Upper gastrointestinal safety of oral bisphosphonate in hospitalized patients

Oral bisphosphonates are effective medications for the prevention of fractures in people suffering from osteoporosis. They are associated with gastrointestinal adverse reactions the most severe being an esophageal ulcer. It is unclear if oral bisphosphonates have a similar gastrointestinal safety profile in the hospital setting as in the community setting because hospitalized patients are often bedridden which may hinder proper drug administration.

INTRODUCTION

To evaluate the incidence of upper gastrointestinal symptoms in hospitalized patients taking oral bisphosphonate.

METHODS

This single-center prospective cohort study included hospitalized adult patients actively taking risedronate or alendronate. Upper gastrointestinal symptoms were actively assessed at the baseline and 1 to 5 h following the administration of the oral bisphosphonate.

RESULTS

A total of 298 patients were included in the study. The mean age was 64 ± 15 years. During the follow-up period, gastric and esophageal symptoms affected 32 patients (10.7%). Epigastric burning, dysphagia, and regurgitation were reported in 4.4% (n = 13), 3% (n = 9), 2.7 (n = 8), and 2.3% (n = 7) patients, respectively. Heartburn, retro-sternal pain, and odynophagia were observed in 1.7% (n = 5), 1.7% (n = 5), and 0.3% (n = 1) patients.

CONCLUSION

The incidence of adverse reaction was similar to that reported in community trials. The administration of oral bisphosphonate in hospitalized patients does not represent an additional risk for upper gastrointestinal adverse events. Treatment should be optimized during the hospital stay to improve the pharmacological management of osteoporosis.

Performance of predictive tools to identify individuals at risk of non-traumatic fracture: a systematic review, meta-analysis, and meta-regression

There is no consensus on which tool is the most accurate to assess fracture risk. The results of this systematic review suggest that QFracture, Fracture Risk Assessment Tool (FRAX) with BMD, and Garvan with BMD are the tools with the best discriminative ability. More studies assessing the comparative performance of current tools are needed.

INTRODUCTION

Many tools exist to assess fracture risk. This review aims to determine which tools have the best predictive accuracy to identify individuals at high risk of non-traumatic fracture.

METHODS

Studies assessing the accuracy of tools for prediction of fracture were searched in MEDLINE, EMBASE, Evidence-Based Medicine Reviews, and Global Health. Studies were eligible if discrimination was assessed in a population independent of the derivation cohort. Meta-analyses and meta-regressions were performed on areas under the ROC curve (AUCs). Gender, mean age, age range, and study quality were used as adjustment variables.

RESULTS

We identified 53 validation studies assessing the discriminative ability of 14 tools. Given the small number of studies on some tools, only FRAX, Garvan, and QFracture were compared using meta-regression models. In the unadjusted analyses, QFracture had the best discriminative ability to predict hip fracture (AUC = 0.88). In the adjusted analysis, FRAX with BMD (AUC = 0.81) and Garvan with BMD (AUC = 0.79) had the highest AUCs. For prediction of major osteoporotic fracture, QFracture had the best discriminative ability (AUC = 0.77). For prediction of osteoporotic or any fracture, FRAX with BMD and Garvan with BMD had higher discriminative ability than their versions without BMD (FRAX: AUC = 0.72 vs 0.69, Garvan: AUC = 0.72 vs 0.65). A significant amount of heterogeneity was present in the analyses.

CONCLUSIONS

QFracture, FRAX with BMD, and Garvan with BMD have the highest discriminative performance for predicting fracture. Additional studies in which the performance of current tools is assessed in the same individuals may be performed to confirm this conclusion.

Direct medical costs attributable to peripheral fractures in Canadian post-menopausal women

This study determined the cost of treating fractures at osteoporotic sites (except spine fractures) for the year following fracture. While the average cost of treating a hip fracture was the highest of all fractures ($46,664 CAD per fracture), treating other fractures also accounted for significant expenditures ($5,253 to $10,410 CAD per fracture).

INTRODUCTION

This study aims to determine the mean direct medical cost of treating fractures at peripheral osteoporotic sites in the year post-fracture (through 2 years post-hip fracture).

METHODS

Health administrative databases from the province of Quebec, Canada were used to estimate the cost of treating peripheral fractures at osteoporotic sites for the year following fracture (through 2 years for hip fractures). Included in costs analyses were physician claims, emergency and outpatient clinic costs, hospitalization costs, and subsequent costs for treatment of complications.

RESULTS

A total of 15,827 patients (mean age 72 years) who suffered one fracture at an osteoporotic site had data for analyses. Hip/femur fractures had the highest rate of hospital stays related to fracture (91%) and the highest rate of hospital stays associated with a post-fracture complication (8%). In the year following fracture, the mean (SD) costs (2009 Canadian dollars) of treating acute fractures and post-fracture complications were: hip/femur fracture $46,664 ($43,198), wrist fracture $5,253 ($18,982), and fractures at other peripheral sites $10,410 ($27,641). The average (SD) cost of treating post-fracture complications at the hip/femur in the second year post-fracture was $1,698 ($12,462). Hospitalizations associated with the fracture accounted for 88% of the total cost of fracture treatment.

CONCLUSIONS

The treatment of hip fractures accounts for a significant proportion of the costs associated with the treatment of peripheral osteoporotic fractures. Interventions to reduce the incidence of fractures, particularly hip fractures, would result in significant cost savings to the health care system and would preserve quality of life in many patients.

The impact of two educational interventions on osteoporosis diagnosis and treatment after fragility fracture: a population-based randomized controlled trial

This study assessed whether osteoporosis diagnosis and treatment after an osteoporotic fracture can be increased by providing osteoporosis reading material to patients and family doctors or by watching a videocassette about osteoporosis. Educating patients about osteoporosis had little impact on whether a woman received an osteoporosis diagnosis or treatment.

INTRODUCTION

The purpose of this study was to investigate the impact of two education-based interventions on osteoporosis diagnosis and treatment in women ≥ 50 years of age after fragility fracture.

METHODS

Six to eight months after fracture, women were randomized into three groups: (1) control, (2) written materials, or (3) videocassette and written materials. Written materials for both the patient and physician detailed osteoporosis, fragility fracture, and available treatments; written materials for physicians were provided through patients. The educational videocassette presented similar information as the written material, but in greater depth. Rates of osteoporosis diagnosis and treatment following intervention were compared among groups using survival analysis methods. Statistical significance was set at p < 0.0167.

RESULTS

At randomization, 1,174 women were without osteoporosis diagnosis and treatment, and after follow-up, 12% of the control group, 15% of the written materials group (p = 0.073), and 16% (p = 0.036) of the videocassette and written materials group were diagnosed with osteoporosis (statistical comparisons to control). Treatment rates were 8% for the control group, 12% for the written materials group (p = 0.052), and 11% for the videocassette and written materials group (p = 0.157). At randomization, 1,314 women were without treatment and after follow-up therapy was initiated in 10% of the control group, 13% of the written materials group (p = 0.107), and 13% of the videocassette and written materials group (p = 0.238).

CONCLUSIONS

The educational interventions assessed in this trial were not satisfactory to increase osteoporosis diagnosis or treatment in recently fractured women to a clinically meaningful degree.

The role of mineralization and organic matrix in the microhardness of bone tissue from controls and osteoporotic patients

Degree of mineralization of bone (DMB) is a major intrinsic determinant of bone strength at the tissue level but its contribution to the microhardness (Vickers indentation) at the intermediary level of organization of bone tissue, i.e., Bone Structural Units (BSUs), has never been assessed. The purpose of this study was to analyze the relationship between the microhardness, the DMB and the organic matrix, measured in BSUs from human iliac bone biopsies. Iliac bone samples from controls and osteoporotic patients (men and women), embedded in methyl methacrylate, were used. Using a Vickers indenter, microhardness (kg/mm2) was measured, either globally on surfaced blocks or focally on 100 microm-thick sections from bone samples (load of 25 g applied during 10 sec; CV=5%). The Vickers indenter was more suited than the Knoop indenter for a tissue like bone in which components are diversely oriented. Quantitative microradiography performed on 100 microm-thick sections, allowed measurement of parameters reflecting the DMB (g/cm3). Assessed on the whole bone sample, both microhardness and DMB were significantly lower (-10% and -7%, respectively) in osteoporotic patients versus controls (p<0.001). When measured separately at the BSU level, there were significant positive correlations between microhardness and DMB in controls (r2=0.36, p<0.0001) and osteoporotic patients (r2=0.43, p<0.0001). Mineralization is an important determinant of the microhardness, but did not explain all of its variance. To highlight the role of the organic matrix in bone quality, microhardness of both osteoid and adjacent calcified matrix were measured in iliac samples from subjects with osteomalacia. Microhardness of organic matrix is 3-fold lower than the microhardness of calcified tissue. In human calcanei, microhardness was significantly correlated with DMB (r2=0.33, p=0.02) and apparent Young's modulus (r2=0.26, p=0.03). In conclusion, bone microhardness measured by Vickers indentation is an interesting methodology for the evaluation of bone strength and its determinants at the BSU level. Bone microhardness is linked to Young's modulus of bone and is strongly correlated to mineralization, but the organic matrix accounts for about one third of its variance.

Positive effect of etidronate therapy is maintained after drug is terminated in patients using corticosteroids

Following a 52-wk randomized controlled trial of intermittent cyclic etidronate therapy in patients using corticosteroids, we performed a 52-wk open-label trial of calcium alone in 114 corticosteroid-treated patients to determine whether the beneficial effect of etidronate is maintained after the drug is discontinued. All patients were given 500 mg/d of elemental calcium. Sixty-one and 53 patients made up the former placebo and etidronate groups, respectively. A total of 89 (98%) of patients in the former placebo and etidronate groups remained on corticosteroids throughout the second year. The mean (SE) percentage change in bone mineral density of the lumbar spine, femoral neck, and trochanter were compared between groups. The difference between groups in mean percentage change from baseline (wk 0, initiation of etidronate or placebo therapy) in the bone density of the lumbar spine, femoral neck, and trochanter, following 104 wk, was 3.8 (0.9), 3.0 (1.1), and 4.3 (1.1), respectively (p < 0.05, all sites), in favor of the former etidronate group. While not significant, the former placebo group demonstrated a slightly larger rate of decline in bone density over the second year than the former etidronate group at all three sites. Following the discontinuation of etidronate therapy, there was no accelerated bone loss and there was evidence of a residual protective effect in both the lumbar spine and femoral neck for up to 1 yr posttreatment.

Continued breast cancer risk reduction in postmenopausal women treated with raloxifene: 4-year results from the MORE trial. Multiple outcomes of raloxifene evaluation

Raloxifene, a selective estrogen receptor modulator approved for the prevention and treatment of postmenopausal osteoporosis, has shown a significant reduction in breast cancer incidence after 3 years in this placebo-controlled, randomized clinical trial in postmenopausal women with osteoporosis. This article includes results from an additional annual mammogram at 4 years and represents 3,004 additional patient-years of follow-up in this trial. Breast cancers were ascertained through annual screening mammograms and adjudicated by an independent oncology review board. A total of 7,705 women were enrolled in the 4-year trial; 2,576 received placebo, 2,557 raloxifene 60 mg/day, and 2,572 raloxifene 120 mg/day. Women were a mean of 66.5-years old at trial entry, 19 years postmenopause, and osteoporotic (low bone mineral density and/or prevalent vertebral fractures). As of 1 November 1999, 61 invasive breast cancers had been reported and were confirmed by the adjudication board, resulting in a 72% risk reduction with raloxifene (relative risk (RR) 0.28, 95% confidence interval (CI) 0.17, 0.46). These data indicate that 93 osteoporotic women would need to be treated with raloxifene for 4 years to prevent one case of invasive breast cancer. Raloxifene reduced the risk of estrogen receptor-positive invasive breast cancer by 84% (RR 0.16, 95% CI 0.09, 0.30). Raloxifene was generally safe and well-tolerated, however, thromboembolic disease occurred more frequently with raloxifene compared with placebo (p=0.003). We conclude that raloxifene continues to reduce the risk of breast cancer in women with osteoporosis after 4 years of treatment, through prevention of new cancers or suppression of subclinical tumors, or both. Additional randomized clinical trials continue to evaluate this effect in postmenopausal women with osteoporosis, at risk for cardiovascular disease, and at high risk for breast cancer.

The vitamin D analogue EB 1089 prevents skeletal metastasis and prolongs survival time in nude mice transplanted with human breast cancer cells

1,25-Dihydroxyvitamin D has potent antiproliferative and anti-invasive properties in vitro in cancer cells. However, its calcemic effect in vivo limits its therapeutic applications. Here, we report the efficacy of EB 1089, a low calcemic analogue of vitamin D, on the development of osteolytic bone metastases after intracardiac injection of the human breast cancer cell line MDA-MB-231 in nude mice. Animals injected with tumor cells were implanted simultaneously with osmotic minipumps containing either EB 1089 or vehicle. Both groups remained normocalcemic for the duration of the experiment. The total number of bone metastases, the mean surface area of osteolytic lesions, and tumor burden within bone per animal were markedly decreased in EB1089-treated mice. Furthermore, longitudinal analysis revealed that mice treated with EB1089 displayed a marked increase in survival and developed fewer bone lesions and less hind limb paralysis over time as compared with untreated animals. These results suggest that EB1089 may be beneficial in the prevention of metastatic bone lesions associated with human breast cancer.

Management of corticosteroid-induced osteoporosis

OBJECTIVES

To educate scientists and health care providers about the effects of corticosteroids on bone, and advise clinicians of the appropriate treatments for patients receiving corticosteroids.

METHODS

This review summarizes the pathophysiology of corticosteroid-induced osteoporosis, describes the assessment methods used to evaluate this condition, examines the results of clinical trials of drugs, and explores a practical approach to the management of corticosteroid-induced osteoporosis based on data collected from published articles.

RESULTS

Despite our lack of understanding about the biological mechanisms leading to corticosteroid-induced bone loss, effective therapy has been developed. Bisphosphonate therapy is beneficial in both the prevention and treatment of corticosteroid-induced osteoporosis. The data for the bisphosphonates are more compelling than for any other agent. For patients who have been treated but continue to lose bone, hormone replacement therapy, calcitonin, fluoride, or anabolic hormones should be considered. Calcium should be used only as an adjunctive therapy in the treatment or prevention of corticosteroid-induced bone loss and should be administered in combination with other agents.

CONCLUSIONS

Bisphosphonates have shown significant treatment benefit and are the agents of choice for both the treatment and prevention of corticosteroid-induced osteoporosis.

Predicting subsequent bone density response to intermittent cyclical therapy with etidronate from initial density response in patients with osteoporosis

We investigated whether an increase in lumbar spine bone mineral density (LS BMD) at 6 months or at 12 months could predict the response to intermittent cyclical therapy (ICT) with etidronate, defined in one of two ways: (i) an increase in LS BMD at 24 months (improvement) or (ii) an increase in LS BMD > or = 0.028 g/cm2 (significant improvement). The latter is a precision term calculated from test-retest values for LS BMD in osteoporotic patients. Two hundred and forty-seven patients (32 men; 5 premenopausal and 210 postmenopausal women) were followed for 24 months by dual-energy X-ray absorptiometry (DXA) and were not taking estrogen, calcitonin or fluoride during treatment with ICT-etidronate. One hundred and fifty patients had a LS BMD measurement after 6 months of treatment with ICT-etidronate and 205 patients had one at 12 months. Baseline characteristics (mean;SD) were as follows: age, 66;11 years; years since menopause, 21;10; number of vertebral fractures at baseline, 0.87;1.26; LS BMD T-score, -2.8; 1.2. After 24 months of treatment with ICT-etidronate, 81% of the patients had an improvement, and 55% had a significant improvement at the LS. Only 6% significantly lost bone (loss of 0.028 g/cm2 or more). The mean percent change from baseline in LS BMD was 5.1% (95% confidence interval 4.2% to 6.0%). The results for men and postmenopausal women were similar to those for the entire group. Accuracy and sensitivity were marginally, but not significantly, higher when response was predicted using 12 month versus 6 month LS BMD measurements. The positive predictive values of improvement at 6 or 12 months were 89% and 90% respectively for improvement at 24 months, and 66% and 68% for significant improvement at 24 months. Identification of nonresponders was less successful and similar at 6 months and 12 months. Forty percent and 39% of the patients, who had no improvement at 6 or 12 months respectively, also had no improvement at 24 months, i.e., were true negatives, while 77% and 71% had no significant improvement at 24 months. The results may reflect slow response in a small subgroup of patients rather than nonresponse; however, no response at 1 year might identify patients whose rate of response is sufficiently slow that alternative therapy is justified. These data demonstrate a good response rate to ICT-etidronate and may help reduce the need for follow-up BMD measurements in those who show an early improvement.

Functional evidence for two types of parathyroid adenoma

OBJECTIVE

The carboxyterminal parathyroid hormone (C-PTH)/intact (I-) PTH ratio is influenced by serum calcium concentrations in man, increasing to a maximum value in hypercalcaemia and decreasing to a minimum value in hypocalcaemia. We decided to use this ratio to screen for parathyroid tumour with a normal sensitivity to calcium, symptomatic mainly through a mass effect.

DESIGN AND SUBJECTS

Nineteen patients with hypercalcaemia and elevated or inappropriate PTH, were studied in the basal state and during CaCl2 and Na2EDTA infusion and compared with 26 normal individuals. They all had one parathyroid adenoma removed surgically, and two remained hypercalcaemic.

RESULTS

In the basal state, the patients were hypercalcaemic (ionized calcium 1.44 +/- 0.12 vs. 1.23 +/- 0.03 mmol/l, P < 0.001) and had elevated PTH levels (I-PTH: 10.8 +/- 8.0 vs. 2.3 +/- 0.6 pmol/l, P < 0.001; C-PTH: 31.6 +/- 38.9 vs. 5.25 +/- 1.11 pmol/l, P < 0.001) when compared with normals. Their mean C-PTH/I-PTH ratio was similar to normals (2.7 +/- 1.3 vs. 2.4 +/- 0.6, NS) but, when individual values were considered, three patients had elevated values at 4.9, 5.3 and 5.8 (normal = 1.2-3.6). The regression line between basal C- and I-PTH revealed a significantly higher slope in these patients (P < 0.0001). The 16 patients with a normal basal C-PTH/I-PTH ratio had, as a group, an increased set point of I- or C-PTH stimulation by calcium and increased values of stimulated and non-suppressible I- and C-PTH, but these abnormalities were not all present in the smaller tumours (< or = 200 mg). Only three tumours in that group were larger than 1000 mg. Serum calcium concentration was related to the increased set point and non-suppressible fraction of I-PTH in these patients (r2 = 0.797). The three patients with a high basal C-PTH/I-PTH ratio had large tumours (2346, 4364 and 17,300 mg) and were more difficult to study, requiring a larger decrease in calcium concentration to achieve maximal stimulation. In the basal state, they were already expressing a non-suppressible level of I- or C-PTH and already had a maximal C-PTH/I-PTH ratio. Our data further suggest a normal set point of I- and C-PTH stimulation in the two patients who achieved sufficient hypocalcaemia and a normal set point of C-PTH/I-PTH ratio modulation in these three patients. Their hypercalcaemia was essentially related to the non-suppressible fraction of PTH. Furthermore, larger tumours were less active than smaller ones and produced less stimulated I-PTH/100 mg of tissue.

CONCLUSIONS

These data indicate two types of parathyroid tumours when calcium sensitivity is considered: (1) a majority of small tumours with abnormal sensitivity to calcium, symptomatic through an abnormal set point and an increased non-suppressible fraction and (2) a smaller number of larger tumours, with normal sensitivity to calcium and an increased non-suppressible fraction, of PTH.

Intermittent etidronate therapy to prevent corticosteroid-induced osteoporosis

BACKGROUND AND METHODS

Osteoporosis is a recognized complication of corticosteroid therapy. Whether it can be prevented is not known. We conducted a 12-month, randomized, placebo-controlled study of intermittent etidronate (400 mg per day for 14 days) followed by calcium (500 mg per day for 76 days), given for four cycles, in 141 men and women (age, 19 to 87 years) who had recently begun high-dose corticosteroid therapy. The primary outcome measure was the difference in the change in the bone density of the lumbar spine between the groups from base line to week 52. Secondary measures included changes in the bone density of the femoral neck, trochanter, and radius and the rate of new vertebral fractures.

RESULTS

The mean (+/-SE) bone density of the lumbar spine and trochanter in the etidronate group increased 0.61 +/- 0.54 and 1.46 +/- 0.67 percent, respectively, as compared with decreases of 3.23 +/- 0.60 and 2.74 +/- 0.66 percent, respectively, in the placebo group. The mean differences between the groups after one year were 3.72 +/- 0.88 percentage points for the lumbar spine (P = 0.02) and 4.14 +/- 0.94 percentage points for the trochanter (P = 0.02). The changes in the femoral neck and the radius were not significantly different between the groups. There was an 85 percent reduction in the proportion of postmenopausal woman with new vertebral fractures in the etidronate group as compared with the placebo group (1 of 31 patients vs. 7 of 32 patients, P = 0.05), and the etidronate-treated postmenopausal women also had significantly fewer vertebral fractures per patient (P = 0.04).

CONCLUSIONS

Intermittent etidronate therapy prevents the loss of vertebral and trochanteric bone in corticosteroid-treated patients.

Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 7. Fluoride therapy for osteoporosis

OBJECTIVE

To present the latest findings on the use of fluoride in the treatment of osteoporosis.

OPTIONS

Plain sodium fluoride (NaF), enteric-coated sodium fluoride (EC-NaF), sodium monofluorophosphate (Na2FPO4), slow-release sodium fluoride (SR-NaF); fluoride with a calcium supplement.

OUTCOMES

Fracture and loss of bone mineral density in osteoporosis; increased bone mass, prevention of fractures and improved quality of life associated with treatment.

EVIDENCE

Relevant clinical studies and reports were examined, with an emphasis on recent prospective, randomized, controlled trials. Clinical practices in European countries were also considered.

VALUES

Reducing fractures, increasing bone mineral density and minimizing side effects of treatment were given a high value.

BENEFITS, HARMS AND COSTS

NaF therapy stimulates bone formation and may be effective in preventing osteoporotic fractures. It may be an acceptable alternative treatment to estrogen or bisphosphonate therapy and useful in premenopausal and corticosteroid-induced osteoporosis and in some patients with mild osteogenesis imperfecta. Toxic effects are dependent on formulation and dosage. They include a range of gastrointestinal and musculoskeletal conditions. EC-NaF is associated with less toxicity than plain NaF; its gastrointestinal toxicity is negligible. Na2FPO4 has no gastrointestinal toxicity, but can give rise to skeletal toxicity. SR-NaF appears to have no side effects when given intermittently. Carcinogenicity has not been found in vivo with fluoride therapy, despite in vitro results.

RECOMMENDATIONS

New data indicate that fluoride therapy should be re-evaluated as a potentially effective treatment of osteoporosis with minimal side effects. More studies are needed of slow-release fluoride formulations, intermittent treatment schedules and calcium supplementation of fluoride. Studies should be undertaken to see if it is advantageous to initiate treatment with antiresorptive agents before or in combination with fluoride. Conclusive data have not been presented regarding the benefit of any specific type of calcium supplement. Further studies on the basic mechanism of action of fluoride on the skeleton are necessary to evaluate fluoride's potential to stimulate bone formation therapeutically.

Urokinase overproduction results in increased skeletal metastasis by prostate cancer cells in vivo

We previously reported that urokinase (uPA) is produced by the human prostate cancer cell line, PC-3, and could function as a growth factor for cells of the osteoblast phenotype. To examine the role of uPA in metastasis to the skeleton and to extraskeletal sites, we have developed a homologous model of uPA overexpression in a rat prostate cancer cell line. Full length cDNA encoding rat (r) uPA was isolated and subcloned as a 1.4-kilobase XbaI-BspHI fragment in the sense and antisense orientation into the Moloney murine leukemia retroviral vector pYN. The control (pYN) and experimental (pYN-ruPA, pYN-ruPA-AS) plasmids were transfected into Dunning R 3227, Mat LyLu rat prostate carcinoma cells. Experimental clones expressing at least 5-fold higher (pYN-ruPA) or 3-fold lower (pYN-ruPA-AS) than controls were selected, and control and experimental cells were inoculated into the left ventricles of inbred male Copenhagen rats. Animals were sacrificed at timed intervals to examine the evolution of metastatic lesions. Control animals developed metastases to the lumbar vertebrae resulting in spinal cord compression and hind limb paralysis at 20-21 days postinoculation. Animals inoculated with cells overexpressing uPA developed hind limb paralysis significantly earlier (by day 14-15 postinoculation). Additionally, more widespread skeletal (ribs, scapula, and femora) metastases were seen. Serum from experimental animals showed a progressive elevation in alkaline phosphatase levels, and histological examination of lumbar metastases revealed markedly increased osteoblastic activity over that observed in control animals. In contrast to this, animals inoculated with cells underexpressing uPA developed hind limb paralysis significantly later (days 25-29 postinoculation) and displayed decreased tumor metastasis. These studies support a role for the catalytic domain of uPA in enhancing both skeletal and nonskeletal prostate cancer invasiveness and are consistent with a role for the growth factor domain of uPA in mediating an osteoblastic skeletal response.

Blood glucose measurements during symptomatic episodes in patients with suspected postprandial hypoglycemia

Postprandial (reactive) hypoglycemia is a controversial disorder because its symptoms are not specific, the presence of symptoms often correlates weakly with blood glucose concentrations measured after oral glucose administration, and glucose levels have rarely been measured when symptoms have developed spontaneously. In this study, we measured blood glucose in 28 patients with suspected postprandial hypoglycemia while they were experiencing their typical symptoms, in capillary blood collected on filter paper. Five patients (18 percent) had symptoms of "hypoglycemia" that were associated with blood glucose levels of 2.8 mmol per liter (50 mg per deciliter) or less, and eight other patients (29 percent) had symptoms associated with glucose levels of 2.9 to 3.3 mmol per liter on at least one occasion. Six (5 percent) of 132 reported symptomatic episodes that were associated with blood glucose levels of 2.8 mmol per liter or less, and 16 (12 percent) with levels of 2.9 to 3.3 mmol per liter. In 140 measurements made in 17 normal subjects, blood glucose levels were never found to be less than 2.8 mmol per liter, and levels of 2.9 to 3.3 mmol per liter were found only twice. No specific symptom was associated with low glucose levels in the patients with suspected hypoglycemia. The relief of symptoms by ingesting food was more often associated with low than with normal blood glucose levels: 86 percent of episodes in which blood glucose values were less than or equal to 3.3 mmol per liter were relieved by eating, as compared with 53 percent of episodes in which values were more than 3.3 mmol per liter (P less than 0.007). No correlation was found between plasma glucose levels measured after oral glucose administration and blood glucose levels measured during symptoms. We conclude that postprandial hypoglycemia is infrequent, even in a referral population, and that recording blood glucose measurements during spontaneously occurring symptomatic episodes is necessary to establish the diagnosis since symptoms are not specific and oral glucose-tolerance testing is not helpful.

Suppression of T4 secretion in a metastatic follicular carcinoma

Despite total thyroidectomy, a patient with metastatic follicular carcinoma of the thyroid remained biologically euthyroid three months after stopping thyroxine (T4) therapy. Thyroid hormone production was investigated by means of a modified tri-iodothyronine (T3) suppression test, in which serum T4 was used as a suppression marker. After three weeks of oral T3 (Cytomel) therapy (50 micrograms/day), the serum T4 decreased from normal (108 nmol/L) to undetectable values. However, even though suppressive therapy was effective in preventing TSH dependent hormone secretion by the tumor, it did not prevent tumor growth and the eventual death of the patient.

Estrogen replacement decreases the set point of parathyroid hormone stimulation by calcium in normal postmenopausal women

Estrogens decrease serum total and ionized calcium (Ca) concentrations in postmenopausal women with or without primary hyperparathyroidism, but cause little or no increase in serum PTH suggesting a modification of the relationship between the two. In order to define this relationship, we studied the effect of conjugated estrogens on total and ionized serum Ca and serum PTH concentrations in five normal postmenopausal women, before and after 3, 11, and 23 weeks of therapy. Dynamic tests of parathyroid gland function, based on 2-h iv infusions of CaCl2 and NaEDTA, were performed at each time. Total and ionized serum Ca and carboxylterminal PTH were measured every 15 min during the infusions, and parathyroid function was evaluated by a nonlinear 4-parameter mathematical model. Estrogen therapy caused decreases in serum total [2.36 +/- 0.04 (SD) mmol/L, baseline vs. 2.19 +/- 0.05 mmol/L, 23 weeks, P less than 0.005) and ionized calcium (1.27 +/- 0.01 mmol/L, baseline vs. 1.21 +/- 0.02 mmol/L, 23 weeks, P less than 0.005]; the decreases were evident at 3 weeks and persisted for the duration of the study. Serum PTH concentrations did not change (8.94 +/- 1.84 pmol/L, baseline vs. 8.98 +/- 2.38 pmol/L, 23 weeks). Three parameters of the parathyroid function, the maximal response to hypocalcemic stimulation, the nonsuppressible fraction of circulating PTH, and the slope of PTH on calcium at the set point were not affected by estrogen treatment. The fourth parameter, the set point of PTH stimulation by serum total calcium (2.16 +/- 0.04 mmol/L, baseline vs. 1.97 +/- 0.07 mmol/L, 23 weeks, P less than 0.0166) or by serum ionized Ca (1.19 +/- 0.04 mmol/L, baseline vs. 1.12 +/- 0.03 mmol/L, 23 weeks, P less than 0.01), was decreased by estrogen treatment. This was evident at the earliest time point studied and persisted thereafter. The decrease in ionized Ca set point only explained 40% of the decrease in total calcium set point, the remaining 60% being related to hemodilution of plasma protein during therapy. We conclude that estrogen replacement can influence parathyroid function in postmenopausal women by resetting the set point of PTH stimulation by ionized Ca. This in turn could contribute to the estrogen-induced changes in their Ca balance.

Premenopausal bone mineral content relates to height, weight and calcium intake during early adulthood

The influence of dietary and anthropometric factors on bone mineral content was studied in 183 healthy premenopausal French-Canadian women aged between 40 and 50 years and living in the same area. Dietary evaluation of their calcium (Ca), caffeine and alcohol intake since the age of 20 was performed in all cases. Age, height, weight, exercise level, cigarette smoking, parity and estrogen were also recorded. Bone mineral content of the L2 to L4 vertebrae (BMCL, n = 183) and forearm (BMCF, n = 137) were measured respectively by dual and single photon absorptiometry. While stepwise regression analysis showed a significant relationship between total BMCL and height, weight and Ca intake, this only occurred with weight and Ca intake when BMCL was corrected for height of L2-L4 (BMCL/cm) or for bone scan area of L2-L4 (BMCL/cm2). BMCF expressed per unit of length correlated to height only. When subjects were divided into three groups according to their Ca intake (less than 500 mg/day, between 500 and 1000 mg/day and greater than 1000 mg/day), the mean BMC adjusted for significant covariables (height and weight) was statistically different for the low and high intake groups at both sites (BMCF, F = 3.9, P = 0.02; BMCL, F = 4.2, P less than 0.02; BMCL/cm, F = 6.1, P less than 0.005; BMCL/cm2, F = 4.4, P less than 0.02). These findings indicate that, of the variables considered, Ca intake, height and weight were the only significant factors related to bone mass in our homogeneous population. It is therefore suggested that Ca intake in early adulthood influences the axial and appendicular bone mass in premenopausal women.

Iliac bone histomorphometry in adults and children with osteogenesis imperfecta

Histomorphometric analysis was performed on transiliac undecalcified bone biopsies taken from eight adults and four children with osteogenesis imperfecta. Double tetracycline labelling done before the biopsy allowed measurement of the calcification rate in 11 patients. The adults, as well as the children, had thin iliac cortices and considerably decreased trabecular bone volume. In addition, the calcification rate was significantly reduced. Since the thickness index of osteoid seams was low or normal in all subjects, it indicated a reduced bone formation at the cellular level. In the adults, there was no significant increase in the parameters of bone resorption or in the bone formation rates at the basic multicellular unit and the tissue levels. Thus the histomorphometric profile of iliac bone in osteogenesis imperfecta is characterised by cortical and trabecular osteoporosis with decreased activity of the individual osteoblasts. These findings would suggest the use of therapeutic agents stimulating bone formation rather than agents inhibiting bone resorption in osteogenesis imperfecta.

The pituitary-thyroid axis after hemithyroidectomy in euthyroid man

The pathogenesis of euthyroid goiter is assumed to be TSH dependent, but most studies have not demonstrated elevation of serum TSH. To elucidate the early events involved in thyroid growth, we studied thyroid function in eight euthyroid patients subjected to hemithyroidectomy for solitary cold nodules preoperatively and 2, 15, 60, and 90 days and 36 months, postoperatively. Although within the euthyroid range, serum T4 decreased at 30 days and thereafter up to 90 days (P less than 0.01). Basal serum TSH rose significantly by the 30th day and remained elevated for the entire 90-day period (P less than 0.001). The serum TSH response to TRH was exaggerated from days 15-90 (P less than 0.001). Thirty-six months postoperatively, all parameters of thyroid function were similar to control values, with the exception of one patient who showed an exaggerated response of serum TSH to TRH. We conclude that 1) the dynamic phase of recuperation post hemithyroidectomy is TSH dependent, 2) the serum TSH increase occurs within normal limits and is a temporary event, and 3) 3 yr postoperatively, a new steady state is achieved with normal parameters of thyroid function. Thus, we believe that TSH plays a dominant role in the genesis of goiter.