Measurement Of Total Body Calcium Research Articles

Total body-calcium measurements: comparison of twodelayed-gamma neutron activation facilities

This study compares two independently calibrated delayed-gamma neutron activation (DGNA) facilities, one at the Brookhaven National Laboratory (BNL), Upton, New York, and the other at the Children's Nutrition Research Center (CNRC), Houston, Texas that measure total body calcium (TBCa). A set of BNL phantoms was sent to CNRC for neutron activation analysis, and a set of CNRC phantoms was measured at BNL. Both facilities showed high precision (<2%), and the results were in good agreement, within 5%.

A modified bottle manikin phantom for in vivo neutron activation analysis.

An artificial skeleton was designed and placed inside a bottle manikin absorber phantom to provide a new reference standard for measurements of total body calcium by in vivo neutron activation analysis at Brookhaven National Laboratory. The composition of the epoxy-based calcium and phosphorus mixture used to construct the skeleton, the dimensions and weight of each bone are given for two phantoms representing an adult male and female. Also, the dimensions, composition, and weights of overlays designed to simulate the influence of obesity on in vivo neutron activation analysis are given for each.

Comparison of the determination of body calcium by in-vivo neutron activation analysis (IVNAA) and dual energy X-ray absorptiometry (DEXA)

The measurement of total body calcium is an important tool in the diagnosis and treatment of many diseases associated with bone. This measurement is done by IVNAA or DEXA. A knowledge of normal bone mineral mass for a given person, is necessary to determine whether or not a measured quantity is normal or low. The factors that determine bone mineral mass in a person are not clearly known. IVNAA indicates that bone mineral mass is a function of height but not the age whereas the reverse is indicated by DEXA. In this work, we have measured the bone mineral mass of over 200 normal volunteers by IVNAA and DEXA and have developed a methametical model for DEXA (for lumbar spine and femoral neck) as a function of height, age, weight and years after menopause. In determining the bone mineral mass, height is the predominant factor under 20 years of age and age appers to be the dominant factor for over 20 years. The equation derived is useful in calculating the normal bone mineral mass in a patient against which the measured value can be compared.

Absolute measurements of total-body calcium using prompt gamma neutron analysis and internal chlorine standardization: results in renal patients

Measurement of total-body calcium (TBCa) is important in the study of several medical conditions. Neutron activation analysis (NAA) is sufficiently precise for serial measurements, but in order to provide single, absolute determinations of TBCa, it requires a correction for body habitus. A method is described for the absolute determination of TBCa by comparing the total-body chlorine, obtained by NAA, with that obtained by stable bromine dilution. The method is applied to a group of 30 patients who had been treated for chronic renal failure, and significant differences are found between measured values of TBCa and those predicted for 'normal' healthy subjects. The overall experimental error in the absolute determination of TBCa is estimated to be 8%, for a dose equivalent of 3.1 mSv (based on skin dose, and a quality factor of 10 for neutrons).

In vivo measurements of total body calcium by chlorine internal standardization.

At Singleton Hospital, Swansea a 252Cf-based instrument is in regular clinical use for measurements of total body calcium (TBCa) by in vivo neutron activation analysis. The thermal neutron induced reaction, 40Ca(nγ)41Ca, is employed which results in the emission of prompt 6.420 MeV gamma rays.

Total body calcium in patients with inflammatory bowel disease: a longitudinal study

1. Serial measurements of total body calcium have been made by prompt gamma-neutron activation analysis in 13 patients with inflammatory bowel disease over a mean period of 23 months. Changes in spinal trabecular bone mineral density and radial shaft bone mineral content were also assessed by using quantitative computed tomography and single photon absorptiometry, respectively. 2. The mean annual decreases (95% confidence intervals) were: total body calcium, 7.8% (-12.0 to -3.7%; P less than 0.001); spinal trabecular bone mineral density, 2.5% (-5.0 to +0.1%; 0.05 less than P less than 0.1), radial bone mineral content, 2.1% (-3.4 to -0.8%; P less than 0.01). 3. No significant correlations were found between rates of change of the three variables. However, there were significant positive correlations between the baseline values for total body calcium and radial bone mineral content (r = 0.638, P less than 0.05), spinal bone mineral density and radial bone mineral content (r = 0.854, P less than 0.01), and total body calcium and spinal bone mineral density (r = 0.876, P less than 0.001). 4. These results demonstrate rapid decreases in total body calcium in patients with inflammatory bowel disease which, in conjunction with the significant decrease in radial shaft bone mineral content, indicate increased rates of cortical bone loss. Whilst values for bone mass at different skeletal sites showed positive correlations within individuals, no relationship was found between the rates of change in bone mass at these sites. 5. The rapid bone loss observed in some subjects emphasizes the importance of early detection of osteoporosis by bone densitometry and the need for effective prophylactic measures to be established in this group of patients.

Measurement of total body calcium by a new technique of prompt-gamma in-vivo activation analysis

Measurement of total body calcium by a new technique of prompt-gamma in-vivo activation analysis

Assessment of bone mineral content and bone mass by non-invasive radiologic methods.

Methods for quantitative determination of bone mineral and bone mass in normal subjects and in patients with metabolic bone disorders can be measured by the Compton scattering technique, the neutron activation analysis, by measurement of metacarpal bone mass, by single and dual photon absorptiometry, and by quantitative computed tomography. Measurement on metacarpal bone (radiogrammetry) seems to be able to distinguish between resorption and/or new bone formation at the periosteal and/or endosteal surface. The intraindividual observer variation on combined cortical thickness (D-d), cortical area (D2-d2), metacarpal bone mass (D2-d2)/D2-varies from 0.7 to 2.5 per cent and the interindividual observer variation from 1.0 to 5.8 per cent. Single photon absorptiometry measures bone mineral content in the forearm with great precision. The reproducibility using repeated measurements and automatic selection of the measuring area is about one per cent and can be used to follow changes in mineral content with time in patients with metabolic bone diseases. The dual photon absorptiometry may be used for measurements of bone mineral content in lumbar spine, in the femoral neck and measurement of total body calcium with an accuracy of less than 6 per cent and a precision below 3 per cent. Quantitative computed tomography has the ability to measure trabecular and cortical bone both centrally and peripherally. Using CT scanning, scanner related changes with time (day-to-day variation +/- 4%), patient repositioning (less than 1.5%), and fat concentration (residual uncertainty of approximately 1/6 of the biologic variation) are important factors influencing the accuracy and reproducibility of the values of the measured bone mineral content.(ABSTRACT TRUNCATED AT 250 WORDS)

Total body calcium measurements using neutron-activation analysis in Cushing's syndrome.

Total body calcium content (TBCa) was estimated by in vivo neutron activation analysis in 16 patients (14 female, 2 male) with active Cushing's syndrome, pituitary driven in all but two cases. Apart from being nonreproductive, patients were unselected. TBCa was below the predicted young normal value in all patients (mean +/- SD, 85.2 +/- 5.8% of predicted, P less than 0.01 vs. predicted) and in 13 of the 16 patients, was also below the predicted value when allowance was made for expected postmenopausal skeletal losses (mean +/- SD, 92.7 +/- 12.5% of predicted, P less than 0.02). However, individual values of TBCa were significantly lower (P less than or equal to 0.05) than the predicted normal range, corrected for postmenopausal losses, in only 3 patients (19% of the group). Initial TBCa apparently was not related to duration of the disease or to current urinary-free cortisol levels. At presentation, radiographic signs of significant osteoporosis (multiple vertebral and/or rib fractures) were present in four patients, three of whom had subnormal or borderline TBCa compared with the young normal predicted range. TBCa measurements were repeated in 9 patients 1-10 years after successful treatment, and were generally unchanged. During this period, only one vertebral fracture (consistent with simple postmenopausal osteoporosis) appeared in these patients. We conclude that bone mass tends to be low in newly diagnosed Cushing's syndrome, but that significant reduction beyond expected postmenopausal losses is relatively uncommon.(ABSTRACT TRUNCATED AT 250 WORDS)

Skeletal mass in long term hemodialysis patients.

Histomorphometric analyses of bone, bony radiographic analysis, bone densitometry and total body mineral content in hemodialyzed patients indicate that skeletal mass is quite variable in patients receiving hemodialysis for one to three years.1’2’3 No long term studies of skeletal mass are available in patients receiving hemodialysis treatments for five to ten years. This study estimates skeletal mass by measurements of total body calcium by neutron activation analysis.KeywordsNeutron Activation AnalysisRenal OsteodystrophyBody CalciumSkeletal MassTotal Body CalciumThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Bone loss in rheumatoid arthritis and primary generalized osteoarthrosis: effects of corticosteroids, suppressive antirheumatic drugs and calcium supplements.

The annual rate of bone loss in rheumatoid arthritis (RA) and primary generalized osteoarthrosis (PGOA) was determined by measurement of total body calcium (TBCa). The mean annual rate of bone loss in 24 patients with RA treated with nonsteroidal anti-inflammatory drugs (NSAIDs) alone was 3.4%. This rate of bone loss was not reduced in ten RA patients responding to suppressive antirheumatic drugs (4.3%) or seven patients receiving oral calcium supplements (4.5%). The mean annual rate of loss of TBCa in 19 patients with PGOA was 1.6%, a figure which probably represents age-associated bone loss. The rate of bone loss in PGOA was significantly less than that in RA patients not receiving corticosteroids. The mean annual rate of change of TBCa in 30 RA patients receiving corticosteroids (+0.7%) was significantly less than that in any of the other RA groups despite an initial normalized bone mass which was significantly less than in those RA patients receiving NSAIDs alone. The data supported the hypothesis that bone loss occurred early in the course of corticosteroid therapy and thereafter the drugs might have a protective effect on the loss of bone in RA.

Changes in total body calcium following surgery for primary hyperparathyroidism

The aims of this study were to measure the deficit in total body calcium in patients with primary hyperparathyroidism and to observe whether this deficit was reversed by parathyroidectomy. Total body calcium was measured in five women and three men preoperatively, and the mean was found to be 11% below that of ageand sex-matched controls after normalization for postmenopausal age and body size ( P < 0.01). Following parathyroidectomy, repeat total body calcium measurements showed an increase of 7.1% over an average period of 14 months ( P < 0.03). In patients with primary hyperparathyroidism, total body calcium returns toward normal following surgical removal of the adenoma.

The precision and accuracy of noninvasive measurements of total body calcium in the rat.

It has been proposed that the adult castrated male rat may be used as a model of human postmenopausal osteoporosis. If such a model is valid then the total body calcium of castrated rats should progressively decrease compared with normal rats. To search for this age-related difference, it will be necessary to use a measurement technique with a precision which is small compared with the magnitude of the change to be detected. From measurements of total body calcium by neutron activation and by whole body ashing of eight dead rats, it has been shown that total body calcium can be measured with an accuracy and precision which should allow distinction between the expected lifetime changes in normal and castrated rats.

Effect of slow neutron absorption on measurement of total body calcium in vivo

Reviews the effect of chlorine and, in addition, reports on studies made on hydrogen and nitrogen absorption using the neutron beam from the MRC Cyclotron. Some observations are also made on the effects of the relatively low concentration of hydrogen and the high concentration of nitrogen in bone.

Total body neutron activation analysis of calcium: calibration and normalisation

An irradiation system has been designed, using a neutron beam from a cyclotron, which optimises the uniformity of activation of calcium. Induced activity is measured in a scanning, shadow-shield whole-body counter. Calibration has been effected and reproducibility assessed with three different types of phantom. Corrections were derived for variations in body height, depth and fat thickness. The coefficient of variation for repeated measurements of an anthropomorphic phantom was 1.8% for an absorbed dose equivalent of 13 mSv (1.3 rem). Measurements of total body calcium in 40 normal adults were used to derive normalisation factors which predict the normal calcium in a subject of given size and age. The coefficient of variation of normalised calcium was 6.2% in men and 6.6% in women, with the demonstration of an annual loss of 1.5% after the menopause. The narrow range should make single measurements useful for diagnostic purposes.

Changes in total body calcium on prolonged maintenance hemodialysis with high and low dialysate calcium.

In vivo neutron activation analysis was used to measure sequential changes in total body calcium in 25 unselected patients with end-stage renal disease on dialysis for a period as long as 5 years. In 7 unselected patients (group 1), dialysis with a calcium solution of 5.0 mg/100 ml resulted in significant calculated daily loss of calcium (-321 +/- SEM 76 mg/day) while dialysis with 6.5 mg/100 ml resulted in a significant calculated calcium gain (182 +/- SEM 103 mg/day; p less than 0.0025). The remaining 18 patients (group 2) were dialyzed with a dialysate calcium of 6.5 mg/100 ml and sequential total body calcium measurements showed no significant calcium losses (-12 +/- SEM 68 mg/day) for a period as long as 2 years.

Measurement of total body calcium in some disease

The irregular shape of the human body and the non-uniformity of distribution of elements within the body makes absolute quantitation using in-vivo neutron activation relatively difficult. However, if the mass of an element can be assessed with reasonable accuracy, then a single measurement of a patient could reveal how far body content varied from normal. The determination of total body calcium is of importance in the study of bone disease. We have assessed the accuracy of measuring this quantity by varying the size of phantoms used for calibration and the distribution of element within these phantoms.

Osteoporosis and long-term corticosteroid therapy.

Sequential measurements of total body calcium by in-vivo neutron activation analysis were made in five patients treated with corticosteroid drugs for severe inflammatory disease. No evidence of osteoporosis was seen to develop during the course of 20-33 months of study. In one case a substantial rise in total body calcium was found.

Absolute measurement of total body calcium (bone mass) in vivo.

Abstract Using total body neutron activation analysis (TBNA) and total body counting, a technique has been established to quantitate body calcium in grams with an estimated accuracy of 5.2 per cent (see below). Five cadavers of various body size were activated and counted to establish the ratio of their induced 49 Ca activity to a fixed calcium standard, activated and counted under identical conditions. The cadaver skeletons were then ashed and chemically analyzed to establish the specific activity; i.e., the 49 Ca activity induced per gram of skeletal calcium. Variations in specific activity between cadavers were linearly related to body weight divided by height (kilogram per meter). The TBNA results from subjects of various sizes measured in vivo could then be converted to grams of calcium using the cadavers as comparison standards. In 8 normal men, total body calcium ranged from 933 to 1,361 Gm., average 1,093 Gm. Data for body calcium from cadaver analyses from the literature plus the present results were inspected. The relationship between skeletal calcium and skeletal length suggests that total body calcium increases as 15 the cube of skeletal length. Applying this relationship to normal men measured by TBNA, the expression y=0.203 x 3 was derived where y=calcium in grams and x=height in meters. In 5 patients with known osteopenia from various causes, bone mass was shown to be reduced 23 to 35 per cent below the expected normal.

Effects of porcine calcitonin on calcium metabolism in osteoporosis.

ABSTRACT The effect of the administration of porcine calcitonin together with dietary Ca and P supplements for a period of 3 months to 7 osteoporotic patients was evaluated by means of clinical observation, Ca-balance studies, kinetic tracer studies, and neutron activation analysis. Clinical improvement was evidenced in this study by a decrease in back pain and a cessation of spontaneous fractures. The compartmental analysis and the balance studies indicated a decrease in the resorption rate, and a small increase in the Ca balance. Direct measurement of total body calcium by in-vivo neutron activation analysis also showed a small increase in the calcium concentration in the skeleton of several of the patients. Taken by themselves, the objective data are not highly significant, but together with the clinical findings, they suggest a potential efficacy of calcitonin therapy. The three month period studied appears to be insufficient for the accumulation of significant amounts of calcium. The direction of the...