Estimation of Total Body Calcium from the Bone Mineral Content of the Forearm

The representativity of forearm in bone mineral content (BMC) measurements for estimation of total body calcium is investigated in this article. It is shown that there is a very high correlation between weight and calcium content of examined bone pieces, that there is a high correlation between weight of individual bones and BMC values, that the BMC values from various parts of the skeleton are reasonably well correlated, that the weight of individual bones is highly correlated to the weight of total skeleton, and that there is a reasonably high correlation (r=0.85) between BMC measurements in the distal part of the forearm and total weight of the skeleton. It is concluded that BMC measurements of the distal part of the forearm give an estimate of total body calcium.     

Correlation of radial bone mineral content with total body calcium in chronic renal failure.

Loss of bone mineral of the skeleton in renal disease can be measured directly by total body neutron activation analysis (TBNAA), and also by an absorptiometric technique applied to the appendicular skeleton (radius). In the present study the results of these two techniques are compared in 25 patients with renal insufficiency, 53 patients with end-stage renal failure on dialysis, and 24 normal control subjects. It is apparent that there is good correlation between total body calcium(TBCa) and bone mineral content (BMC) in all groups studied. The correlation in the normal contrast group was 0.944 as compared to 0.919 for the renal patients and 0.892 for patients with end-stage renal failure on dialysis. In order to measure the relative deficit in TBCa in individual patients from the absolute Ca measurement, it is necessary to normalize the data for sex, age, and skeletal size. For this purpose, an empirically derived relationship was used to predict the normal skeletal Ca in each subject, based on weight, height, sex, and age. The measured TBCa divided by the predicted TBCa is referred to as the calcium ratio. This ratio is useful in expressing the relative deficit of Ca in individual renal patients. In similar manner, BMC data were normalized, with the same relationship used to obtain BMC ratios. The normalization procedures allow both the TBCa and BMC measurements to be used to quantitate the Ca deficit in individual patients with renal insufficiency. However, the correlation coefficient relating changes in TBCa and BMC in individual patients on dialysis was very poor (0.25). It is clear that the BMC measurement alone cannot always predict the level of the total body Ca in individual patients with renal failure. In like manner, TBCa measurement alone does not define the distribution of total body Ca between the skeleton and soft tissue in these patients. However, taken together, the BMC measure along with that of TBCa does suggest possible alterations in the skeletal calcium distribution associated with renal disease.     

Comparison of phalangeal ultrasound and dual energy X-ray absorptiometry in healthy male and female adolescents

The aims of this study were to determine if there is a correlation between dual energy X-ray absorptiometry (DXA) and phalangeal quantitative ultrasound (QUS) in identifying children and adolescents with low bone density, and to assess if body size influences the results of the two techniques to the same degree. Measurements were performed in 67 girls and 83 boys aged 14 to 19 y using DBM Sonic 1200 (IGEA, Carpi, Italy) and the DXA equipment (LUNAR Radiation Corp., Madison, WI, USA). Twelve adolescents (eight males and four females) reported a past history of nonosteoporotic fractures. Lumbar spine bone mineral density (LS BMD), total body bone mineral density (TB BMD) and total body bone mineral content (TB BMC) correlated positively with age, height, BMI and weight, in both genders. Amplitude-dependent speed of sound (Ad-SOS) was positively correlated with age, height and Tanner stages in both genders and negatively correlated with BMI in females. TB BMD, TB BMC and LS BMD positively correlated with Ad-SOS only in males. In females, there were no significant correlations between Ad-SOS, TB BMD, TB BMC and LS BMD measurements. Twelve teenagers with previous fractures (high impact fractures) were found to have lower DXA and QUS values than age-matched teenagers without fractures but the statistical significance was found only in relation to TB BMD values (p = 0.02). In conclusion, we obtained results similar to those that have been reported by other authors using different QUS techniques. Furthermore, the Ad-SOS measurements taken at the distal metaphysis of the proximal phalanges correlate poorly with LS BMD and TB BMD measured by DXA in growing subjects. (E-mail: zhalaba@poczta.onet.pl)     

Bone composition in the distal forearm

Recent data have indicated that measurements of bone mass in the very distal part of the forearm is superior to more proximal measurements in identifying osteoporosis. Bone slices from the distal part of the forearm were obtained from 16 necropsies and the trabecular fraction of the total dry bone weight was measured in adjacent bone slices, 8 mm thick. Prior to autopsy bone mass at the corresponding sites was measured using a multipath single photon absorptiometric method by which scans are obtained proximal (proximal BMC) and distal (distal BMC) to the site, where the ulna and radius are 8 mm apart. The accuracy of bone measurements at the two sites was virtually similar (r = 0.98 and r = 0.94, respectively). In both areas the amount of trabecular bone increased towards the metaphysis with a trabecular/cortical ratio ranging from 10 to 60% (wt/wt). If bone composition is known it is possible to estimate rates of bone loss from the two compartments.     

Bone mineral content in the forearm measured by photon absorptiometry. Principles and reliability.

A method for estimating total bone calcium is reported. The method is based on two-dimensional scanning photon absorptiometry on the distal part of the forearm. The following factors are investigated: precision of measurements on standards and human subjects; linearity; the effect of varying bone orientation; amount of fat and soft tissue; and the relation between weight and content of calcium and phosphate. The results show that the method is eminently suitable for rapid, easy, and atraumatic measurement of local bone calcium in vivo.     

Changes in calcanean bone mineral occurring spontaneously and during hormone replacement therapy in early post-menopausal women.

The spontaneous calcanean bone loss occurring in healthy early post-menopausal women and the effect of two hormone replacement therapies (HRT's) were investigated in a longitudinal study. There was no difference between the right and left calcanean BMC or BMD (p > 0.15). The spontaneous bone loss was similar at all the skeletal sites measured, with a mean spontaneous loss in calcanean BMD of 1.6% over one year. Both HRT's significantly (p < 0.01) prevented the bone loss from all skeletal sites irrespective of the weight-bearing or content of trabecular bone, and (for the weight-bearing bones) there was even a gain in calcanean BMC and BMD and spinal BMD (p < 0.01). Bone mineral of the calcaneus and the spine correlated equally to body weight (r approximately 0.4, p < 0.001), whereas bone mineral in the forearm was not correlated to body weight. The correlations between the changes in bone mineral at the sites measured were all significant (r approximately 0.2-0.4).     

Representativity of regional to total bone mineral in healthy subjects and 'anticonvulsive treated' epileptic patients. Measurements by single and dual photon absorptiometry

Dual photon (153Gd) and single photon (125I) absorptiometry were used to measure the regional bone mineral content (BMC) and density (BMD), as well as the total body mineral content (TBBM) and density (TBBD), in sixty-nine healthy subjects and in twenty-three epileptics on phenobarbitone. The BMCs (and BMDs) of all regions were significantly correlated to each other and to the TBBM (and TBBD). No difference in the ability to discriminate between the different study groups was found for the various regions, excepting the BMD of the head. The relationship between the forearm BMC and TBBM was highly significant, and identical in the five groups. The relationships between spinal BMC and forearm BMC, and TBBM differed in the five groups. It is concluded that some local measurement may be used as estimates of the total body bone mineral in some groups of patients with minor metabolic bone disease and healthy subjects.     

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.     

绝经妇女身体软组织重量与骨密度的相关性

目的 :探讨绝经后妇女身体软组织重量和骨密度 (BMD)之间的关系。方法 :选择 6 2例绝经期健康日本妇女 ,应用双能X 线法 (Dexa)测定其第 2～ 4腰椎、双侧股骨转子间和桡骨中、下 1/ 3交界处BMD ,同时测定身体肌肉组织 (TLM)和脂肪组织 (TFM )重量 ,并对软组织重量与身体各部位的BMD进行相关性分析。结果 :全身TLM重量及体重与正位腰椎BMD呈正相关 (r =0 .4 5及 0 .35 ) ,而TFM百分比与腰椎、股骨转子间和桡骨远端BMD呈负相关 (r=- 0 .17)。随着年龄增长 ,BMD呈下降趋势 ,6 0岁组与 5 0及 70岁组比较差异有显著性 (分别P <0 .0 1,P <0 .0 5 )。结论 :身体内软组织重量中TLM重量、体重与全身各部位的BMD有相关性 ,其中体重和TLM重量与腰椎BMD的相关性较好 ,TFM重量与BMD的相关性不明显。     

Regional and total skeletal measurements in the early postmenopause.

In a cross-sectional study of 70 early postmenopausal women, regional bone measurements were compared with total body calcium (TBCa). Spinal and forearm trabecular bone were mainly related to age and time since menopause. In contrast, TBCa and forearm integral (cortical and trabecular) and cortical bone were unrelated to age, although the time since menopause also had some influence. Forearm integral and cortical bone measurements were quite well correlated with TBCa (r = 0.84 and 0.73, respectively, P less than 0.001). The correlation between spinal bone measurements and any of the forearm measurements, even purely trabecular bone, was weak (r less than 0.52, P less than 0.001). Our results show quite clearly that forearm bone measurements cannot be used to predict bone density in the vertebrae. Loss of ovarian function affects bone in general, and trabecular bone in particular. Bone measurements at specific anatomical sites are clearly necessary for studies of metabolic bone diseases and their response to treatment.     

Bone mass of the axial and the appendicular skeleton in women with Colles' fracture: its relation to physical activity

Summary. The aim of this investigation was to elucidate whether Colles' fractures in middle-aged women were indicative of generalized bone loss (osteopenia) and whether bone mass of the axial and the appendicular skeleton was related to the extent of daily physical activity. Thirty-six patients (aged 50–73 years) with previous Colles' fracture were studied. The median time elapse after the injury was 18 months (range 9–20·5 months). Bone mineral content of the 2nd, 3rd, and 4th lumbar vertebrae (lumbar BMC) and both distal forearms (forearm BMC) were determined by dual-photon (¹⁵³Gd) absorptiometry. The physical activity level was graded according to a standard interview and a bicycle ergo meter test. Mean lumbar BMC was reduced by 9% compared to age-matched normal women (P < 0·05), mean forearm BMC was reduced by 5% (NS). Twenty patients showed spinal osteopenia by either conventional radiography or absorptiometry (95% confidence limits 38–72%). The fracture-related bone loss from the forearms was most prominent when the fracture had occurred in the dominant forearm, suggesting that the loss of ‘dominant’ forearm activity per se results in bone loss. No relation between working capacity and forearm BMC was found. However, the working capacity was positively related to lumbar BMC (P < 0·01), even if the common relationship to age was eliminated (P < 0·05). The data suggest that the bone mass of the axial skeleton reflects the extent of daily physical activity. Patients with Colles' fractures represent an easily definable population which might benefit from prophylactic measures against vertebral bone loss and compression fractures. One of these could be physical exercise.     

Bone mass measured by photon absorptiometry: comparison of forearm, heel, and spine

We assessed bone mass quantification at different skeletal sites by single and dual photon absorptiometric (SPA and DPA) methods. Improved DPA measurement of spinal bone mineral density in young healthy subjects showed a short- and long-term precision of 1.2% and 1.6%. Compared to the conventional DPA method the imprecision was reduced by more than 50%. The appendicular measurements were more precise (0.5-1.2%). We present the intercorrelations and predictive errors between peripheral measurements and improved spinal and total body bone measurements in early postmenopausal women (n = 144) recruited in 1988. To compare the improved system with the conventional methods, we retrieved data on age-matched early postmenopausal women (n = 151) recruited in 1983. In the 1988 population all peripheral methods had similar predictive errors in estimation of spinal bone mineral density (SEE = 11-13%) and total body bone mineral density (SEE = 4-5%). Measurement of trabecular bone in the heel and distal forearm did not improve the validity of predicting spinal bone mass. In a cadaver study (n = 11) the predictive error in estimation of the spinal ash weight from forearm measurements was of the same magnitude (15%) as that in estimation of the spinal BMC from the forearm (16%). We conclude that the predictive error in estimation of spinal bone mass from peripheral bone measurements is more likely to be caused by intra-skeletal variation in bone mass than by precision errors. However, this does not reflect the inability of peripheral bone mass measurements to predict fracture risk.     

Bone Mineral Content and Estimated Total Body Calcium in Normal Children and Adolescents

Bone mineral content in the distal part of the forearm was measured in 301 normal children and adolescents aged from 7–20 years to estimate total body calcium in these age groups. From year 7 to 9 and from year 15 to 20 the mean values in boys were significantly higher than those in girls. In the lower age groups there was a slow increase in estimated total body calcium with age, followed by a sharp increase at the age of puberty.     

Bone mineral content and estimated total body calcium in normal children and adolescents.

Bone mineral content in the distal part of the forearm was measured in 301 normal children and adolescents aged from 7-20 years to estimate total body calcium in these age groups. From year 7 to 9 and from year 15 to 20 the mean values in boys were significantly higher than those in girls. In the lower age groups there was a slow increase in estimated total body calcium with age, followed by a sharp increase at the age of puberty.     

Bisphosphonate whole body retention test: relations to bone mineralization rate, renal function and bone mineral content in osteoporosis and metabolic bone disorders

The bisphosphonate whole body retention test (WBR) has been used to estimate bone mineralization rate (bone turnover). Bisphosphonates given i.v. are taken up by bone or excreted in urine. The aim of the present investigation was to test the efficacy of WBR in estimating bone mineralization rate (m) and to evaluate the influence of renal function (Clcr) and bone mass (forearm bone mineral content; BMC) on WBR. The 24-h retention of 3.7 MBq 99mTc-HMBP (1-hydroxymethylene-1,1-bisphosphonate) (Osteoscan) given i.v. was measured by a medium sensitive whole body counter in thirty-one patients with hyperparathyroidism (n = 14), hyperthyroidism (n = 8) or hypothyroidism (n = 9) (group 1) and in seventy-six females with postmenopausal spinal crush fracture osteoporosis (group 2). In the same individuals m was calculated from a 7-day 47Ca-kinetic study using the expanding calcium pool model. Multiple regression analysis of WBR vs. m and Clcr in group 1 disclosed that WBR correlated positively to m [rp = 0.49, P less than 0.01 (rp = partial correlation coefficient)] and inversely to Clcr (rp = -0.44, P less than 0.02). Inclusion of BMC in the analysis did not reveal any significant partial correlation between WBR and BMC (rp = -0.33, 0.05 less than P less than 0.10). In group 2 WBR correlated inversely to Clcr (rp = -0.48, P less than 0.001) but showed no significant relation to m (rp = 0.10, NS).(ABSTRACT TRUNCATED AT 250 WORDS)     

双能X线骨密度仪测量双侧前臂骨面积、骨矿含量和骨矿密度的比较

目的比较健康人优势和非优势前臂的骨面积（Ａｒｅａ）、骨矿含量（ＢＭＣ）和骨矿密度（ＢＭＤ）。方法采用双能Ｘ线骨密度仪测量５５例１６～７３岁（平均年龄５２岁）健康志愿者双侧前臂（优势臂均为右臂）的Ａｒｅａ、ＢＭＣ和ＢＭＤ。结果右前臂各部位Ａｒｅａ、ＢＭＣ显著高于左前臂（Ｐ＜０．００１和Ｐ＜０．０５）,除桡骨远端１／３段ＥＭＤ右前臂显著高于左前臂外（Ｐ＜０．０１）,其余部位ＢＭＤ左右侧无差别。结论优势臂的Ａｒｅａ和ＢＭＣ均高于非优势臂,而ＢＭＤ两者差别不大。     

Osteoporosis of the slender smoker revisited by epidemiologic approach

A representative sample of 285 70-year-old Danish women were examined by case history, 125I photon absorptiometry of both forearms (BMC), and lateral X-rays of the spine. Fat mass was calculated from height (H), weight (W) and estimated lean body mass (LBM) as W-LBM/H kg m-1. Seventy-five participants with previous or present disease or treatment known to influence the calcium metabolism were excluded. The remaining 210 women included the final study groups of seventy-seven long-term smokers and 103 non-smokers. Within both groups BMC correlated positively to fat mass, r = 0.447 and 0.560, respectively (P less than 0.001). The slopes of the regression lines and their positions were similar (P greater than 0.05). Hence, for a certain degree of overweight smoking per se does not influence BMC to a significant degree. Although the smokers were less obese (P less than 0.005) and tended to have lower BMC (P less than 0.10) their frequency of non-violent post-menopausal fractures, 40.3%, was the same as for non-smokers, 44.7%. The respective frequencies of definite osteoporotic fractures (i.e., spinal crush and fractures of the hip, proximal humerus and distal forearm) were comparable as well. In conclusion, the influence of smoking on the female skeleton seems mainly to be caused by the associated slenderness.     

Bone turnover in postmenopausal osteoporosis. Effect of calcitonin treatment.

To investigate the effectiveness of calcitonin treatment of postmenopausal osteoporosis in relation to bone turnover, we examined 53 postmenopausal osteoporotic women before and after one year of therapy with salmon calcitonin (sCT), at the dose of 50 IU every other day. Baseline evaluation revealed that 17 (32%) patients had high turnover (HTOP), and 36 (68%) normal turnover osteoporosis (NTOP) as assessed by measurement of whole body retention (WBR) of 99mTc-methylene diphosphonate. The two groups did not differ in terms of bone mineral content (BMC) measured by dual photon absorptiometry at both lumbar spine and femoral diaphysis. However, HTOP patients had higher levels of serum osteocalcin (OC) and urinary hydroxyproline excretion (HOP/Cr). Multivariate regression analysis showed no correlation between parameters of bone turnover (WBR, OC, HOP/Cr) and both femoral and vertebral bone density; the latter being negatively correlated only with the years elapsed since menopause (R2 = 0.406). Treatment with sCT resulted in a significant increase of vertebral BMC in the 53 patients taken as a whole group (+/- 7%, P less than 0.001). When the results obtained in HTOP and NTOP were analyzed separately, only those with HTOP showed a marked increment of spinal BMC (+22%, P less than 0.001), NTOP subjects neither gained nor lost bone mineral during the study. Femoral BMC decreased in the whole group after sCT therapy (-3%, P less than 0.003). However, HTOP patients maintained initial BMC values, whereas those with NTOP lost a significant amount of bone during the study period (-5%, P less than 0.001). The increase of vertebral bone mass was associated with a marked depression of bone turnover detectable in both subsets of patients and in the whole group. In conclusion: (a) assessment of bone turnover cannot help predict the severity of bone loss in postmenopausal osteoporosis; (b) calcitonin therapy appears to be particularly indicated for patients with high-turnover osteoporosis, resulting in a net gain of bone mineral in the axial skeleton and a slowing of bone loss in the appendicular bones.     

Rates of bone loss in normal women: evidence of accelerated trabecular bone loss after the menopause

We have followed the changes in bone mass over 2 years in 42 premenopausal, seven perimenopausal and 76 postmenopausal women. The latter had passed a natural menopause between 6 months and 7 years previously. Bone mass was measured every 3 months at the proximal and distal forearm sites by single photon absorptiometry, and every 6 and 12 months in the lumbar spine and whole body by dual photon absorptiometry. The relative content of trabecular bone is approximately 15, 50, 60 and 20% at these four sites. Before the menopause there was a significantly low rate of bone loss from the two forearm sites and the whole body, whereas the spinal loss was insignificant. The rate of loss was five- to ten-fold higher at all sites after the menopause (P less than 0.001). With increasing menopausal duration the rate of loss declined at the two forearm sites and whole body (P less than 0.01). The distal forearm loss was larger than the proximal, both before and after the menopause (P less than 0.01). From the forearm results we thus conclude that a slightly larger loss of trabecular than cortical bone takes place both before and immediately after the menopause. The loss of both types of bone is, however, much larger after the menopause and this rapid bone loss seems to take place throughout the skeleton.     

Relationship between local and total body bone mineral in epileptic patients and normal subjects

Summary. Total body bone mineral (TBBM), measured by dual photon absorptiometry, and local body bone mineral content (BMC), measured by single photon absorptiometry, in both forearms were determined in 49 epileptic patients, 19 receiving phenytoin and 30 receiving carbamazepine, and in 55 controls. A highly significant correlation was found between BMC and TBBM in the patients (r = 0·81, SEE = 10·6%), as well as in the controls(r = 0·78, SEE = 9·9%). Furthermore, the intercepts and the slopes were virtually of the same order. The patients on phenytoin had a mild generalised osteomalacia, independent of method used, whereas the patients on carbamazepine did not have this side-effect. It is concluded that BMC of the forearm can be used as a valid estimate of total body bone mineral in groups of epileptic patients and in normal subjects.