Bone Mass In Young Adults Research Articles

Birth weight and bone mass in young adults from Brazil

Background Birth weight is positively associated with adult bone mass. However, it is not clear if its effect is already evident in early adulthood. Objective To investigate the association between birth weight, adult body size, the interaction between them and bone mass in young adults. Methods Bone densitometry by DXA was performed on 496 individuals (240 men) aged 23–24 years from the 1978/79 Ribeirão Preto (southern Brazil) birth cohort, who were born and still residing in the city in 2002. Birth weight and length as well as adult weight and height were directly measured and converted to z-scores. The influence of birth weight and length, and adult weight and height on bone area (BA), bone mineral content (BMC) and bone mineral density (BMD) at the lumbar spine, proximal femur and femoral neck were investigated through simple and multiple linear regression models. Adjustments were made for sex, skin color, gestational age, physical activity level, smoking status and dietary consumption of protein, calcium and alcohol. Interaction terms between birth weight and adult weight, and birth length and adult height were tested. Results Men in the highest tertile of birth weight distribution had greater BA and BMC at all three bone sites when compared with their counterparts in the lowest tertiles ( p < 0.008). For BMD, this trend was observed only in the lumbar spine. Adult weight and height were positively associated with BA and BMC at all three bone sites ( p < 0.05). For BMD, these associations were seen for adult weight, but for adult height an association was observed only in the lumbar spine. Birth weight retained positive associations with proximal femur BA and BMC after adjustments for current weight and height. No interaction was observed between variables measuring prenatal growth and adult body size. Conclusion Birth weight and postnatal growth are independent determinants of adult bone mass in a sample of Brazilian adults. This effect is already evident in early adulthood.

Bone mass in young adults with Down syndrome

Down syndrome (DS) is a frequent cause of intellectual disability. With the increasing life expectancy of these patients, concerns have been raised about the risk of osteoporosis. In fact, several investigators have reported a reduced bone mass in DS. However, the results may be confounded by comorbid diseases, and differences in lifestyle habits and body size. Therefore, we planned to determine anthropometric and lifestyle factors influencing bone mineral density (BMD) in young adults with DS. Thirty-nine patients with DS (mean age 26 years) and 78 controls were studied. Areal BMD was measured by dual x-ray densitometry (DXA); volumetric BMD at the lumbar spine and femoral neck was estimated with published formulae. DS patients had lower areal BMD than controls at all regions (spine, hip and total body). Height and projected bone area were also lower. There were no differences between both groups regarding estimated volumetric BMD at the femoral neck. However, spine volumetric BMD was also lower in DS than controls. In multivariate analysis, DS, male sex, little physical activity and low sunlight exposure were associated with lower spine volumetric BMD; on the other hand, fat mass and sunlight exposure were associated with femoral neck volumetric BMD. This study shows that patients with DS had a reduced areal BMD, but it is in part a consequence of the reduced body size, particularly at the femoral neck. Physical activity and sunlight exposure are associated to volumetric BMD and should be stimulated in order to maintain an adequate bone mass in these patients.

Physical activity builds strong bones in children

Osteoporosis is a very important health problem for older adults. It is clear that bone mineral accrual during childhood is important in determining peak bone mass in young adulthood, which, in turn is critical for prevention of osteoporosis later in life as bone mass is lost.In this issue of The Journal, Janz et al evaluate the longitudinal effects of physical activity on bone mass. They found that higher levels of daily physical activity were associated with greater whole body and trochanter bone mass in both boys and girls.It should be clear that physical activity has numerous beneficial effects. Bone health is an important one. Pediatricians must advocate for more physical activity for children in school as well as at home. Osteoporosis is a very important health problem for older adults. It is clear that bone mineral accrual during childhood is important in determining peak bone mass in young adulthood, which, in turn is critical for prevention of osteoporosis later in life as bone mass is lost. In this issue of The Journal, Janz et al evaluate the longitudinal effects of physical activity on bone mass. They found that higher levels of daily physical activity were associated with greater whole body and trochanter bone mass in both boys and girls. It should be clear that physical activity has numerous beneficial effects. Bone health is an important one. Pediatricians must advocate for more physical activity for children in school as well as at home.

Osteoporosis diagnosis and screening

Osteoporosis and osteoporotic fracture are major causes of morbidity and mortality in the United States and worldwide. Nearly half of all women and one quarter of men >50 years of age will experience an osteoporosis-related fracture during their lifetime. The diagnosis of osteoporosis in postmenopausal women and older men can be made definitively by comparing bone mineral density (BMD) measurements from dual-energy x-ray absorptiometry (DXA) to mean peak bone mass in young adults. Efforts to increase access to DXA and improve the sensitivity and specificity of osteoporosis risk assessment instruments may help ensure that individuals with osteoporosis are diagnosed early. The early identification of individuals with low BMD and/or clinical risk factors, accurate diagnosis of osteoporosis and osteopenia, and initiation of appropriate treatment are crucial to reducing the incidence of vertebral and nonvertebral fractures. The World Health Organization is moving toward absolute risk assessment and this may help to better identify patients for screening and treatment in the future.

Bone mass in young adults: relationship with gender, weight and genetic factors

To determine the relationship of the bone mass attained in young adults with anthropometric and genetic factors. Cross-sectional study of normal individuals. We studied 341 healthy subjects between 22 and 45 years of age. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) and correlated with body weight, height and nine polymorphisms in six genes involved in sex steroid metabolism (17-hydroxylase, aromatase and 5-reductase) and activity (oestrogen receptors (ER)-alpha and -beta, and androgen receptor). The BMD was higher in men than in women (spine: 1.048 +/- 0.120 vs. 1.034 +/- 0.112; hip: 0.907 +/- 0.131 vs. 0.822 +/- 0.104 g cm(-2), P < 0.001). However, the difference was due, at least in part, to the larger body size in men and diminished markedly after height adjustment. There was a negative correlation between age and hip BMD. Body weight was the single most influential factor on spine and hip BMD in both sexes, explaining 8-9% of BMD variance. Amongst the genetic factors studied, a common CA repeat polymorphism in ER-beta showed a significant association with BMD in women (P = 0.03 at the spine, and 0.008 at the hip). The relationship between ER-beta genotype and BMD persisted after adjustment by body weight and age, explaining a further 2-3% of BMD variance. Allelic variants of other genes studied were not related with BMD. Body weight and allelic variants of ER-beta are associated with BMD in young adults.

Vitamin D status as a determinant of peak bone mass in young Finnish men.

Severe vitamin D deficiency causes rickets, but scarce data are available about the extent to which vitamin D status determines the development of the peak bone mass in young adults. Our aim was to evaluate the prevalence of vitamin D deficiency [serum 25-hydroxyvitamin D (25-OHD) less than the lower limit of the reference range of 20-105 nmol/liter] and the relationship between vitamin D status and peak bone mass among young Finnish men. A cross-sectional study of determinants of peak bone mass with data on lifestyle factors collected retrospectively was performed in 220 young men, aged 18.3-20.6 yr. One hundred and seventy men were recruits of the Finnish Army, and 50 were men of similar age who had postponed their military service for reasons not related to health. Bone mineral content, bone mineral density, and scan area were measured in lumbar spine and upper femur by dual energy x-ray absorptiometry. Serum 25-OHD concentrations were followed prospectively for 1 yr. In July 2000, only 0.9% of the men had vitamin D deficiency, but 6 months later, in the winter, the respective percentage was 38.9%. After adjusting for age, height, weight, exercise, smoking, calcium, and alcohol intake, there existed a positive correlation between serum 25-OHD and bone mineral content at lumbar spine (P = 0.057), femoral neck (P = 0.041), trochanter (P = 0.010), and total hip (P = 0.025). The correlation coefficients for the bone mineral densities at the four measurement sites were 0.035, 0.061, 0.056, and 0.068, respectively. No correlation was found to scan area. We conclude that vitamin D deficiency is very common in Finnish young men in the winter, and it may have detrimental effects on the acquisition of maximal peak bone mass. As in Finland vitamin D supplementation to infants is now stopped at the age of 3 yr, it can be asked whether at our latitude it should be continued from that age onward, not for the prevention of rickets, but as prophylaxis for osteoporosis.

Lactose malabsorption and intolerance and peak bone mass

Background & Aims: Lactose malabsorption per se is not associated with alterations of bone mineral density (BMD) or calcium intake, but when intolerance symptoms are present a lower calcium intake and reduction of BMD values are evident. The purpose of this study was to evaluate whether lactose intolerance interferes with the achievement of an adequate peak bone mass in young adults. Methods: Of 103 enrolled healthy subjects, 55 proved to be lactose malabsorbers with H2 breath test after lactose administration, and 29 of them experienced intolerance symptoms (diarrhea, abdominal pain, bloating, flatulence). Lumbar and femoral BMD by dual-energy X-ray absorptiometry was measured, and calcium intake and biochemical indices of bone and mineral metabolism were evaluated. Results: Lumbar and femoral BMD, calcium intake, and mineral metabolism did not differ between malabsorbers and absorbers, although among malabsorbers, intolerant subjects showed significant alterations of all these parameters in comparison with tolerant subjects. A strict correlation was evident between BMD values and both severity of symptoms and calcium intake and between calcium intake and severity of symptoms. Conclusions: Lactose intolerance prevents the achievement of an adequate peak bone mass and may, therefore, predispose to severe osteoporosis.GASTROENTEROLOGY 2002;122:1793-1799

Reduced bone mineral density in postmenopausal women self-reporting premenopausal wrist fractures

Postmenopausal fractures are associated with low bone mass; however, the role of low peak bone mass in young adults in determining subsequent osteoporosis suggests that premenopausal fractures may also be relevant. We therefore sought to determine whether a self-reported previous history of premenopausal wrist and nonwrist fractures could also be associated with bone density and therefore be used to predict osteoporosis. We recruited 453 volunteer women with a median age of 64 years (range 50–83 years), with no metabolic bone disease, previous femoral neck fracture, or prevalent vertebral fracture. Bone density at the femoral neck (FN) and lumbar spine (LS) was measured using a Lunar DPX-L. As expected, the 319 women who did not report any fracture had a higher T score at LS (−0.93 ± 1.44) than the 134 women who reported a previous fracture at any site and at any age (T score −1.60 ± 1.21, p < 0.001). The findings for the FN were similar. Compared with fracture-free women, the women who reported a first wrist fracture before menopause now had a lower LS T score (−1.77 ± 1.20, n = 15, p < 0.05), whereas those who reported a nonwrist fracture showed no significant decrease in their LS T score (−1.26 ± 1.00, n = 36). When both wrist and nonwrist fractures had occurred after menopause, the T score was significantly lower. Twenty percent of the fracture-free women were osteoporosis patients. After adjusting for body weight, age, hormonal replacement therapy (HRT), and hip fracture in the family, the relative risk (RR) of osteoporosis for premenopausal wrist fractures was 2.7 (95% confidence interval 1.4–4.3) vs. 1.2 (0.7–2.4) for women with premenopausal nonwrist fractures. We conclude that self-reported premenopausal wrist fractures, but no other fractures occurring before menopause, are likely to be associated with osteoporosis at 65 years of age, and therefore constitute strong grounds for screening.

Weight-bearing physical activity is essential for normal skeletal development during childhood and adolescence and for achieving and maintaining peak bone mass in young adults

Barbara Drinkwater, Ph.D., FACSM, believes that emphasis must be placed on osteoporosis prevention since no therapy is totally effective in treating osteoporosis. Dr. Drinkwater's section is rich in exercise tips for girls and women of all ages. Since we do not know the threshold level of physical activity required to maintain bone nor the amount of activity needed to increase bone mass, she recommends that you encourage clients to engage in a variety of activities—those that develop cardiovascular fitness, strength, balance, flexibility, and include weight-bearing activities.

Osteoporosis: Its pediatric causes and prevention opportunities

Osteoporosis is the most common metabolic bone disease in western societies, and is characterized by a reduction of bone mass leading to the increased susceptibility to fractures. With increases in life expectancy and in the number of elderly people, bone loss and fractures are becoming more common in the United States and throughout the world. As a consequence, an epidemic of bone fractures among the elderly is expected. In this respect, it is obvious that the emphasis should be on the development of strategies for maximizing bone gain and preventing bone loss and subsequent osteoporosis. This paper discusses the concepts that are the foundation for primary prevention of osteoporosis: the measures that should be implemented during childhood and adolescence, with the goal of optimizing bone mass in young adulthood. Some important concepts, such as peak bone mass and calcium intake threshold, as well as the original studies of adolescent females and their bone mass acquisition are presented. It becomes clear that osteoporosis could have its roots during growth, and it should be treated as such. Teenagers should therefore be targeted as a population at risk, and preventive measures should be implemented by means of adequate calcium intake, proper diet, and exercise programs aimed at increasing peak bone mass.

A meta-analysis of the effect of calcium intake on bone mass in young and middle-aged females and males

Evidence of a direct relationship between dietary calcium and bone mass in young adults is inconsistent. Therefore, a meta-analysis was performed to evaluate the existing literature concerning this relation in premenopausal women and adult men between the ages of 18 and 50. A computer-aided search of published papers from 1966 through 1994 was conducted. The quality of each study was assessed by examining the study design. The results of the well-designed studies wer combined to obtain quantitative conclusions. A total of 33 eligible studies were identified in the literature, representing 27 cross-sectional studies, two longitudinal and four intervention studies. The results of the cross-sectional studies in permenopausal females showed a significant correlation coefficient (r = 0.13, 95%-confidence interval = 0.09-0.16) as well as partial correlation coefficient (partial r = 0.08, 95%-confidence interval = 0.05-0.12), both weighted by sample size. The intervention studies found that calcium supplementation of approximately 1000 mg/d in premenopausal women can prevent the loss of 1% of bone/y at all bone site except in the ulna. In conclusion, the studies published to date seem to offer overall evidence that calcium intake is positively associated with bone mass in premenopausal females. This association is fairly consistent across the different study designs and is strengthened by the fact that the results are based only on studies with a high methodological quality. In males, too few studies (only three) were published to draw firm conclusions.

Urinary calcium, sodium, and bone mass of young females

Calcium is an important determinant of peak bone mass in young adults because of its influence on skeletal development during growth. Attainment of maximum peak bone mass requires optimal positive balance between calcium intake and obligatory losses of calcium, primarily in urine and feces. Urinary excretion is an important determinant of calcium retention in the body. Accordingly, the purpose of this study was to evaluate the influence of various nutrients on urinary calcium excretion, and to assess their impact on bone mass of young females, aged 8-13 y, during early puberty. The study was conducted in 381 healthy white females in pubertal stage 2. From each participant we collected basic anthropometric measurements, a 3-d food record, blood, a 24-h urine sample, and bone mass measurements of the total body and forearm by dual X-ray absorptiometry. Urinary sodium was found to be one of the most important determinants of urinary calcium excretion: [urinary calcium (mmol/d) = 0.01154 x urinary sodium (mmol/d) + 0.823], whereas calcium intake had relatively little impact: [urinary calcium (mmol/d) = 0.02252 x calcium intake (mmol/d) + 1.5261]. Urinary calcium was much higher at a calcium intake of approximately 37.5 mmol/d (1500 mg/d), supporting the notion that calcium is a threshold nutrient. Calcium intake had a significant positive influence on the bone mineral content and density of the whole body and radius shaft whereas urinary calcium had a negative influence, presumably by reducing calcium accretion into the skeleton.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone mass is low in relatives of osteoporotic patients.

To determine whether the failure to attain normal bone mass in young adulthood contributes to the later development of osteoporotic fractures. Case-control study. Referral-based bone clinic at a large teaching hospital. Sequential sample of 35 asymptomatic relatives, aged 19 to 59 years, of patients with osteoporotic fractures, and 24 patients with osteoporotic fractures. Bone mineral density in the spine was measured by quantitative computed tomographic scanning. Bone mineral content in the os calcis was measured in 19 of the relatives of osteoporotic patients by single-photon absorptiometry. The values for bone mineral density in the spine were corrected to age 50 years with the regression equation derived from the normal values in the controls. The values were lower in relatives of osteoporotic patients than in controls. In men, the mean values (+/- standard deviation [SD]) for relatives were 91 +/- 16 mg/cm3, and for controls, 129 +/- 21 mg/cm3 (P less than 0.001). In women, the mean values for relatives were 96 +/- 17 mg/cm3 and for controls, 126 +/- 19 mg/cm3 (P less than 0.001). In the osteoporotic patients, the corrected mean value for men was 53 +/- 12 mg/cm3, and for women, 77 +/- 20 mg/cm3. The os calcis values did not correlate with the spine values and were mostly well within the normal range. Mean bone mass is lower in apparently healthy young and middle-aged adult relatives of osteoporotic patients than in normal persons with no family history of osteoporosis. Our findings suggest that the failure to attain an adequate peak bone mass may play an important role in the later development of osteoporotic fractures. Relatives of osteoporotic patients should be advised to have measurements of bone mass taken. This measurement should be taken at the spine, because peripheral sites do not appear to provide adequate information about early osteoporosis.

Bone status and fracture rates in two regions of Yugoslavia

Bone status and fracture rates were evaluated in two Yugoslav populations with very different dietary habits. In district A (Podravina) the daily calcium intake was about twice that in district B (Istra). There were similar but smaller differences in the intakes of other nutrients. In district B metacarpal cortical width was reduced in all age groups of both sexes but the difference tended to decrease with age. The proximal femur fracture rate was higher in district B than district A but there was no difference between the forearm fracture rates in the two districts. Our results confirm that bone mass at any age is clearly the result of age and sex and most probably other genetically determined factors but also show that this expression is nutrition related. The data suggest that nutrition (in particular the calcium intake) is an important determinant of bone mass in young adults but seems to have little effect on age-related bone loss in either males or females. The main determinant of cortical bone mass in the elderly seems to be the cortical bone mass in middle life. The proximal femur fractures of old people reflect declining cortical bone mass but the distal forearm fractures of middle-aged women are unrelated to cortical bone mass or nutritional status.