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Results for “Absorptiometry, Photon”

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PubMed1992

Bone mineral density of the axial skeleton in acromegaly.

Acromegaly is characterized by growth hormone (GH) hypersecretion and insulin-like growth factor-I (IGF-I) excess, both of which stimulate osteoblast proliferation. At diagnosis, GH excess has usually been present for years. Furthermore, impaired gonadotropin secretion with hypogonadism is frequent. To date, studies of changes in bone mineral density (BMD) in acromegaly have been limited and the available data inconsistent. To investigate the effects of GH excess on proximal femur and lumbar spine BMD, a case series of 25 patients with acromegaly (8 eugonadal, 17 hypogonadal) documented by high plasma GH and IGF-I concentrations was studied. BMD was measured using dual-photon absorptiometry, hormonal and biochemical measurements, which included GH, IGF-I, serum calcium, phosphate, alkaline phosphatase, 1,25 dihydroxy vitamin D and urinary calcium and hydroxyproline excretion. Seven patients were re-studied after IGF-I was suppressed for six months by the somatostatin analog 201-995 (five patients) or pituitary adenomectomy (two patients). BMD was normal in 22 patients and was decreased at one site each in one eugonadal and two hypogonadal patients. BMD was similar between the eugonadal and hypogonadal groups at all sites. Urinary hydroxyproline excretion was equally increased in both groups. There was no correlation between any of the hormonal or biochemical parameters and the age, sex, race and body mass index matched Z-scores of BMD at any site. Following normalization of IGF-I for 6 mo in seven patients, there was no significant change of BMD. We conclude that proximal femoral and lumbar spine BMD is normal in most patients with active acromegaly, including those who are hypogonad. Successful treatment of acromegaly does not result in major short-term changes in BMD.

Absorptiometry, Photon↗

PubMedDate not supplied

[A method for the in vivo measurement of the mineral content in an experimental animal].

Bone mineral content measurement is not as widely used in experimental conditions as in clinical practice because of the lack of adequate experimental methods. An in vivo measurement method of bone mineral content in the rat is here presented. Measurements were made at the proximal tibio-peroneal segment, which has a mainly trabecular structure, by means of single photon absorptiometry. The presence of the fibula, having cortical structure, has been shown not to affect the read values, which can be therefore attributed to the tibial metaphysis, having a mainly trabecular structure. Expressing mineral content values as a function of the measured bone diameter has proven useless. Limb repositioning on the instrument holding device is critical for the reproducibility of the measurement, but the latter is not affected by the repositioning method. Method reproducibility (depending on either the intrinsic instrumental error or the repositioning error) is 5-6%. This relatively low reproducibility of the suggested method does not prevent its use in the study of physiological and pathological variations of bone mineral content in rats, and of the means to influence it.

Absorptiometry, Photon↗

PubMed1997

[Bone mineral content and its influence factors of children aged 0-16 in a city and village].

The radial and ulnar bone mineral content (BMC) was measured by single-photon absorptiometry, and the effects of multiple independent variables on BMC and bone width (BW) were explored using multiple regression analysis in 332 rural and city children aged 0-16 years in Henan province from 1994 to 1995. BMC, BW, BMC/BW and forearm length increased with age increasing, and the BMC in city children aged 0-6 years was higher than that in rural children. Radial BMC was positively related to BW in the measured sites. Age, body weight and height (or length) all had significantly positive and independent effects on radial BMC in both groups. The positive correlation of radial BMC with age was observed, however, the ratio of radial BMC to body weight was negative correlation. The BW in measured site and forearm length increased with ages. After adjusted for body size, there were no significant effects of sex, age and body weight on radial BW except height (length). This study shows that overall body size rather than adiposity is the important factor for bone BMC, so that it is needed to consider several variables, for example, BMC, BMD, BMC/body weight and BMC/age.

Absorptiometry, Photon↗

PubMed1992

Total body bone density in amenorrheic runners.

Many studies have suggested that the positive effect of running on bone mass does not fully compensate for the negative effects of athletic amenorrhea. These studies have made this conclusion based on measurements of bone at a limited number of sites. This study used dual-photon absorptiometry to measure bone mineral content and bone mineral density in the total body as well as in several regions in amenorrheic runners (N = 13), eumenorrheic runners (N = 13), and sedentary controls (N = 12). The subjects were 21-35 years old. Runners had run at least 40 km/week for at least the past 3 years. Controls had body mass indices similar to those of the runners. The amenorrheic women had significantly lower values for total bone mineral content (P = .01), total bone mineral density (P = .04), and total bone mineral content as a percent of normal values (P = .04) than eumenorrheic women, but they were not significantly different from the controls. When total bone mineral content and total bone mineral density were adjusted for body weight, there were no significant differences among the groups. The eumenorrheic subjects had significantly greater bone mineral density in the trunk than the amenorrheic women; eumenorrheics and controls had significantly greater bone mineral density in the spine compared with amenorrheics. Lumbar spine bone mineral density showed a trend toward greatest values for controls and lowest for amenorrheic women (P = .069), although this measurement is relatively imprecise. Arms and legs showed no significant differences among the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗

PubMed1992

[Osteoporosis in rheumatoid arthritis].

Rheumatoid arthritis may be associated with generalized, as well as, juxta-articular osteoporosis. To assess the skeletal distribution of bone loss, bone mass was measured in women with rheumatoid arthritis, using single photon absorptiometry and dual energy X-ray absorptiometry. Bone loss was more rapid in the distal metaphyseal region of the radius than in the diaphyseal region. Bone loss in the legs was correlated with gait disturbance and bone loss in the third lumbar vertebra was recognized only in the patients treated with corticosteroids for more than 1 year. These results indicate that rheumatoid arthritis was not universally associated with generalized osteoporosis. Patients treated with corticosteroids are likely to be at risk from generalized osteoporosis.

Absorptiometry, Photon↗

PubMed2004

Bone mass evaluation in children - comparison between methods.

Peak adult bone mass should be optimized during childhood and adolescence. The physiology of bone mass accretion during these early years of life has been extensively studied, due to the development of reliable, precise, little or noninvasive methods of bone mass assessment. The purpose of this review is briefly to describe quantitative aspects of bone mass accretion during intrauterine life, childhood and adolescence and to describe the methods that have been used to assess bone mass in children in terms of precision, accuracy, ease of use, invasiveness and normative data. In particular, we review major methods such as radiographic methods, photon absorptiometry, dual-energy X-ray absorptiometry, quantitative ultrasound, quantitative computerized tomography and other methods less frequently used.

Absorptiometry, Photon↗

PubMed1991

Effect of calcium supplementation on bone mass in patients operated on for hyperparathyroidism.

Photon absorptiometry was used to measure bone mass in the lumbar vertebrae, proximal femur, mid-radius and distal radius in eight pairs of closely matched female patients with primary hyperparathyroidism before, and 1, 3 and 6 months after operation. One of each pair was randomised to receive 3 g of oral calcium supplementation/day for three months postoperatively, and the other to serve as a control. After successful operations on the parathyroids, the bone mass in the lumbar vertebrae, proximal femur, and distal radius increased by roughly 7% during the first six months in both the treated and the control patients. This study shows that oral calcium supplementation after operation for hyperparathyroidism does not result in any additional increase in bone mass beyond the effect that is caused by the operation.

Absorptiometry, Photon↗

PubMed1991

[Indications for surgical treatment of secondary hyperparathyroidism].

From 1978 to 1990 subtotal parathyroidectomy was carried out on 41 patients for secondary hyperparathyroidism. The indications for parathyroidectomy and suitable operative time, especially in the point of view of renal osteodystrophy are discussed. Serum ALP and PTH level and the presence of generalized fibrous osteitis were good indicators for parathyroidectomy. Furthermore, 99mTc-Pyrophosphate bone scintigraphy and Dual Photon Absorptiometry were proved to be valuable for patient selection for parathyroidectomy. Parathyroidectomy for patients in whom 99mTc-pyrophosphate bone uptake is diminished or patients in whom bone mineral contents are dramatically decreased must be carefully performed.

Absorptiometry, Photon↗

PubMed1991

Bone mass and bone diminution of the axial and peripheral skeleton in normal and osteoporotic Austrian females.

Measurements of bone mass were performed in 133 healthy Austrian women using the quantitative computed tomography technique of the lumbar spine and single photon absorptiometry of the distal forearm. The data were compared with those of 110 Austrian females with osteoporotic spine fractures. A significant difference in mean bone density of the lumbar spine was observed between normal and osteoporotic patients in every decade, whereas forearm measurements showed statistical differences in the seventh and eighth decade but not in the sixth decade. Compared to age matched controls, bone mass of osteoporotic women showed the following diminution: sixth decade: distal forearm: -12.7%, spine: -46.8%; seventh decade: distal forearm: -19.0%, spine: -36.7%, eighth decade: distal forearm: -15.4%, spine: -33.7%. It appears that postmenopausal osteoporosis involves greater loss of bone in the spine in the first decade after menopause and slows down after this period, whereas loss of forearm bone mineral density (BMD) increases with advancing age.

Absorptiometry, Photon↗

PubMed1991

Radiographic techniques for early detection of osteoporosis.

Sequelae of osteoporosis such as fracture and deformities usually occur when the bone mass has been severely reduced. Since the lost bone mass cannot be replaced, management of osteoporosis is aimed at preventing, halting, or retarding its progression. Early detection of osteoporosis and the identification of individuals at high risk for the disease are crucial if therapy is to be effective. Several radiographic techniques are currently available for osteoporosis screening, including dual photon absorptiometry (DPA), quantitative computed tomography (QCT), and dual-energy radiographic absorptiometry (DRA). This paper discusses the relative value and limitations of these techniques.

Absorptiometry, Photon↗

PubMed1991

The contributions of growth and puberty to peak bone mass.

Lumbar spine bone mass was measured by dual photon absorptiometry (DPA) in 236 subjects aged between 3 and 30 years. Expected values of bone mineral density (BMD) and bone mass (BMC) for the lumbar vertebrae L2 to L4 were derived as a function of age, by non-linear regression analysis. The selected regression equation was the sum of two logistic expressions, one of which was assigned to growth at the time of puberty and the other to the slower long term component of growth. Growth during puberty contributed about 50% of peak bone mass in females, while in males this contribution was closer to 15%. No increase was found in lumbar spine bone mass in females after puberty.

Absorptiometry, Photon↗

PubMed1991

Estimation of bone mineral density in children with juvenile rheumatoid arthritis.

Bone mineral content of different areas of the skeleton was measured by dual photon absorptiometry in 20 children with juvenile rheumatoid arthritis (JRA) and compared to 20 age and sex matched healthy children. Spinal density was similar in both groups in prepubertal children but decreased in the postpubertal girls with JRA. Total bone density was also decreased in the postpubertal girls. Six children with JRA had repeat scans 12 to 24 months later; in 3 children total bone mineral content increased significantly with an intensive management program. Our study suggests that bone mineral density does not show a pubertal increase in children with JRA, as it does in healthy children.

Absorptiometry, Photon↗

PubMed1991

The effect of a stiff spinal implant on the bone-mineral content of the lumbar spine in dogs.

The response of canine lumbar vertebral bone to the application of a stiff transpedicular screw-plate implant from the third to the fifth lumbar vertebra, without arthrodesis, was investigated. Five groups of six dogs each were studied: dogs that had not had an operation (control group); dogs that had had a sham operation, with survival periods of three and six months; and dogs that had received an implant, with survival periods of three and six months. The results were the same in specimens from the control group and the group that had had a sham operation. In the groups that had received an implant, dual-photon absorptiometry revealed an insignificant decrease in bone-mineral content at the bypassed fourth lumbar segment (17 per cent at three months and 12 per cent at six months). When the data for the three and six-month intervals were pooled, the mean decrease in bone-mineral content of 14 per cent was significant. Histomorphic study yielded similar results; the mean decrease in bone-mineral content for the pooled three and six-month specimens was significant (16 per cent). Losses were similar for the ventral and dorsal columns. Histomorphometric analysis also showed a significant (13 per cent) loss of bone-mineral content at the adjacent caudad (sixth lumbar) vertebra for the pooled three and six-month groups. The results of the methods of analysis of loss of bone-mineral content correlated strongly. Under these experimental conditions, a stiff spinal implant caused loss of bone-mineral content of the bypassed vertebral segment, although the loss was less than anticipated and did not increase between three and six months.

Absorptiometry, Photon↗

PubMed1991

Bone mineral content at three sites in normal perimenopausal women.

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

Absorptiometry, Photon↗

PubMedDate not supplied

Assessment of bone mineral content in children.

Quantitative digital radiography (QDR) is a new technique for measuring bone mineral content that offers improved precision, shorter study times, and less radiation exposure than single-photon absorptiometry (SPA), dual-photon absorptiometry (DPA), and quantitative computed tomography (CT) scanning. To evaluate application of QDR to a pediatric population, the bone mineral density (BMD) of both proximal femurs and lumbar spine was determined in 20 normal children aged 4-15 years. Duplicate measures indicated a precision less than 2%. A small left side/right side difference was sometimes found in the BMD of the proximal femurs. This difference was not related to age, sex, or handedness, and there was no history of significant injury to, or problems with, either lower extremity. QDR will greatly enhance early evaluation and treatment of many conditions that adversely affect the immature skeleton.

Adolescent↗

PubMed1990

Alterations of calcium metabolism in spontaneously hypertensive rats.

We have examined the femurs of eight male spontaneously hypertensive rats and eight male Wistar Kyoto rats, aged 24 weeks. The mineral density of the bones was determined at the mid-point of the femurs by dual photon absorptiometry and the calcium content was estimated on bone ash by atomic absorption spectrophotometry. The data show that spontaneously hypertensive rats have lower bone density and calcium content than do age-matched Wistar Kyoto rats.

Absorptiometry, Photon↗

PubMed1990

ITI implants with overdentures: a prevention of bone loss in edentulous mandibles?

Changes in the bone mineral content (BMC) of edentulous mandibles with osseointegrated ITI implants supporting overdentures were measured in vivo by dual-photon absorptiometry. The BMC measurements were performed 3 weeks postoperatively and at the 2-year follow-up visit. Measurements were made in the ITI site (anteriorly), the premolar region just behind the fixtures, and the standard site of the mandible for obtaining reference values of the age-related MBC loss. The increased function of the mandible after this treatment seems to cause a load-related bone formation that minimizes, or in some cases may counteract, the physiologic age-related BMC loss leading to osteoporosis.

Absorptiometry, Photon↗

PubMed1990

[Total bone mineral content in premenopausal women].

Because of the controversy about the loss of bone mass in premenopausal women, we decided to study the total mineral bone content (TMBC), measured by dual-photon absorptiometry (DPA), a technique with low variation coefficient and high level of discrimination, in a group of 96 premenopausal women with a age range between 20-49 years, who were selected by homogeneous criteria of habits and life stile and body mass lower than 25. In all women, the TMBC were quantify in supine with the densitometer type Norland XR-26 and its value correlated with age following the "Pearson's test"; there were not statistical significance. We concluded that women in a fertile period of life do not lose bone mass as a TMBC, which mean the importance of obtaining the bone mass peak during the childhood and adolescency.

Absorptiometry, Photon↗