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PubMed2004

Mice deficient in 11beta-hydroxysteroid dehydrogenase type 1 lack bone marrow adipocytes, but maintain normal bone formation.

Glucocorticoids (GCs) exert potent, but poorly characterized, effects on the skeleton. The cellular activity of GCs is regulated at a prereceptor level by 11beta-hydroxysteroid dehydrogenases (11betaHSDs). The type 1 isoform, which predominates in bone, functions as a reductase in intact cells and regenerates active cortisol (corticosterone) from circulating inert 11-keto forms. The aim of the present study was to investigate the role of this intracrine activation of GCs on normal bone physiology in vivo using mice deficient in 11betaHSD1 (HSD1(-/-)). The HSD1(-/-) mice exhibited no significant changes in cortical or trabecular bone mass compared with wild-type (Wt) mice. Aged HSD1(-/-) mice showed age-related bone loss similar to that observed in Wt mice. Histomorphometric analysis showed similar bone formation and bone resorption parameters in HSD1(-/-) and Wt mice. However, examination of bone marrow composition revealed a total absence of marrow adipocytes in HSD1(-/-) mice. Cells from Wt and HSD1(-/-) mice exhibited similar growth rates as well as similar levels of production of osteoblastic markers. The adipocyte-forming capacity of in vitro cultured bone marrow stromal cells and trabecular osteoblasts was similar in HSD1(-/-) and Wt mice. In conclusion, our results suggest that 11betaHSD1 amplification of intracellular GC actions in mice may be required for bone marrow adipocyte formation, but not for bone formation. The clinical relevance of this observation remains to be determined.

11-beta-Hydroxysteroid Dehydrogenase Type 1↗
PubMed2000

Mineral density and bone strength are dissociated in long bones of rat osteopetrotic mutations.

Bone mineral density (BMD) and mechanical strength generally show strong positive correlations. However, osteopetrosis is a metabolic bone disease with increased skeletal density radiographically and increased risk of fracture. We have evaluated mechanical strength and mineral density in three osteopetrotic mutations in the rat (incisors-absent [ia/ia], osteopetrosis [op/op], and toothless [tl/tl]) to test the hypothesis that reduced bone resorption in one or more of these mutations results in weaker bones in the presence of greater mineral density and skeletal mass. Peripheral quantitative computed tomography (pQCT) was used to analyze BMD and cross-sectional geometry in the tibial diaphysis and metaphysis as well as the femoral diaphysis and femoral neck. The bending breaking force of tibial and femoral midshafts was obtained using the three-point bending test and femoral neck strength was tested by axial loading. Osteopetrotic mutants were significantly smaller than their normal littermates (NLMs) in each stock. The pQCT analysis showed that BMD and bone mineral content (BMC) were higher than or equal to NLMs in all skeletal sites measured in the osteopetrotic mutants. However, the mechanical breaking force was equal to or lower than their NLMs in all sites. The cross-sectional structure of long bone shafts was markedly different in osteopetrotic mutants, having a thin cortex and a medullary area filled with primary trabecular bone. These results indicate that osteopetrotic mutations in the rat increase bone density and decrease bone strength. The tibial diaphysis was significantly weaker in tl/tl and ia/ia mutants and the tibial metaphysis showed the greatest increase in BMD in all mutants. These data are another illustration that an increased BMD does not necessarily lead to stronger bones.

Animals↗
PubMed2000

Cross-sectional geometry, bone strength, and bone mass in the proximal femur in black and white postmenopausal women.

Osteoporosis is characterized by both a low bone mass and a disruption of the architectural arrangement of bone tissue, leading to decreased skeletal strength and increased fracture risk. Although there are well-known ethnic differences in bone mass and fracture risk, little is known about possible ethnic differences in bone structure. Therefore, we studied cross-sectional geometry in the hip in a sample of postmenopausal black and white women in order to investigate ethnic differences that might contribute to differences in bone strength and ultimately hip fracture risk. We recruited 371 postmenopausal black and white women who were entering the Women's Health Initiative (WHI) clinical trials in Detroit. Bone density measurements of the proximal femur were done by dual-energy X-ray absorptiometry (DXA) using a Hologic 1000 Plus bone densitometer. The DXA data were used for hip structure analysis, which treats the entire proximal femur as a continuous curved beam from the proximal shaft to the femoral neck. This permits the analysis of cross-sectional geometric properties in two narrow regions corresponding to thin (5 mm) cross-sectional slabs seen on edge. The results indicate significant ethnic differences in bone density, cross-sectional geometry, and dimensional variables. Specifically, the black women have a significantly higher bone density in both locations (10.1% and 4.1% for the neck and shaft, respectively); greater cross-sectional geometric properties in the neck (ranging from 6.1% to 11.6%), but a smaller endocortical diameter in the neck (3.6%). There are fewer significant differences in cross-sectional geometry in the shaft location. Our data suggest that the spatial distribution of bone is arranged in the femoral neck to resist greater loading in black women compared with white women.

Absorptiometry, Photon↗
PubMed2000

Associations between maternal peak bone mass and bone mass in prepubertal male and female children.

The aim of this study was to estimate heritability of bone density in premenopausal women, prepubertal male, and prepubertal female child pairs. We studied 291 pairs (mothers, mean age, 33 years, range 22-45 years; children, mean age, 7.92 years, range 7.32-8.92 years). Bone density and body composition were assessed by dual-energy X-ray absorptiometry. Height and weight were measured in both mother and child. Body size-adjusted heritability estimates for areal bone density (g/cm2) were all statistically significant (femoral neck, 59%; lumbar spine, 38%; total body, 41%) and were consistently and significantly higher in mother-daughter pairs (n = 105) as compared with mother-son pairs (n = 186). Heritability estimates for bone mineral apparent density (BMAD; g/cm3) were marginally lower but remained statistically significant at all sites (femoral neck, 51%; lumbar spine, 32%; total body, 38%). Maternal osteopenia was associated with significant reductions in bone mass at all sites in the children (femoral neck, 0.75 SD and p < 0.0001; lumbar spine, 0.61 SD and p < 0.0001; total body, 0.43 SD and p = 0.012). Mother-child bone areal bone density correlation coefficients and prediction of low bone mass in the child were greater (but this did not reach statistical significance) if the corresponding anatomical site in the mother was used for prediction with the exception of the total body. These data confirm that heritability of bone mass extends to prepubertal children and is gender- and possibly site-specific as well as under separate genetic control to growth. Furthermore, the strength of the mother-child association is such that bone density screening of mothers would make it possible to identify most prepubertal children at higher risk of osteoporosis in later life.

Absorptiometry, Photon↗
PubMed2002

Responses of bone turnover markers and bone mineral density to growth hormone therapy in children with isolated growth hormone deficiency and multiple pituitary hormone deficiencies.

Growth hormone deficiency (GHD) is an important cause of decreased bone mass in childhood and adolescence. The role of other pituitary hormone deficiencies on bone mass is still a query in children. Thirty-nine children (28 with isolated GHD [IGHD] and 11 with multiple pituitary hormone deficiency [MPHD]) were investigated to show the effects of IGHD vs MPHD on bone status. Bone turnover markers (calcium, phosphate, alkaline phosphatase [ALP] Bone ALP [BALP], osteocalcin [OSC], carboxyterminal propeptide of type-1 collagen [CPP-I], parathyroid hormone [PTH]) were measured before and every four months during growth hormone (GH) therapy; bone mineral density (BMD) of the lumbar spine was measured before and every six months during therapy. All bone turnover markers except calcium and PTH increased significantly during 1 year of GH therapy. There were no differences in the levels of bone turnover markers between children with IGHD and MPHD at baseline, and after 4, 8 and 12 months of therapy. Lumbar spine BMD SDS of all patients increased significantly during 1 year of therapy (p = 0.035 after 6 months and p <0.001 after 12 months compared with baseline). BMD SDS of both IGHD and MPHD groups were similar at baseline and after 6 and 12 months of therapy (p = 0.235, p = 0.295 and p = 0.384). Height SDS (HtSDS) at baseline was the most important predictor of baseline BMD SDS in children with GHD (t = 4.166, p <0.001). DeltaHtSDS was also positively related to deltaBMD SDS after 1 year of GH therapy. In conclusion, there was no difference in bone status of the patients with IGHD and MPHD at baseline. GH therapy yielded similar increases in bone mass in both groups. Increase in height contributed to increase in BMD during 1 year of GH therapy.

Age Determination by Skeleton↗
PubMed1991

Histologic evaluation of combining tetracycline and allogeneic freeze-dried bone on bone regeneration in experimental defects in baboons.

Tetracyclines (TTC) have been used both systemically and locally during periodontal bone grafting procedures, but previous work regarding the effect of TTC on new bone formation has been contradictory. The purpose of this study was to determine if the use of locally applied TTC in combination with freeze-dried bone allografts (FDBA) would enhance bone regeneration in an experimental alveolar bone osseous defect grafting system. Pre-weighed freeze-dried bone allograft particles (300-500 mu diameter) were placed in nylon mesh chambers (250 mu pore size) and rehydrated with either 10 micrograms/ml aqueous TTC or sterile distilled water. Empty chambers were used as further controls. The chambers were placed in the posterior mandible of baboons in surgically created windows. After 3 and 5 weeks, the chambers were retrieved, processed histologically, and analyzed histometrically for new bone formation. The TTC-rehydrated FDBA demonstrated much greater (greater than 5x) new bone formation than the water rehydrated FDBA. These results strongly suggest that locally-applied TTC in combination with FDBA enhances new bone formation in experimental alveolar bone defects.

Administration, Topical↗
PubMed2005

Effect of recombinant human bone morphogenetic protein 7 on bone density during distraction osteogenesis of the rabbit mandible.

OBJECTIVES: To examine whether the quality of bone generation in distraction osteogenesis of the rabbit mandible is enhanced by administering recombinant human bone morphogenetic protein 7 (rhBMP-7) to the lengthened site at the end of the distraction phase. STUDY DESIGN: Prospective randomized study of 24 rabbits undergoing distraction osteogenesis of the mandible, followed by injection of rhBMP-7 or a lactate buffer. SETTINGS: McGill University animal care facility. METHODS: Twenty-four white New Zealand rabbits underwent unilateral mandibular osteotomy and application of an Orthofix uniplanar M-100 fixator (Orthofix Inc., Verona, Italy) to the mandible. Mandibular distraction was carried out for 3 weeks. The animals were divided into three groups: group 1 (eight rabbits), control group: distraction, no injection; group 2 (eight rabbits), study group: distaction + injection of 200 microg of rhBMP7-lactate buffer; group 2 (eight rabbits), comparison group: distraction + injection of lactate buffer. All rabbits were sacrificed 7 weeks after surgery. The mandibles underwent radiology and bone densitometry analysis. MAIN OUTCOME MEASURES: Radiology assessment of bone generation within distracted segments and objective analysis of bone mineral density. RESULTS: Radiology confirmed the presence of bone generate within distraction sites. Densitometry showed a difference in bone mineral density among the three groups (p < .05). CONCLUSION: Local injection of a single dose of 200 microg of rhBMP-7 did enhance bone density when compared with the control group, although not in a statistically significant way when analyzed by an x-ray bone densitometer. This study serves as a starting point for future studies in bone tissue engineering by guiding the strategic administration of rhBMPs and the use of new state-of-the-art technologies, such as micro CT scanning, to analyze in a more detailed way, the effects of rhBMP administration.

Absorptiometry, Photon↗
PubMed1991

Calcium and phosphorus requirement of swine from weaning to market weight: II. Development of response curves for bone criteria and comparison of bending and shear bone testing.

Three trials involving 251 crossbred pigs were conducted to establish response surfaces for effects of Ca/P levels (70, 85, 100, 115 and 130% of NRC [1979] estimated requirements) and time (weaning to market) on bone criteria and to compare bending and shear bone testing. Nine replicates, each consisting of five pigs, were used over the three trials. One pig per replicate was slaughtered every 4 wk following the start of the trials. Third metacarpals and metatarsals (3M) and fourth metacarpals and metatarsals (4M) were collected at slaughter; the bone length, bending or shear stress, and dry, fat-free ash percentage (DFF%) were determined. Most bone criteria increased (P less than .01) at a decreasing rate (P less than .05) in response to increasing dietary Ca/P intake and increased linearly (P less than .01) with time on test, although bone length and stress increased at a decreasing rate with time on test. Asymptotic models relating continuous effects of total Ca + P intake ratio (CAP; expressed as a percentage of NRC) and number of days on test before slaughter to bone measurements were fit to least squares slaughter time by diet means. Bone length and DFF% reached 98% maximum at or near 100% the NRC estimated CAP level; however, to reach 98% of maximum bone shear and breaking stress higher CAP levels were required. Shear testing of bones was more desirable than bend testing as a method of determining bone strength due to reduced variability, better discrimination of Ca/P and time effects and ease of calculation.

Animals↗
PubMed1981

The plated femur: relationships between the changes in bone stresses and bone loss.

Calculations were made of the alterations in the in vivo cyclic bone stresses due to the application of various plates on the canine femoral shaft. The plate configurations analyzed were those used by previous investigators when studying the influence of plating on bone remodeling. The magnitude of the reduction in the loads borne by the bone tissue and the degree of shift in the bone stress neutral axis during the stance phase of gait was influenced by the geometry of the plate, the plate elastic modulus, and the location of plate application. From a correlation of the calculated alterations in bone stresses with the resulting measured changes in bone mass, it appears that bone remodeling is very sensitive to small changes in cyclic bone stresses. Changes in cyclic bone stresses of 1 MPa (less than 1 percent of the ultimate strength) can cause measurable differences in bone remodeling after a period of a few months.

Animals↗
PubMed1999

[Bone and hormones. Effects of parathyroid hormone on the bone].

ACTION OF PTH: Parathyroid hormone (PTH) stimulates both bone formation and bone resorption. It also stimulates synthesis of 1,25-dihydroxyvitamin D3 which increases intestinal absorption of calcium and phosphorus and stimulates bone resorption. In bone tissue, PTH acts mainly on osteoblasts which, unlike osteoclasts, carry PTH receptors. PTH also exerts an indirect action on osteoclasts, increasing their number and activity. IMPACT OF INSUFFICIENT PTH: In the absence of PTH, bone remodeling is greatly reduced. Increased bone density has been observed in patients with hypoparathyroidism studied 10 years after total thyroidectomy. IMPACT OF EXCESS PTH: Chronic excess of PTH accelerates bone loss. In primary hyperparathyroidism, reduction of bone density to the order of 10% has been observed, which corresponds to one standard deviation compared with normal subjects of the same age and sex. The hypothesis of an increased risk of fractures remains unresolved. ADMINISTRATION OF PTH: Intermittent rather than continuous subcutaneous administration appears to be necessary to observe the anabolic effects of PTH on bone. The conjunction of favorable anabolic effects demonstrated in animal models, concerning both bone density and mechanical properties, and early studies in humans, provide converging arguments similar to those observed in preclinical investigations, suggest that PTH could be a promising treatment for osteoporosis.

Animals↗
PubMed2000

Effect of growth hormone and pamidronate on bone blood flow, bone mineral and IGF-I levels in the rat.

So far it is not known whether the growth hormone (GH) has an effect on the local blood circulation in bones. Using male rats we studied the local blood circulation in the tibia and the distal end of the femur (by means of the uptake of 85Sr-microspheres), the density and ash weight of the tibia, the urinary excretion of pyridinoline (PD) and deoxypyridinoline (DPD) as an indicator of bone resorption and the blood levels of IGF-I after the administration of human GH (4 mg/kg s.c. daily for 4 weeks) and/or bisphosphonate pamidronate (Aredia, CIBA-Geigy, administered in the dose of 3 mg/kg i.p. on day 1, 2, 9 and 10). The rats were divided into four groups: 1. controls, 2. GH, 3. pamidronate, 4. GH plus pamidronate. After the administration of GH, we observed a significant increase in bone blood flow (and in the uptake of 85Sr-microspheres), a decrease in the density and ash weight of the tibia and increased urinary excretion of PD and DPD; IGF-I levels in the blood were non-significantly elevated. Simultaneously administered pamidronate inhibited all significant effects of GH and it also decreased the IGF-I levels in rats treated with GH. After the administration of pamidronate itself the bone density and ash weight of the tibia were increased and urinary DPD excretion was decreased. In view of the known vascular effects of IGF-I, we assume that the increase in bone blood flow after the administration of GH and its reduction after simultaneous administration of pamidronate could be mediated by the changes of IGF-I blood levels, although the effect of pamidronate on IGF-I is still not clear. Regarding the role of blood circulation in rat bones, we consider that our present results are further evidence for the relationship between the blood circulation in bones and bone resorption, although these results do not show how active is bone blood circulation in the regulation of bone tissue metabolism.

Amino Acids↗
PubMed2002

Effects of treatment with ibandronate on bone mass, architecture, biomechanical properties, and bone concentration of ibandronate in ovariectomized aged rats.

OBJECTIVE: To investigate the effects of treatment with ibandronate, a highly potent nitrogen-containing bisphosphonate, on bone loss, bone quality, biomechanical properties, and bone concentrations in aged ovariectomized rats. METHODS: Eight-month-old female Wistar rats were ovariectomized (Ovx) or sham-operated. Treatment was started 10 weeks following Ovx with subcutaneous ibandronate in doses of 0.2, 1.0, 5.0, or 25 micro g/kg/day for 12 mo. Additional groups received 25 or 125 micro g/kg intermittently every 25 days, resulting in the same total dose as compared to 1.0 or 5.0 micro g/kg/day, respectively. Bone analyses by x-ray densitometry, peripheral quantitative computed tomography (pQCT), dual energy x-ray absorptiometry (DEXA), histomorphometry, 3-point bending, and compression tests were performed in femora, tibiae, and lumbar vertebrae in separate groups at the beginning and the end of treatment. Ibandronate concentration in tibiae and vertebrae was determined by gas chromatography mass spectroscopy at the end of the study. RESULTS: Ovariectomy resulted in a significant reduction in bone mass (p <or= 0.0001) and strength (p < 0.05) by 10 weeks after surgery in long bones, while only a trend was present in vertebrae. When compared to age matched Ovx controls, ibandronate resulted in a dose dependent increase in bone mineral density (BMD), trabecular bone volume and trabecular number, load to failure (Fmax), and yield load in long bones and vertebrae. The lowest significant dose, which was different from Ovx controls, ranged between 0.2 and 1.0 micro g/kg/day, with higher doses not differing from sham controls. Increased trabecular separation (p <or= 0.0001) was fully prevented by all doses. Vertebral BMD (pQCT and DEXA) positively correlated with Fmax by r = 0.88 (p <or= 0.0001) both; correlation of femoral Fmax versus cortical BMD was r = 0.61 (p <or= 0.0001). CONCLUSION: Bone concentrations of ibandronate were linear with the dose, suggesting linear kinetics in the applied dose range. In general, the same total cumulative ibandronate dose given provided equivalent results, independent of the administration schedule.

Absorptiometry, Photon↗
PubMed1976

[Recent progress in morphology and diagnosis of bone diseases and bone tumors (author's transl)].

1. Bone structure is shaped by a specialized bone cell system comprising osteoblasts, osteocytes and osteoclasts. --2. The function of this bone cell system is impaired by metabolic bone disease altering bone structure, bone mass and mineral content. --3. In metabolic bone disease a striking improvement in morphologic diagnosis could be obtained recently using undecalcified preparations of bone tissue as well as histomorphometric methods. --4. For exact diagnosis and successful therapy of bone tumors interdisciplinary cooperation is mandatory. The advantages of modern morphologic methods are proven helpful in diagnosing benign and malignant bone tumors.

Age Factors↗
PubMed2003

[An experimental study of demineralized bone matrix to repair bone defects as a scaffold of tissue engineering].

OBJECTIVE: To evaluate application of the sponge of demineralized bone matrix (SDBM) in tissue engineering of bone. METHODS: SDBM was prepared from long bone of rabbits. Bone marrow cells were flushed from the bone shaft of femurs of a two-month-old New Zealand white rabbit. After the cells were cultured for 9 days, the flasks were added into dexamethasone (10(-8) mol/L), beta-glycerophosphate sodium (10 mmol/L) and L-ascorbic acid (50 micrograms/ml). After 5 weeks, the cultured cells were collected and marked by 5-Bromo-2'-dexyouridine (BrdU). The grand sum of cells seeded on a piece of SDBM was about (4-6) x 10(6). The composites of cells and SDBM (tissue engineered chip, TEC) were implanted into muscles and bone defects of radius in rabbits. A standard procedure was applied to make a 10 mm long defect bilaterally in the radius of nine skeletally mature male New Zealand white rabbits. All of the 18 defects were randomly divided into three groups: group I, six defects were grafted by TEC; group II, six defects were grafted with SDBM alone; group III, six defects were empty. RESULTS: The results of radiographic and histological evaluation showed that all of the defects were repaired in group I and group II at 6 weeks, none of the defects was repaired in group III. The results of BrdU staining showed that the staining was positive in group I, but negative in group II. Biomechanical test showed that the compressive ultimate strength (CUS) of new bone in TEC implanted group was comparable with normal radius (P = 0.623) and in SDBM implanted group was significant lower than normal radius (P = 0.038). CONCLUSIONS: The TEC can form cartilage and bone tissue in muscles and repair segmental bone defects. SDBM is a kind of effective natural scaffold in tissue engineering of bone.

Animals↗
PubMed2003

Prefabrication of vascularized bone flap induced by recombinant human bone morphogenetic protein 2 (rhBMP-2).

An experimental model for the prefabrication of a vascularized bone flap was developed in this study. To form vascularized bone in the desired configuration and to increase the survival rate of the grafted bone, a muscle vascularized pedicle (MVP) was transformed into vascularized bone by the inducer recombinant human bone morphogenetic protein 2 (rhBMP-2). The muscle flap (8 x 8 mm) raised on saphenous vessels in the rat thigh was sandwiched between same-size collagen (Terudermis) sheets in the presence or absence of impregnated 25 microg of rhBMP-2 for the experimental group and the control group, respectively. The flaps were harvested 1, 2 and 3 weeks postoperatively. Bone transformation was detected by gross examination, radiology, and histologic testing. No evidence of muscle tissue transformation was found in control flaps, whereas all of the experimental flaps produced new bone. Saphenous vessels were observed to supply the new bone upon harvesting, and the newly formed vascularized bone showed good configuration with shape of the Terudermis sheet. This study indicates that this model of effective bone reconstruction could be potentially applied in a therapeutic setting.

Animals↗
PubMed2005

[Repair of bone defect with allograft demineralized bone containing basic fibroblast growth factor in rabbits].

OBJECTIVE: To evaluate the ability of inductive osteogenesis of allograft demineralized bone containing basic fibroblast growth factor (bFGF/ALB) in repairing bone defect. METHODS: Thirty-two New Zealand white rabbits were randomly divided into four groups (groups A,B,C and D, n=8). A segmental bone defect of 15 mm in length was made on the bilateral radius respectively and the defects filled with ALB/bFGF in group A, with ALB in group B, with bFGF in group C and without any materials in group D serving as blank control. At 2, 4, 6 and 8 weeks after operation, all restored bones were evaluated by roentgenography, histological observation and Ca2+ detection of osteotylus. RESULTS: The X-ray films showed that groups A and B had a little shadow of bone formation at 2 weeks, while groups C and D had transparent shadow; that group A had denser shadow and new bone formation at 4 weeks and 6 weeks, groups B and C had a little increase of shadow and group D had little shadow at fractured ends; and that group A had formation of bone bridge at 8 weeks, the new formed bone in fractured ends of group B closed with each other, the gap still existed in group C, and the defects filled with the soft tissue in group D. The Ca2+ content of group A was higher than that of groups B, C and D at 4 weeks (P<0.05) and 8 weeks (P<0.01). The histological observation showed that the degree of bone restoration of group A was superior to that of groups B, C and D. CONCLUSION: bFGF/ALB is a good material to improve bone restoration.

Absorbable Implants↗
PubMed1989

[Changes in bone mineral content and bone metabolism related to menopause].

Although the phenomenon of postmenopausal osteoporosis has attracted attention, there have been no parameter-matched studies of pre- and postmenopausal difference in metacarpal bone mineral status and bone metabolism. Therefore the authors compared metacarpal bone loss in a group of 41 postmenopausal volunteers (average postmenopausal duration: 39.3 months) and 28 age- and body size-matched controls (age 50-54), using the MD method. Perimenopausal changes in bone metabolism were also examined in these groups. The result revealed that the reduction in the metacarpal bone mineral status due to menopause occurs mainly in the bone mineral density such as GSmin and sigma GS/D. The reduction rate was the highest for the index of GSmin, corresponding to 5.1% per year. Serum levels of Alp and osteocalcin were significantly higher and the U-Ca/cr ratio tended to be higher in the postmenopausal subjects than in controls. The serum levels of calcium regulating hormones such as PTH and calcitonin in these two groups did not differ significantly. However the estrone and the estradiol levels, were significantly lower in postmenopausal subjects. Significant correlations were found between Alp and the postmenopausal period (r = 0.4684), and between the U-Hpr/cr ratio and postmenopausal period (r = -0.5332). It therefore appeared that estradiol is mainly related to postmenopausal bone metabolism causing insufficient suppression of bone resorption. However, calcium regulating hormones appeared to be not directly related to the postmenopausal bone loss mechanism. Bone turnover decreased with the postmenopausal period.

Alkaline Phosphatase↗
PubMed1989

Measurements of bone mass and bone density.

X-ray-based procedures are available to measure bone mineral density in vitro at almost any skeletal site. These bone density measurements are not useful in the diagnosis of the cause of bone loss but at present are the only tests available for assessing bone mass prior to the occurrence of irreversible changes such as fractures or vertebral compression, which are easily recognizable on x-rays. When fractures are present, the severity of the bone loss and the risk for future fractures can be assessed. Repeated measurements permit estimation of the rate of bone loss, which gives useful information for monitoring treatment effect or course of the disease. Measurement of total body calcium is of less clinical importance because of the predominantly trabecular bone loss that generally occurs in metabolic bone disease. Dual-energy x-ray absorptiometry (DEXA) and quantitative computed tomography (QCT) of the spine are of about equal clinical value in the first approach to the patient with metabolic bone disease, although DEXA allows greater variety in sampling sites. For repeated measurements, DEXA provides better precision at significantly lower radiation burden. For bone mineral measurements, the lumbar spine appears to be the most sensitive skeletal site.

Bone Density↗