Quantification of bone mineral contents using dual photon absorptiometry in a normal Japanese population — total body bone mineral

We established reference values for total body bone mineral of normal Japanese subjects utilizing dual photon absorptiometry. The index of measurement, total body bone mineral content (TBBM) divided by lean body mass (LBM), might be suitable for the evaluation of total body bone mineral. TBBM/LBM did not correlate with age in male subjects; however, reduced bone mineral was noted in female subjects after fifth decade. The rate of change in bone after the fifth decade was 0.82% per year. The bone mineral density (BMD) of each region including total body also showed a significant decrease with aging in women after the age of 40. Again no significant age-related changes were obtained in male BMD of any region (head, trunk, pelvis, legs, arms). The annual loss in women after the bone loss began was 0.72% in total body BMD. The rate of BMD change in each region of bone after 40 years of age ranged from 0.91% (trunk) to 0.51% (arms) per year. The bone mineral content (BMC) in “trunk” portion of TBBM decreased significantly with aging, while BMC of other portions did not show a significant age-related change. These results differ slightly from results which we have already reported for lumbar spine BMD, in which case average annual rates of bone loss once begun, were 0.32% for male and 0.97% for female.     

Changes in bone mineral content in the femur following total hip arthroplasty

Bone mineral content (BMC) in the distal end of the femoral shaft was monitored with single-photon gamma-absorptiometry for 72 weeks after surgery in 46 patients with coxarthrosis treated by total hip arthroplasty (THA). After an initial increase, which was greater in men than in women, BMC decreased during the first postoperative year to approximately the initial value in men, whereas in women the final outcome was a 10% net loss. No influence of the type of operation or of the preoperative or postoperative capacity of the patients could be demonstrated. The loss of bone mineral was surprisingly low compared with that noted after other injuries of similar or even less magnitude.     

Changes in bone mineral content during long-term CAPD. Indication of a sex-dependent bone mineral loss

Change in bone mineral content (BMC) was evaluated in a longitudinaltrial comprising 12 women and 11 men with chronic renal diseasetreated with CAPD and 1-alpha-OH-D3 for 2 years. The patientsserved as their own controls. No patients were treated withsteroids. Median age was 54 and 60 years for women and men respectively.No significant difference in 1-alpha-OH-D3 dosage or serum 1,25(OH)₂D3was found between the genders in the study period. Bone mineral content at the distal radius deteriorated significantlyin the females with a median decrease of 12% over 2 years, i.e.approximately 6% per year (P<0.001 and 95% confidence limits8–20%). No significant change was noted in the males.There was no correlation between age and BMC change. Serum total alkaline phosphatase decreased nonsignificantlyin both sexes. Total serum calcium increased significantly (P<0.05)and serum phosphate decreased significantly (P<0.05) in thewomen. Serum albumin and body weight decreased significantlyin the males (P<0.01 and P<0.05) while no change was seenin the females. The demonstrated decrease in BMC in the female patients of approximately6% per year exceeds the commonly observed loss of 1–2%per year in healthy women when measured with the same technique.Tentatively, the severe mineral loss in the women could indicatea sex-hormone-related disturbance in bone metabolism of uraemicfemales.     

A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children: the university of Saskatchewan bone mineral accrual study.

To investigate the influence of physical activity on bone mineral accrual during the adolescent years, we analyzed 6 years of data from 53 girls and 60 boys. Physical activity, dietary intakes, and anthropometry were measured every 6 months and dual-energy X-ray absorptiometry scans of the total body (TB), lumbar spine (LS), and proximal femur (Hologic 2000, array mode) were collected annually. Distance and velocity curves for height and bone mineral content (BMC) were fitted for each child at several skeletal sites using a cubic spline procedure, from which ages at peak height velocity (PHV) and peak BMC velocity (PBMCV) were identified. A mean age- and gender-specific standardized activity (Z) score was calculated for each subject based on multiple yearly activity assessments collected up until age of PHV. This score was used to identify active (top quartile), average (middle 2 quartiles), or inactive (bottom quartile) groups. Two-way analysis of covariance, with height and weight at PHV controlled for, demonstrated significant physical activity and gender main effects (but no interaction) for PBMCV, for BMC accrued for 2 years around peak velocity, and for BMC at 1 year post-PBMCV for the TB and femoral neck and for physical activity but not gender at the LS (all p < 0.05). Controlling for maturational and size differences between groups, we noted a 9% and 17% greater TB BMC for active boys and girls, respectively, over their inactive peers 1 year after the age of PBMCV. We also estimated that, on average, 26% of adult TB bone mineral was accrued during the 2 years around PBMCV.     

Bone mineral content in the senescent rat femur: an assessment using single photon absorptiometry

The single photon absorptiometry technique was evaluated for measuring bone mineral content (BMC) of the excised femurs of the rat, and the system was used to examine the changes in cortical and trabecular bone from young adult (6 mo), mature adult (12 mo), and senescent (24 mo) male and female animals. BMC of the femur midshaft, representing cortical bone, apparently increased progressively with advancing age. The width of the femur at the scan site also increased with age. Normalizing the midshaft BMC by width partially compensated for the age-associated increase. However, when bone mineral values were normalized by the cortical area at the scan site, to take into account the geometric differences in the femurs of different aged animals, maximum bone densities were found in the mature adult and these values decreased slightly in the femurs from senescent rats. In contrast, the BMC of the femur distal metaphysis, representing trabecular bone, decreased markedly in the aged rat. The loss of trabecular bone was also evident from morphological examination of the distal metaphysis. These findings indicated that bone mineral loss with age was site specific in the rat femur. These studies provided additional evidence that the rat might serve as a useful animal model for specific experiments related to the pathogenesis of age-associated osteopenia.     

Age-related changes in bone mineral content and density in intact male F344 rats.

This study was undertaken to determine whether age-related bone loss occurs in intact male F344 rats. Bone loss was assessed in male F344 rats aged 3 to 27 months by scanning different bones using peripheral quantitative computed tomography (pQCT) densitometry. Cancellous and cortical bones were analyzed at the vertebra, proximal tibial metaphysis (PTM), and the neck of the femur. Cortical bone was also analyzed at the tibial and femoral diaphysis and at the tibio-fibula junction. In the vertebra, cancellous bone mineral content (Cn. BMC) did not change significantly with age. Cancellous bone mineral density (Cn. BMD) gradually decreased from 9 months onwards; and at 27 months of age, there was a 29% (p < 0.0001) decrease, when compared with 9-month-old animals. No significant change was observed in cortical bone mineral content (Ct. BMC) and cortical bone mineral density (Ct. BMD) with age. In the PTM, bone loss started to occur after 18 months of age. At 27 months of age, Cn. BMC decreased by 58% (p < 0.0001) and Cn. BMD also decreased by 58% (p < 0.0001). Ct. BMC decreased by 28% (p < 0.0001) in 27-month-old animals, whereas Ct. BMD was not affected by aging. At the tibio-fibula junction, Ct. BMC and Ct. BMD decreased after 18 months of age. At 27 months, Ct. BMC and Ct. BMD had decreased by 8% (p < 0.001) and 3% (p < 0.0001), respectively. Ct. BMC in the tibial diaphysis did not change significantly with age, whereas Ct. BMD decreased by 1% (p < 0.05) at 27 months. In the neck of the femur, Cn. BMC increased up to 24 months of age. Cn. BMD increased up to 18 months of age and decreased by 9% (p < 0.05) at 24 months and 11% (p < 0.001) at 27 months of age when compared with 18-month-old animals. Ct. BMC and Ct. BMD increased with age. In conclusion, although some components of the PTM decreased appreciably with age, in this study, most of the bone parameters analyzed either increased or did not change significantly with age. We conclude that unlike male Sprague Dawley rats, male F344 rats appear not to be a good model for studying age-related bone loss as occurs in aging men.     

Differences in estimates of change of bone accrual and body composition in children because of scan mode selection with the prodigy densitometer.

Girls of age 10-13 yr with Tanner stage I-III maturation status (n = 155) were measured using the Prodigy (GE Lunar) densitometer. Bone area (BA), bone mineral content (BMC), and bone mineral density (BMD) were assessed for the whole body, lumbar spine, and proximal femur using the Thin (T) and Standard (S) scan modes at years 1 and 3 of the study. The differences obtained between the T and S mode at year 1 were 1-2% for the lumbar spine and proximal femur and 5-11% for the whole body. For those girls whose default mode changed from T at year 1 to S mode at year 3, the estimated gain in BA, BMC, and BMD was 3.4%, 7.6%, and 3.1% respectively, lower than that obtained when scanning with the T mode at both times for the whole body. Small changes in magnitude but large intersubject variability were noted in BA, BMC, and BMD of the lumbar spine and proximal femur when scanned with the default mode of T at year 1 and S at year 3 compared to T or S at both years. Errors of this size are comparable to the changes expected with longitudinal intervention studies and are, therefore, clinically relevant.     

Longitudinal Change in Bone Density,Geometry, and Estimated Bone Strength in Older Men and Women From The Gambia: Findings From the Gambian Bone and Muscle Aging Study (GamBAS)

Musculoskeletal aging in the most resource-limited countries has not been quantified, and longitudinal data are urgently needed to inform policy. The aim of this prospective study was to describe musculoskeletal aging in Gambian adults. A total of 488 participants were recruited stratified by sex and 5-year age band (aged 40 years and older); 386 attended follow-up 1.7 years later. Outcomes were dual-energy X-ray absorptiometry (DXA) (n = 383) total hip areal bone mineral density (aBMD), bone mineral content (BMC), bone area (BA); peripheral quantitative computed tomography (pQCT) diaphyseal and epiphyseal radius and tibia (n = 313) total volumetric BMD (vBMD), trabecular vBMD, estimated bone strength indices (BSIc), cross-sectional area (CSA), BMC, and cortical vBMD. Mean annualized percentage change in bone outcomes was assessed in 10-year age bands and linear trends for age assessed. Bone turnover markers, parathyroid hormone (PTH), and 25-hydroxyvitamin D (25(OH)D) were explored as predictors of change in bone. Bone loss was observed at all sites, with an annual loss of total hip aBMD of 1.2% in women after age 50 years and in men at age 70 years plus. Greater loss in vBMD and BSIc was found at the radius in both men and women; strength was reduced by 4% per year in women and 3% per year in men (p trend 0.02, 0.03, respectively). At cortical sites, reductions in BMC, CSA, and vBMD were observed, being greatest in BMC in women, between 1.4% and 2.0% per annum. Higher CTX and PINP predicted greater loss of trabecular vBMD in women and BMC in men at the radius, and higher 25(OH)D with less loss of tibial trabecular vBMD and CSA in women. The magnitude of bone loss was like those reported in countries where fragility fracture rates are much higher. Given the predicted rise in fracture rates in resource-poor countries such as The Gambia, these data provide important insights into musculoskeletal health in this population. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Osteopenia after ankle fractures. The influence of early weight bearing and muscle activity

Fifty-seven patients surgically treated for ankle fractures were followed for two years with bone mineral content (BMC) estimations at various levels of both lower extremities. Maximum BMC reduction was seen four months after operation. Bone mineral was partly regenerated during the remainder of the first year. There was hardly any regeneration during the second year. The persisting bone mineral deficit was between 3.5% and 9% depending on the region measured. BMC changes were minor in the contralateral limb and mainly consisted of a slight gain. During the first six postoperative weeks, patients (1) performed active movements of the ankle and subtalar joints but did not bear weight; (2) wore a plaster of paris cast without bearing weight; or (3) bore full weight in a plaster cast. The bone mineral loss was similar in the three treatment groups.     

Evaluation of densitometric bone-muscle relationships in Crohn's disease

BACKGROUND: Patients with Crohn's disease (CD) are 1.4 to 2.5 times more likely than the normal population to sustain a fracture but the factors involved in the pathogenesis are not clearly understood. Bone mass is affected both by nutrition and by muscular activity. Trauma excepted, the largest voluntary loads on bones come from muscle contraction, not body weight. AIM: To assess the relationship between bone mass (bone mineral content) and muscle mass (lean mass) in CD patients. METHODS: Adult CD patients who had had a whole body, lumbar and hip densitometric evaluation were selected. Information regarding age, gender, weight, duration of CD, age at diagnosis, use of glucocorticoids and disease activity during the year before densitometric evaluation and laboratory parameters were collected. RESULTS: Data from 65 patients (28.8+/-10.6 years, F=44, M=21) were analyzed. Lumbar bone mineral content (BMC), BMC in both hips, total and regional BMC significantly correlated with body weight and total and regional lean mass (LM). In multiple regression analysis, only total LM was shown to be independently associated with lumbar BMC, BMC in both hips and total BMC. LM in upper and lower limbs was shown to be independently associated with BMC in upper and lower limbs, respectively. CONCLUSIONS: These results suggest that muscular mass and activity, rather than overall body weight, are important determinants of bone mass and, hence of bone strength in Crohn's disease. Thus, the management of bone loss in inflammatory bowel disease should address the effects of both nutrition and exercise on muscle mass.     

Age-related differences in total and regional bone mass: A cross-sectional study with DXA in 429 normal women

Total body bone mineral content (TBBMC), total body bone mineral density (TBBMD) and regional bone mineral content (BMC) and density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA) in 429 normal women aged 15–83 years, of whom 242 were premenopausal and 187 postmenopausal. The population was divided into 5-year age groups. In the premenopausal women no changes in TBBMC, TBBMD or regional BMC and BMD were observed with age, and TBBMC and TBBMD values correlated well with body weight (p<0.001). Postmenopausal women showed an overall reduction in bone mass (p<0.001), more marked at the axial level than peripherally (1.6% vs. 0.8%/year). The values of TBBMC and TBBMD correlated well with chronological age, time since the onset of menopause and body weight (p<0.001). In these women age did not correlate with body weight, which suggests that postmenopausal bone mass loss depends more on chronological age and time since the onset of menopause than on other variables. The stability observed in bone mass values from ages 15–19 to menopause highlights the importance of stimulating the acquisition of an appropriate peak bone mass in women before adolescence begins.     

Non-responders to hormone replacement therapy for the prevention of postmenopausal bone loss: Do they exist?

Hormone replacement therapy (HRT) prevents postmenopausal bone loss, but the prevalence of non-responders in healthy early postmenopausal women is not known. In order to study this, we reviewed data from three published studies, each carried out in a randomized, placebo-controlled, longitudinal design over 2 year, that used seven hormone replacement therapies. Bone mineral content (BMC) was measured in the distal forearm by single photon absorptiometry. A mathematical model for elimination of measurement errors was applied to published BMC data. After this correction, we found that only 1.2% of early healthy postmenopausal women who are receiving HRT in conventional doses will lose more than 1% of forearm BMC per year. In conclusion, most, if not all, healthy early postmenopausal women who might need HRT against loss of bone will respond positively in forearm BMC to such therapy.     

Does postmenopausal bone loss respond to estrogen replacement therapy independent of bone loss rate?

Bone loss in postmenopausal women can be treated by hormonal substitution therapy. We investigated whether rapid bone losers (as opposed to nonrapid losers) respond sufficiently to estrogen treatment. A sample of 88 early postmenopausal women was followed up for a 2-year observation period in which bone mineral content (BMC) was followed up every 3 months. From these data, 20 women were classified as rapid losers (bone loss greater than 3% per year) and 68 women as nonrapid losers. The women were allocated to treatment with estradiol in 4, 2, and 1 mg doses daily and followed up for 1 year. The mean response on BMC was dose-dependent, ranging from +1.6% per year with the 4 mg dose to -0.2% per year with the 1 mg dose. In none of the groups was there any difference in response between rapid and nonrapid losers. It is concluded that the BMC loss during observation in some participants (rapid losers) is considerable and that these participants respond in the same manner as nonrapid losers.     

Vertebral Bone Mineral Density, Content and Area in 8789 Normal Women Aged 33–73 Years Who Have Never Had Hormone Replacement Therapy

The vertebral bone mineral density (BMD), bone mineral content (BMC) and bone area of the lumbar spine were measured using a bone densitometer in 8789 women aged 33–73 years who had had no previous hormone replacement therapy (HRT). The overall relationship between BMD and age was analyzed on a year-by-year basis, and comprised three separate regions that could each be described by a straight line: 33–46 years (gradient = 0.00166 g cm⁻²/year), 47–63 years (gradient = 0.0121 g cm⁻²/year) and 64–73 years (gradient = 0.0045 g cm⁻²/year). Above the age of 50 years our results were higher than the BMD in most previous reports. In those 3198 women who knew the time of their last menstrual period (mean age 49.25 years, SD 4.83) bone loss was most rapid in the first 10 menopausal years. In the whole group, the relationship between BMC and age was found to be similar to that of BMD, with three distinct regions, including a rapid drop between the ages of 47 and 63 years (gradient 0.781 g/year). Bone area showed a much more gradual (though significant) decrease with age. Based on WHO definitions and using BMD as an indicator, the percentage of women with osteoporosis varied from zero in the younger age group to about 30% of women aged over 70 years; in contrast, where BMC was used, although the trend with age had a similar shape, the percentages at each year were about half those derived from the corresponding BMD values. Osteopenia derived in the same way occurred in about 50% of women over 70 years using either BMD or BMC. The results presented here provide a reliable local reference range for lumbar spine bone densitometry measurements. They also show that for this site BMD and BMC cannot be used interchangeably to define osteoporosis. Received: 13 March 1998 / Accepted: 23 September 1998     

Bone mineral status of Polish men in the course of normal ageing

Age-related changes in the bone mineral content (BMC) of men are conditioned by both genetic and environmental factors distinctive for particular populations. This results in considerable differences between various populations concerning the prevalence of osteopenia and osteoporosis, and the occurrence of normal variability in BMC among adult and elderly men. The aim of the study was to evaluate the variation of BMC with age in an ethnically homogenous sample of 405 healthy men, aged 20-60 years, all occupationally active inhabitants of the city of Wroclaw, Lower Silesia, Poland. Trabecular and total BMC at the ultradistal radius of the nondominant hand were assessed by peripheral quantitative computerized tomography using the Stratec 960 densitometer. Among Polish men a distinct phase of maximal BMC values (around the age of 30) was distinguished, with a subsequent, quite rapid decline in bone mass. For example, the peak value of trabecular BMC decreased by approximately 13.2% per decade. In Polish men up to 30-34 years old trabecular and total BMC even exceeded reference values by 10%; however, from 35 years onwards their BMC was lower than standard values. This unfavourable phenomenon of BMC decline was augmented with age, and finally BMC values in men aged 55 and over were 30-35% lower than reference values. The significant discrepancies found between the data presented in this study and reference values probably result from inter-populational differences in the lifestyles of healthy ageing men. The results also confirm that bone density (with its age-related changes in the course of normal male ageing) is one of the biological features characteristic of this particular regional population.     

Bone mineral acquisition during adolescence and early adulthood: A study in 574 healthy females 10–24 years of age

Low bone mass is known to be associated with an increased risk of fractures. Osteoporosis prevention by maximizing bone mass will be crucial and requires a better knowledge of bone mass acqusition during adolescence. Bone mass was assessed in 574 healthy volunteer females aged 10–24 years. Spine bone mineral density (BMD) in anteroposterior (AP L2–4) and lateral (LAT L3) views was measured using dual-energy X-ray absorptiometry (DXA) and AP bone mineral content (BMC) was calculated. At the same time, spine AP-BMD (L2–4) was evaluated in 333 normal menstruating women, aged 27–47 years. Bone values, osteocalcin and IGF-1 serum concentrations were correlated with chronological age, skeletal age, pubertal stages and time after menarche. In this cross-sectional study, AP- and LAT-BMD and BMC increased dramatically between skeletal ages 10 and 14 or until the first year after menarche. Between 14 and 17 skeletal years of age, AP-BMD and BMC increased moderately, whereas LAT-BMD remained unchanged. After skeletal age 17, or the fourth year after menarche, there was no significant increase in BMD or BMC, and their values did not differ from those of menstruating women. A serum osteocalcin peak was observed at skeletal ages 11–12 or at stage P3, whereas IGF-1 peaked at 13–14 skeletal years of age or at P4 and the first year after menarche. Eighty-six per cent of the adult bone mass of the spine is acquired before skeletal age 14 or the second year after menarche; therefore osteoporosis prevention programs will be particularly effective before that age.     

Variation in lumbar spine bone mineral content by age and gender in apparently healthy Indians

The aim of this study was to assess variation in bone mass from childhood through later age and to examine bone health status of Indian males and females. Lumbar spine (LS) bone mineral content (BMC) was measured by dual energy X-ray absorptiometry of lumbar vertebrae (L1–L4) in 683 males and 858 females (5–70 years) from Pune, India and apparent bone mineral density (BMAD) was calculated. A cubic regression model was fitted to describe the change in bone mineral content (BMC) with age in males and females separately. Regression analysis revealed that peak LS BMC was achieved around 26 years (63.6 ± 11.0 g) for males and 30 years (54.1 ± 11.6 g) for females. After 50 years of age, BMC showed an average annual decrease of 2.7% in males and 4.1% in females. Males had 11–15% higher mean BMAD than females after 50 years of age. T scores of 19% males and 28% females above 50 years, were less than −2.5 and T scores of 36% males and 43% females were between −1.0 and −2.5 when compared with the Lunar reference database. Low peak bone mass at a young age and higher bone loss in adults are alarming features of apparently healthy Indians.     

Heterogeneity in the growth of the axial and appendicular skeleton in boys: implications for the pathogenesis of bone fragility in men.

Men with spine fractures have reduced vertebral body (VB) volume and volumetric bone mineral density (vBMD). Men with hip fractures have reduced femoral neck (FN) volume and vBMD, site-specific deficits that may have their origins in growth. To describe the tempo of growth in regional bone size, bone mineral content (BMC), and vBMD, we measured bone length, periosteal and endocortical diameters, BMC, and vBMD using dual-energy X-ray absorptiometry in 184 boys aged between 7 and 17 years. Before puberty, growth was more rapid in the legs than in the trunk. During puberty, leg growth slowed while trunk length accelerated. Bone size was more advanced than BMC in all regions, being approximately 70% and approximately 35% of their predicted peaks at 7 years of age, respectively. At 16 years of age, bone size had reached its adult peak while BMC was still 10% below its predicted peak. The legs accounted for 48%, whereas the spine accounted for 10%, of the 1878 g BMC accrued between 7 and 17 years. Peripubertal growth contributed (i) 55 % of the increase in leg length but 78% of the mineral accrued and (ii) 69% of the increase in spine length but 87% of the mineral accrued. Increased metacarpal and midfemoral cortical thickness was caused by respective periosteal expansion with minimal change in the endocortical diameter. Total femur and VB vBMD increased by 30-40% while size and BMC increased by 200-300%. Thus, growth builds a bigger but only slightly denser skeleton. We speculate that effect of disease or a risk factor during growth depends on the regions maturational stage at the time of exposure. The earlier growth of a regions size than mass, and the differing growth patterns from region to region, predispose to site-specific deficits in bone size, vBMD, or both. Regions further from their peak may be more severely affected by illness than those nearer completion of growth. Bone fragility in old age is likely to have its foundations partly established during growth.     

Different trends of age-related diminution of bone mineral content in the lumbar spine,femoral neck,and femoral shaft in women

Summary The bone mineral content (BMC) was measured by dual photon absorptiometry of¹⁵³Gd simultaneously in the lumbar spine, femoral neck, and femoral shaft in a cross-sectional study of 113 healthy women aged 20–89 years. The measurements suggest differences in the patterns of bone mineral decrease at the three sites of the skeleton in relation to age. The lumbar spine BMC decreases mainly during the usual time of menopause, whereas BMC decreases linearly in the femoral neck from young adulthood to old age. The femoral shaft BMC is nearly unaltered until the seventh decade, and thereafter BMC declines significantly. In each of the three age groups selected according to the usual time for menopause there was significant correlations between BMC of the scanning sites and nearly identical variance of BMC with age, suggesting homogeneity in the female population with regard to rate of bone diminution.     

Bone mineral content of mandibles: Normal reference values—Rate of age-related bone loss

Summary The purpose was to obtain the normal sex- and age-related reference values for the bone mineral content (BMC) in the bones of the mandible and the forearms, as estimated by dual-photon absorptiometry; to examine the effect of tooth loss on the mandibular BMC, i.e., BMC in the basal part of the mandible; and to analyze the rate of the sex- and age-related BMC loss in the mandible in normal old edentulous individuals ≥70 years of age and its relationship to the corresponding BMC loss in the forearm bones. The following groups were measured: young dentate adults (n=100; women (W): men (M)=1∶1), young, long-term edentulous W (n=15), and old edentulous individuals (n=24 W, 10 M). In the old group the BMC measurements were repeated after a 2- or 3-year period (n=18 W, 10 M). The analyses indicate that the mandibular BMC reference values differ by sex and age; but correction for the state of dentition seems of minimal benefit. The average BMC loss (%) in the bones of the mandible and the forearms seems to be higher in old W (1.5 and 1.4% per year) than in old M (0.9 and 0.7% per year), but of the same magnitude in each sex. The relationship between the BMC loss (%) in the two sites was significant (P<0.01) but rather weak. Thus, it seems important to follow the sex- and age-related BMC loss in the mandible separately.