Higher Bone Mineral Content Research Articles

Effect of bone density on body composition estimates in young adult black and white women

Bone mineral content (BMC) and density (BMD) by dual x-ray absorptiometry, total body water (TBW) by the deuterium oxide (D2O) dilution technique, and body density (Bd) by hydrostatic weighing were measured in 26 black (B) and 26 white (W) young adult women. Both groups were similar in age, height, weight, and total skinfolds; however, black subjects had significantly higher BMC and BMD. Formulas to estimate percent body fat (%BF) from Bd included Siri's two-component equation for the reference man, which assumes a fat free body density (FFBd) of 1.100 g.ml-1, and an adjusted two-component formula that assumes a lower FFBd of 1.095 g.ml-1. Percent body fat was also predicted from TBW and by several multicomponent models that corrected for individual subject variation in measured BMC and TBW. The two groups did not differ significantly in %BF predictions by any of the methods. However, the difference in %BF between the groups was halved with the four-component model (B = 21.9%; W = 23.6%) as compared with that calculated from the Siri two-component densitometric model (B = 21.2%; W = 24.2%). Within each racial group, %BF was not significantly different when predicted by two-component or multicomponent models. However, %BF of individuals with the highest and lowest BMD was substantially under- and overpredicted, respectively, by Siri's equation.(ABSTRACT TRUNCATED AT 250 WORDS)

Fracture risk as determined by prospective and retrospective study designs.

Both retrospectively and prospectively designed studies consistently show low bone mass and/or bone mineral content (BMC) to be risk factor for low-trauma fractures in postmenopausal women. Along with the reports of such studies there has been concern expressed that BMC measurements overlap between fracture groups, i.e., some women with high BMC develop fractures and some women with low BMC do not. In these commonly used epidemiologic study designs, BMC does not discriminate between those who have and have not experienced the untoward event at some level of the exposure factor. The ability to discriminate is more properly determined by the sensitivity and specificity of the measured value. To contrast the concepts of risk and sensitivity, a nested case-control study was conducted within a 24-year cohort study of women at risk for osteoporosis. We found that for each 1.0 decrement of BMC z-scores, the adjusted relative risk for the prospective study design was 1.67, while the odds ratio obtained from the most recent BMC z-score measurements was 1.87. A receiver operating characteristic (ROC) curve, calculated from the nested case-control study data, showed that BMC z-scores, measured after low-trauma fracture, have both low sensitivity and low specificity to detect existing fracture status.

Dietary Calcium and Bone Mineral Status of Children and Adolescents

We studied 164 healthy, white children aged 2 to 16 years; there were 88 boys and 76 girls. By the method of single photon absorptiometry, we found that age, height, and weight correlated positively with bone mineral content of the radius bone. In the children's diet, most of those aged 2 to 11 years met the recommended dietary allowance (800 mg daily) for calcium. Children older than 11 years had low dietary calcium intake; only 15% met the recommended dietary allowance for calcium (1200 mg daily). Dietary calcium intake was associated with bone mineral status. Children ingesting more than 1000 mg of calcium daily had higher bone mineral content than those ingesting less. Almost all serum determinations of calcium, phosphate, magnesium, alkaline phosphatase, parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D were within normal limits and had no correlation with children's bone mineral status.

Bone Mineral Content at Three Sites in Normal Perimenopausal Women

Bone mineral content (BMC) in 217 healthy white women between the ages of 40 and 55 years was measured using single- and dual-photon absorptiometry. The sites measured included the distal radius, midradius, proximal femur, and lumbar spine. The relationship between BMC and age was constant over the age range studied when the confounding effect of menopause was controlled. Women with low body mass indices (BMIs) had significantly lower BMC than women with average or greater than average BMIs. More active women had higher BMC than less active women at both appendicular and axial sites. A trend suggesting that women with higher calcium intake may have higher BMC was statistically significant only at the midradial site. A trend of postmenopausal women having lower BMC than pre- or perimenopausal women was also statistically significant only at the midradial site. Only modest correlations were found between the various sites. These correlations are too weak to allow accurate clinical predictions of BMC at axial sites from the BMC at an appendicular site in individual patients.

Forearm Bone Mineral Content in Relation to age and the Menopause. A Study of Chinese Han Women and Italian Women

Summary Forearm bone mineral content was estimated in 226 Chinese Han women and I15 Italian women. The Chinese women aged 3 1-50 years had a higher bone mineral content than the Italian women, but in the Chinese women over 50, the bone mineral content decreased much more markedly than in the Italian women. The onset of a decrease in bone mineral content was clearly (P<O.Ol) associated with the menopause in both groups of women, but on average the loss in Chinese women started 4 years after the menopause, whilst in Italian women it started a year after the menopause. The possible reasons for these differences are discussed.

Walking Habits and Health-Related Factors in a 70-Year-Old Population

Walking and other physical activities were studied in a representative population sample of 619 70-year-old people in the city of Gothenburg, Sweden. Walking was the most common physical activity declared, and two thirds of those without an obvious disability walked 30 min or more every day. Subjects who took a daily walk of at least 30 min had a significantly better climbing capacity, higher bone mineral content and lower concentration of blood triglycerides than subjects who walked less. Male 'walkers' had a significantly larger lung volume than 'non-walkers'. Walkers had a more positive attitude towards physical activity as well as a higher estimation of their own physical fitness than non-walkers.

Longitudinal study of bone mineral content in the lumbar spine, the forearm and the lower extremities after spinal cord injury

Bone mineral content (BMC) of the lumbar spine, femoral neck and shaft, and proximal tibia was measured by dual photon absorptiometry in six men and two women after traumatic spinal cord injuries. In six of these patients, BMC of the distal forearm was measured as well. The patients were 18-49 years old at injury and had complete motor lesions from C7 to L1. All but one had some spasticity, and they all used a wheelchair. The initial BMC measurements were carried out from 9-167 days (median 43) post-injury and followed up by 5-13 (median 8) measurements up to 31-53 months (median 41) after the injury. BMC of the lumbar spine and distal forearm remained nearly unchanged in the whole period, and the measurements were within the normal range, except for the lumbar spine when Harrington rods in the scanned area induced high BMC values. In the lower extremities the BMC decreased after injury. New steady-state levels for BMC were reached at 2 years post-injury for the proximal tibia and the femoral neck at 40-50% and 60-70% respectively of normal values. For the femoral shaft the decrease in BMC was more slow and it seems that a steady-state was not reached within our observation period for several of the patients. This longitudinal study indicates, in agreement with a previous cross-sectional study, that normal muscle function and load bearing is necessary to prevent bone loss.

Predicting fractures in women by using forearm bone densitometry

In 1,076 women the forearm bone mineral content (BMC) had been measured with single photon gamma absorptiometry (SPA) 10-16 years ago. The incidence of fractures incurred in the ensuing years (1975-1985) was recorded. The BMC had been significantly less in those women who were to have the types of fractures that are related to bone fragility but only in women measured during the first post- menopausal decades. From age 50-69, diminished BMC at the distal forearm site was associated with a threefold increase of relative risk whereas at the proximal site there was about a sixfold increase in relative risk. This association was not evident in the population over 70 years of age because of a high frequency of fractures (mostly of the spine) in subjects with relatively high BMC values. Body weight and grip strength were significantly lower in the fracture group over 70 years of age.

Functional biomechanics of the thoracolumbar vertebral cortex

Studies were conducted on human cadaver thoracolumbar vertebrae, at the T 12−L 5 level, of five males and six females. Isolated vertebral bodies, free of posterior elements, were first scanned using dual photon absorptiometry and then underwent axial compressive loading. All of the vertebral bodies failed as a result of compressive fractures of the bone. Results indicated that the mechanical load-deflection response was non-linear and biphasic. The mean cross-sectional areas of the vertebral bodies progressively increased from L 1, to L 5. The maximum load carrying capacity was not dependent upon spinal level. The bone mineral content (BMC) obtained using dual photon absorptiometry in the lateral projected plane increased from L, to L5. Male vertebral bodies consistently had higher BMC than female specimens. The cortical shell contributed 12·44% (mean) of the total cross-sectional area in the male, 17·56% in the female; 8·85% of the BMC in the male and 1654% in the female. In contrast, it accounted for 43·8% (mean) of the total load in the male compared to 35·2% in the female specimens. Mean failure loads of decorticated vertebrae were significantly lower ( p<0.001) when compared with that of the adjacent intact vertebral bodies. In one osteoporotic spine, the cortical shell accounted for 74% of the total strength. The anatomical placement of the thin shell which enables it to act as an encasing element to resist the collapse of the trabeculae under compression, and the difference in rigidity of the two structural components, and their differing sensitivity to metabolic influences, seem to explain this relatively high magnitude of load absorption in spite of its limited contribution to vertebral geometry.

Differential effects of thiazide and estrogen upon bone mineral content and fracture prevalence

Individual and combined effects of thiazides and estrogens upon bone mineral content at four sites (proximal radius, distal radius, os calcis, lumbar spine) and fracture prevalence were assessed retrospectively in 993 postmenopausal women. Compared with untreated women, use of thiazide alone was associated with significantly higher bone mineral content (P less than or equal to .01); nonspine fracture prevalence in this group was reduced by one-half (P = .07). Estrogen alone also was associated with significantly higher bone mineral content (P less than or equal to .0001); nonspine fracture prevalence was reduced by almost one-half (P = .07). The users of both estrogen and thiazide had the highest bone mineral content levels, which were significantly different than the thiazide-only group at four bone sites (P less than or equal to .001), and the estrogen-only group for three bone sites (P less than or equal to .05). Nonspine fracture prevalence for the users of both drugs was 17% that of the untreated group (P = .02). The relationships with spine fracture prevalence were less consistent; however, estrogen users appeared to have a lower spine fracture prevalence rate and higher spinal bone mineral content than thiazide users. These findings suggest a potential role for thiazides in the prevention of osteoporosis.

Effects of soy formulas on mineral metabolism in term infants.

We studied 40 healthy term infants who received a soy-based formula containing either a single carbohydrate (glucose polymers) or dual carbohydrates (glucose polymers and sucrose). Ten exclusively breast-fed infants served as controls for the first four months of the study. All infants were studied at 2 weeks, 2 months, and 4 months of age for anthropometric development, biochemical values, and bone mineral content. There were no differences among the three groups in weight, length, or head circumference gains. Serum levels of calcium, phosphorus, magnesium, copper, 25-hydroxycholecalciferol, and alkaline phosphatase were also similar. However, at 4 months of age, the breast-fed group had a higher plasma zinc level than both formula-fed groups, and at 2 and 4 months of age, it had higher bone mineral content and bone density.

3 CALCIUM AND BONE MINERAL STATUS OF LACTATING TEENS CONSUMING VARIOUS CALCIUM INTAKES

Lactating adolescent mothers have been shown to have decreased bone mineral content (BMC). The present study was to evaluate an increased dietary calcium (Ca) intake on the Ca and BMC of lactating teens. Three groups of women were studied: 14 adolescent (Low Adol) consuming 900 mg Ca (56% RDA), 20 adolescents (High Adol) consuming 1600 or 2000 mg (100 or 125%, RDA), and 12 adults consuming 1200 mg (100% RDA). All lactating subjects were studied at 2, 8 and 16 wks postpartum. Serum Ca, phosphorus, magnesium, alkaline phosphatase, 25-OH vitamin D parathyroid hormone (PTH), calcitonin (CT) and albumin remained normal for all 3 groups. By 16 wks, the CT levels were higher in the Low Adol group compared to the High Adol and adult groups (13.78±5.06, M±SD vs 9.94±8.12, 9.13±3.87 pg/ml, p<.05). PTH and CT levels increased during lactation for the Low Adol while the other 2 groups remained unchanged. BMC was similar at 2 wks, but after 16 wks, the Low Adol group had a decrease in BMC of 10% (p<.05). This was significantly different than the High Adol and adult groups which maintained their BMC. All adol dietary Ca and P intakes were correlated with changes in their BMC during lactation (r= 0.45, p<0.01 for Ca; r=0.47, p<.01 for P). By 16 wks, the adult group had a higher BMC than either the Low Adol (1.003 vs 0.866, p<.01) or the High Adol (0.899, p<.02) groups. These results suggest that bone loss during lactation for teens is accompanied by increased PTH and CT levels and that a high Ca intake appears to protect against this bone loss.

Is Parathyroidectomy of Benefit in Primary Hyperparathyroidism?

A retrospective survey was performed on 265 patients with primary hyperparathyroidism who had received three forms of treatment on a non-randomised basis. 'Successful' surgery (normalisation of serum calcium) was carried out in 142 patients, 'unsuccessful' surgery (persistence of hypercalcaemia after neck exploration) in 33 and no surgery in 90. Patients subjected to surgery were significantly younger than patients in the unoperated group and their serum calcium values at the time of decision were approximately 10 per cent higher. The mean follow-up period was significantly longer in the operated groups. The percentages of patients who had died were similar in each group. Clinical events relating to renal stones depended on the presence or absence of calculi at the time of decision rather than on the method of treatment. At the time of follow-up the prevalence of hypertension, renal impairment and vertebral crush fractures were similar in all three groups. Forearm osteo-densitometry showed a higher bone mineral content in the 'successful' group than in the other two groups. In spite of the selection bias inherent in a study of this kind, it is clear that untreated hyperparathyroidism is compatible with long survival and a lack of demonstrable deleterious effects on kidney and bone.

Osteoarthrosis: Sex‐specific relationship to osteoporosis

Examination of an Eskimo skeletal series demonstrated at least two etiologically distinct groups of joint deterioration divided along sex lines. Low bone mineral content (BMC) among women and high BMC among men were associated with osteoarthrosis on the tibial plateau. This finding contradicts conventional wisdom based on clinical observation, which suggests that reduced skeletal mass prevents osteoarthrosis.

Use of bone mineral content determination in the evaluation of osteodystrophy among hemodialysis patients.

During a period of 2 years, bone mineral content (BMC) was measured regularly in patients undergoing regular dialysis treatment (RDT). Low BMC values were found to be correlated to long duration of uremia, raised alkaline phosphatase activity, hyperaluminemia, hypermagnesemia, hypophosphatemia and clinical osteodystrophy. High levels of BMC loss were found among patients with relatively high initial BMC levels and severely calciopenic patients actually gained bone density during the investigation. Serum alkaline phosphatase activity and serum immunoreactive parathyroid hormone (PTH) levels were positively related to bone loss. It is suggested that the low BMC among RDT patients is caused by a predialytic loss that is arrested by entrance into a dialysis programme. Investigations using BMC or total body calcium as a measure of therapeutic effect must take account of this. The role of hypermagnesemia and hyperaluminemia remains undefined. Patients with BMC reduced below ca. 80% of normal may be candidates for treatment with active vitamin D metabolites.

Growth and bone mineralization of normal breast-fed infants and the effects of lactation on maternal bone mineral status

To determine if human milk provides for adequate growth and bone mineralization during the lst yr of life, 91 term infants were evaluated. Infants were divided into three groups human milk alone, human milk with supplemental vitamin D, and Similac. Lactating mothers who were receiving supplements of calcium and vitamin D were also studied to determine the effects of lactation on their bone mineral status. Blood was drawn from infants and mothers for measurements of serum calcium, phosphate, alkaline phosphatase, and 25-hydroxyvitamin D. Bone mineral content was measured by photon absorptiometry. Growth was similar between breast-fed and formula-fed infants. Regardless of type of feeding, male infants grew heavier and longer than corresponding female infants. Serum calcium and phosphate levels were similar among the three infant groups: only 25-hydroxyvitamin D levels at 4 months and serum alkaline phosphatase at 2 wk and 6 months of age were different among the three infant groups. Biochemical and vitamin D values were similar among the lactating mothers. There were no differences in infant bone mineral content among the three groups, but male infants had higher bone mineral content than female infants. There were no effects of the duration of lactation of maternal bone mineral content or vitamin D status.

The relation between bone mineral content, experimental compression fractures, and disc degeneration in lumbar vertebrae.

The bone mineral content and the ultimate compressive strength were determined in 109 fresh lumbar vertebrae from 36 different subjects, 31 to 79 years of age. The degree of macroscopic disc degeneration and the types of fracture were determined. Three types of fracture-central, wedge and transverse-were found, but only under magnification and at simultaneous movements of the fracture segment. The central type of fracture was found predominantly in specimens with high bone mineral content surrounded by normal discs. The wedge type of fracture was consistent with lower bone mineral content and more severe disc degeneration.