Risk factors for spinal osteoporosis in men

Androgens regulate bone resorption activity of isolated osteoclasts in vitro

For many years it has been recognized that sex steroids have profound effects on bone metabolism. The current perception is that estrogen decreases bone resorption and androgen increases bone deposition. To investigate the potential for androgens to directly modulate bone resorption, we have examined avian osteoclast and human and mouse osteoclast-like cells for androgen responsiveness. There was a dose-dependent decrease in resorption activity in response to alpha-dihydrotestosterone (alpha-DHT), beta-DHT, testosterone, or the synthetic androgen RU1881. This decrease was blocked by cotreatment with the specific androgen antagonist hydroxyflutamide. Further examination of avian osteoclasts revealed that the cells exhibited specific and saturable nuclear binding of tritiated RU1881 and that alpha-DHT stimulated the activity of the androgen response element as measured by using a chloramphenicol acetyltransferase reporter plasmid. In addition, avian osteoclasts responded to androgen treatment with elevated production and secretion of transforming growth factor beta, a well documented response to androgen exposure in other cell systems. Treatment with either alpha-DHT or beta-DHT for 24 hours resulted in a significant dose-dependent decrease in secretion of cathepsin B and tartrate-resistant acid phosphatase. This response to beta-DHT, a stereoisomer of alpha-DHT that is inactive in other androgen receptor-dependent systems, supports the hypothesis that the osteoclast androgen receptor has unusual ligand-binding properties. Taken together, these results confirm the presence of functional androgen receptors in these cells and support the conclusion that osteoclasts are able to respond directly to androgens in vitro and thus are potential androgen target cells in vivo.

Osteoporosis in men. New insights into aetiology, pathogenesis, prevention and management

Osteoporosis is increasingly recognised in men. Low bone mass, risk factors for falling and factors causing fractures in women are likely to cause fractures in men. Bone mass is largely genetically determined, but environmental factors also contribute. Greater muscle strength and physical activity are associated with higher bone mass, while radial bone loss is greater in cigarette smokers or those with a moderate alcohol intake. Sex hormones have important effects on bone physiology. In men, there is no abrupt cessation of testicular function or 'andropause' comparable with the menopause in women; however, both total and free testosterone levels decline with age. A common secondary cause of osteoporosis in men is hypogonadism. There is increasing evidence that estrogens are important in skeletal maintenance in men as well as women. Peripheral aromatisation of androgens to estrogens occurs and osteoblast-like cells can aromatise androgens into estrogens. Human models exist for the effects of estrogens on the male skeleton. In men aged > 65 years, there is a positive association between bone mineral density (BMD) and greater serum estradiol levels at all skeletal sites and a negative association between BMD and testosterone at some sites. It is crucial to exclude pathological causes of osteoporosis, because 30 to 60% of men with vertebral fractures have another illness contributing to bone disease. Glucocorticoid excess (predominantly exogenous) is common. Gastrointestinal disease predisposes patients to bone disease as a result of intestinal malabsorption of calcium and colecalciferol (vitamin D). Hypercalciuria and nephrolithiasis, anticonvulsant drug use, thyrotoxicosis, immobilisation, liver and renal disease, multiple myeloma and systemic mastocytosis have all been associated with osteoporosis in men. It is possible that low-dose estrogen therapy or specific estrogen receptor-modulating drugs might increase BMD in men as well as in women. In the future, parathyroid hormone peptides may be an effective treatment for osteoporosis, particularly in patients in whom other treatments, such as bisphosphonates, have failed. Men with idiopathic osteoporosis have low circulating insulin-like growth factor-1 (IGF-1; somatomedin-1) concentrations, and IGF-1 administration to these men increases bone formation markers more than resorption markers. Studies of changes in BMD with IGF-1 treatment in osteoporotic men and women are underway. Osteoporosis in men will become an increasing worldwide public health problem over the next 20 years, so it is vital that safe and effective therapies for this disabling condition become available. Effective public health measures also need to be established and targeted to men at risk of developing the disease.

Bone mass in middle-aged osteoporotic men and their relatives: familial effect

Severe idiopathic osteoporosis in middle-aged men is still poorly understood. The aim of this study was to assess the contribution of genetic factors in these patients. We studied 38 men (mean age +/- SD, 50 +/- 11 years) presenting with vertebral or peripheral bone fractures due to primary osteoporosis and 73 of their relatives divided into four subgroups: 19 brothers, 22 sisters, 13 sons, and 19 daughters. The control group comprised 199 age-matched subjects. In all subjects, we measured bone mineral density (BMD) and calculated the Z score at the lumbar spine (LS) and femoral neck (FN) based on the fitted BMD value in the controls. LS BMD values were lower in each of the four subgroups compared with the age-matched controls. The mean Z score for the overall group of 73 relatives was decreased compared with the age-matched controls (-1. 28 +/- 1.48 at the LS and -1.03 +/- 1.19 at the FN) and was not influenced by gender or by whether the relatives were siblings or children. An LS Z score < -1) was found in 54.8% of the relatives of osteoporotic patients versus 17.4% of the control subjects (risk ratio, 3.2). Alcohol and tobacco abuse are well-known risk factors for osteoporosis in men. Among the 38 osteoporotic patients, 7 were heavy smokers (>20 pack-years), 8 were both heavy smokers and drinkers (>80 g/day for at least 10 years and gammaGT > 40 UI/l), and 23 had neither of these risk factors. BMD, Z score, and anthropometric data were the same in patients with and without risk factors. Decreases in LS and FN Z scores were similar in relatives of patients with and without risk factors. In conclusion, low BMD is observed in relatives of osteoporotic men with or without risk factors for osteoporosis, indicating that familial factors contribute to primary osteoporosis in middle-aged men.

Effect of recent alcohol intake on parathyroid hormone and mineral metabolism in men

The mechanisms by which alcohol intake, particularly moderate alcohol intake, effects bone metabolism are poorly defined. We have examined the relationship between mineral metabolism and recent self-reported alcohol intake (SRAI) across a wide range of such intakes in a series of 104 men aged 32 to 78 years of age in an outpatient setting. A morning nonfasting urine, serum specimen and recent SRAI were obtained from each subject. SRAI was reported as between 0 and 45 oz/week. SRAI correlated positively with liver function tests, including serum bilirubin (r = 0.30, p = 0.002), alkaline phosphatase (r = 0.30, p = 0.004), and aspartate aminotransferase (SGOT) (r = 0.29, p = 0.006). SRAI correlated with serum calcium corrected for albumin (r = -0.39, p < 0.001), estradiol (r = 0.43, p < 0.001), and immunoreactive parathyroid hormone (iPTH) (r = -0.51, p < 0.001), as well as urinary calcium (per 100 mg of creatinine) (r = 0.55, p < 0.001). We have arbitrarily divided the participants into two groups on the basis of their reported alcohol intake. Individuals in the first group had intakes ranging from none to moderate intake (drank 8.4 oz or less of ethanol per week, equivalent to an average of two drinks daily or less). Those in the second group had moderate or heavier intake, with >8.4 oz of ethanol intake/week. Mean serum iPTH was significantly greater in those in the first group (none to moderate), compared with the second group (moderate or heavier) (56.0 +/- 3.4 and 39.9 +/- 2.0 pM/liter, respectively). Calcium corrected for serum albumin was significantly greater in individuals in the first, compared with the second, group (9.23 +/- 0.05 vs. 8.88 +/- 0.07 mg/dl, respectively). In addition, urinary calcium (corrected per 100 mg of creatinine) was significantly lower in the former, compared with the latter (3.1 +/- 0.4 vs. 8.4 +/- 1.1 mg/100 mg of creatinine, respectively). Similarly, urinary excretion of collagen crosslinks (corrected per 100 mg of creatinine) was significantly less in men in the second group, compared with the first group (316 +/- 38 vs. 530 +/- 78 nM/100 mg of creatinine, respectively). Not surprisingly, a series of correlations between iPTH and age, 250-hydroxyvitamin D, and testosterone were significant in individuals with none to moderate SRAI, but not moderate or heavier SRAI. Significant independent predictors of serum iPTH in the entire group of men were age (beta = 0.215, p = 0.025), SRAI (beta = -0.281, p = 0.003), 250-hydroxyvitamin D (beta = -0.309, p = 0.002), and testosterone (beta = -184, p = 0.048). We have concluded that, in free-living men, alcohol intake >8.4 oz/week was associated with decreased serum iPTH concentrations.

Testosterone replacement therapy

The benefits conferred by testosterone replacement therapy are substantial, both in the short term for the eradication of symptoms of androgen deficiency, and in the long term for the prevention of osteoporosis. As with any long-term treatment there are risks that must be considered, but overall the benefits achieved far outweigh potential risk. Ideally, androgen replacement therapy should provide physiological serum testosterone levels, as well as DHT and estradiol levels, and correct the clinical symptoms of androgen deficiency in hypogonadal men. This goal is difficult to achieve because the dose dependency of androgen-dependent physiological processes is not known. Androgen preparations that are currently available do not fulfill all criteria for an ideal androgen replacement therapy. Parenteral testosterone esters are effective, safe, practical, and inexpensive. The transdermal testosterone systems provide an alternative to testosterone esters in selected patients but these preparations are expensive. Ongoing studies are showing the benefits of testosterone replacement therapy in aging men, but there is concern about side effects on cardiovascular system and prostate. Thus, clinical decision regarding testosterone therapy in older men should be better defined.

[Aetiologic features of osteoporosis in male patients aged less than 50 years: study of 28 cases with a comparative series of 30 patients over the age of 50]

PURPOSE

To study the aetiologic factors of osteoporosis (OP) in young male patients, we conducted a retrospective study of male osteoporosis observed in our department during the past 20 years.

METHODS

Patients included in the study were over 16 years of age and had a fracture or a decreased bone mineral density with a T score (assessed at the spine or at the spine and femoral neck) below -2.5 SD. The age and circumstances of diagnosis, serum and 24-hour urinary calcium and phosphorus investigations, hormonal measurements (including parathyroid hormone, thyroid hormones, cortisol and testosterone), bone biopsy and the final diagnosis were analyzed.

RESULTS

One hundred and nineteen patients responded to the defined diagnosis criteria. Twenty-eight were less than 50 years of age (group I or young male osteoporosis). Data were compared with those of 30 patients more than 50 years of age (group II). In group I, an aetiology was found in 17 out of 28 cases (60.7%) (secondary osteoporosis: OP II), while 11 out of 28 patients (39.3%) had primary or idiopathic osteoporosis (OP I). In group II, the frequency of OP I was 19 out of 30 cases (63.3%) and 11 out of 30 patients (36.6%) had OP II. However, the frequency of OP II did not differ significantly between the two groups (P = 0.11). The aetiology in group I was either hypogonadism (6 out of 17), alcoholism (2 out of 17), mastocytosis (2 out of 17), primary biliary cirrhosis (1 out of 17), osteogenesis imperfecta (1 out of 17), idiopathic hypercalciuria (1 out of 17), corticosteroid treatment (1 out of 17) or ankylosing spondylitis (1 out of 17). Multiple causes were found in 5 out of 17 cases. The causes of osteoporosis in group II included hypogonadism (2 out of 11), alcoholism (2 out of 11), idiopathic hypercalciuria (2 out of 11), glucocorticosteroid therapy (6 out of 11) and rheumatoid arthritis (1 out of 11).

CONCLUSIONS

Our results were compared to those of the various series reported in the literature which, though focusing on male osteoporosis, often included elderly patients. To determine whether osteoporosis in young male is more often OP II, further prospective studies are required.

Risk factors for osteoporotic fracture

Fracture prevention requires the identification of individuals at risk prior to fracture. Bone density, a history of previous fractures, biochemical markers, and the frequency and types of falls are important risk factors for fractures. There are also many other risk factors for bone loss, falls, and fractures. When considered alone or in combination, risk factors can identify a wide range of fracture risk among individuals. Persons with multiple risk factors are at greater risk than are those with either a single risk factor or none. It is not possible to modify some risk factors such as age and gender. Although it is possible in theory to modify other risk factors such as calcium or vitamin D deficiency, the resulting benefits are often small. In contrast, the determination of BMD provides a precise, noninvasive measure of fracture risk, and effective treatments are available to prevent bone loss and increase BMD. Current BMD represents the cumulative, combined influence of all past and current risk factors for bone loss, and prospective changes in biochemical markers and BMD can be used to monitor treatment efficacy. Persons with low BMD and those with multiple risk factors may benefit the most from treatments to preserve or increase BMD. Bone density should always be measured directly, because it is not possible to predict this parameter and fracture risk from other risk factors for bone loss.

Secondary osteoporosis. Diagnostic considerations

This article discusses the important secondary causes of osteoporosis that contribute significantly to bone loss and that seem to increase fracture risk, including hypogonadism, endogenous and exogenous thyroxine excess, hyperparathyroidism, malignancies, gastrointestinal diseases, medications, vices, and connective tissue diseases.

Association between corticosteroid use and vertebral fractures in older men with chronic obstructive pulmonary disease

Osteoporosis is a major complication of long-term corticosteroid administration, but the magnitude of the effect in patients with chronic obstructive pulmonary disease (COPD) is not well defined. In a cross-sectional study, we evaluated the association between steroid use and vertebral fractures in 312 men, 50 yr of age or older, with COPD. Subjects were evaluated according to their corticosteroid use: Never Steroid Users (NSU) (n = 117), Inhaled Steroid Users (ISU) (n = 70), and Systemic Steroid Users (SSU) (n = 125). The prevalence of one or more vertebral fractures was 48.7% in the NSU group, 57.1% in the ISU group, and 63.3% in the SSU group. Compared with NSU, SSU were two times as likely to have one or more vertebral fractures: age-adjusted odds ratio (OR) = 1.80; 95% CI, 1.08 to 3.07. This relationship was primarily due to a strong association between continuous systemic steroid use and vertebral fractures: age-adjusted OR = 2.36; 95% CI, 1.26 to 4.38. In addition, fractures in SSU were more likely to be multiple and more severe. A weaker relationship existed between inhaled steroid use and vertebral fractures: age-adjusted OR = 1.35; 95% CI, 0.77 to 2.56 compared with NSU. These data indicate that vertebral fractures are common in older men with COPD; the likelihood of these fractures is greatest in those men using continuous systemic steroids.

Bone marker and bone density responses to dopamine agonist therapy in hyperprolactinemic males

The aim of this prospective study was to evaluate the bone mineral density (BMD) at lumbar spine and femoral neck levels and biochemical parameters of bone turnover in 20 consecutive hyperprolactinemic males before and after an 18-month treatment with different dopamine agonists. Six patients received bromocriptine at a dose of 2.5-10 mg/day; 7 patients received quinagolide at a dose of 0.075-0.3 mg/day; 7 patients received cabergoline at a dose of 0.5-1.5 mg/week. BMD, serum PRL, testosterone, dihydrotestosterone, and osteocalcin (OC), and urinary cross-linked N-telopeptides of type I collagen (Ntx) levels were measured before and every 6 months during treatment. At study entry, BMD values were lower in patients than controls at both lumbar spine (0.82 +/- 0.03 vs. 1.18 +/- 0.01 g/cm2; P < 0.001) and femoral neck (0.85 +/- 0.02 vs. 0.92 +/- 0.02 g/cm2; P < 0.05) levels. Osteopenia or osteoporosis was diagnosed in 16 patients at the lumbar spine and in 6 of them at the femoral neck level. A significant inverse correlation was found between lumbar spine and femoral neck BMD values and both PRL levels and disease duration (P < 0.01). In the 20 patients, serum OC levels were significantly lower (2.1 +/- 0.1 vs. 9.3 +/- 2.4 microg/L; P < 0.01), whereas Ntx levels were significantly higher (157.8 +/- 1.1 vs. 96.4 +/- 7.4 nmol bone collagen equivalent/mmol creatinine; P < 0.001) than control values. A significant inverse correlation was found between serum PRL and OC (P < 0.01), but not Ntx, levels. After 18 months of treatment, serum PRL levels were suppressed, and gonadal function was restored in all 20 patients, as shown by the normalization of serum T (from 2.2 +/- 0.2 to 5.0 +/- 0.2 microg/L) and dihydrotestosterone (0.3 +/- 0.02 vs. 0.5 +/- 0.01 nmol/L) levels, without any significant difference among groups. A progressive significant increase in serum OC levels together with a significant decrease in Ntx levels were observed after 6, 12, and 18 months of treatment in the 3 groups of patients. A slight, although significant, increase in BMD values was recorded in all patients after 18 months of bromocriptine, quinagolide, and cabergoline treatment, serum OC levels were normalized after treatment, whereas neither urinary Ntx levels nor BMD values were normalized by 18 months of treatment with dopaminergic agents. In conclusion, treatment with bromocriptine, quinagolide, and cabergoline for 18 months, although successfull in suppressing serum PRL levels and restoring gonadal function, was unable to restore lumbar spine and femoral neck BMD and normalize Ntx levels. However, BMD was slightly increased during treatment, suggesting that additional bone loss was prevented after treatment of hyperprolactinemia.

Fracture risk among patients with urolithiasis: a population-based cohort study

In a population-based retrospective cohort study, 624 Rochester, Minnesota residents with an initial symptomatic episode of urolithiasis in 1950 to 1974 were followed for 11,909 person-years for subsequent age-related fractures. During this period of observation, the number of patients with a first vertebral fracture was over four times the number expected on the basis of vertebral fracture incidence rates in the general population of Rochester [standardized morbidity ratio (SMR), 4.3; 95% confidence interval, 3.4 to 5.3]. The risk of vertebral fracture was elevated among men as well as women, and was associated with increasing age and with the use of corticosteroids for more than six months. However, vertebral fracture risk was increased nearly fourfold (SMR 3.9; 95% confidence interval, 3.0 to 4.9) among the urolithiasis patients without such exposure, which suggests that corticosteroids do not completely account for the association with vertebral fractures. There was no increase in the risk of hip, pelvis, proximal humerus or distal forearm fractures in this cohort of patients, and their survival was not impaired. Additional studies are needed to define the pathophysiology of vertebral fractures among patients with urolithiasis.

Epidemiology of spinal osteoporosis

Approximately 30% of postmenopausal white women in the United States have osteoporosis, and 16% have osteoporosis of the lumbar spine in particular. Bone density of the spine is positively associated with greater height and weight, older age at menopause, a history of arthritis, more physical activity, moderate use of alcoholic beverages, diuretic treatment, and current estrogen replacement therapy, whereas later age at menarche and a maternal history of fracture are associated with lower levels of density. Low bone density leads to an increased risk of osteoporotic fractures. Fracture risk also increase with age. Vertebral fractures affect approximately 25% of postmenopausal women, although the exact figure depends on the definition used. Recent data show that vertebral fracture rates are as great in men as in women but, because women live longer, the lifetime risk of a vertebral fracture from age 50 onward is 16% in white women and only 5% in white men. Fracture rates are less in most nonwhite populations, but vertebral fractures are as common in Asian women as in those of European heritage. Other risk factors for vertebral fractures are less clear but include hypogonadism and secondary osteoporosis; obesity is protective of fractures as it is of bone loss. Compared with hip fractures, vertebral fractures are less disabling and less expensive, costing approximately $746 million in the United States in 1995. However, they have a substantial negative impact on the patient's function and quality of life. The adverse effects of osteoporotic fractures are likely to increase in the future with the growing number of elderly people.

Immunologic aspects of osteoporosis

Osteoporosis is a major cause of morbidity in older people. There are a large number of risk factors for the development of osteoporosis. However, these risk factors eventually must mediate their effects through modulation of bone remodeling. A variety of compounds including hormones and nutrients modulate bone remodeling. In addition to these well-characterized substances, the immune system plays a role in bone remodeling through pro-inflammatory cytokines. Specifically, interleukin-1 (IL-1), IL-11, interferon-g are known to influence osteoclasts and osteoblasts. Recently, the cytokine IL-6 has joined ranks with these cytokines as a bone reactive agent. IL-6 has been shown to increase with age and menopause. Additionally, murine models suggest that IL-6 plays a central role in bone resorption. Finally, in vitro studies demonstrate that IL-6 induces osteoclast activity. In this review, we will discuss the pathogenesis of osteoporosis in the context of aging and IL-6.

The localization of androgen receptors in human bone

Androgens have important effects on the human skeleton, and deficiency has been associated with bone loss in both males and females. The skeletal actions of androgens may be mediated directly via the androgen receptor (AR) or indirectly via the estrogen receptor after aromatization to estrogens. The presence of androgen receptors has been demonstrated in bone cells and chondrocytes in vitro, but their presence in human bone in situ has not been reported. In order to provide further evidence for a direct action of androgens on bone via androgen receptors, we have used specific monoclonal antibodies to investigate the expression of human AR in normal developing and osteophytic bone of both sexes. In the growth plates from the developing bone, androgen receptors were predominantly expressed in hypertrophic chondrocytes and in osteoblasts at sites of bone formation. They were also observed in osteocytes in the bone, and in mononuclear cells and endothelial cells of blood vessels within the bone marrow. In the osteophytes, androgen receptors were widely distributed at sites of endochondral ossification in proliferating, mature, and hypertrophic chondrocytes and at sites of bone remodeling in osteoblasts. They were also expressed in osteocytes and mononuclear cells within the bone marrow. The pattern and number of cells expressing the receptor was similar in both sexes. Our results show for the first time the presence and distribution of androgen receptors in normal developing human and osteophytic bone in situ and further provide evidence for a direct action of androgens on bone and cartilage cells.

The effects of smoking on bone mass and the rates of bone loss among elderly Japanese-American men

Bone density and bone loss rates were examined among Japanese-American men categorized as current cigarette smokers, past smokers, and nonsmokers. The design included a retrospective study of smoking and bone density and a prospective study of current smoking and bone loss rates. The mean length of follow-up was 5 years; the setting was the island of Oahu. The subjects included 1303 men in the Hawaii Osteoporosis Study, 51-82 years old at their initial examination. Twenty percent were current smokers, 45% past smokers, and 35% had never smoked. Their bone density was measured at the distal and proximal radius and calcaneus using single photon absorptiometry. Compared with never smokers, current and past smokers had significantly lower bone density, especially in the predominantly cancellous calcaneus (4.8 and 4.3% lower, respectively) and partially trabecular distal radius (1.8 and 3.3% lower, respectively). The magnitude of the smoking effect was linked strongly to the duration of smoking and also to the number of cigarettes smoked. Bone loss rates subsequent to the initial measurement were greater in the current smokers than the never smokers (20.5, 27.2, and 9.7% greater at the calcaneus, distal, and proximal radius, respectively) but the differences did not achieve significance. Smokers of more than one pack per day had 32.0, 77.6, and 30.7% greater loss rates than never smokers in these same sites; the difference achieved significance at the distal radius. The results from the distal radius suggest that these smokers may increase their fracture risk 10-30% per decade of smoking. The adverse effects of smoking appeared to be greater in cancellous than cortical bone.

Long-term effect of testosterone therapy on bone mineral density in hypogonadal men

In both men and women, a decrease in bone mineral density (BMD) is a major symptom of hypogonadism. Although the effects of estrogens on osteoporosis in women are well documented, comparatively little is known about the effects of long term testosterone substitution on BMD in hypogonadal men. Therefore, we studied BMD in 72 hypogonadal patients (37 men with primary and 35 men with secondary hypogonadism) under testosterone substitution therapy that continued for up to 16 yr. Thirty-two of these men were also seen before initiation of therapy. At annual intervals, trabecular BMD of the lumbar spine was measured by quantitative computed tomography, a true volumetric and reproducible method for long term serial BMD measurements. Serum levels of testosterone increased to the normal range in all androgen-treated hypogonadal men. The most significant increase in BMD was seen during the first year of testosterone treatment in previously untreated patients, when BMD increased from 95.2 +/- 5.9 to 120.0 +/- 6.1 mg/cm3 hydroxyapatite (mean +/- SE). Long term testosterone treatment maintained BMD in the age-dependent reference range in all 72 hypogonadal men, independent of the type of hypogonadism. Transdermal testosterone patches applied to the scrotum were as effective in normalizing BMD as im testosterone enanthate injections. In summary, testosterone therapy increases BMD in hypogonadal men regardless of age. The greatest increase is seen during the first year of treatment in previously untreated patients with low initial BMD. In hypogonadal men, BMD can be normalized and maintained in the normal range by continuous, long term testosterone substitution.

How do you know who needs prevention or treatment?

Osteoporosis is preventable with the various therapeutic options available today. It is therefore important to reach the patient who needs to be treated. If based only on clinical risk factors there is much room for therapeutic misassignation in both directions: too many and too few treatments. Generally speaking, only bone mass measurement can yield the correct risk for future fracture, and clinical factors taken alone might be misleading. Clinical factors can be used to modulate the therapeutic intervention based on assessment of bone mass. In very elderly people with several risk factors (poor vision, poor balance and awkward gait, use of psychotropic drugs, etc), bone mass measurements probably become less crucial in therapeutic decision, because factors other than bone mineral have also to be actively assessed. All in all, the use of cut offs of bone mineral density balanced with the clinical decision based on an individual examination, will allow assessment of the therapeutic level in a particular patient. A therapeutic intervention will never be an all or nothing phenomenon based on computerized data.

Osteoporosis in men

Hip fractures in men account for one third of all hip fractures and have a higher mortality than in women. The public health burden will increase as the increase in the numbers of elderly men in the community increases. In addition, the age-specific incidence of hip fractures may be increasing in some, but not all, countries. Vertebral fractures may be a public health problem as recent studies suggest that the prevalence in the community is 20-30%, similar to that reported in women. Forearm fractures should probably not be regarded as a public health problem. Peak bone mass is higher in men than women because men have bigger bones. Peak bone mineral density is the same. The amount of trabecular bone lost at the spine and iliac crest during ageing is similar in men and women. Cortical bone loss is less in men because endocortical resorption is less and periosteal formation is greater. Bone loss accelerates in elderly men because endocortical resorption and increasing cortical porosity increase the surface available for resorption. Bone fragility is less in men than women because: (a) the cross-sectional surface of the bone is larger; (b) trabecular bone loss is less as a percentage of the higher peak bone mass; (c) trabecular bone loss occurs by thinning rather than perforation; and (d) periosteal appositional growth compensates for endocortical resorption by maintaining the bending strength of bone. Reduced BMD in men with fractures may be due to reduced peak bone size and mass, and bone loss. Bone loss occurs by reduced bone formation. Whether men with fractures have increased bone fragility due to reduced periosteal appositional growth during ageing is unknown. The age-related decline in testosterone, adrenal androgens, growth hormone, and insulin-like growth factor 1 may contribute to reduced bone formation and bone loss. Men with vertebral fractures often have hypogonadism or illnesses with few clinical features that should be considered with a high index of suspicion (alcoholism, myeloma, malabsorption, primary hyperparathyroidism, haemochromatosis, Cushing's disease). Secondary hyperparathyroidism may contribute to bone loss by activating bone turnover and so increasing the number of bone remodelling units with impaired bone formation in each. There is no proven treatment for osteoporosis in men because there have been no trials using anti-fracture efficacy as an end point. Testosterone replacement should be considered in men with proven hypogonadism and vitamin D deficiency should be corrected if present. Calcium supplements and bisphosphonates are reasonable options given the lack of information.

Smoking and the human vertebral column: a review of the impact of cigarette use on vertebral bone metabolism and spinal fusion

Chronic cigarette consumption has significant adverse effects on the human spinal column. Multiple mechanisms induced by tobacco use lead to less strong, less healthy, mineral-deficient vertebrae with reduced bone blood supply and fewer and less functional bone-forming cells among chronic smokers. Compared to nonsmokers, chronic smokers develop advanced bony degradation, are more likely to suffer from spinal column degenerative disease, and seem more susceptible to traumatic vertebral injury. Spinal fusion procedures in chronic smokers are less often clinically and radiographically successful, compared to similar procedures performed among nonsmokers for definitive biological, physiological, and mechanical reasons.

Fractures after thyroidectomy in men: a population-based cohort study

Bone mass is purportedly reduced by an endogenous or exogenous excess of thyroid hormone or, perhaps, by calcitonin deficiency. Patients who have undergone thyroidectomy could be subject to all of these effects, yet their practical implications in terms of fracture risk are poorly defined. Interpretation is further hampered by the focus on women, where results may be influenced by involutional osteoporosis. Consequently, we assessed the potential for fractures among the 136 Rochester, Minnesota men who underwent thyroidectomy between 1935 and 1979, relative to a group of age-matched control men from the community. With 2194 person-years of follow-up in each group, survival free of any fracture of vertebra, proximal humerus, distal forearm, pelvis, or proximal femur was similar in the two groups (p = 0.23), and the relative risk of any of these fractures for thyroidectomized patients versus their controls was increased only 1.5-fold (95% CI, 0.7-3.2). The difference was entirely accounted for by a statistically significant excess of proximal femur fractures in the men with thyroidectomy. Risk factors for fractures among men with thyroidectomy included greater age at surgery, greater extent of surgery, and the presence of risk factors for secondary osteoporosis. Thus, thyroidectomy, performed mainly for adenoma or goiter, seems to have little overall influence on the risk of age-related fractures in men. However, the association with hip fractures requires further evaluation.

Alcohol, cytokines, and estrogen in the control of bone remodeling

Alcohol has been identified as a risk factor for the development of osteoporosis. Chronic alcohol abuse has been shown to decrease bone mass and increase the incidence of fractures. Although the exact mechanism by which alcohol influences bone metabolism is not clear, it is likely a combination of both direct and indirect effects on bone cells. Alcohol has the potential to alter bone metabolism indirectly through its effects on gonadal hormones and through the secretion of cytokines shown to be critical factors in postmenopausal osteoporosis. Data are summarized here demonstrating that interleukin-1 and tumor necrosis factor play a direct causal role in the bone loss due to estrogen deficiency. In addition, studies are cited showing that these same cytokines are produced in alcohol-induced liver disease with the potential to enhance bone loss in post-menopausal women and in male patients. Although there are not yet data directly supporting the role of cytokines in bone loss due to alcohol consumption, the studies presented herein are intended to stimulate further research on the role of alcohol, estrogen, and cytokines in osteoporotic bone loss.

Alcohol-induced bone disease: impact of ethanol on osteoblast proliferation

The habitual consumption of even moderate quantities of alcohol (1 to 2 drinks/day) is clearly linked with reduced bone mass (osteopenia). Biochemical and histological evaluation of patients with alcoholic bone disease reveal a marked impairment in bone formation in the face of relatively normal bone resorption. Experiments using well-defined osteoblastic model systems indicate that the observed reductions in bone formation result from a direct, antiproliferative effect of ethanol on the osteoblast itself. As bone remodeling and mineralization are dependent on osteoblasts, it follows that the deleterious effect of alcohol on these cells would result in slowed bone formation, aberrant remodeling of skeletal tissue and, ultimately, osteopenia and fractures. The skeletal consequences of alcohol intake during adolescence, when the rapid skeletal growth ultimately responsible for achieving peak bone mass is occurring, may be especially harmful. The specific subcellular mechanisms whereby ethanol inhibits cell proliferation are, as yet, unknown. During the last few years, attention has shifted from nonspecific membrane perturbation effects to actions on certain signaling proteins. Specifically, there is increasing evidence that ethanol may exert significant effects on transmembrane signal transduction processes that constitute major branches of cellular control mechanisms. At present, abstinence is the only effective therapy for alcohol-induced bone disease. An improved understanding of the pathogenesis of alcohol-induced bone disease may eventually result in alternative therapeutic avenues for those who are unable to abstain.

The role of testosterone in cyclosporine-induced osteopenia

Our laboratory has demonstrated that the immunosuppressants Cyclosporin A (CsA) and tacrolimus (FK506), in vivo in the rat, produce a high-turnover osteopenia. CsA is known to decrease serum testosterone (Test) levels both in the rat and in human transplant patients. Less is known of FK506's effect on androgens. CsA-induced hypogonadism may contribute to the aforementioned bone loss because hypogonadism itself is a risk factor for osteoporosis and fracture. The aim of this study was to assess serum androgen levels following CsA and FK506 therapy and to see wether Test replacement therapy, in the form of 28-day controlled release subcutaneous pellet implants, could prevent CsA-induced osteopenia. Two experiments were conducted. In experiment I, four groups of 6-month-old male Sprague-Dawley rats received the following: (A) CsA vehicle and placebo pellet, (B) Test 15 mg pellet and CsA vehicle, (C) CsA 10 mg/kg and placebo pellet, (D) Test 15 mg pellet and CsA 10 mg/kg. In experiment II, two groups of rats received (E) FK506 vehicle and (F) FK506 4 mg/kg. CsA, FK506, and vehicles were given for 28 days by daily oral gavage. The rats were weighted and bled on days 0, 14, and 28. All rats received double fluorescent labeling, and on day 28 the tibiae were removed for histomorphometry. Whole blood was assayed for CsA and FK506 levels. Serum was assayed for total and free Test as well as for osteocalcin (BGP), blood urea nitrogen (BUN), creatinine, and calcium. Whole blood monoclonal CsA levels measured by fluorescent immunoassay were in the therapeutic range, while a drug concentration profile showed good absorption of FK506. Those rats receiving Test and FK506 lost weight, while those receiving CsA remained constant. BUN was only marginally elevated in the CsA-treated groups on day 28 (p < 0.05), while creatinine was unchanged. On day 28, total and free Test was significantly reduced in the CsA-treated rats versus control (p < 0.05), while Test replacement therapy maintained total Test levels above vehicle (p < 0.01) and free Test levels similar to vehicle on day 28. FK506 did not lower total or free Test levels. BGP levels were significantly increased in the CsA (p < 0.01) and FK506 (p < 0.001) groups on day 28. BGP in the groups receiving Test alone and in combination with CsA remained similar to vehicle. Histomorphometry confirmed CsA- and FK506-induced high-turnover osteopenia. The Test alone group marignally increased bone formation. Test replacement failed to prevent the CsA-induced bone loss. In conclusion, immunosuppressive doses of CsA, but not FK506, lowers serum total and free Test. Hypoandrogenemia does not seem to be a major factor in CsA-induced osteopenia because bone loss occurs despite Test replacement.

Adverse effects of corticosteroid therapy for COPD. A critical review

Inhaled and systemic corticosteroids are commonly prescribed for the treatment of COPD. Despite their frequent use, there is insufficient evidence regarding efficacy of steroid therapy in COPD. While awaiting the results of more definitive prospective trials, the clinician must evaluate whether the benefits of such therapy outweigh the potential for adverse events. This is particularly pertinent in the population of patients with COPD who generally are older, less active, and have significant tobacco use histories, all of which may place them at greater risk for adverse effects. In this review, we examine the current scientific evidence supporting the many purported adverse systemic effects associated with the use of corticosteroids in the treatment of COPD.

Steroid sulfatase activity in osteoblast cells

We have demonstrated steroid sulfatase activity in osteoblast cells and characteristics of the enzyme were also investigated. Cell free homogenate of rat osteoblast cell line, UMR106-01 and human osteoblast cell lines, MG-63, HOS were incubated with [3H] dehydroepiandrosterone-sulfate (DHEA-sulfate) or [3H] estrone-sulfate (E1-sulfate). The formation of DHEA or E1 from the corresponding substrate was identified by crystallization to constant specific activity. Michaelis constant (K(m)) for DHEA-sulfate was estimated as 2.1 x 10(-8)M in UMR106-01, 7.4 x 10(-7)M in MG-63, 5.8 x 10(-7)M in HOS and that for E1-sulfate was 4.1 x 10(-7)M, 3.0 x 10(-7)M, 9.8 x 10(-7)M, respectively. The expression of steroid sulfatase messenger ribonucleic acid in human osteoblast cells, HOS and MG-63 was first demonstrated by reverse transcription-polymerase chain reaction. The existence of steroid sulfatase in human and rat osteoblast cells suggests that osteoblast cells have the capacity to convert circulating sulfo-conjugated steroids to more active androgens and estrogens. This may indicate an important role of bone in facilitating hormonal action.

Bone fractures associated with luteinizing hormone-releasing hormone agonists used in the treatment of prostate carcinoma

BACKGROUND

Luteinizing hormone-releasing hormone agonists (LHRH-a) have become an established treatment for certain patients with prostate carcinoma. LHRH-a are known to decrease bone mineral density. The purpose of this study was to determine the risk of bone fracture in men receiving LHRH-a for prostate carcinoma.

METHODS

A retrospective chart review and phone interviews were conducted to determine the incidence of bone fractures occurring in patients receiving LHRH-a for the treatment of prostate carcinoma. Abstracted data included the number of monthly LHRH-a injections, age, clinical stage of disease, sites of metastases, and bone fracture history.

RESULTS

Twenty of the 224 patients (9%) treated with LHRH-a for prostate carcinoma between 1988 and 1995 at 3 teaching hospitals had at least 1 bone fracture during treatment with LHRH-a. The duration of treatment to the time of fracture ranged from 1 to 96 months (mean, 22.2 months). Seven fractures (32%) were osteoporotic in nature (i.e., vertebral compression fractures or hip fractures after a fall from standing), whereas 8 fractures (36%) were associated with a significant traumatic event (i.e., a motor vehicle accident, boxing, etc.) and 5 were of mixed etiology. Two of 22 fractures (9%) were pathologic.

CONCLUSIONS

This study demonstrated a 9% fracture incidence in a cohort of patients receiving LHRH-a for prostate carcinoma for up to 96 months. The incidence of osteoporotic fractures was 5%.

The influence of alcohol consumption on the risk of vertebral deformity. European Vertebral Osteoporosis Study Group

The influence of alcohol consumption on the risk of osteoporosis is not well established. The aim of this study was to determine the relationship between frequency of alcohol consumption and the risk of vertebral deformity across different European populations. A population survey method was used. Men and women aged 50 years and over were recruited from population-based sampling frames in 36 centres from 19 European countries. Subjects were invited to attend by letter of invitation for an interviewer-administered questionnaire and lateral spinal radiographs. Vertebral deformity was defined morphometrically using the McCloskey-Kanis method. Data from 14237 individuals were available for this analysis. Alcohol consumption was compared between the 809 men and 884 women with vertebral deformity and the 5905 men and 6639 women without vertebral deformity. The frequency of alcohol intake was greater in men than women. Overall, there was no detectable association between frequency of alcohol intake and vertebral deformity in either men or women. Stratification by age showed that women 65 years and over who took alcohol on more than 5 days per week had a reduced risk of vertebral deformity compared with those taking alcohol less than once per week. This protection was most obvious after adjusting for age, centre, body mass index, smoking, current level of physical activity and previous fractures (odds ratio [OR] = 0.65; 95% confidence intervals [CI] = 0.43, 0.99). There was a smaller and non-significant protective effect amongst men aged 65 years and over and this was most apparent amongst moderately frequent drinkers (1-4 days per week) (OR = 0.81; 95% CI = 0.62, 1.08). There was no association between the occurrence of vertebral deformity and frequency of alcohol consumption in younger men and women. Overall, the effects of the frequency of alcohol consumption on vertebral deformity were modest. In older women, regular consumption on more than 5 days per week is associated with a reduced risk. Further, prospective data are required to confirm these findings. It is also necessary to investigate, in terms of amount of alcohol consumed, at what level the benefits of regular intake are obviated by the increased risks from alcohol excess.

Ovariectomy and orchidectomy induce a transient increase in the osteoclastogenic potential of bone marrow cells in the mouse

Withdrawal of gender steroids in both women and men is associated with an increase in bone turnover with bone resorption exceeding bone formation leading to bone loss. To further investigate this process, the osteoclastogenic potential of mouse bone marrow cells was assessed at different timepoints after ovariectomy (ovx) or orchidectomy (orx). Cocultures of osteoclast-free fetal mouse long bones together with bone marrow from ovariectomized or orchidectomized mice indicated that the withdrawal of gender steroids in female and male mice induces a transient increase in osteoclastogenesis. The osteoclastogenic potential of the bone marrow cells was increased 7 days after ovx or orx. However, osteoclastic resorption was not increased at 3 days after surgery and had normalized 30 days after either ovx or orx. These results suggest that the withdrawal of gender steroids induces a transient increase in osteoclastogenesis in mice of both genders, which is associated with the early phase of rapid bone loss.

Estrogen therapy and osteoporosis: principles & practice

Postmenopausal osteoporosis is linked clearly to estrogen deprivation. Recent research has identified estrogen receptors in bone cells and in other organ systems that help to regulate bone remodeling and calcium homeostasis. Long-term use of estrogen in appropriate doses reduces the risk of hip fractures by 50% to 60% and the risk of vertebral deformation by 90%. This protective effect is maintained as long as estrogen is taken and adequate levels of biologically active estrogen are achieved. Thus, the type, dose, and route of administration of estrogen need to be individualized and the efficacy of treatment monitored by annual bone density testing and selective ultilization of biochemical bone markers. The ability of estrogen therapy to increase bone mass is enhanced by added androgens and progestin therapy, calcium supplementation, and exercise.

Bone mineral density and hormonal status in men with systemic lupus erythematosus

A loss in bone mass was reported in premenopausal systemic lupus erythematosus (SLE) women, but this problem has not been studied in SLE males. We evaluated bone mineral density (BMD) in SLE males and the relationship between prolactin (PRL) and testosterone with BMD. We also studied the controversial effect of steroid therapy on BMD in these patients. We measured BMD in the lumbar spine and at the hip in 20 SLE men (mean age 37 y) and in the controls (n = 40). We measured PRL and testosterone in serum and saliva. The mean dose of prednisone at the time of study was 11.6 mg; and cumulative dose was 17.6 g. No significative decrease in BMD was detected in SLE males vs controls; either in the lumbar spine (1.00 +/- 0.1 vs 1.05 +/- 0.1 g/cm2) or in the femoral neck (0.84 +/- 0.1 vs 0.87 +/- 0.1 g/cm2). No patient or control had osteoporosis or fractures. We did not find any relationship between BMD and cumulative dose and baseline dose of corticosteroids. The mean values of PRL and testosterone (serum and salivary) were in the normal range. We did not find any correlation between BMD, PRL and androgens. This study did not show a loss in bone mass in SLE men on corticosteroid therapy.

Prediction of fracture risk. II: Other risk factors

Many osteoporotic fractures are probably preventable-by definition, prevention requires identification of those at risk prior to fracture. There is a continuum in fracture risk and a very wide range in risk among individuals. Bone density, previous fractures, and the frequency and types of falls are important risk factors for fractures. There are also many other risk factors for bone loss, falls, and fractures. People with multiple risk factors are at greater risk than those with either a single risk factor or none. Identification of risk factors can help when planning interventions. For example, dietary deficiencies are amenable to dietary modification or supplementation; however, the effects of many risk factors have not been quantified separately, making it difficult to determine the importance. In addition, it is not possible to accurately predict current bone density and fracture risk from risk factors for bone loss; bone density should always be measured directly.

Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes

It is apparent that bone density in male athletes can be reduced without a concomitant decrease in testosterone, suggesting that bone density and testosterone concentrations in the normal range are not closely related in male athletes. Further research is necessary to monitor concurrent changes in bone density and testosterone over a period of time in exercising males. In any case, the effect of exercise on the male reproductive system does not appear as extreme as that which can occur in female athletes, and any impact on bone density is not nearly as evident. These results imply that factors apart from testosterone concentrations must be responsible for the observed osteopenia in some male athletes. Many factors have the potential to adversely affect bone density, independently of alterations in reproductive function. These include low calcium intake, energy deficit, weight loss, psychological stress, and low body fat, all of which may be associated with intense endurance training. Future research investigating skeletal health in male athletes should include a thorough assessment of reproductive function in addition to these other factors.

Aromatization of androgens is important for skeletal maintenance of aged male rats

A nonsteroidal aromatase inhibitor vorozole (VOR) was administered to aged (12 months old) male Wistar rats and its effect was compared with the effect of androgen deficiency. The rats were either sham-operated (SHAM) or orchidectomized (ORCH) and treated with or without VOR. Thus, four experimental groups were created (SHAM, ORCH, SHAM + VOR, ORCH + VOR). The follow-up period was 4 months. At the end of the experimental period, bone mineral density (BMD) of the first four lumbar vertebrae and right femur was measured ex vivo with dual-energy X-ray absorptiometry, bone formation was evaluated by serum osteocalcin, and bone resorption by urinary excretion of (deoxy)pyridinoline. Orchidectomy increased bone resorption 2- to 3-fold whereas bone formation was only slightly increased. Treatment of intact male rats with VOR also increased bone resorption (+30% increase) whereas bone formation was not increased in this SHAM + VOR group. Their BMD was 7% lower in the femur (P < 0.01) and 6% lower in the lumbar vertebrae (P < 0.01) compared with the SHAM group that had not received VOR. Moreover, this decrease of bone mineral density was not significantly different from the expected decrease of bone density observed in the ORCH groups (6-10%). This was also reflected by a decrease of calcium content of the first four lumbar vertebrae of 15% (P < 0.001) in the SHAM + VOR group and 9-14% (P < 0.05) in the ORCH groups compared with the SHAM group, respectively. These data therefore suggest that inhibition of aromatization of androgens into estrogens increases bone resorption and bone loss similar to that observed after complete removal of androgens. Aromatization of androgens into estrogens may therefore, at least partly, explain the effects of androgens on skeletal maintenance.

Bone quality in the lumbar spine in high-performance athletes

Little is known about the influence of high-performance training on the bone quality of the lumbar spine, in particular, the effects on bone mineral density (BMD) in athletes with high weight-bearing demands on the spine. Measurements were therefore performed in internationally top-ranked high-performance athletes of different disciplines (weight lifters, boxers, and endurance-cyclists). The measurements were carried out by dual-energy X-ray absorptiometry, and the results compared with the measurements of 21 age-matched male controls. The BMD of the high-performance weight lifters was greater than that of the controls by 24% (0.252 g/cm2) on the AP view by 23% (0.200 g/cm2) on the lateral view (P < 0.01), while difference in BMD between the boxers and the controls was +17% (0.174 g/cm2) on the AP view and +19% (0.174 g/cm2) on the lateral view. The BMD of the lumbar spine in all endurance cyclists was lower than that in the controls (AP view -10%, 0.105 g/cm2; lateral view -8%, 0.067 g/cm2; P > 0.05). The results show that training program stressing axial loads of the skeleton may lead to a significant increase of BMD in the lumbar spine of young individuals. Other authors' findings that the BMD of endurance athletes may decrease are confirmed. Nevertheless the 10% BMD loss of cyclists was surprisingly high.

Effects of dihydrotestosterone alone and combined with estrogen on bone mineral density, bone growth, and formation rates in ovariectomized rats

Androgens are associated with the greater skeletal mass and size in men compared with women and have been used as anabolic agents promoting skeletal growth and mineral accretion in both sexes, but specific effects on growth and bone formation in the female skeleton are not well understood. The effects of 5 alpha-dihydrotestosterone (DHT) alone, and in combination with 17 beta-estradiol on bone and bone growth were studied in female ovariectomized (OVX) rats with established osteopenia. Eight weeks after OVX, rats were given 0.1 mg 17 beta-estradiol and/or 2.5 mg or 10 mg DHT administered by controlled-release pellets for 2 months. Body weights decreased with estrogen treatment but increased with DHT. Bone mineral density increased with the highest dose of DHT relative to OVX controls and the estrogen treated group. Dry and ashed bone weights and ash/dry weight ratios increased in the estrogen and DHT treated animals compared to the baseline OVX controls. Total bone calcium was greater with DHT and estrogen combined with DHT. The percent of calcium in the ash increased in all DHT treated groups. When normalized to final body weight, the total femur calcium content was significantly increased in the estrogen and estrogen with DHT groups, but not in the DHT groups compared with the baseline OVX and OVX control groups. The periosteal bone formation rates were increased with the high dose DHT alone and combined with estrogen. OVX rats had increased endochondral bone elongation rates relative to controls but this was decreased with estrogen treatment. DHT combined with estrogen increased endochondral growth rates relative to the estrogen treated group. Trabecular bone volume was decreased in all OVX groups relative to the base line group, but there were no significant effects observed with any treatments. Cancellous bone formation rates were suppressed with estrogen treatment but were partially reversed when combined with DHT. DHT treatments also increased most cancellous bone formation indices over OVX controls. While estrogen is known to preserve skeletal mass by reducing bone turnover, DHT increased skeletal mass by promoting bone growth and formation with concomitant increases in total body mass. DHT had greater effects on cortical bone and partially mitigated the suppressive effects of estrogen on bone growth and formation in the female skeleton.

The relationship of sustained exercise training and bone mineral density in aging male runners

Fifty-six men aged 42-73 years (50.2 +/- 10.0 years), who were competitive distance runners 20-25 years previously, were examined for bone mineral density (BMD) to determine the relationship between sustained distance running and BMD. Subjects were classified as being highly trained (HT, n = 17), moderately trained (MT, n = 29) or untrained (UT, n = 10) according to their training in recent years. Subjects in each group were of similar age (HT 46.5 +/- 2.01, MT 53.0 +/- 1.51, UT 46.7 +/- 2.44 years) and lean body mass. Total body weight (kg) and percentage fat, however, were significantly greater (P < 0.05) in the UT group than in either the MT or HT groups (UT 80.6 +/- 2.44 kg, 22.0 +/- 1.16%; MT 74.9 +/- 1.51 kg, 17.5 +/- 0.61%; HT 70.5 +/- 1.71 kg, 13.5 +/- 0.59%). Lumbar vertebrae and hip region BMD (g.cm-2) was determined via dual energy X-ray absorptiometry (DEXA). No differences in BMD were found among the three groups in either the lumbar (HT 1.00 +/- 0.02, MT 1.02 +/- 0.03, UT 1.07 +/- 0.04 g.cm-2) or the hip regions (HT 0.99 +/- 0.03, MT 0.98 +/- 0.02, UT 1.06 +/- 0.04 g.cm-2). Furthermore, none of the groups had BMD that was significantly different from age-matched normative values taken from a reference database. A moderate correlation was found between body weight and BMD when combining all subjects (r = 0.38 for lumbar and r = 0.41 for hip). These results indicate that middle-aged to older males who have sustained exercise training in the form of running do not have significantly different lumbar vertebrae or hip region BMD compared to individuals who run less or not at all.

The epidemiology of osteoporosis. The oriental perspective in a world context

In the past 3 decades, the incidence of osteoporotic hip fracture increased in Hong Kong Chinese by 2-fold to reach an incidence of approximately 10 per 1000 in women and men who are 70 years of age or older. It has been projected that 50% of all hip fractures in the world will occur in Asia by the next century. The bone mineral density of Asian populations is comparable to that of whites after adjusting for height and weight. Physical inactivity, a low dietary calcium intake, and falls have been found to be major risk factors for hip fractures in Asia. Other risk factors are cigarette smoking, heavy alcohol consumption, and multiparity. Population strategies to increase physical activity and calcium intake and to prevent falls in Oriental populations will be effective in the prevention of osteoporosis and hip fracture because of the high attributable risk for these factors.

Effects of weight loss on bone mineral density in rats

OBJECTIVE

To evaluate the effects of weight loss on bone mineral density (BMD).

METHODS

Eight-week-old female rats were divided into 4 groups: Those in Group A received a restricted diet for 4 weeks; those in Group B received a restricted diet and were treated with estrogen; those in Group C were castrated; and those in Group D underwent sham operations. The rat's body weight (BW) and vaginal smears were checked, and their femoral BMD was measured.

RESULTS

The BW and BMD at 12 weeks were lower in Groups A and B than in Groups C and D; thereafter, however, these values increased for Groups A and B, but were still lower than those in Group D even at 20 weeks. In Group C, the BMD did not decrease, but it was significantly lower than that in Group D at 16 and 20 weeks. Group A showed continuous diestrus 2 weeks after dietary restriction began, but recovered to a 4-day cycle 2 weeks after the initiation of free food consumption.

CONCLUSION

Weight loss had a greater effect on BMD than hypoestrogenism.

Metabolic bone disease of liver cirrhosis: is it parallel to the clinical severity of cirrhosis?

Metabolic bone disease has long been recognized in chronic liver disease, especially cholestatic or alcoholic liver diseases. The aim of the present study was to investigate the prevalence and severity of osteodystrophy in cirrhotic men and the correlation of its incidence with the clinical severity of cirrhosis in an endemic area of post-necrotic hepatitis. We measured serum levels of osteocalcin, 25-hydroxyvitamin D, parathyroid hormone mid-molecule, calcium and testosterone in 74 cirrhotic men (Child-Pugh's classification grade A n = 30, B n = 21 and C n = 23) and 16 healthy controls. Standard X-rays and bone mineral densities of lumbar spine were performed in 30 patients with post-necrotic cirrhosis and 10 healthy controls. Serum levels of osteocalcin, parathyroid hormone and testosterone were significantly lower in patients with cirrhosis than in controls. Changes paralleling an increased severity of cirrhosis were found in serum levels of 25-hydroxyvitamin D and testosterone, but not in the serum levels of osteocalcin and parathyroid hormone. The lumbar bone mineral density was significantly lower in patients with post-necrotic cirrhosis than in controls (0.97 +/- 0.13) vs 1.07 +/- 0.12 g/cm2, P < 0.05) and was correlated with serum 25-hydroxyvitamin D levels (r = 0.467; P < 0.005). There was no correlation between the bone mineral density and serum osteocalcin or the clinical severity of cirrhosis. The prevalence of spinal osteoporosis, as defined by a lumbar bone mineral density greater than two standard deviations below the mean value of the controls, was 20% in cirrhotic patients compared with 10% in controls. Two (6.7%) patients (both grade C) had spinal compression fractures compared with none in the control group. In conclusion, serum osteocalcin and lumbar bone mineral density were significantly lower in cirrhotic men than in controls. However, they were not correlated with each other or the clinical severity of cirrhosis.

Ethanol inhibits human osteoblastic cell proliferation

The habitual consumption of alcoholic beverages is clearly associated with low bone mass and an increased prevalence of skeletal fractures. Microscopic analysis of skeletal tissue from alcoholic patients reveals reduced osteoblast number and suppressed bone formation activity with a relative sparing of resorptive indices. The decreased number of osteoblasts observed in alcoholic subjects results from either impaired proliferation or accelerated senescence. Polyamines and ornithine decarboxylase (ODC), the rate-limiting enzyme for polyamine synthesis, are essential for cell proliferation in a variety of cell types. To determine if the adverse effect of ethanol on osteoblast number involves modulation of polyamine biosynthesis, we examined the effect of ethanol on parameters of cell growth and ODC activity in a human osteoblast-like osteosarcoma cell line (TE-85). Ethanol markedly impaired DNA synthesis and cell proliferation in a dose-dependent fashion, but alkaline phosphatase activity (a marker of differentiated osteoblast function) remained intact, and accelerated apoptosis was not evident. Thus, the reduced osteoblastic cell number was a result of a direct effect on proliferative processes rather than a nonspecific toxic effect of ethanol to accelerate cell death. Induction of ODC activity was impaired in ethanol-exposed cell cultures in a dose-dependent fashion that paralleled the antiproliferative effects. Finally, supplemental polyamine administration substantially improved DNA synthesis in ethanol-exposed UMR 106-01 cell cultures. These data confirm a direct inhibitory effect of ethanol on osteoblast proliferation without overt cellular toxicity that may, in part, explain the reduced bone mass observed in those who consume excessive amounts of alcohol.

Smoking is a risk factor for osteoporosis in women with inflammatory bowel disease

BACKGROUND

Some patients with inflammatory bowel disease have reduced bone mineral density, but the risk factors for osteoporosis in these patients are unclear.

METHODS

To evaluate the effect of smoking and other lifestyle factors on bone mineral density in patients with inflammatory bowel disease, we studied 67 patients with ulcerative colitis, 78 with Crohn's disease, 7 with indeterminate colitis, and 73 healthy control subjects. Bone mineral density of the lumbar spine and the proximal femur was measured, using dual-energy X-ray absorptiometry. Measures of smoking and other lifestyle factors were assessed in an interview.

RESULTS

The female ex- or current smokers with inflammatory bowel disease (n = 38) had lower age- and sex-adjusted Z-scores of bone mineral density than the female patients who had never smoked (n = 34) (Z-scores in the lumbar spine, -0.277 (1.283) (mean (standard deviation)) and 0.487 (1.056), respectively; p = 0.008; and in the femoral neck, -0.626 (1.055) and -0.013 (1.019); p = 0.015). These differences were not explained by the type or treatment of the disease, the menstrual history, or the use of estrogen preparations. In male patients no differences in bone mineral density were found between ex- or current smokers and non-smokers. Coffee drinking and alcohol consumption were not associated with bone mineral density in these patients.

CONCLUSIONS

Smoking is associated with low bone mineral density in women with inflammatory bowel disease. This association is not related to the body mass index, the medical treatment, or the type of disease.