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Biomedical subjects

D Slosman

Publications and source records attributed to D Slosman.

At least 19 recordsLinked to original sources
PubMed1999

Non-invasive diagnosis of venous thromboembolism in outpatients.

BACKGROUND: We designed a simple and integrated diagnostic algorithm for acute venous thromboembolism based on clinical probability assessment of deep-vein thrombosis (DVT) or pulmonary embolism (PE), plasma D-dimer measurement, lower-limb venous compression ultrasonography, and lung scan to reduce the need for phlebography and pulmonary angiography. METHODS: 918 consecutive patients presenting at the emergency ward of the Geneva University Hospital, Geneva, Switzerland, and Hôpital Saint-Luc, Montreal, Canada, with clinically suspected venous thromboembolism were entered into a sequential diagnostic protocol. Patients in whom venous thromboembolism was deemed absent were not given anticoagulants and were followed up for 3 months. FINDINGS: A normal D-dimer concentration (<500 microg/L by a rapid ELISA) ruled out venous thromboembolism in 286 (31%) members of the study cohort, whereas DVT by ultrasonography established the diagnosis in 157 (17%). Lung scan was diagnostic in 80 (9%) of the remaining patients. Venous thromboembolism was also deemed absent in patients with low to intermediate clinical probability of DVT and a normal venous ultrasonography (236 [26%] patients), and in patients with a low clinical probability of PE and a non-diagnostic result on lung scan (107 [12%] patients). Pulmonary angiography and phlebography were done in only 50 (5%) and 2 (<1%) of the patients, respectively. Hence, a non-invasive diagnosis was possible in 866 (94%) members of the entire cohort. The 3-month thromboembolic risk in patients not given anticoagulants, based on the results of the diagnostic protocol, was 1.8% (95% CI 0.9-3.1). INTERPRETATION: A diagnostic strategy combining clinical assessment, D-dimer, ultrasonography, and lung scan gave a non-invasive diagnosis in the vast majority of outpatients with suspected venous thromboembolism, and appeared to be safe.

Acute Disease↗
PubMed1999

Bone mineral mass and calcium and phosphate metabolism in young men: relationships with vitamin D receptor allelic polymorphisms.

The genetic bases of peak bone mass determinants are still poorly understood, particularly in males. We investigated the relationship between vitamin D receptor (VDR) 3'- and 5'-gene polymorphisms (as determined by the restriction enzymes BsmI and FokI) and bone mineral mass, and calcium and inorganic phosphate (Pi) metabolism in an homogeneous cohort of young healthy men. In 104 healthy subjects, aged 24.3 +/- 3.1 yr (mean +/- SD; range, 20.7-38.7), standardized bone mineral density (BMD; z-scores) at the levels of lumbar spine and femoral trochanter, i.e. bone mineral content adjusted for age, body size, and bone area, significantly differed between VDR 3'-end alleles (BsmI), whereas crude areal BMD or bone mineral content did not. Among BsmI homozygotes BB, BMD (z-scores) were significantly lower only in subjects also carrying the f allele at the VDR-5' polymorphic site (FokI). Serum PTH levels were significantly higher in the BB genotype at baseline and remained so under either a low or a high calcium-phosphorus diet. Moreover, on the low calcium-phosphorus diet, BB subjects had significantly decreased tubular Pi reabsorptive capacity and plasma Pi levels. Our results underline the importance of identifying multiple single base mutation polymorphisms within candidate genes of bone mineral mass and suggest a role for environmental/dietary factor interactions with VDR gene polymorphisms in peak bone mineral mass in men.

Adult↗
PubMed1998

Protein supplements increase serum insulin-like growth factor-I levels and attenuate proximal femur bone loss in patients with recent hip fracture. A randomized, double-blind, placebo-controlled trial.

BACKGROUND: Elderly persons who have osteoporotic hip fracture are often undernourished, particularly with respect to protein. Protein malnutrition may contribute to the occurrence and outcome of hip fracture. OBJECTIVE: To investigate whether oral protein supplements benefit bone metabolism in patients with recent hip fracture. DESIGN: 6-month, randomized, double-blind, placebo-controlled trial with a 6-month post-treatment follow-up. SETTING: University orthopedic ward. PATIENTS: 82 patients (mean age, 80.7 +/- 7.4 years) with recent osteoporotic hip fracture. Patients received calcium supplementation, 550 mg/d, and one dose of vitamin D, 200,000 IU (at baseline). INTERVENTION: Protein supplementation, 20 g/d, or isocaloric placebo (among controls). MEASUREMENTS: Bone mineral density, biochemical markers of bone remodeling, calciotropic hormone levels, biochemically evaluated nutritional and immunologic status, and muscle strength were measured every 6 months. RESULTS: Compared with controls, patients who received protein supplements had significantly greater increases in serum levels of insulin-like growth factor-I (85.6% +/- 14.8% and 34.1% +/- 7.2% at 6 months; difference, 51.5 percentage points [95% CI, 18.6 to 84.4 percentage points]; P = 0.003) and an attenuation of the decrease in proximal femur bone mineral density (-2.29% +/- 0.75% and -4.71% +/- 0.77% at 12 months; difference, 2.42 percentage points [CI, 0.26 to 4.59 percentage points]; P = 0.029). Seven and 13 new vertebral deformities were found among patients who received protein supplements and controls, respectively (P > 0.2). Median stay in rehabilitation wards was shorter for patients who received protein supplements than for controls (33 days [CI, 29 to 56 days] and 54 days [CI, 44 to 62 days]; difference, 21 days [CI, 4 to 25 days]; P = 0.018). CONCLUSION: Protein repletion after hip fracture was associated with increased serum levels of insulin-like growth factor-I, attenuation of proximal femur bone loss, and shorter stay in rehabilitation hospitals.

Activities of Daily Living↗
PubMed1998

Familial resemblance for bone mineral mass is expressed before puberty.

Genetic factors are known to explain a major proportion of peak bone mineral mass variance. Whether the influence of these genetic factors is expressed before the pubertal bone mineral mass accrual and whether there is tracking of bone mineral mass during pubertal growth, however, are not clearly established. We prospectively investigated correlations for bone mineral content (BMC), density, and bone size between prepubertal daughters and their premenopausal mothers. Height, weight, lumbar spine (LS), femoral neck (FN) and mid-femoral diaphysis BMC, bone area (BA), areal bone mineral density (aBMD), and volumetric bone mineral apparent density (BMAD) were evaluated in 138 mothers (mean age +/- SD, 40.0 +/- 4.0 yr) and their daughters (8.1 +/- 0.7 yr), who were then remeasured at yearly intervals for 2 yr. Eight-year-old prepubertal daughters had reached 78% and 44% of their mothers' height and weight, respectively. At the various skeletal sites, they had reached 33-43% of their mothers' BMC, 47-69% of their BA, 59-78% of their aBMD, and 75-105% of their BMAD. All body size and bone traits (age-adjusted Z-scores) were significantly correlated between prepubertal daughters and their mothers (r: 0.22-0.36, P < 0.01), except midfemoral diaphysis BMAD. Heritability estimates (1/2 h2), after adjustment for body size and dietary calcium intake, showed that 18-37% of bone traits were directly determined by maternal descent. During the next 2 yr, growth was accompanied by a marked increase of BMC, aBMD, and BA, whereas BMAD changed very little. In contrast, during this period, there were only minor changes in body size or bone trait Z-scores (i.e. < 0.5 Z-scores), which were thus highly correlated between consecutive measurements (r: 0.75-0.92, P < 0.0001). Accordingly, mother-daughter correlations remained unchanged over that period. Although more than 60% of peak bone mineral mass is gained during puberty (mostly at the expense of an increase in bone size while volumetric bone density slightly changes), familial resemblance for most bone traits is already present between daughters and their mothers before puberty. In the girls, moreover, yearly measurements were highly correlated, suggesting tracking of bone traits during pubertal growth. These results indicate that genetic susceptibility to osteoporosis may already be detectable in early childhood.

Adult↗
PubMed1998

Vitamin D receptor gene start codon polymorphisms (FokI) and bone mineral density: interaction with age, dietary calcium, and 3'-end region polymorphisms.

Osteoporosis is a polygenic disease, whose determining loci have not yet been identified. Vitamin D receptor (VDR) gene polymorphisms in the 3'-end region (as determined by the enzymes BsmI and ApaI) have been inconsistently associated with bone mineral mass. More recently, VDR start codon polymorphisms (as determined by the enzyme FokI) have been found to be related to adult bone mineral density (BMD) in pre- and postmenopausal American women. We investigated the association between BMD and FokI genotypes in premenopausal European-Caucasian women as well as in prepubertal girls from the same genetic background and examined the interaction with VDR 3'-end region polymorphisms and with dietary calcium intake. Areal BMD (g/cm2) was measured by dual-energy X-ray absorptiometry at the level of the lumbar spine, femoral neck, and femoral shaft in 177 healthy premenopausal women (age range, 18.7-56.0 years) as well as in 155 prepubertal girls (age range, 6.6-11.4 years). Genotyping for FokI, BsmI, and ApaI VDR polymorphisms was performed using polymerase chain reaction methods. FokI genotype-dietary calcium interaction was cross-sectionally analyzed in all subjects and longitudinally in 103 prepubertal girls enrolled in a calcium intervention trial. The prevalence of FokI VDR gene polymorphisms in this cohort was 15% for ff, 50% for Ff, and 35% for FF. In the whole cohort of premenopausal women or prepubertal girls, no significant association was found between FokI VDR gene polymorphisms and BMD, even adjusted for age (Z score), weight, height, and calcium intake. Further analysis of FokI VDR gene polymorphisms and dietary calcium intake suggested a possible interaction in BMD determination, since a trend for an association with FokI genotypes was more evident at high than low calcium intake in both cross-sectional and longitudinal studies. Furthermore, cross-genotyping FokI and either BsmI or ApaI VDR polymorphisms suggested that the ff genotype was associated with a significantly lower lumbar spine BMD in bb and aa prepubertal girls. FokI VDR gene polymorphisms were not significantly associated with BMD in healthy European-Caucasian females. However, cross-genotyping of the VDR 3'-end and start codon polymorphic regions may provide a further insight into the complex determination of BMD.

Absorptiometry, Photon↗
PubMed1997

Cost-effectiveness of noninvasive diagnostic aids in suspected pulmonary embolism.

BACKGROUND: Noninvasive instruments such as plasma D-dimer measurement (DD) and lower-limb compression ultrasonography (US) are being increasingly advocated to reduce the number of necessary angiograms in patients having suspected pulmonary embolism (PE) and a nondiagnostic lung scan. We therefore designed a decision analysis model (1) to evaluate the cost-effectiveness of combining these noninvasive diagnostic aids with lung scan and angiography in the diagnosis of PE and (2) to determine the optimal sequence and combination of tests taking into account the clinical probability of PE. METHODS: We performed a cost-effectiveness analysis based on literature data, including data from a management study in our institution. Six diagnostic strategies were compared with the reference, ie, lung scan followed when nondiagnostic (low or intermediate probability) by angiography. In all strategies, PE was ruled out by a normal or near-normal scan, a negative DD (plasma level below 500 micrograms/L), or a negative angiogram. Pulmonary embolism was diagnosed and anticoagulant treatment was undertaken in the presence of a high-probability lung scan, deep vein thrombosis showed by US, or a positive angiogram. In case of a nondiagnostic scan (low or intermediate probability), patients could be either treated or not treated, or undergo other tests, according to the selected strategy. RESULTS: Under baseline conditions (prevalence of PE, 35%), strategies combining DD and US with lung scan, angiography being done only in case of an inconclusive noninvasive workup (DD level > 500 micrograms/L, normal US, and nondiagnostic lung scan), were most cost-effective. This approach yielded a 9% incremental cost reduction and a 37% to 47% decrease in the number of necessary angiograms compared with the reference strategy (scan +/- angiography). For patients with a low clinical probability of PE (< or = 20%), withholding treatment from those with a low-probability lung scan without performing an angiogram proved safe and highly cost-effective (30% cost reduction), provided US showed no deep vein thrombosis. CONCLUSION: The DD test and US are cost-effective in the diagnostic workup of PE, whether performed after or before lung scan, thus allowing centers devoid of lung scanning and/or angiography facilities to screen patients with suspected PE and avoid costly referrals. In patients with a low clinical probability, a low-probability lung scan, and a normal US, treatment may be withheld without resorting to angiography.

Algorithms↗
PubMed1997

Calcium-enriched foods and bone mass growth in prepubertal girls: a randomized, double-blind, placebo-controlled trial.

High calcium intake during childhood has been suggested to increase bone mass accrual, potentially resulting in a greater peak bone mass. Whether the effects of calcium supplementation on bone mass accrual vary from one skeletal region to another, and to what extent the level of spontaneous calcium intake may affect the magnitude of the response has, however, not yet been clearly established. In a double-blind, placebo-controlled study, 149 healthy prepubertal girls aged 7.9+/-0.1 yr (mean+/-SEM) were either allocated two food products containing 850 mg of calcium (Ca-suppl.) or not (placebo) on a daily basis for 1 yr. Areal bone mineral density (BMD), bone mineral content (BMC), and bone size were determined at six sites by dual-energy x-ray absorptiometry. The difference in BMD gain between calcium-supplemented (Ca-suppl.) and placebo was greater at radial (metaphysis and diaphysis) and femoral (neck, trochanter, and diaphyses) sites (7-12 mg/cm2 per yr) than in the lumbar spine (2 mg/cm2 per yr). The difference in BMD gains between Ca-suppl. and placebo was greatest in girls with a spontaneous calcium intake below the median of 880 mg/d. The increase in mean BMD of the 6 sites in the low-calcium consumers was accompanied by increased gains in mean BMC, bone size, and statural height. These results suggest a possible positive effect of calcium supplementation on skeletal growth at that age. In conclusion, calcium-enriched foods significantly increased bone mass accrual in prepubertal girls, with a preferential effect in the appendicular skeleton, and greater benefit at lower spontaneous calcium intake.

Absorptiometry, Photon↗
PubMed1997

Are younger children at highest risk of renal sequelae after pyelonephritis?

BACKGROUND: The general belief about the relation between risk of renal sequelae after pyelonephritis and age is that infants are at highest risk and children older than 5 years at lower risk. This assumption has led to differences in treatment based on age. The aim of this prospective study was to investigate the occurrence of renal lesions in children aged 0-16 years. METHODS: Between May, 1994, and January, 1996, all children aged 0-16 years who were admitted to our department with a diagnosis of probable pyelonephritis and a positive urine culture were included in this prospective study. All patients received antibiotics for 7-21 days. During the acute phase of urinary-tract infection, scintigraphy with technetium-99m-dimercaptosuccinic acid (DMSA) and ultrasonography were done. Voiding cystourethrography was undertaken at least 6 weeks after the end of antibiotic treatment. When scintigraphy showed renal parenchymal lesions, repeat scintigraphy was done after at least 2 months to assess the progression of renal lesions. For the analysis, children were grouped by age according to presumed risk of renal sequelae after pyelonephritis: high risk (< 1 year), moderate risk (1-5 years), low risk (> 5 years). FINDINGS: 201 patients were enrolled in the study (119 < 1 year, 47 aged 1-5 years, 35 > 5 years). During the acute phase of urinary-tract infection, renal lesions were found in 66 (55%) infants under 1 year, in 37 (79%) children aged 1-5 years, and in 24 (69%) children older than 5 years. Of these 127 children, 108 underwent repeat scintigraphy after an average of 3 months (50 < 1 year, 36 aged 1-5 years, 22 > 5 years). Overall, renal scars were found on repeat scintigraphy in 20 (40%) infants under 1 year, in 31 (86%) children aged 1-5 years, and in 14 (64%) children older than 5 years. 38 (36%) of these 65 patients had vesicoureteric reflux. Among 88 children who had a first documented urinary-tract infection and underwent repeat scintigraphy, renal scars were found in 20 (43%) under 1 year, in 26 (84%) aged 1-5 years, and in eight (80%) older than 5 years. INTERPRETATION: This study did not confirm the conventional view that the risk of renal scars after pyelonephritis diminishes with age. We believe that all children, irrespective of age, will benefit from any measure that prevents the development of renal sequelae.

Adolescent↗
PubMed1997

D-dimer testing for suspected pulmonary embolism in outpatients.

The plasma level of D-dimer, a fibrin degradation product (FDP), is nearly always increased in the presence of acute pulmonary embolism (PE). Hence, a normal D-dimer level (below a cutoff value of 500 micrograms/L by enzyme-linked immunosorbent assay [ELISA]) may allow the exclusion of PE. To assess the negative predictive value of a D-dimer concentration below 500 micrograms/L in outpatients with suspected PE, and the safety of withholding anticoagulant treatment from such patients, we performed D-dimer assays, lower limb venous compression ultrasonography, and lung scans in 671 consecutive outpatients presenting in the Emergency Center of the Geneva University Hospital with suspected PE. Pulmonary angiography was reserved for patients with an inconclusive noninvasive workup. Patients with a normal D-dimer concentration were discharged without anticoagulant treatment and followed for 3 mo. The prevalence of PE was 29%, and D-dimer (using a cutoff of 500 micrograms/L) had a diagnostic sensitivity for PE of 99.5%. Overall diagnostic specificity of D-dimer was 41%, but it was lower among older patients. Of the 198 patients with a D-dimer concentration below the cutoff value, 196 were free of PE, one had a PE, and one had incomplete information because of loss to follow-up. Thus, the negative predictive value of D-dimer concentration fell between 197 of 198 and 196 of 198 cases of PE (99% [95% CI: 96.4 to 99.9]). Using a cutoff value of 4,000 micrograms/L, the overall specificity of D-dimer concentration for PE was 93.1%. In conclusion, a plasma D-dimer concentration below 500 micrograms/L allows the exclusion of PE in 29% of outpatients suspected of having PE. Withholding anticoagulation from such patients is associated with a conservative 1% risk of thromboembolic events during follow-up.

Adolescent↗
PubMed1996

Diagnosis of pulmonary embolism by a decision analysis-based strategy including clinical probability, D-dimer levels, and ultrasonography: a management study.

BACKGROUND: Assessment of the clinical probability of pulmonary emboli sm, plasma D-dimer measurement, and lower-limb venous compression ultrasonography have all been advocated in the workup of suspected pulmonary embolism, to minimize the requirement for pulmonary angiography in patients with nondiagnostic lung scans. However, their contribution has not been assessed prospectively. METHODS: Three hundred eight consecutive patients who came to the emergency department with suspected pulmonary embolism were managed according to a diagnostic protocol that included clinical probability assessment, lung scan, and sequential noninvasive tests: plasma D-dimer measurement by enzyme-linked immunosorbent assay (a concentration <500 microgram/L ruled out pulmonary embolism) and lower-limb B-mode venous compression ultrasonography (a positive finding was diagnostic of venous thromboembolism). Patients without pulmonary embolism according to the diagnostic workup did not receive anticoagulant treatment. The safety of this approach was assessed by a 6-month follow-up. RESULTS: of the 308 patients, 106 (34%) had a diagnostic lung scan (normal in 43 and high probability in 63). For the remaining 202 patients, noninvasive workup was diagnostic in 125 (62%). Pulmonary embolism was ruled out by a low clinical probability and a nondiagnostic scan in 48 patients and a D-dimer level less than 500 microgram/L in 53; pulmonary embolism was established by a high clinical probability and a nondiagnostic scan in seven patients and by a finding of a deep vein thrombosis on ultrasonography in 17. Therefore, only 77 of these 202 patients underwent pulmonary angiography (negative in 55; positive in 22). At 6-month follow-up (completed for 99.4% of the study population), only two of the 199 patients in whom the diagnostic protocol had ruled out pulmonary embolism (1.0% [95% confidence interval, 0.1 to 3.6]) had a thromboembolic event (pulmonary embolism, one; deep vein thrombosis, one). CONCLUSIONS: This decision analysis strategy yielded a definitive noninvasive diagnosis in 62% of patients with a nondiagnostic scan and appears to be safe.

Adolescent↗
PubMed1996

Three- to five-dimensional biomedical multisensor imaging for the assessment of neurological (dys) function.

This report describes techniques and protocols implemented at the Geneva Canton University Hospitals (HUG) for the combination of various biomedical imaging modalities and sensors including electromagnetic tomography, to study, assess, and localize neurological (dys) function. The interest for this combination stems from the broad variety of information brought out by (functional) magnetic resonance imaging, magnetic resonance spectroscopy, computed tomography, single-photon emission tomography, positron emission tomography, and electromagnetic tomography. Combining these data allows morphology, metabolism, and function to be studied simultaneously, the complementary nature of the information from these modalities becoming evident when studying pathologies reflected by metabolic or electrophysiologic dysfunctions. Compared with other current multimodality approaches, the one at the HUG is totally compatible with both clinical and research protocols, and efficiently addresses the multidimensional registration and visualization issues. It also smoothly integrates electrophysiology and related data as fully featured modalities.

Computer Graphics↗
PubMed1996

Lack of effects of recombinant growth hormone on muscle function in patients requiring prolonged mechanical ventilation: a prospective, randomized, controlled study.

OBJECTIVE: To evaluate the benefit of recombinant human growth hormone administration on muscle strength and duration of weaning in critically ill patients undergoing prolonged mechanical ventilation. DESIGN: Prospective, randomized, controlled, single-blind study. SETTING: Intensive care unit. PATIENTS: Twenty patients requiring > or = 7 days of mechanical ventilation for acute respiratory failure. INTERVENTION: Random assignment to receive either 0.43 IU (approximately 0.14 mg) recombinant growth hormone/kg body weight/day (treated group), or saline (nontreated group) for 12 days. MEASUREMENTS AND MAIN RESULTS: Nutritional support was guided by indirect calorimetry. Cumulative nitrogen balance was positive throughout the study period in the treated group 17.3 (44.9 +/- 17.3[SEM] g/12 days) vs. the nontreated group (-65.8 +/- 11.8 g/12 days) (p<.0001). Despite similar initial plasma concentrations, recombinant growth hormone supplementation resulted in marked increases in growth hormone, insulin like growth factor-1, and insulin concentrations (p<.05, .02, and .0001, respectively, vs. nontreated group). Body impedance determined net fat-free mass increased in the treated group (0.8 +/- 0.6 kg) vs. the nontreated group (-1.1 +/- O.5 kg) (p<.03). Initial peripheral muscle function, assessed by computer-controlled electrical stimulation of the adductor pollicis, was similarly lower in treated and nontreated groups than sex and age-matched normal controls, and decreased further during the study period. Arterial blood gases, cumulative total mechanical ventilation time, and number of hrs/day of mechanical ventilation during weaning were similar in both patient groups. Only three of the ten patients in each group were weaned from mechanical ventilation by day 12. CONCLUSIONS: Daily administration of recombinant growth hormone in mechanically ventilated patients with acute respiratory failure promotes a marked nitrogen retention. However, this reaction is accompanied neither by an improvement in muscle strength nor by a shorter duration of ventilatory supports.

Acute Disease↗
PubMed1996

Recombinant human growth hormone in chronic and acute respiratory insufficiency.

Chronic respiratory insufficiency leads to protein-calorie malnutrition (PCM). PCM results in increased morbidity (e.g., infection), which in turn promotes further body wasting. The latter leads to respiratory muscle dysfunction and acute respiratory failure. Nutritional support alone is generally insufficient to counterbalance this hypoxemic and stress-related muscle catabolism. Recombinant human growth hormone (rhGH) can preserve or replenish nitrogen reserves, mostly contained in body muscle mass. It was hypothesized that rhGH, through its ability to improve muscle mass and function, could be a valuable therapeutic adjunct in both chronic and acute respiratory insufficiency. The results are controversial, and the beneficial effects of rhGH in patients with chronic and acute respiratory insufficiency, in terms of improvement of respiratory function, morbidity, and quality of life, remain to be shown. Well-designed studies, specifically targeting these end points as well as cost-effectiveness, are needed to better define the place of rhGH in the nutritional support of these patients.

Acute Disease↗
PubMed1995

The role of dual energy X-ray absorptiometry of lumbar spine and proximal femur in the diagnosis and follow-up of osteoporosis.

Dual energy x-ray absorptiometry techniques have been validated for the quantitative assessment of bone mass at two skeletal sites particularly at risk of osteoporotic fracture, i.e., lumbar spine and proximal femur. These measurements assess areal bone mineral density (BMD), which integrates the size of the bone and its thickness, as well as the true volumetric density. Areal density provides useful information relative to fracture risk, since there is an inverse relationship between incidence of osteoporotic fractures and areal BMD. Although lumbar spine BMD measurements by a lateral view could offer the advantage over conventional anteroposterior projection of avoiding osteophytes and posterior element osteoarthritis, it does not seem to be superior in diagnostic sensitivity, except possibly for corticosteroid-induced bone loss. Femoral neck BMD appears to be a significantly better predictor of fracture of the proximal femur. Since this measurement does not appear to be influenced by osteoarthritis, it would be the most suitable for the diagnosis of osteoporosis in the elderly. However, the potential for error in terms of both accuracy and precision for dual x-ray absorptiometry measurements of lumbar spine and proximal femur emphasizes the need for strictly controlled conditions of measurement.

Absorptiometry, Photon↗
PubMed1995

Vitamin-D-receptor-gene polymorphisms and change in lumbar-spine bone mineral density.

Common vitamin-D-receptor (VDR) gene allelic variants predict bone mineral density. We analysed VDR alleles and rate of change of lumbar-spine bone mineral density over 18 months in 72 elderly subjects. 9 BB homozygotes lost bone mineral density but 26 homozygotes for the alternative genotype (bb) did not (mean change -2.3 [SE 1.0] vs 0.9 [0.7]% per year, p < 0.05), irrespective of calcium intake. Among 37 heterozygotes (Bb), however, change in bone mineral density correlated with calcium intake (r = 0.35, p < 0.03). This association between a genetic marker and rate of bone loss in the elderly suggests that the effect of calcium intake on maintenance of bone mass could relate to VDR gene polymorphisms.

Aged↗
PubMed1995

[Peak bone mass: facts and uncertainties].

Peak bone mass, which can be defined as the amount of bony tissue present at the end of the skeletal maturation, is an important determinant of osteoporotic fracture risk in adulthood. The techniques of single or dual energy absorptiometry measure the so-called "areal" or "surface" bone mineral density (BMD), a variable which has been shown to be directly related to bone strength. During puberty the gender difference in bone mass becomes expressed. This difference appears to be essentially due to a more prolonged bone maturation period in males than in females, with a larger increase in bone size and cortical thickness, as there is no significant sex difference in the volumetric trabecular density at the end of pubertal maturation. At the beginning of the 3rd decade, there is a large variability in the normal values of areal BMD in axial and appendicular skeleton. This large variance, which is observed at sites particularly susceptible to osteoporotic fractures in adulthood, such as lumbar spine and femoral neck, is barely reduced after correction for statural height, and does not appear to substantially increase during adult life. It is generally accepted that peak bone mass at any skeletal site is attained in both sexes during the mid-thirties. However, recent studies indicate that in healthy caucasian females, bone mass accumulation can virtually be completed before the end of the second decade, for both lumbar spine and femoral neck. Several variables are supposed to influence bone mass accumulation during growth: heredity, sex, diet components, endocrine factors, mechanical forces, and exposure to risk factors.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗