Osteoporosis and low bone mass in premenopausal and perimenopausal women

There is a significantly inverse relationship between dietary riboflavin intake and prevalence of osteoporosis in women but not in men: Results from the TCLSIH cohort study

Background

Epidemiological evidence for the relationship between riboflavin intake and bone health is inconsistent, and this relationship has not been examined in Chinese population. This study aimed to investigate the relationship between dietary intake of riboflavin and prevalence of osteoporosis in a Chinese adult population.

Methods

A total of 5,607 participants (mean age, 61.2 years; males, 34.4%) were included in this cross-sectional study. We calculated the riboflavin intake by using the food frequency questionnaire (FFQ) in combination with Chinese food composition database. Bone mineral density (BMD) was detected by an ultrasound bone densitometer. Multivariable logistic regression models were used to evaluate the relationship between dietary riboflavin intake and prevalence of osteoporosis.

Results

In this population, the dietary intake of riboflavin ranged from 0.13 to 1.99 mg/d, and the proportion of abnormal BMD was 36.6%. The prevalence of osteoporosis decreased gradually with increasing quartiles of riboflavin intake, before and after adjustment for a range of confounding factors. In the final model, the multivariate-adjusted ORs (95% CI) across the quartiles of riboflavin intake were 1.00 (reference), 0.84 (0.54, 1.31), 0.59 (0.34, 1.04), and 0.47 (0.22, 0.96), respectively (P for trend < 0.05). In sex-disaggregated analysis, similar results to the total population were observed in women, while no significant results were found in men.

Conclusion

The dietary riboflavin intake was negatively associated with the prevalence of osteoporosis. However, the association was significant in women but not in men. Our findings indicated that women are more sensitive to riboflavin intake in maintaining a normal BMD.

Large-scale osteocyte lacunar morphological analysis of transiliac bone in normal and osteoporotic premenopausal women

Bone's ability to adapt is governed by the network of embedded osteocytes, which inhabit individual pores called lacunae. The morphology of these lacunae and their resident osteocytes are known to change with age and diseases such as postmenopausal osteoporosis. However, it is unclear whether alterations in lacunar morphology are present in younger populations with osteoporosis. To investigate this, we implemented a previously validated methodology to image and quantify the three-dimensional morphometries of lacunae on a large scale with ultra-high-resolution micro-computed tomography (microCT) in transiliac bone biopsies from three groups of premenopausal women: control n = 39; idiopathic osteoporosis (IOP) n = 45; idiopathic low BMD (ILBMD) n = 19. Lacunar morphometric parameters were measured in both trabecular and cortical bone such as lacunar density (Lc.N/BV), lacunar volume (Lc.V), and lacunar sphericity (Lc.Sr). These were then compared against each other and also with previously measured tissue morphometries such as bone volume density (BV/TV), trabecular separation (Tb.Sp), trabecular number (Tb.N), and others. We detected no differences in lacunar morphology between the IOP, ILBMD and healthy premenopausal women. In contrast, we did find significant differences between lacunar morphologies including Lc.N/BV, Lc. V, and Lc. Sr in cortical and trabecular regions within all three groups (p < 0.001), which was consistent with our previous findings on a subgroup of the healthy group. Furthermore, we discovered strong correlations between Lc. Sr from trabecular regions with the measured BV/TV (R = -0.90, p < 0.05). The findings and comprehensive lacunar dataset we present here will be a crucial foundation for future investigations of the relationship between osteocyte lacunar morphology and disease.

Bone Quality in CKD Patients: Current Concepts and Future Directions - Part I

BACKGROUND

There is ample evidence that patients with CKD have an increased risk of osteoporotic fractures. Bone fragility is not only influenced by low bone volume and mass but also by poor microarchitecture and tissue quality. More emphasis has been given to the quantitative rather than qualitative assessment of bone health, both in general population and CKD patients. Although bone mineral density (BMD) is a very useful clinical tool in assessing bone strength, it may underestimate the fracture risk in CKD patients. Serum and urinary bone biomarkers have been found to be reflective of bone activities and predictive of fractures independently of BMD in CKD patients. Bone quality and fracture risk in CKD patients can be better assessed by utilizing new technologies such as trabecular bone score and high-resolution imaging studies. Additionally, invasive assessments such as bone histology and micro-indentation are useful counterparts in the evaluation of bone quality.

SUMMARY

A precise diagnosis of the underlying skeletal abnormalities in CKD patients is crucial to prevent further bone loss and fractures. We must consider bone quantity and quality abnormalities for management of CKD patients. Here in this part I, we are focusing on advances in bone quality diagnostics that are expected to help in proper understanding of the bone health in CKD patients.

KEY MESSAGES

Assessment of bone quality and quantity in CKD patients is essential. Both noninvasive and invasive techniques for the assessment of bone quality are available.

Premenopausal osteoporosis

In premenopausal women, bone mineral density measurement by dual-energy X-ray absorptiometry should not be used as the sole guide for diagnosis or treatment of osteoporosis, universal screening with bone mineral density is not advised and the World Health Organization classification of bone status should not be applied. A diagnosis of premenopausal osteoporosis is reserved for those with evidence of fragility and may also be considered in women with low bone mass and an ongoing secondary cause of osteoporosis. Idiopathic osteoporosis in young women is rare. A thorough evaluation of secondary causes is indicated in all patients, with glucocorticoid treatment a common secondary cause of low bone mass and osteoporosis. Hypoestrogenism may be the primary cause of low bone mass and contribute to excessive bone loss in many conditions associated with premenopausal osteoporosis, and should be treated unless contra-indicated. The mainstay of treatment in premenopausal females with low bone mass includes risk factor reduction, advocating a healthy, active lifestyle and optimal treatment of secondary causes of bone loss. The safety of bone-specific therapy, especially long term and during pregnancy, remains uncertain. Bisphosphonates, teriparatide, denosumab and estrogen treatment increase bone density in premenopausal women with osteoporosis, but there are no study data confirming short-term fracture prevention with use of these agents.

Osteoporosis in Premenopausal Women: A Clinical Narrative Review by the ECTS and the IOF

CONTEXT

Consensus regarding diagnosis and management of osteoporosis in premenopausal women (PW) is still lacking due to few studies carried out in this population.

DESIGN

The European Calcified Tissue Society and the International Osteoporosis Foundation convened a working group to produce an updated review of literature published after 2017 on this topic.

RESULTS

Fragility fractures in PW are rare and mostly due to secondary osteoporosis (ie, in presence of an underlying disease such as hormonal, inflammatory, or digestive disorders). In absence of another disorder, low bone mineral density (BMD) together with fragility fractures qualifies as idiopathic osteoporosis. In contrast, low BMD alone does not necessarily represent osteoporosis in absence of bone microarchitectural abnormalities. BMD increases in PW with osteoporosis when the underlying disease is treated. For example, in celiac disease, an increase of 9% in radius trabecular volumetric density was achieved after 1 year of gluten-free diet, while anti-tumor necrosis factor alpha improved BMD in PW with inflammatory bowel diseases. In amenorrhea, including anorexia nervosa, appropriately delivered estrogen replacement therapy can also improve BMD. Alternatively, antiresorptive or anabolic therapy has been shown to improve BMD in a variety of conditions, the range of improvement (3%-16%) depending on skeletal site and the nature of the secondary cause. No studies were powered to demonstrate fracture reduction. The effects of bisphosphonates in childbearing women have been scantly studied and caution is needed.

CONCLUSION

The majority of PW with osteoporosis have an underlying disease. Specific therapy of these diseases, as well as antiresorptive and anabolic drugs, improve BMD, but without evidence of fracture reduction.

How to manage osteoporosis before the age of 50

This narrative review discusses several aspects of the management of osteoporosis in patients under 50 years of age. Peak bone mass is genetically determined but can also be affected by lifestyle factors. Puberty constitutes a vulnerable period. Idiopathic osteoporosis is a rare, heterogeneous condition in young adults due in part to decreased osteoblast function and deficient bone acquisition. There are no evidence-based treatment recommendations. Drugs use can be proposed to elderly patients at very high risk. Diagnosis and management of osteoporosis in the young can be challenging, in particular in the absence of a manifest secondary cause. Young adults with low bone mineral density (BMD) do not necessarily have osteoporosis and it is important to avoid unnecessary treatment. A determination of BMD is recommended for premenopausal women who have had a fragility fracture or who have secondary causes of osteoporosis: secondary causes of excessive bone loss need to be excluded and treatment should be targeted. Adequate calcium, vitamin D, and a healthy lifestyle should be recommended. In the absence of fractures, conservative management is generally sufficient, but in rare cases, such as chemotherapy-induced osteoporosis, antiresorptive medication can be used. Osteoporosis in young men is most often of secondary origin and hypogonadism is a major cause; testosterone replacement therapy will improve BMD in these patients. Diabetes is characterized by major alterations in bone quality, implying that medical therapy should be started sooner than for other causes of osteoporosis. Primary hyperparathyroidism, hyperthyroidism, Cushing's syndrome and growth hormone deficiency or excess affect cortical bone more often than trabecular bone.

Articular Cartilage Degradation and Aberrant Subchondral Bone Remodeling in Patients with Osteoarthritis and Osteoporosis

Osteoarthritis (OA) and osteoporosis (OP) are two skeletal disorders associated with joint structures. Occasionally, OA and OP occur in the same patient. However, the effect of OP changes on OA progression in patients with osteoporotic OA (OP-OA) has not been reported, especially the potential association between subchondral bone and articular cartilage. Thus we investigated the alterations in the microstructure, biomechanical properties, and remodeling of subchondral bone as well as their association with cartilage damage in the hip joint of patients with OP-OA. Thirty-nine femoral head specimens were obtained from patients who underwent total hip arthroplasty (OA group, n = 19; OP-OA group, n = 20), and healthy specimens from cadaver donors were used (control group, n = 10). The microstructure and biomechanical properties of subchondral bone were evaluated by micro-computed tomography and micro-finite-element analysis. Histology, histomorphometric measurements, and immunohistochemistry were used to assess subchondral bone remodeling and cartilage damage. Linear regression analysis was performed to elucidate the relationship between subchondral bone and articular cartilage. In the subchondral bone of the OP-OA group, compared with that of the OA group, aberrant bone remodeling leads to an inferior microstructure and worsening biomechanical properties, potentially affecting transmission of loading stress from the cartilage to the subchondral bone, and then resulting in accelerated OA progression in patients with OP-OA. The results indicate that changes in subchondral bone could affect OA development and the improvement in subchondral bone with bone-metabolism agents may help mitigate OA progression when OP and OA coexist in the same patients. © 2019 American Society for Bone and Mineral Research.

Prevalence of Low Bone Density and Comorbid Hypogonadism in Patients With Chronic Pancreatitis

OBJECTIVES

Patients with chronic pancreatitis (CP) are at increased risk of low bone mineral density (BMD), although the prevalence of low BMD in patients with CP in the United States is lacking. We aimed to determine the prevalence of low BMD and identify potential risk factors, including hypogonadism and use of opioid medications, in subjects with CP in the United States.

METHODS

This was a prospective, observational study. Subjects with CP underwent dual-energy x-ray absorptiometry scan. Blood was assayed for vitamin D, sex hormones, and a metabolic panel. History was obtained for fractures, menopause, hypogonadal symptoms, and opioid medication doses. Low BMD was defined by both World Health Organization and the International Society for Clinical Densitometry criteria.

RESULTS

Depending on criteria used, 37% to 55% of our cohort had low BMD. Subjects with low and normal BMD had similar vitamin D levels. Hypogonadism was present in 27% of nonmenopausal subjects and was associated with reduced lumbar spine BMD in subjects 30 years or older.

CONCLUSIONS

Patients with CP are at increased risk of low BMD, which is likely multifactorial. Hypogonadism, possibly related to opioid pain medications, may be an independent risk factor for low BMD in CP.

Osteoporosis in premenopausal women

PURPOSE OF REVIEW

The scope of this review was to review the newest developments in the context of the existing knowledge on premenopausal bone fragility. Fragility fractures are common in postmenopausal women and men and diagnostic criteria for osteoporosis have been agreed and multiple pharmacological treatments have been developed over the last 25 years. In premenopausal women, fragility fractures and very low bone mass are uncommon and osteoporosis in premenopausal women has therefore attracted much less interest.

RECENT FINDINGS

Recent studies have highlighted that lifestyle and dietary habits affect premenopausal bone mass. Bone mass may be improved by sufficient intake of calcium and vitamin D together with increased physical activity in premenopausal women with idiopathic osteoporosis. If pharmacological treatment is needed, teriparatide has been demonstrated to efficiently increase bone mass; however, no fracture studies and no comparative studies against antiresorptive therapies have been conducted. Pregnancy affects bone turnover and mass significantly, but pregnancy-associated osteoporosis is a rare and heterogeneous condition.

SUMMARY

The diagnosis of osteoporosis should only be considered in premenopausal women with existing fragility fractures, diseases or treatments known to cause bone loss or fractures. Secondary causes of osteoporosis should be corrected or treated if possible. The women should be recommended sufficient intake of calcium and vitamin and physical activity. In women with recurrent fractures or secondary causes that cannot be eliminated, for example glucocorticoid or cancer treatment, pharmacological intervention with bisphosphonates or teriparatide (not in the case of cancer) may be considered.

Causes of low peak bone mass in women

Peak bone mass is the maximum bone mass that accrues during growth and development. Consolidation of peak bone mass normally occurs during early adulthood. Low peak bone mass results from failure to achieve peak bone mass genetic potential, primarily due to bone loss caused by a variety of conditions or processes occurring at younger ages than usual. Recognized causes of low peak bone mass include genetic causes, endocrine disorders, nutritional disorders, chronic diseases of childhood or adolescence, medications, and idiopathic factors.

Premenopausal Osteoporosis

Most premenopausal women with low trauma fracture(s) or low bone mineral density have a secondary cause of osteoporosis or bone loss. Where possible, treatment of the underlying cause should be the focus of management. Premenopausal women with an ongoing cause of bone loss and those who have had, or continue to have, low trauma fractures may require pharmacologic intervention. Clinical trials provide evidence of benefits of bisphosphonates and teriparatide for bone mineral density in several types of premenopausal osteoporosis, but studies are small and do not provide evidence regarding fracture risk reduction.

Effect of two jumping programs on hip bone mineral density in premenopausal women: a randomized controlled trial

PURPOSE

To determine the effect of two jumping programs on hip bone mineral density (BMD) in women.

DESIGN

Randomized controlled trial.

SETTING

Approximately 20 cities in the Mountain West.

SUBJECTS

Sixty premenopausal women, aged 25 to 50 years, completed the intervention.

INTERVENTION

Subjects were randomly assigned to a control group or one of two jumping groups. The Jump 10 group performed 10 jumps with 30 seconds rest between jumps, twice daily for 16 weeks, while the Jump 20 group performed the same protocol but with 20 jumps.

MEASURES

Hip BMD was measured by using dual-energy x-ray absorptiometry.

ANALYSIS

Analysis of variance and covariance.

RESULTS

At 8 weeks, unadjusted percentage change in hip BMD was significantly different among groups (F = 5.4, p = .0236). Specifically, compared with controls, the Jump 20 women had significantly greater gains in hip BMD and the Jump 10 women had marginally greater improvements. Following 16 weeks of jumping, differences between the Jump 10 and the Jump 20 groups compared with controls were significant (F = 4.2, p = .0444), especially after adjusting for the covariates (F = 7.3, p = .0092).

CONCLUSION

After 16 weeks of high-impact jump training, hip BMD can be improved in premenopausal women by jumping 10 or 20 times, twice daily, with 30 seconds of rest between each jump, compared with controls.

Levels of serum estradiol and lifestyle factors related with bone mineral density in premenopausal Mexican women: a cross-sectional analysis

BACKGROUND

Many factors, such as heredity, ethnicity, nutrition and other lifestyle factors, have been related to bone mineral density in postmenopausal women. Additionally, bone mass has been significantly associated with decreased estrogen levels. However, fewstudies have been conducted on premenopausal women. The present study was designed to estimate the relationship between low bone mineral density and levels of serum estradiol and lifestyle factors in premenopausal Mexican women.

METHODS

A cross-sectional study was conducted in 270 women between 40 and 48 years of age who participate in the Health Workers Cohort Study. Information on socio-demographic and lifestyle factors were obtained through a self-administered questionnaire. Body mass index and serum estradiol were measured with standard procedures; bone mineral density was assessed using dual-energy X-ray absorptiometry. Multiple linear and logistic regression models were computed to evaluate the relationship between low bone mineral density and levels of serum estradiol and lifestyle factors.

RESULTS

In linear regression analysis levels of estradiol, body mass index, physical activity, and vitamin D intake were positively related to bone mineral density. Age, cigarette smoking and caffeine were inversely associated with BMD. Finally, the odds of low bone mineral density increase significantly when the premenopausal women had low levels of serum estradiol (OR = 4.93, 95 % CI: 2.14, 11.37).

CONCLUSION

These data support that low serum estradiol, advancing age, lower physical activity, lower vitamin D intake, cigarette smoking, and higher amount of caffeine intake are linked to low bone mineral density in premenopausal Mexican women.

Evaluation and management of the premenopausal woman with low BMD

Interpretation of bone mineral density (BMD) results in premenopausal women is particularly challenging, since the relationship between BMD and fracture risk is not the same as for postmenopausal women. In most cases, Z scores rather than T scores should be used to define "low BMD" in premenopausal women. The finding of low BMD in a premenopausal woman should prompt thorough evaluation for secondary causes of bone loss. If a secondary cause is found, management should focus on treatment of this condition. In a few cases where the secondary cause cannot be eliminated, treatment with a bone active agent to prevent bone loss should be considered. In women with no fractures and no known secondary cause, low BMD is associated with microarchitectural defects similar to young women with fractures; however, no longitudinal data are available to allow use of BMD to predict fracture risk. BMD is likely to be stable in these women with isolated low BMD, and pharmacologic therapy is rarely necessary. Assessment of markers of bone turnover and follow-up bone density measurements can help to identify those with an ongoing process of bone loss that may indicate a higher risk for fracture, and possible need for pharmacologic intervention.

Influence of number of deliveries and total breast-feeding time on bone mineral density in premenopausal and young postmenopausal women

OBJECTIVES

Pregnancy and lactation have been associated with decline in bone mineral density (BMD). It is not clear if there is a full recovery of BMD to baseline. This study sought to determine if pregnancy or breast-feeding or both have a cumulative effect on BMD in premenopausal and early postmenopausal women.

STUDY DESIGN

We performed single-center cohort analysis. Five hundred women aged 35-55 years underwent routine BMD screening from February to July 2011 at a tertiary medical center. Patients were questioned about number of total full-term deliveries and duration of breast-feeding and completed a background questionnaire on menarche and menopause, smoking, dairy product consumption, and weekly physical exercise. Weight and height were measured. Dual-energy X-ray absorptiometry was used to measure spinal, dual femoral neck, and total hip BMD.

MAIN OUTCOME MEASURES

Associations between background characteristics and BMD values were analyzed.

RESULTS

Sixty percent of the women were premenopausal. Mean number of deliveries was 2.5 and mean duration of breast-feeding was 9.12 months. On univariate analysis, BMD values were negatively correlated with patient age (p=0.006) and number of births (p=0.013), and positively correlated with body mass index (p<0.001). On multiple (adjusted) logistic regression analysis, prolonged breast-feeding duration, but not number of deliveries, was significantly correlated to a low BMD (p=0.008). An effect was noted only in postmenopausal women. The spine was the most common site of BMD decrease.

CONCLUSIONS

Prolonged breast-feeding may have a deleterious long-term effect on BMD and may contribute to increased risk of osteoporosis later in life.

Low-energy fractures without low T-scores characteristic of osteoporosis: a possible bone matrix disorder

BACKGROUND

Osteoporotic fractures commonly occur after low-energy trauma in postmenopausal women with reduced bone quantity documented by low bone mineral density (BMD). Low-energy fractures, however, have also been reported to occur in premenopausal women with normal or near-normal BMD, suggesting the existence of a bone quality abnormality.

METHODS

Bone quality and quantity were evaluated in a cross-sectional study of three groups of premenopausal white females: (1) twenty-five subjects with low-energy fracture(s) and BMD in the normal range (t-scores &gt; -2.0), (2) eighteen subjects with low-energy fracture(s) and BMD in the osteoporotic range (t-scores ≤ -2.5), and (3) fourteen healthy volunteers (controls). Bone quality was assessed with use of Fourier transform infrared spectroscopy and histomorphometry in iliac crest bone samples obtained from all subjects; bone quantity was assessed by dual x-ray absorptiometry and histomorphometry.

RESULTS

The collagen crosslinking ratio in the non-low-BMD subjects with fractures was 13% greater than the ratio in the low-BMD subjects with fractures and 14% greater than the ratio in the controls (p &lt; 0.001 for both). Cancellous bone volume was 29% greater (p &lt; 0.01) and trabecular separation was 31% less (p &lt; 0.01) in the non-low-BMD subjects with fractures than in the low-BMD subjects with fractures; the values in the non-low-BMD subjects did not differ from those in the controls. Bone turnover did not differ among the groups, and osteomalacia was not present in any subject. Thus, the non-low-BMD subjects with fractures maintained bone quantity, but the collagen crosslinking ratio, a parameter of bone quality, was abnormal. In contrast, the low-BMD subjects with fractures did not have this collagen crosslinking abnormality but did have abnormal bone quantity.

CONCLUSIONS

This study highlights a collagen crosslinking abnormality in patients with low-energy fractures and nonosteoporotic t-scores. Reports have indicated that altered collagen crosslinking is associated with subnormal fracture resistance. A finding of nonosteoporotic bone mass in a patient with low-energy fractures would justify assessment of bone material quality, which currently requires a bone biopsy. Further studies are needed to search for possible noninvasive tests to diagnose abnormal crosslinking. Since no specific therapies for abnormal collagen crosslinking are currently available, studies are also needed to explore novel therapeutic modalities to reverse the underlying collagen crosslinking abnormality.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Premenopausal osteoporosis

Osteoporosis has traditionally been considered a disorder of postmenopausal women, but low bone mass and accelerated bone loss can also occur early in life causing premenopausal osteoporosis. There are a few risk factors that increase a woman's risk of premenopausal osteoporosis, including drugs, hormonal and nutritional factors, and physical in-activity, which need to be identified and managed accordingly. Lifestyle modification is of importance in preventing progressive bone loss in premenopausal women and should be actively encouraged.

Osteoporosis in young adults: pathophysiology, diagnosis, and management

Postmenopausal osteoporosis is mainly caused by increased bone remodeling resulting from estrogen deficiency. Indications for treatment are based on low areal bone mineral density (aBMD, T-score  ≤ -2.5), typical fragility fractures (spine or hip), and more recently, an elevated 10-year fracture probability (by FRAX®). In contrast, there is no clear definition of osteoporosis nor intervention thresholds in younger individuals. Low aBMD in a young adult may reflect a physiologically low peak bone mass, such as in lean but otherwise healthy persons, whereas fractures commonly occur with high-impact trauma, i.e., without bone fragility. Furthermore, low aBMD associated with vitamin D deficiency may be highly prevalent in some regions of the world. Nevertheless, true osteoporosis in the young can occur, which we define as a T-score below -2.5 at spine or hip in association with a chronic disease known to affect bone metabolism. In the absence of secondary causes, the presence of fragility fractures, such as in vertebrae, may point towards genetic or idiopathic osteoporosis. In turn, treatment of the underlying condition may improve bone mass as well. In rare cases, a bone-specific treatment may be indicated, although evidence is scarce for a true benefit on fracture risk. The International Osteoporosis Foundation (IOF) convened a working group to review pathophysiology, diagnosis, and management of osteoporosis in the young, excluding children and adolescents, and provide a screening strategy including laboratory exams for a systematic approach of this condition.

A framework for the development of guidelines for the management of glucocorticoid-induced osteoporosis

This paper provides a framework for the development of national guidelines for the management of glucocorticoid-induced osteoporosis in men and women aged 18 years and over in whom oral glucocorticoid therapy is considered for 3 months or longer.

INTRODUCTION

The need for updated guidelines for Europe and other parts of the world was recognised by the International Osteoporosis Foundation and the European Calcified Tissue Society, which set up a joint Guideline Working Group at the end of 2010.

METHODS AND RESULTS

The epidemiology of GIO is reviewed. Assessment of risk used a fracture probability-based approach, and intervention thresholds were based on 10-year probabilities using FRAX. The efficacy of intervention was assessed by a systematic review.

CONCLUSIONS

Guidance for glucocorticoid-induced osteoporosis is updated in the light of new treatments and methods of assessment. National guidelines derived from this resource need to be tailored within the national healthcare framework of each country.

The prevalence of recognized contributors to secondary osteoporosis in South East Asian men and post-menopausal women. Are Z score diagnostic thresholds useful predictors of their presence?

The prevalence of secondary contributors to osteoporosis in our population of SE Asian patients is high. Though various low thresholds Z score values have been proposed as suggestive of a high likelihood of secondary osteoporosis, they appear to have only limited discriminatory value in identifying a secondary cause.

INTRODUCTION

Many patients with osteoporosis have significant secondary contributors towards their bone loss. The sensitivity and diagnostic utility of using Z score thresholds to screen for secondary osteoporosis have not yet been convincingly demonstrated nor has there been any previous attempt to estimate the prevalence of secondary osteoporosis in South East Asia. We aimed to study the prevalence of commonly recognized contributors and to determine the discriminatory ability of Z score thresholds in screening for them in Singaporean men and post-menopausal women with osteoporosis.

METHOD

Three hundred thirty-two consecutive patients seen at the osteoporosis clinic of the largest hospital in Singapore were evaluated. The frequencies of the different contributors were determined and sensitivities, specificities, and positive and negative predictive values (PPV and NPV) of pre-specified Z score cut-off values calculated.

RESULTS

Vitamin D deficiency was present in 18.5% of the patients, hyperthyroidism in 10.11%, primary hyperparathyroidism in 1%, secondary hyperparathyroidism in 6%, hypercalciuria in 21.63%, glucocorticoid use in 8.43%, and hypogonadism in 9.4% of males. A Z score value of <-1 had a sensitivity of 71.7 % and NPV of 66.2 % in identifying the presence of a secondary contributor in post-menopausal women. The sensitivity and NPV of a similar threshold in men was 59.1 and 40 %, respectively. ROC curves used to investigate various Z score diagnostic thresholds for sensitivity and specificity showed that they provided poor predictive value for the presence of secondary osteoporosis.

CONCLUSION

Secondary contributors are common in our patients with osteoporosis. Z score diagnostic thresholds have only limited value in discriminating between primary and secondary osteoporosis.

Premenopausal women with idiopathic low-trauma fractures and/or low bone mineral density

INTRODUCTION

In men, idiopathic osteoporosis (IOP) is often associated with low serum insulin-like growth factor (IGF-1) and reduced bone formation. The characteristics of premenopausal women with IOP are not well defined. We aimed to define the clinical, reproductive, and biochemical characteristics of premenopausal women with unexplained osteoporosis.

METHODS

This is a cross-sectional study of 64 women with unexplained osteoporosis, 45 with fragility fractures, 19 with low bone mineral density (BMD; Z-score less than or equal to -2.0) and 40 normal controls. The following are the main outcome measures: clinical and anthropometric characteristics, reproductive history, BMD, gonadal and calciotropic hormones, IGF-1, and bone turnover markers (BTMs).

RESULTS

Subjects had lower BMI and BMD than controls, but serum and urinary calcium, serum estradiol, vitamin D metabolites, IGF-1, and most BTMs were similar. Serum parathyroid hormone (PTH) and the resorption marker, tartrate-resistant acid phosphatase (TRAP5b), were significantly higher in both groups of subjects than controls and directly associated in all groups. Serum IGF-1 and all BTMs were directly associated in controls, but the association was not significant after controlling for age. There was no relationship between serum IGF-1 and BTMs in subjects. There were few differences between women with fractures and low BMD.

CONCLUSIONS

Higher serum TRAP5b and PTH suggest that increased bone turnover, possibly related to subclinical secondary hyperparathyroidism could contribute to the pathogenesis of IOP. The absence of differences between women with fractures and those with very low BMD indicates that this distinction may not be clinically useful to categorize young women with osteoporosis.

Abnormal bone microarchitecture and evidence of osteoblast dysfunction in premenopausal women with idiopathic osteoporosis

CONTEXT

Idiopathic osteoporosis (IOP) in premenopausal women is an uncommon disorder of uncertain pathogenesis in which fragility fractures occur in otherwise healthy women with intact gonadal function. It is unclear whether women with idiopathic low bone mineral density and no history of fragility fractures have osteoporosis.

OBJECTIVE

The objective of the study was to elucidate the microarchitectural and remodeling features of premenopausal women with IOP.

DESIGN

We performed transiliac biopsies after tetracycline labeling in 104 women: 45 with fragility fractures (IOP), 19 with idiopathic low bone mineral density (Z score ≤-2.0) and 40 controls. Biopsies were analyzed by two-dimensional quantitative histomorphometry and three-dimensional microcomputed tomography. Bone stiffness was estimated using finite element analysis.

RESULTS

Compared with controls, affected women had thinner cortices; fewer, thinner, more widely separated, and heterogeneously distributed trabeculae; reduced stiffness; and lower osteoid width and mean wall width. All parameters were indistinguishable between women with IOP and idiopathic low bone mineral density. Although there were no group differences in dynamic histomorphometric remodeling parameters, serum calciotropic hormones, bone turnover markers, or IGF-I, subjects in the lowest tertile of bone formation rate had significantly lower osteoid and wall width, more severely disrupted microarchitecture, lower stiffness, and higher serum IGF-I than those in the upper two tertiles, suggesting that women with low turnover IOP have osteoblast dysfunction with resistance to IGF-I. Subjects with high bone turnover had significantly higher serum 1,25 dihydroxyvitamin D levels and a nonsignificant trend toward higher serum PTH and urinary calcium excretion.

CONCLUSIONS

These results suggest that the diagnosis of IOP should not require a history of fracture. Women with IOP may have high, normal or low bone turnover; those with low bone turnover have the most marked deficits in microarchitecture and stiffness. These results also suggest that the pathogenesis of idiopathic osteoporosis is heterogeneous and may differ according to remodeling activity.

Individual trabeculae segmentation (ITS)-based morphological analysis of high-resolution peripheral quantitative computed tomography images detects abnormal trabecular plate and rod microarchitecture in premenopausal women with idiopathic osteoporosis

Idiopathic osteoporosis (IOP) in premenopausal women is a poorly understood entity in which otherwise healthy women have low-trauma fracture or very low bone mineral density (BMD). In this study, we applied individual trabeculae segmentation (ITS)-based morphological analysis to high-resolution peripheral quantitative computed tomography (HR-pQCT) images of the distal radius and distal tibia to gain greater insight into skeletal microarchitecture in premenopausal women with IOP. HR-pQCT scans were performed for 26 normal control individuals and 31 women with IOP. A cubic subvolume was extracted from the trabecular bone compartment and subjected to ITS-based analysis. Three Young's moduli and three shear moduli were calculated by micro-finite element (microFE) analysis. ITS-based morphological analysis of HR-pQCT images detected significantly decreased trabecular plate and rod bone volume fraction and number, decreased axial bone volume fraction in the longitudinal axis, increased rod length, and decreased rod-to-rod, plate-to-rod, and plate-to-plate junction densities at the distal radius and distal tibia in women with IOP. However, trabecular plate and rod thickness did not differ. A more rod-like trabecular microstructure was found in the distal radius, but not in the distal tibia. Most ITS measurements contributed significantly to the elastic moduli of trabecular bone independent of bone volume fraction (BV/TV). At a fixed BV/TV, plate-like trabeculae contributed positively to the mechanical properties of trabecular bone. The results suggest that ITS-based morphological analysis of HR-pQCT images is a sensitive and promising clinical tool for the investigation of trabecular bone microstructure in human studies of osteoporosis.

Bone microarchitecture and stiffness in premenopausal women with idiopathic osteoporosis

CONTEXT

Idiopathic osteoporosis (IOP) is an uncommon disorder in which low areal bone mineral density (aBMD) and/or fractures occur in otherwise healthy premenopausal women.

OBJECTIVES

Our objectives were to characterize bone mass, microarchitecture, and trabecular bone stiffness in premenopausal IOP and to determine whether women with low aBMD who have never fractured have abnormal microarchitecture and stiffness.

DESIGN, SETTING, AND PATIENTS

We conducted a prospective cohort study of 27 normal controls and 31 women with IOP defined by low trauma fracture (n = 21) or low BMD (Z score <or=-2.0; n = 10).

MAIN OUTCOME MEASURES

We assessed aBMD by dual-energy x-ray absorptiometry; volumetric BMD and cortical and trabecular microarchitecture of the radius and tibia by high-resolution (82 microm) peripheral quantitative computed tomography; and trabecular bone stiffness (elastic moduli), estimated by micro-finite element analysis.

RESULTS

Fracture subjects did not differ from controls by age or body mass index, which was lower in low-BMD subjects than controls. Fracture subjects also had lower aBMD than controls at all sites (P < 0.05-0.0001). Bone size was similar in controls and fracture subjects but 10.6% smaller in low-BMD subjects (P < 0.05). Every trabecular parameter in both fracture and low-BMD groups was markedly worse than controls (P < 0.01-0.0001). Cortical thickness was significantly lower in both fracture and low-BMD groups at the tibia but not radius. Bone stiffness estimated by micro-finite element analysis was comparably reduced in low-BMD and fracture groups.

CONCLUSION

Premenopausal women with IOP had marked trabecular microarchitectural deterioration at the radius and tibia. Cortical parameters were affected only at the tibia. Although they had not fractured, microarchitectural deterioration was similar in IOP women with low BMD and those with fractures.

Clinical characteristics and medication use among premenopausal women with osteoporosis and low BMD: the experience of an osteoporosis referral center

AIMS

Osteoporosis is uncommon in premenopausal women, and most cases have a secondary cause. Women with osteoporosis and no known secondary cause are said to have idiopathic osteoporosis (IOP). We aimed to estimate the proportion of premenopausal women seen in our referral center with IOP as opposed to secondary osteoporosis, to describe their clinical characteristics, to compare women with a low-trauma fracture history with those with low bone mineral density (BMD) alone, and to estimate the frequency of bisphosphonate use.

METHODS

We reviewed medical records from all premenopausal women evaluated for osteoporosis or low BMD in our center during 2005. We included premenopausal women diagnosed on the basis of low-trauma fracture, low BMD or both (Z score < or= -2.0 or T score < or = -2.5), or both.

RESULTS

Among these patients (n = 61; mean age 37 +/- 8), 57 (93%) were Caucasian, 34 (57%) had a family history of osteoporosis, and 26 (43%) had used bisphosphonates. The most common secondary causes were amenorrhea (34%, n = 21), anorexia nervosa (16%, n = 10), and glucocorticoid exposure (13%, n = 8). After exclusion of secondary causes, 39% (24 of 61) of the entire group and 48% (14 of 29) of the fracture group were thought to have IOP. Women with a known secondary cause had lower BMD Z scores at the spine and hip than those with IOP. Women with low BMD and no fractures had shorter stature and weighed less than those with fractures, but overall differences between the groups were not statistically significant. Bisphosphonates had been prescribed for 38% (11 of 29) of women with a fracture history and 47% (15 of 32) of women with low BMD and no fractures.

CONCLUSIONS

Our findings suggest that IOP is common among premenopausal women with osteoporosis or low BMD evaluated at a referral center. The smaller stature of women diagnosed only on the basis of BMD criteria raises the question of whether their areal BMD measurements are spuriously low because of smaller bone size. The high proportion of premenopausal women who had been prescribed oral bisphosphonates for low BMD measurements is of concern, as such women are likely to be at low short-term risk of fracture, and a more conservative approach to therapy is preferable in this group.

Treatment of premenopausal women with low bone mineral density

Interpretation of bone mineral density (BMD) results in premenopausal women is particularly challenging, because the relationship between BMD and fracture risk is not the same as for postmenopausal women. Z scores rather than T scores should be used to define "low BMD" in premenopausal women. The finding of low BMD in a premenopausal woman should prompt an evaluation for secondary causes of bone loss. If a secondary cause is found, management should focus on treatment of this condition. In some cases in which the secondary cause cannot be addressed, such as glucocorticoid therapy or cancer chemotherapy, treatment with a bone-active agent to prevent bone loss should be considered. In women with no fractures and no known secondary cause, low BMD may not signify compromised bone strength. BMD is likely to remain stable in these women, and pharmacologic therapy is rarely justified. Assessment of markers of bone turnover and follow-up bone density measurements can help to identify those with an ongoing process of bone loss that may indicate a higher risk for fracture, and possible need for pharmacologic intervention.

Secondary osteoporosis: a review of the recent evidence

OBJECTIVE

To review several causes of secondary osteoporosis as well as screening recommendations for underlying disorders.

METHODS

We conducted a review of the literature on many of the causes of osteoporosis that have been published during the past 15 years, focusing on those sources available from 2000 through the present. Indeed, more than two-thirds of the articles that we reviewed were printed during the past 6 years. These reports examined secondary osteoporosis in general, as well as many of the specific causes.

RESULTS

Secondary osteoporosis occurs in almost two-thirds of men, more than half of premenopausal and perimenopausal women, and about one-fifth of postmenopausal women. Its causes are vast, and they include hypogonadism, medications, hyperthyroidism, vitamin D deficiency, primary hyperparathyroidism, solid organ transplantation, gastrointestinal diseases, hematologic diseases, Cushing's syndrome, and idiopathic hypercalciuria. These causes have their own pathogenesis, epidemiologic features, and effect on the skeleton.

CONCLUSION

The causes of secondary osteoporosis are numerous, and an understanding of their characteristics with respect to bone density and potential fracture risk is essential in the management of osteoporosis. A heightened awareness of the possibility of their existence is necessary to provide optimal care.

Principais causas de diminuição da massa óssea em mulheres na pré-menopausa encaminhadas ao ambulatório de doenças ósteo-metabólicas de um Hospital Terciário de Curitiba

Selecionamos mulheres pré-menopausadas com redução da DMO encaminhadas ao ambulatório de Metabolismo Ósseo do Hospital de Clínicas da UFPR, com o objetivo de definirmos o perfil destas pacientes em relação aos fatores de risco e prováveis causas secundárias de osteoporose. Trinta e quatro mulheres foram estudadas (1948 anos). Em 29 pacientes (85,3%) a coluna lombar estava acometida, 8 (23,5%) apresentaram Z-score < -2,5 e 21 (61,8%) Z-score entre -1,0 e -2,5. Vinte pacientes (58,8%) apresentaram redução da DMO em fêmur, 2 (6,2%) com Z-score < -2,5 e 18 (56,2%) com Z-score entre -1,0 e -2,5. Causa secundária foi identificada em 26 pacientes (76,5%). Este estudo demonstra que a realização de densitometria óssea é importante em mulheres na pré-menopausa com fatores de risco para redução da massa óssea, uma vez que permite o início precoce do tratamento e a prevenção das complicações relacionadas.

Glucocorticoid-induced osteoporosis and its treatment

Osteoporosis and fractures are frequent and important consequences of glucocorticoid therapy. Many factors contribute to bone loss during glucocorticoid therapy, such as underlying disease, malnutrition, vitamin D insufficiency, hypogonadism, and low body weight. Bone loss occurs particularly in the first few months of glucocorticoid treatment and affects more cancellous than cortical bone, with reduced bone formation and increased bone resorption. The risk of fracture increases rapidly in patients with glucocorticoid therapy. The existence of a threshold is not well defined but the risk of fracture is increased in patients with higher doses of glucocorticoids. Other effects include altered production of gonadal sex hormones, inhibition of intestinal calcium absorption, and enhancement of renal excretion of calcium. Prevention of glucocorticoid-induced osteoporosis is based on general measures such as calcium and vitamin D supplementation, adequate protein intake, regular physical exercise, and specific therapies. Bisphosphonates, which are potent bone resorption inhibitors, have been shown to increase bone mineral density and to decrease fracture risk, so that they represent the first choice in the prevention of glucocorticoid-induced osteoporosis. Glucocorticoid-induced osteoporosis is a major burden to those whom it affects. It can be prevented provided efficacious preventive measures are introduced early during glucocorticoid treatment.

LEVEL OF EVIDENCE

Level V (expert opinion). See the Guidelines for Authors for a complete description of the levels of evidence.

Osteoporosis in otherwise healthy perimenopausal and early postmenopausal women: physical and biochemical characteristics

Population studies have shown that about 3-5% of perimenopausal women already have osteoporosis according to the WHO definition of osteoporosis for postmenopausal women ( t -score<or=-2.5). In general, this bone loss arises from well-characterized diseases or conditions that affect acquisition of peak bone mass and/or the rate of bone loss after peak bone mass has been attained. However, there often remains a subset of these women, with no identifiable cause of bone loss. This group has so far been little studied. We prospectively evaluated a group of 60 perimenopausal and early postmenopausal women (mean age 52.2+/-2.5 years) who were found to have apparently unexplained low bone mass, and we compared them to 120 controls matched for age and menopausal status. These women were extensively investigated, including by detailed questionnaire and laboratory testing. Of the 60 women with osteoporosis, only three were found to have previously undiagnosed disorders (two with subclinical hyperthyroidism and one with elevated serum PTH levels) that might have contributed to their low bone mass. On the other hand, osteoporotic patients were characterized by a significantly lower body weight, higher prevalence of personal and parental histories of fractures and a higher level of bone turnover as assessed by increased serum osteocalcin and bone alkaline phosphatase levels and urinary type I collagen C-telopeptide (CTX) excretion, as compared to controls. These findings support theories of a genetic contribution to osteoporosis and underline the predictive value of a previous history of personal and familial fracture in the identification of osteoporosis in early postmenopausal women.

Effects of coffee consumption and smoking habit on bone mineral density

This study aims to investigate how a person's smoking and coffee consumption habits in the premenopausal stage can affect the postmenopausal BMD values. Two hundred females in the postmenopause stage were evaluated. The average daily coffee consumption and smoking habits in the premenopause stage and the demographic characteristics, age and duration of menopause of all the cases were identified and noted. The bone mineral density (BMD) evaluations of these cases were made with Dual Energy X-ray Absorbsiometer (DEXA) technique. The relationship of the questioned risk factors with BMD and differences among the groups were investigated. No correlation was found between the amount of coffee consumption and BMD. The BMD values of the smokers' group were lower than non-smokers' group. As a result, advancing age, duration of menopause and smoking habits have been identified to be risk factors in relation to OP.

Idiopathic osteoporosis in premenopausal women

Although osteoporosis predominantly affects older postmenopausal women, low bone mineral density also occurs in men and younger women. In men, it is often unexplained by recognized secondary causes. These men with idiopathic osteoporosis have reductions in serum IGF-I as well as indices of reduced bone formation. Younger women also experience bone loss of unknown etiology (IOP). Whether premenopausal women with IOP have similar decreases in IGF-I levels and reduced indices of bone formation is unknown. We prospectively evaluated a group of premenopausal women with unexplained low bone mass and compared them to normal premenopausal women with respect to serum concentrations of IGF-I. Thirteen premenopausal women (34.2+/-2.3 years) with low bone density (mean lumbar spine T-score -2.26+/-0.20) were compared with 13 premenopausal women (35.7+/-1.7 years) with normal bone density of similar age, height and ethnic composition. Body mass index (BMI) was lower in subjects than controls (20.5+/-0.7 versus 25.2+/-1.1 kg/m(2), P<0.01). A family history of osteoporosis and a history of fragility fractures were found more frequently in subjects than controls (P< or =0.05). Calciotropic hormones did not differ between the two groups. In contrast to our observations in men with idiopathic osteoporosis, mean serum IGF-I concentrations did not differ between subjects and controls (subjects: 22.5+/-2.2 nmol/l versus controls: 20.8+/-1.6 nmol/l; NS). Moreover, serum IGF-I levels did not correlate significantly with serum estradiol or with BMD at either the lumbar spine or femoral neck. However, lower follicular phase serum estradiol levels among non-oral contraceptive users were found in subjects as compared to controls (subjects: 124.1+/-13 pmol/l versus controls 194.9+/-24 pmol/l, P=0.06). Calculated free, bioavailable estradiol levels were significantly lower overall in subjects than controls (0.6+/-0.1 versus 1.2+/-0.2 pmol/l, P<0.05). Total serum estradiol levels correlated with BMD at the femoral neck (r=+0.50; P<0.05). Free, bioavailable estradiol correlated with BMD and BMAD at the lumbar spine (r=+0.54, P<0.01 and r=+0.54, P<0.05, respectively) and femoral neck (r=+0.60 and r=+0.55 respectively, both P<0.01). Urinary NTX excretion, although within the normal premenopausal range, was 45% higher in subjects than controls (41.6+/-5.9 nmol BCE/l versus 28.3+/-2.4 nmol BCE/l; P<0.05). Bone-specific alkaline phosphatase activity was also higher (17.4+/-1.6 ng/ml versus 14.7+/-0.8 ng/ml), although the difference was not statistically significant. These results suggest differences in the pathogenesis of idiopathic osteoporosis in women as compared to men with IOP.

Treatment of low bone mass in premenopausal women: when may it be appropriate?

The diagnosis and treatment of osteoporosis in postmenopausal women has been well defined. Criteria for making a diagnosis using bone density testing has been established and widely disseminated. However, the definition established by the World Health Organization for osteoporosis cannot be used for other populations such as premenopausal women without further study. Measuring bone mass in premenopausal women should be done infrequently and only if specific and significant risk factors are present. Premenopausal women have a low risk for fracturing but women with low bone mass are at a greater risk for developing fractures before and after menopause. The major reason for low bone mass is the failure to reach peak bone mass because of genetic influences, although some environ-mental factors may also play a role. Hormonal therapy for hypogonadism, treatment of diseases such as hyperpara-thyroidism, and keeping medications with detrimental effects on bone to a minimum are important components of treatment. Pharmacologic treatment of low bone mass in premenopausal women has not been well studied although on rare occasions it may be appropriate in women with low bone mass, defined as a Z score of -2 or less, and the presence of other diseases or risk factors. Caution is urged because of the unknown effects of treatment in this population. Further study of the implications of low bone mass and the effects of treatment in this group of women is needed.

Ipriflavone modulates IGF-I but is unable to restore bone in rats

Previously it has been reported that ipriflavone can prevent bone loss in ovarian hormone deficient rats. The present study evaluated whether ipriflavone was able to restore bone mass in osteopenic ovariectomized rats. Seventy-two, 90 day-old Sprague-Dawley rats were divided into six groups (sham two groups; ovariectomized four groups). Thirty-five days from the date of surgery, one sham and one ovx group were killed to verify the occurrence of bone loss. The remaining four groups were sham, ovx, ovx + ipriflavone (100 mg[sol ]kg body weight per day), or ovx + 17beta-estradiol (10 microg[sol ]kg body weight daily) for a period of 65 days. Ipriflavone was ineffective in restoring bone density and unlike estrogen did not prevent bone resorption as evidenced by increased (p < 0.05) urinary excretion of hydroxyproline and serum tartrate-resistant acid phosphatase activity. Ipriflavone increased (p < 0.05) the expression of IGF-I in the femur. These observations suggest that higher doses of ipriflavone or longer-term studies may be necessary to restore bone mass.

Discrepant areal and volumetric bone density measurements in a young woman with idiopathic low bone mineral density

OBJECTIVE

To discuss a case of idiopathic low bone density in a young woman.

METHODS

We present a detailed report that includes clinical, laboratory, and radiologic assessment of a pre-menopausal woman with idiopathic low bone mass.

RESULTS

A 34-year-old healthy woman of small body habitus was found by dual-energy x-ray absorptiometry to have bone mineral density (BMD) that was less than 2.5 standard deviations below the young and age-matched norm. After a thorough evaluation, no cause of osteoporosis was identified. Calculation of bone mineral apparent density, which minimizes the effect of small skeletal size on areal BMD, resulted in only a modest improvement in T-scores. Measurement of lumbar spine volumetric BMD by quantitative computed tomography, however, revealed a significantly improved T-score of -1.6.

CONCLUSION

This report highlights the complexities of low BMD measurements in otherwise healthy young women as well as the potential application of bone mineral apparent density and quantitative computed tomography in the evaluation of low BMD in young women with small skeletal frames.

The temporal reliability of serum estrogens, progesterone, gonadotropins, SHBG and urinary estrogen and progesterone metabolites in premenopausal women

BACKGROUND: There is little existing research to guide researchers in estimating the minimum number of measurement occasions required to obtain reliable estimates of serum estrogens, progesterone, gonadotropins, sex hormone-binding globulin (SHBG), and urinary estrogen and progesterone metabolites in premenopausal women. METHODS: Using data from a longitudinal study of 34 women with a mean age of 42.3 years (SD = 2.6), we calculated the minimum number of measurement occasions required to obtain reliable estimates of 12 analytes (8 in blood, 4 in urine). Five samples were obtained over 1 year: at baseline, and after 1, 3, 6, and 12 months. We also calculated the percent of true variance accounted for by a single measurement and intraclass correlation coefficients (ICC) between measurement occasions. RESULTS: Only 2 of the 12 analytes we examined, SHBG and estrone sulfate (E1S), could be adequately estimated by a single measurement using a minimum reliability standard of having the potential to account for 64% of true variance. Other analytes required from 2 to 12 occasions to account for 81% of the true variance, and 2 to 5 occasions to account for 64% of true variance. ICCs ranged from 0.33 for estradiol (E2) to 0.88 for SHBG. Percent of true variance accounted for by single measurements ranged from 29% for luteinizing hormone (LH) to 92% for SHBG. CONCLUSIONS: Experimental designs that take the natural variability of these analytes into account by obtaining measurements on a sufficient number of occasions will be rewarded with increased power and accuracy.

Clinical characteristics and etiologic factors of premenopausal osteoporosis in a group of Spanish women

OBJECTIVES

To analyze the clinical characteristics and the principal causes of osteoporosis in premenopausal women.

METHODS

This study included 52 osteoporotic premenopausal women ages 20-51 years (mean 36.2 +/- 7) who were referred to an outpatient rheumatology department for osteoporosis evaluation. Bone mass assessment, automated biochemical profile, urinary calcium excretion, and bone marker assays were performed on all patients. Hormonal measurements were made when a specific etiology was not readily apparent. The diagnosis of osteoporosis was defined by the presence of atraumatic vertebral fractures and/or by densitometric criteria. Previous skeletal fractures, weight, height, body mass index (BMI), age at menarche, and family history of osteoporosis also were recorded.

RESULTS

Twenty-nine patients (56%) had idiopathic osteoporosis and 23 (44%) had secondary osteoporosis. Fifteen patients (29%) had vertebral fractures and 12 had previous peripheral fractures. Patients with secondary osteoporosis showed higher BMI (23.2 +/- 3 v 21.2 +/- 2, P =.02) and lower femoral Z-scores of bone mineral density (BMD) (-2.1 +/- 0.6 v -1.5 +/- 0.9, P =.02) than those with idiopathic disease. The most frequent causes of secondary osteoporosis included Cushing syndrome, pregnancy osteoporosis, and osteogenesis imperfecta. Nearly half of the patients (48%) with idiopathic osteoporosis had a family history of osteoporosis. In addition, 11 patients (38%) with idiopathic osteoporosis had associated hypercalciuria. Except for an increase in urinary calcium excretion (248 +/- 53 v 143 +/- 47 mg/24 h, P <.0001), no other significant differences in the remaining variables analyzed were found between hypercalciuric and normocalciuric patients with idiopathic osteoporosis.

CONCLUSIONS

Idiopathic osteoporosis was the most frequent diagnosis of pre-menopausal osteoporosis in our unit. These patients showed lower BMI and higher femoral neck Z-scores than patients with secondary causes. A family history of osteoporosis and hypercalciuria were factors frequently associated with this disorder.

Genetic and environmental factors affect bone density variances of families of men and women with osteoporosis

Our aim was to assess the relative impacts of genetics and environment in the families of osteoporotic patients and identify the best subgroup of patients to investigate the genes associated with osteoporosis. We recruited 36 men and 47 women with osteoporosis (probands), median age of 52 and 68 yr, and all their siblings (90) and offspring (83). The families were classified as young or old on the basis of the median age of the probands. We measured the bone mineral density at the femoral neck (FN) and lumbar spine (LS) adjusted for age and weight and standardized (Z-score). Physical activity, nutritional calcium, and alcohol and tobacco consumption were investigated. We compared the mean Z-score using linear mixed model and assessed the familial resemblance using intraclass correlation. The mean Z-scores of the families of osteoporotic patients were significantly negative at FN and LS, with no intergeneration or intergender differences. At FN, but not at LS, the mean Z-score was independently lower in the families of male probands (mean +/- SD: -0.57 +/- 0.96, female: -0.18 +/- 0.85, P = 0.012) and in young families (-0.58 +/- 0.94, old families: -0.11 +/- 0.83, P = 0.006). This suggested that the lower Z-score in the families of men with osteoporosis was related to their younger age. There was significant phenotypic resemblance among members in the families. In the families of female probands, the correlation between the probands and her siblings was weak and disappeared after adjustment on environment, and a resemblance appeared within their children (FN: r = 0.61) suggesting that different environment had masked the resemblance in this subgroup. In the families of male probands, a strong resemblance persisted after adjusting for environment, (proband-offspring at FN: r = 0.46 and within offspring at FN: r = 0.66, at LS: r = 0.61). This showed that resemblance was independent of a common measurable environment in these families of men with osteoporosis. In conclusion, mainly young osteoporotic patients, most of whom were male in our study, are affected by the genetic component.