Biochemical measurements of bone turnover in children and adolescents.

Biochemical measurements of bone turnover are helpful in the study of the pathophysiology of skeletal metabolism and growth. However, interpretation of their results is difficult because they depend on age, pubertal stage, growth velocity, mineral accrual, hormonal regulation, nutritional status, circadian variation, day-to-day variation, method of expression of results of urinary markers, specificity for bone tissue, sensitivity and specificity of assays. Three markers of bone formation have been described including their bone specificity and age-related changes: osteocalcin, alkaline phosphatase and its skeletal isoenzyme, procollagen I extension peptides.

Exercise during growth and bone mineral density and fractures in old age.

If exercise is to be recommended during growth, benefits in bone mineral density (BMD) must be maintained in old age and shown to prevent fractures. Our cross-sectional study of soccer players suggests that a high BMD is no longer recorded after retirement and fracture frequency is no less than predicted in old age.

Bone loss following tibial osteotomy: a model for evaluating post-traumatic osteopenia.

The reduced bone mineral density (BMD) found in patients with fractures may, in part, follow rather than precede the fracture. We studied the magnitude and reversibility of bone loss in the 15 months following osteotomy in 21 men and 5 women with localized medial arthritis of the knee. BMD (mean +/- SD), measured using dual-energy X-ray absorptiometry, decreased by a maximum of 35 +/- 21% in the mid-diaphysis of the affected tibia at 9 months after surgery (p < 0.

Calcium intakes among Australian women: Geelong Osteoporosis Study.

Background: Dietary calcium deficiency may be a risk factor for osteoporosis.

Aims: To estimate habitual calcium intakes and prevalence of calcium supplementation among free-living Australian women and validate a calcium-specific food-frequency questionnaire.

Methods: Calcium intakes for 1045 randomly selected women (20-92 years) were estimated by questionnaire which was tested against estimates from four day weighed records kept by 32 randomly selected women.

Effects of alendronate on bone density in men with primary and secondary osteoporosis.

Alendronate has been reported to increase bone mineral density (BMD) and reduce fracture risk in women with osteoporosis. As there are no proven safe and effective treatments available for men with osteoporosis, we compared the effects of alendronate (10 mg/day) on BMD, measured using dual-energy X-ray absorptiometry, in a 12-month prospective, controlled, open label study involving (i) men with primary (n = 23) or secondary osteoporosis (n = 18), (ii) postmenopausal women with primary (n = 18) or secondary (n = 21) osteoporosis, and (iii) 29 male and 14 female untreated controls matched by age, height and weight. The patients had one or more vertebral fractures and ranged in age from 34.

Oral contraceptives and bone mineral density: A population-based study.

Objective: We sought to test the hypothesis that exposure to oral contraceptives protects the skeleton.

Study Design: Multiple regression techniques were used to analyze data for a random sample of 710 Australian women (age range, 20-69 years). Bone mineral density was measured at the lumbar spine, proximal femur, whole body, and distal forearm.

Short stature and delayed puberty in gymnasts: influence of selection bias on leg length and the duration of training on trunk length.

Background: Delays in bone age, the onset of puberty, and skeletal growth in gymnasts could be, in part, the reason for an interest in gymnastics, rather than being the result of vigorous exercise. We hypothesized that short stature and delayed bone age are present at the start of gymnastics, and training delays growth, producing short stature, even after retirement.

Methods: Sitting height and leg length were measured in 83 active female gymnasts, 42 retired gymnasts, and 154 healthy control subjects.

Femoral neck dimensions are unlikely to be associated with age at menarche.

Hip axis length (HAL) has been reported as an independent risk factor for hip fracture. Later puberty may increase bone size because of delayed epiphyseal fusion. We sought to identify associations between bone size at the proximal femur with age at menarche and other indices of growth such as stature.

Age- and gender-specific rate of fractures in Australia: a population-based study.

There is little population-based data concerning fracture rates in Australia. We ascertained all fractures occurring during 2 years in adults aged 35 years and over residing within a defined region (population 218 000), representative of the Australian population. The major strength of this study is the comprehensive ascertainment of fractures, which was ensured by regular searches of the only two radiologic providers in the Geelong Osteoporosis Study region.

The differing tempo of growth in bone size, mass, and density in girls is region-specific.

The differing tempo and direction of growth of the periosteal and endocortical surfaces, and the differing tempo of growth of the axial and appendicular skeleton, may predispose to regional deficits in bone size, bone mineral content (BMC), and volumetric bone mineral density (vBMD). These traits were measured during 2 years by dual x-ray absorptiometry in 109 girls. By 7 years of age, bone size was approximately 80% of its maturational peak, and BMC was approximately 40% of its peak.

Vertebral bone mass, size, and volumetric density in women with spinal fractures.

Bone densitometry provides a measure of bone mass expressed as bone mineral content (BMC) or areal bone mineral density (aBMD). BMC is unadjusted for bone size while aBMD is adjusted for the projected area of the region scanned but not its depth. Because patients with fractures often have reduced bone size, the deficit in BMC or aBMD relative to controls may be partly the result of the comparison of a smaller bone in patients with fractures with a bigger bone in controls without fractures.

Bone loss at the proximal femur and reduced lean mass following liver transplantation: a longitudinal study.

The longevity of recipients of liver transplant may be compromised by spinal osteoporosis and vertebral fractures. However, femoral neck fractures are associated with a higher morbidity and mortality than spine fractures. As there is little information on bone loss at this clinically important site of fracture, the aim of this study was to determine whether accelerated bone loss occurs at the proximal femur following transplantation.

Diagnosis and management of osteoporosis in postmenopausal women: clinical guidelines. International Committee for Osteoporosis Clinical Guidelines.

The authors, all physicians involved in clinical research on bone and practicing clinicians, propose practical guidelines for identifying persons with osteoporosis or those at high risk of developing the disease and for managing patients who may benefit from therapy. These guidelines are based on an analysis of peer-reviewed articles published before November 1998. A flowchart of women who might benefit from treatment is provided, including clinical presentation (recent fracture of the spine, hip, or other bone or no fracture; risk factors for osteoporosis); relevant investigations (bone mineral density measurement and laboratory tests required for the differential diagnosis); and therapeutic management (general measures such as calcium and vitamin D supplementation and specific pharmacologic interventions such as estrogen, bisphosphonates, intranasal calcitonin, raloxifene, fluoride salts, and other compounds that have been assessed in randomized clinical trials).

The structural basis of bone fragility in men.

Understanding of the pathogenesis of bone fragility in men requires knowledge of its structural basis. There is no evidence that gender differences in fracture rates are explained by gender differences in bone mineral content (BMC) or areal bone mineral density (BMD). This is an untested assumption.

Health burden of hip and other fractures in Australia beyond 2000. Projections based on the Geelong Osteoporosis Study.

Objective: To calculate the expected increase in the number of fractures in adults attributable to the predicted increase in the number of elderly Australians.

Data Sources: All fractures in adult residents (> or = 35 years) of the Barwon Statistical Division (total population, 218,000) were identified from radiological reports from February 1994 to February 1996. The Australian Bureau of Statistics supplied predictions of Australia's population (1996 to 2051).

Polymorphism of the vitamin D receptor gene and corticosteroid-related osteoporosis.

Corticosteroid therapy (CST) is associated with reduced intestinal calcium absorption, bone loss and increased fracture risk. As polymorphisms of the vitamin D receptor (VDR) gene may be associated with bone mineral density (BMD) and intestinal calcium absorption, we asked whether patients with a given VDR genotype receiving CST may be at increased or decreased risk for corticosteroid-related bone loss and osteoporosis. We measured areal BMD (g/cm2) by dual-energy X-ray absorptiometry in 193 women (50 premenopausal, 143 postmenopausal) and 70 men with rheumatoid arthritis (n = 44), obstructive airway diseases (n = 128) and other corticosteroid-treated diseases (n = 91).

The effects of gonadectomy on bone size, mass, and volumetric density in growing rats are gender-, site-, and growth hormone-specific.

Peak volumetric bone mineral density (BMD) is determined by the growth in bone size relative to the mineral accrued within its periosteal envelope. Thus, reduced peak volumetric BMD may be the result of reduced mineral accrual relative to growth in bone size. Because sex steroids and growth hormone (GH) influence bone size and mass we asked: What are the effects of gonadectomy (Gx) on bone size, bone mineral content (BMC), areal and volumetric BMD in growing male and female rats? Does GH deficiency (GH-) reduce the amount of bone in the (smaller) bone, i.

Parathyroid hormone deficiency and excess: similar effects on trabecular bone but differing effects on cortical bone.

Parathyroid hormone (PTH) may be anabolic at trabecular bone and catabolic in cortical bone. As many regions of the skeleton contain both types of bone, the effects of PTH deficiency or excess may be difficult to evaluate using bone densitometry, a technique that integrates the cortical and trabecular compartments of bone. We asked the following questions: 1) Is the higher bone mineral density (BMD) in postsurgical hypoparathyroidism due to higher cortical, not trabecular, bone? 2) Is age-related bone loss slowed in patients with postsurgical hypoparathyroidism? 3) Is lower BMD in primary hyperparathyroidism the result of deficits in cortical, not trabecular, bone? BMD of the lumbar spine, proximal femur, distal radius, and femoral midshaft was measured by postero-anterior (PA) scanning, while bone mineral content (BMC) of the third lumbar vertebra was measured by lateral scanning using dual x-ray absorptiometry in 10 women, ages 64.

Moderate exercise during growth in prepubertal boys: changes in bone mass, size, volumetric density, and bone strength: a controlled prospective study.

Cross-sectional studies of elite athletes suggest that growth is an opportune time for exercise to increase areal bone mineral density (BMD). However, as the exercise undertaken by athletes is beyond the reach of most individuals, these studies provide little basis for making recommendations regarding the role of exercise in musculoskeletal health in the community. To determine whether moderate exercise increases bone mass, size, areal, and volumetric BMD, two socioeconomically equivalent schools were randomly allocated to be the source of an exercise group or controls.

Relationships among liver and kidney volumes, lean body mass and drug clearance.

Aims: To determine whether lean body mass (LBM), a possible surrogate of liver and kidney volumes, correlates with hepatic and renal drug clearances.

Methods: Twenty-one disease-free patients with a history of cancer and with normal hepatic and renal function were studied. Salivary pharmacokinetics of oral antipyrine (1200 mg) and 24 h creatinine clearance were determined following the determination of LBM by dual energy X-ray absorptiometry and the determination of liver and kidney volumes by helical CT scanning.

The exclusion of high trauma fractures may underestimate the prevalence of bone fragility fractures in the community: the Geelong Osteoporosis Study.

Fractures associated with severe trauma are generally excluded from estimates of the prevalence of osteoporotic fractures in the community. Because the degree of trauma is difficult to quantitate, low bone mass may contribute to fractures following severe trauma. We ascertained all fractures in a defined population and compared the bone mineral density (BMD) of women who sustained fractures in either "low" or "high" trauma events with the BMD of a random sample of women from the same population.

The deleterious effects of low-dose corticosteroids on bone density in patients with polymyalgia rheumatica.

The beneficial effects of corticosteroid therapy in the treatment of rheumatic diseases may be offset by the occurrence of corticosteroid-related osteoporosis. This problem may be overcome by using low-dose corticosteroids; however, the dose of corticosteroids that is both efficacious and skeletal sparing is uncertain. Therefore, the aim of this study was to determine whether low-dose prednisolone treatment results in bone loss and modifies bone turnover.