributes to this factor. Our results also show that early surgery decreases the risk of premature death in mild cases of the disease.

The direct medical costs of osteoporosis for American women aged 45 and older, 1986

Annual direct medical costs of osteoporosis incurred by American women aged 45 and older are estimated at $5.2 billion in 1986. Costs are stratified by type of care (inpatient hospital, nursing home and outpatient) and by age group (ages 45 to 59, 60 to 74 and 75 and older). Survey data from the National Center for Health Statistics are combined with census data to project utilization estimates from the survey years to 1986. A portion of all health care encounters for diagnoses secondary to osteoporosis are considered to be caused by osteoporosis according to age- and diagnosis-specific attribution weights. These weights are derived from the opinion of a panel of osteoporosis experts. For inpatient hospitalization, the assigned diagnosis related group (DRG) is used to further specify osteoporosis as the cause of hospitalization. The cost components of osteoporosis care for American women in 1986 are inpatient care, $2.8 billion; nursing home care, $2.1 billion; and outpatient care, $0.2 billion. Study results suggest considerable potential future cost-savings of osteoporosis prevention and abatement.