Dual Photon Absorptiometry Research Articles

Reproductive hormones and bone mineral density in women runners

We examined the relationships among reproductive hormone concentrations and bone mineral density (BMD) in 43 women runners classified as eumenorrheic (n = 24), oligomenorrheic (n = 8), or amenorrheic (n = 11). Results were compared with a eumenorrheic nonrunner control group (n = 11). Serum 17 beta-estradiol, progesterone, and dehydroepiandrosterone sulfate concentrations were determined in daily blood samples for 21 days, and integrated concentrations (areas under the curve) were calculated. BMD was assessed at the lumbar spine and proximal femur by dual-photon absorptiometry. As expected, 17 beta-estradiol, progesterone, and lumbar spine BMD were higher in the control and eumenorrheic runner groups than in the oligomenorrheic and amenorrheic runner groups (P less than 0.05). Progesterone concentration was significantly correlated with lumbar spine BMD in the eumenorrheic runners (r = 0.61). None of the steroid hormones was significantly related to BMD in the oligomenorrheic/amenorrheic group. The present data suggest that circulating levels of gonadal steroid hormones affect axial BMD in eumenorrheic runners.

Longitudinal effect of tiludronate on bone mineral density, resonant frequency, and strength in monkeys.

The effect of Tiludronate on bone was studied in 72 growing monkeys (Papio papio), 36 males and 36 females, aged 4-7 years. They were randomly allocated into four groups (18 animals per group, 9 males and 9 females): group I, controls; group II, 10 mg/kg/day; group III, 20 mg/kg/day; and group IV, 40 mg/kg/day of Tiludronate. A total of 12 animals (6 males and 6 females) in each group were sacrificed at the end of treatment (1 year) and 6 animals (3 males and 3 females) per group 1 year later. Bone mineral density (BMD) was measured by dual-photon absorptiometry. Biomechanical properties were evaluated by an impact torsion test and by resonant frequency analysis. Bone mineral measurements indicated that at the end of 1 year of treatment BMD was significantly higher, especially at the distal epiphysis of the radius, than in controls. No significant differences between groups were found in BMD 1 year after stopping treatment. Biomechanical analyses indicated that torsional stiffness increased after treatment. No differences between groups were found 1 year after stopping treatment. Results of resonant frequencies indicated an increased calculated transversal stiffness after treatment and 1 year later and an increased buckling strength 1 year after stopping treatment. In conclusion, the results on the effect of Tiludronate in growing monkeys indicate a profound effect of this drug on bone density and biomechanical properties. The biomechanical results indicate that this drug is safe, with conservation of bone strength despite a change in intrinsic mechanical properties of the bone.

Bone mass of spine and forearm in osteoporosis and in German normals: influences of sex, age and anthropometric parameters.

We measured forearm bone mineral density (BMD) using single photon absorptiometry (SPA) and bone mineral content (BMC) and BMD of lumbar spine by dual photon absorptiometry (DPA). The population consisted of 463 bone healthy subjects, 346 females and 117 males aged 20-85 years. Any underlying bone disease or other diseases known to affect bone mass were excluded by physical examination, thoracic and lumbar radiographs and laboratory screening. Patients with osteoarthritis of lumbar spine were excluded as well as patients taking drugs known to affect bone mass. All bone mass values declined with age. Body height also declined with age by 1.2 cm and 1.8 cm per 10 years (-0.7% and -1%) in females and males respectively. Main effects of age, body height, -surface, -weight and -mass index on bone mass were calculated using multiple regression models. In males and females lumbar BMC measured in gHA depended primarily on body height and secondarily on age. Spinal BMD as measured in g cm-2 was primarily dependent on age and then on height. In females forearm BMD depended primarily on age and then on body surface, in males on body surface only. Using receiver operating characteristic (ROC) analysis the ROC area increased from 0.81-0.85 (n.s.) including body height into spinal BMD values leading to a higher sensitivity of measurements of spinal bone mass in recognizing 58 patients with spinal postmenopausal osteoporosis. Including body surface into forearm BMD measurements ROC area increased from 0.66-0.69 (P = 0.055).(ABSTRACT TRUNCATED AT 250 WORDS)

Bone mass status in different degrees of chronic renal failure

Bone mineral density (BMD) was evaluated in 69 patients with chronic renal failure (CRF) and in healthy controls matched for age, sex, and, for women, menopausal status. Both appendicular (predominantly cortical) and axial (predominantly trabecular) bone mass were measured. Appendicular BMD was measured by single photon absorptiometry on the distal forearm and axial BMD was measured by dual photon absorptiometry on the lumbar spine. Patients were divided into three groups on the basis of creatinine clearance: group 1, 58 to 36 ml/min; group 2,30 to 18 ml/mm; group 3, 15 to 9 ml/min. Both appendicular and axial BMD decreased with the worsening of renal failure. Parathyroid hormone levels were inversely correlated with the values of appendicular BMD. BMD values were significantly lower in post-menopausal than in premenopausal women. Months of menopause were inversely correlated with axial BMD values. Appendicular BMD was lower in CRF patients than in controls, and both appendicular and axial BMD were significantly lower in postmenopausal uremic women than in post-menopausal healthy women.

The effect of hormone replacement therapy on postmenopausal bone loss

Eighty-four postmenopausal women who were randomly allocated to one of four groups, completed a 1 year follow-up. The first group ( n = 20) received 0.625 mg/day conjugated estrogens cyclically (CE; 25 days/month). The second ( n = 23) received 0.625 mg/day of CE continuously, and the third ( n = 17) received 50 μg/day of transdermal 17β-estradiol cyclically (24 days/month). All these groups also received 2.5 mg of medroxiprogesterone acetate sequentially for the last 12 days of hormone replacement therapy, while the fourth group ( n = 24) constituted a treatment-free control group. Dual photon absorptiometry was carried out before therapy and was repeated after 1 year. Serum calcium, phosphate and osteocalcine levels, and the urinary calcium creatinine and hydroxyproline creatinine ratios, were measured prior to treatment and 6 and 12 months thereafter. All treatment groups showed an increase in bone mineral content. This increase was higher in the continuous CE treatment group (4.4%, P < 0.05) and in transdermal group (7.1%, P < 0.01). Concomitant biochemical effects at 6 and 12 months, reduction in urine calcium and hydroxyproline, reduction in blood calcium, phosphate and osteocalcine, were compatible with the observed effects on bone mineral.

Pattern of bone loss related to years from menopause in healthy women

A new x-ray-based (dual-energy x-ray absorptiometry [DEXA]) instrument for measurement of bone mineral in the spine and hips (QDR-1000, Hologic, Inc.) was compared with a commercial dual photon absorptiometry (DPA) instrument that uses a 153Gd source (DP3, Lunar Radiation Corporation). Measurements were made on phantoms and lumbar spines of patients to study accuracy, precision, limitations, and compatibility of results between instruments. Both instruments measure bone mineral of integral bone in terms of area bone density with an entrance exposure of less than 5 mR. For spinal bone mineral measurements, the DEXA instrument had a shorter scanning time and higher resolution images than the DPA system. The DEXA instrument also showed better precision in a spine phantom and reduced influence of thickness for patient measurement. For bone mineral content, accuracy was about equal for both instruments; for measurements of the area of the region of interest, accuracy was better with the DEXA instrument. With both instruments, fat had little effect on bone mineral density in bone phantom studies. Measurements on both instruments were influenced by the location of a bone phantom within the photon beam. Results in patients showed good correlation (r = 0.988) for bone mineral density. Measurements of bone mineral density in patients were consistently lower with the DEXA instrument because of better accuracy in area measurements. The new x-ray-based instrument is a major advance in bone mineral absorptiometry and provides improved, yet less expensive, measurements in research and clinical applications.

Bone mineral density of the lumbar vertebrae in children and adolescents with insulin-dependent diabetes mellitus

To test the hypothesis that bone mineral density (BMD) is lower in children with insulin-dependent diabetes mellitus (IDDM), we measured BMD of the lumbar vertebrae (L-2 to L-4) by dual-photon absorptiometry in 31 boys and 25 girls, mean age 12.3 years, with IDDM of varying clinical duration (range 0.1 to 14.8 years). Mean standard deviation scores (z scores) were determined for L-2-L-4 BMD, weight, height, weight percentile, and weight-adjusted L-2-L-4 BMD index (L-2-L-4 BMD/weight), with reference data from a previously described white, nondiabetic, age-matched control group (n = 221). Compared with nondiabetic control subjects, male patients with short-term IDDM and all female patients with IDDM did not have significantly different L-2-L-4 BMD, weight, weight percentile, height, or BMD index. Boys with IDDM longer than 1 year had significantly lower weight, weight percentile, and height than did age-matched control subjects. When L-2-L-4 BMD of boys with long-term diabetes was corrected for weight, the L-2-L-4 BMD index was significantly greater than that of control subjects, indicating that weight was disproportionately lower than BMD. There were no significant linear correlations between metabolic control and L-2-L-4 BMD. When L-2-L-4 BMD was adjusted for differences in body weight, spinal BMD values in children with IDDM were not lower than in control subjects. These findings indicate that in children with IDDM, as in previously studied nondiabetic youths, body weight and spinal BMD are highly correlated; although BMD is reduced in some children with diabetes, the reduction parallels reductions in growth, and may simply reflect a normal response of the skeleton to a lower weight-bearing load.

Effects of chronic heroin abuse on bone mass and calcium and bone metabolism

AND CALCIUM AND BONEP;t;;BOLISM. M. Pedrazzoni, P.P. Vescovi, G. ., M. Michelini, G. Musetti, L.Maninetti, G. Zaniboni, D. Costi, M. Passeri. Istituto di Clinica Medica Generale, Universita' di Parma, Italy. Few studies have so far been performed on the effects of the chronic abuse of heroin on calcium and bone metabolism. We have examined. bv dual-photon absorptiometry, the total bodf and vertebral mineral density in 22 male heroin addicts at the start of a rehabilitation programme. Compared with normal, age-matched subjects, there was a significant decrease of vertebral bone mineral density, whereas total body mineral density and the fat and muscle mass of drug users were not significantly different from normal controls. Biochemical tests, rmed d in a subset of subjects, !n=13),

Bone histomorphometry after long-term treatment with cyclical phosphorus and etidronate

Objective: To determine whether the osteopenia and unusual fractures observed in children with acute lymphoblastic leukemia (ALL) were related to the disease rather than to its treatment. Design: Prospective analysis of the bone and mineral status in 40 consecutive children with ALL seen in a pediatric tertiary-care referral center. Methods: Biochemical indicators of mineral, endocrine, and vitamin D status were measured before initiation of therapy. Bone mass was determined radiographically and by dual-photon absorptiometry of the lumbar region of the spine (L2-L4). Correlations between clinical observations, leukemia variables, bone mass, and biochemical assessment were determined. Results: At the time of diagnosis musculoskeletal pain was present in 36% of patients and was more common in children with CD10-positive leukemia and leukocyte counts less than 20 × 109 cells/L. Radiographic evidence of osteopenia and fractures was observed in 13% and 10% of children, respectively. The mean bone mineral content was normal. Bone mass measurement z scores correlated with plasma 1,25-dihydroxyvitamin D3 concentrations (r = 0.43, p <0.05). Plasma calcium, magnesium, phosphorus, and 25-hydroxyvitamin D3 levels were normal. Low plasma osteocalcin (mean ± SD, 1.6 ± 1.6 nmol/L) and 1,25-dihydroxyvitamin D3 (33.4 ± 26.4 pmol/L) values were observed. Parathyroid hormone levels were low in 14% of children. Hypercalciuria was detected in 64% of children. Urinary deoxypyridinoline was lower (p <0.01) than in age-matched control subjects. Histomorphometric measurements of iliac bone showed abnormalities in mineralization in the biopsy specimens from three of nine children. Conclusion: Most children with ALL have alterations in bone metabolism and bone mass when first examined. These data suggest defective mineralization as the mechanism for decreased bone mass and implicate the leukemic process as causative. (J PEDIATR 1995;126:557-64)

Assessment of the risk of post-menopausal osteoporosis using clinical factors.

We wished to assess the predictive value of the main clinical risk factors for osteoporosis over a low vertebral bone mineral density. A cross-sectional study was made of a cohort of peri and post-menopausal women (mean age, 54 years). One thousand, five hundred and sixty-five normal white women were selected from among the women referred to our menopause clinic for screening and prevention of osteoporosis. Each woman had replied to a detailed standardized questionnaire including the main clinical risk factors and had her bone density measured using dual photon absorptiometry. The predictive value for a low vertebral bone mineral density (2 SD below the normal young adult value) was assessed for 15 historical and anthropometric variables. Among these, age, age at menarche, weight, height, menopause and its duration, were independent predictors of a low bone mineral density, in a multiple logistic regression analysis. Odds ratios were calculated for each of these variables, weight, menopause and its duration being the three most influential variables. At best this model makes it possible to correctly classify 73% of women with a low bone mineral density and 66% of those with a normal bone mineral density. If this model is used for screening, it could possibly save 25% of bone densitometry examinations. Direct bone densitometry remains indispensable to assess osteoporosis risk, since risk factors alone are not sufficient for accurate delineation of either low or normal bone mineral density.

Calcium balance, growth and skeletal mineralisation in patients with cystoplasties.

Twelve adult female patients and 16 children who had undergone augmentation cystoplasty at least 2 years previously were studied to assess calcium balance and skeletal mineralisation. The serum and 24-h urinary calcium levels were measured and arterial blood gas analysis was performed in all patients. In children, skeletal mineralisation was assessed by serial study of their growth charts, comparing their growth centiles before and after cystoplasty. In adults, skeletal mineralisation was assessed by dual photon absorptiometry (DPA). As previously reported, all patients had a metabolic acidosis, usually with respiratory compensation. Serum and 24-h urinary calcium levels were all within the normal range. Growth charts of the 6 children with colocystoplasties showed an average of 20% reduction in growth potential in 3 of them. Growth charts in the 10 children with ileocystoplasties did not show any change in growth pattern. DPA bone scans in adults were all normal. These results suggest that if calcium is mobilised from bone in patients with a cystoplasty as a result of the metabolic acidosis, then it is reabsorbed from the bladder by the gut segment after an ileocystoplasty; colonic segments are less efficient than ileal segments, however, so that after a colocystoplasty skeletal demineralisation or a reduction in growth potential is more likely.

Lumbar spine and femoral neck bone mineral density in idiopathic scoliosis: a follow-up study.

A follow-up study of the bone mineral densities (BMD) of 22 female subjects with idiopathic scoliosis was performed using dual-photon absorptiometry at an average follow-up period of 30.8 months. Compared to the initial scans, statistically significant increases in lumbar spine and femoral neck BMD were observed. When compared to normal subjects, approximately half of the scoliotic subjects were markedly osteoporotic, having BMD measurements at least two standard deviations below the expected value. Scoliotic curvature data could not be correlated with the BMD data. The observed osteoporosis is not transient and appears characteristic of idiopathic scoliosis.

Hip fracture patients have generalized osteopenia with a preferential deficit in the femur.

Bone density was measured in 31 white women with hip fractures by single- and dual-photon absorptiometry at the radius, lumbar spine and proximal femur. The mean age was 71.4 years. Comparison with premenopausal normals revealed Z-scores as follows: radius, -1.75; spine, -1.45; femoral neck, -2.40; Ward's triangle, -2.41; and trochanter, -1.42. These values altered when calculated for the patient's age by the use of sex- and race-specific regressions against age in a healthy, non-fracture population. The age-corrected Z-scores were as follows: radius, -0.09; spine, -0.18; femoral neck, -0.79; Ward's triangle, -0.44; and trochanter, -0.80. Thus, although our patients had absolute osteopenia at all skeletal sites when compared with young normals, when compared with age-matched normals (relative osteopenia) the only site with a noticeable deficit was the femur. Interpretation of the extent of osteopenia by comparison with young normals may lead to different conclusions than when an age-matched population is used. Patients with hip fractures had a preferential deficit in density of the femur when compared with normal women of their age.

Dual energy x-ray absorptiometry: the effects of beam hardening on bone density measurements.

X-ray tubes have superseded radionuclide sources for dual photon absorptiometry of the spine and hip. However, the use of a polyenergetic spectrum is a potential source of error for x-ray absorptiometers since beam hardening may result in a nonlinear measurement scale for bone mineral density (BMD). A quantitative study of the effects of beam hardening on measurements made with a commercial dual energy x-ray scanner has been performed. Bone was represented by layers of aluminum of linearly increasing thickness which were scanned under water thicknesses ranging from 0 to 25 cm to represent different body thicknesses of soft tissue. Beam hardening had two effects on measured BMD: (i) at a constant true BMD, measured BMD varied with water thickness; (ii) at a constant water thickness, the BMD scale was not precisely linear. For conditions appropriate to spine and hip studies (BMD) values in the range 0.7 to 1.4 g/cm2 and body thickness between 15 and 25 cm) the maximum deviation of measured BMD from a linear scale was 0.023 g/cm2, while the root-mean-square deviation (0.01 g/cm2) was comparable to the measurement precision for a spine or femoral neck scan (about 1%). The largest departures from linearity were found to occur at the thinnest water thicknesses for BMD values in the range 0.2 to 0.6 g/cm2. The effect of scale nonlinearity on the results of longitudinal studies was examined: for a spine scan at 20-cm body thickness, measured changes in BMD slightly overestimated the true change and implied an error of 0.15%/year for a measurement of a true rate of loss of 3% year in a postmenopausal woman.

Hip mineral density in females with a recent hip fracture.

To evaluate the role of local bone mineral density (BMD) in the etiology of hip fractures, we measured the hip BMD using dual photon absorptiometry in 29 females who had recently suffered a hip fracture associated with minimal or moderate, but not major, trauma and compared their BMD to those of 14 young normal females, 58 early postmenopausal normal females, 13 age-matched normal females, and 114 spinal osteoporotic females without a hip fracture. Hip-fractured patients had a BMD significantly lower (P less than 0.001) than that of all other studied groups, suggesting that a low hip BMD is associated with hip fracture risk. A femoral neck BMD below 0.75 g/cm2 suggests an increased likelihood for developing a hip fracture. Peak BMD was measured at 1.03 g/cm2, a value comparable to published normative data. Thus, a loss in hip BMD of approximately 30% from peak mineral density appears necessary before a hip fracture may occur after moderate trauma.

Low-dosage micronized 17ß-estradiol prevents bone loss inpostmenopausal women

With the use of a double-blind, randomized, dose-ranging design, we tested during an 18-month period the degree of protection against postmenopausal bone loss afforded by micronized 17 beta-estradiol in dosages of 0.5, 1.0, and 2.0 mg. All subjects received supplementation to ensure a minimum of 1500 mg calcium daily. Fifty-one subjects completed at least 1 year of follow-up bone density measurements by quantitative computed tomography and by single- and dual-photon absorptiometry. In the placebo group spinal trabecular bone density decreased 4.9% annually (p less than 0.001), whereas in those taking micronized 17 beta-estradiol bone density tended to increase (annual increases of 0.3% in the 0.5 mg micronized 17 beta-estradiol group, 1.8% in the 1.0 mg micronized 17 beta-estradiol group, and 2.5% in the 2.0 mg micronized 17 beta-estradiol group). After completing the double-blind phase, 41 subjects completed an additional 18 months of follow-up while taking 1.0 mg micronized 17 beta-estradiol. During this time one third of the subjects were randomly assigned to discontinue calcium supplements. Among those who previously received placebo, trabecular bone density increased 4.3% annually, whereas among those who had used micronized 17 beta-estradiol, trabecular bone density response was inversely related to the dosage previously used. Additionally and independently, the level of calcium intake showed a statistically significant correlation with the change in spinal trabecular bone density (r = 0.37, p = 0.02). We conclude that micronized 17 beta-estradiol has a continuous skeletal dose-response effect in the range of 0.5 to 2.0 mg and that calcium intake positively modifies the skeletal response to 1.0 mg micronized 17 beta-estradiol.

New approaches for interpreting projected bone densitometry data.

Bone densitometry using dual-photon absorptiometry (DPA) or dual-energy x-ray absorptiometry (DXA) has become a standard method for assessing bone mineral content in the spine and other skeletal regions. A projected areal density, referred to as bone mineral density (BMD,g/cm2), is normally calculated to assess regional bone density and strength. We demonstrate that this measure can be misleading when used to compare bones of different sizes due to inherent biases caused by bone thickness differences. For example, assuming that volumetric bone density remains constant and bony linear dimensions are proportional to height, a 20% increase in height would result in a 20% increase in both the thickness and the BMD of any bone. We describe new analysis methods to reduce the confounding effect of bone size, and we introduce a parameter, bone mineral apparent density (BMAD, g/cm3), that better reflects bone apparent density. Using this parameter, we calculate a quantity that serves as an index of bone strength (IBS, g2/cm4) for whole vertebral bodies. These analyses were applied to lumbar spine (L2-4) DXA measurements in a population of women 17-40 years old and appear to offer advantages to conventional techniques.

Body fat by dual photon absorptiometry: Comparisons with traditional methods in Asians, blacks, and whites.

Measurement of body fat by dual photon absorptiometry (FatDPA ) is based on the physical principles of differential attenuation of discrete photons by fat and other soft tissue components. The three traditional methods of measuring fat are indirect, in that they depend on measuring the fat free mass (FFM) based on the assumed constancy of water, potassium, and density in the FFM. Comparison of FatDPA with fat measured by each of the indirect methods discloses systematic differences which shed light on the nature of the constancy assumptions. The purpose of this report is to study the effects of sex, age, and fatness, as well as race, on the traditional methods for estimating body fat%. In Asians (99 m, 109 f), blacks (64 m, 48 f), and whites (166 m, 212 f), 18 to 94 years, with body mass indices of 16 to 36 kg/m2 , body fat measured by DPA was compared with fat by three traditional methods: total body potassium (TBK; 40 K counting), total body water (TBW; HTO dilution), and underwater weighing (UWW). DPA showed the highest overall correlation with TBW and the lowest with UWW, among the three traditional methods. Asians showed the lowest correlations between FatDPA and FatUWW . On average, FatTBK was higher, while FatUWW was lower than FatDPA . The differences between FatDPA and FatOTHER by the three traditional methods were correlated with age with a negative slope in all groups, the steepest slope being for FatDPA - FatTBK in blacks. Correlations with fatness showed positive slopes for FatDPA - FatTBW and - FatUWW but not for - FatTBK . FatDPA could become a criterion method for body fat, particularly in the young, old or ill, where traditional "constants" become unreliable, if calibration can be accomplished throughout the range of subject size. Ethnicity, age, sex, and fatness as well as illness are potent variables affecting the composition of the FFM; direct measurements of fat are preferable, to avoid artifacts resulting from using indirect methods. © 1992 Wiley-Liss, Inc.

Evaluation of a new set of calibration standards for the measurement of fat content via DPA and DXA

A simulation study was performed to evaluate a new set of calibration standards for estimating the fat content of the body via dual-photon absorptiometry (DPA) and dual-energy x-ray absorptiometry (DXA). The standards, proposed by Nord and Payne [presented at the 2nd meeting of The Bath Conference on Bone Mineral Measurement (1990)] consist of stearic acid (100% fat) and 0.6% NaCl in water (100% lean). They were compared with other standards consisting of average composition adipose/muscle tissues and fatty adipose/lean muscle tissues. Source and detector properties of a Gd-153 DPA system and three commercial DXA systems were modeled. For each system and calibration set, rms errors in the calculated fat contents of simulated tissues having fat mass percentages that ranged from about 4%-44% and thicknesses that ranged from 5-20 cm were determined. Beam hardening errors for the systems were evaluated as was a calibration technique employed by one of the manufacturers to correct for such errors. In general, the smallest rms errors (2% or less when the calibration standards and tissues were of equal thickness) were obtained with the average adipose/muscle standards. Equivalent results were obtained with standards consisting of stearic acid and 0.8% NaCl. The latter is a higher salt content than proposed by Nord and Payne and results from differences in the x-ray attenuation coefficients that were employed in calculating the fat equivalence of water. Other, more convenient standards, such as lucite and water may be employed by using appropriate fat equivalences (approximately 69% for lucite and approximately 10% for water). Beam hardening errors for the DXA systems are considerable, and the simulated correction technique was shown to be effective.

Spinal bone mineral density of normal and osteoporotic women in Korea.

In order to define osteoporosis on the basis of bone mineral measurements, one must define an acceptable normal range or fracture threshold. It is clear that the normal range cannot be compared between different ethnic groups. We have measured spinal bone mineral density (BMD) by dual photon absorptiometry in 277 women without spinal fracture, aged 30-91 years, and in 53 women with asymptomatic spinal fracture to provide such a database for normal Korean women. Peak bone mass at the 3rd decade was 1.24 g/cm2. BMD from age 40-69 was strongly correlated with age (r = -0.7) and the annual decrease averaged 0.018gm/cm2. The rate of annual loss slowed by 50% in women after 70% years of age. Fracture threshold was evaluated at the 90th percentile for spinal BMD in patients with vertebral fractures. The fracture threshold of the vertebra was 0.94 g/cm2. Approximately 50% of normal women over 50 years of age had values below this threshold. These findings suggest that the way of developing low bone mass in Korean women is to peak high and lose fast.