Dual-energy X-ray Absorptiometry Studies Research Articles

Body Composition is Different After Surgical or Pharmacological Remission of Cushing's Syndrome: A Prospective DXA Study.

Patients with active Cushing's syndrome (CS) exhibit an increase of the visceral adipose tissue, increasing the risk of cardiovascular events. Until now, it is not yet clear whether remission of CS leads to a normalization of body composition, or if different strategies to control hypercortisolism could result in a different clinical outcome concerning adipose tissue distribution. Therefore, we analyzed body composition changes using dual-energy X-ray absorptiometry (DXA) in patients with CS in a prospective and controlled study. We considered 23 patients with CS, whose remission was achieved after surgery in 14 or gained with pharmacological treatment in 9 subjects. Clinical and DXA data (lean and fat mass in total body, trunk, and R1 box) were collected during active hypercortisolism and after sustained remission, defined as the normalization of both late night salivary and 24-h urinary cortisol levels, at least for 6 consecutive months. Healthy subjects, matched with CS for gender, age, and BMI, were considered as controls (n=25). After remission of hypercortisolism, body compositions of patients were similar to matched controls; fat mass in total body (-7.53%), trunk (-3.24%), and R1- box (-12.82%, all p<0.01) were decreased from baseline levels. Dividing patients by type of treatment, fat mass reduction was higher in those that achieved surgical remission of CS (total body -17.26%, trunk -22.73%, and R1 box -21.21%, all p<0.05). Surgical remission of hypercortisolism is characterized by improvement of body composition, particularly fat reduction, easily detectable with DXA during routine clinical practice.

On the mark? Is alkaline phosphatase a surrogate for bone density in men with hypogonadism?

The current issue of the BJUI contains a paper by Dubaja et al. 1 that may be of interest to physicians who have patients with hypogonadism. The authors speak to an unappreciated aspect of low testosterone; namely, the loss of bone in men and the possible recovery with treatment. Their retrospective study looked at 140 men with hypogonadism treated with exogenous testosterone replacement or clomiphene citrate testosterone enhancement. These men were also assessed for bone mineral density (BMD) markers at 6, 12 and 24 months after initial treatment. Importantly, dual-energy X-ray absorptiometry (DEXA) was performed a second time after 2 treatment years for a subset of these men. DEXA showed that there was a gain in BMD and a loss of serum alkaline phosphatase (AP) for all the men over time. The loss of AP was rapid but stabilized at 6 months. Testosterone and free testosterone increased as expected but there were no changes in vitamin D, calcium, parathyroid hormone or sex hormone-binding globulin. There was a correlation between AP and testosterone. The authors recognized poor bone density at baseline in those men with testosterone levels <250 ng/dl. Bone mineral density is the best way to predict osteoporosis and fragility fractures 2. Women loose BMD after menopause and that is accompanied by many changes, including gains in AP 3. The decline in serum oestrogens is a factor for women, and oestrogen replacement therapy historically has been used to prevent that loss. Not all men undergo a similar loss, i.e. andropause is not recognized in the same way as menopause. Even though osteoporosis is less common in men, the associated comorbidity may be more significant. There is an age-related decline in testosterone and an acute loss for some men such that they approach their physicians with symptoms. The underlying cause of bone loss in men and women may be the same: serum oestrogen loss. Men who lose testosterone are also losing oestrogen because testosterone is the precursor via aromatase. Repros Therapeutics is developing a way to treat men with secondary hypogonadism. An ongoing 1-year DEXA study recruited eligible men. Key inclusion factors were age < 60 years and body mass index > 25 kg/m2. Remarkably 24% of men failed the screening test because of osteopenia, despite the fact that few of them were old or underweight. The present paper by Dubaja et al. suggests that a readily available serum test may be able to monitor men on testosterone therapies for gain in BMD. Given the relatively low incidence of osteoporosis, screening every man by DEXA is not cost-efficient. The 1 year or more needed to find BMD loss by DEXA also wastes time and resources. Quantitative CT is more costly and is accompanied by high radiation exposure. The use of AP, as suggested in the present study, may represent a reasonable alternative. The paper is not without its weaknesses. There was no indication of whether these men had primary or secondary hypogonadism. Transdermal testosterone should raise testosterone and oestrogen in both groups of men whereas clomiphene citrate works through changes in LH and FSH and requires an intact hypothalamic-pituitary-gonadal axis (useful in men with secondary hypogonadism only). Indeed, the two kinds of treatment will have the opposite effect on LH and FSH 4. The authors recognized the importance of Leydig cells in producing testosterone, yet the effects of a transdermal testosterone would be to shut down testosterone production. We commend their suggestion that other factors that contribute to both bone and Leydig cell function, insulin-like 3 5 and osteocalcin 6 should be studied in relation to AP. The loss of subjects throughout the 2 years was troubling, but it is known that men on transdermal treatments discontinue with disturbing frequency despite satisfaction 7. If those who stayed in the present study were those with the best outcomes in terms of testosterone and BMD, potential bias may exist. If men can be encouraged to continue therapy through positive effects on BMD being detected as early as 6 months, AP monitoring may improve patient compliance. Only DEXA can give that assurance now. The authors noted the need for a larger prospective trial. Nevertheless, their paper provides a rationale for monitoring men on testosterone therapies that can be implemented with minimal cost or the need for new diagnostics. Authors are employees and/or stockholders in Repros Therapeutics.

Targeted assessment of fracture risk in women at midlife.

This study establishes a profile for women at midlife, referred for a dual energy X-ray absorptiometry (DXA), most likely to have osteoporosis, and from this, a pre-DXA screening tool has been developed. These findings inform much needed evidence-based guidelines for targeted and effective screening for osteoporosis and osteoporotic fracture prevention in women at midlife. There is no consensus as to whether women at midlife should undergo screening dual energy X-ray absorptiometry (DXA) to identify osteoporosis (T-score < -2.5). We investigated the prevalence of osteoporosis in women, aged 40-65 years, referred to 42 community-based Australian radiology centres, and identified the characteristics that best predict osteoporosis in women having a screening DXA. One thousand four hundred and two women completed the study questionnaire and had DXA reports available. After excluding women with an established indication for a DXA (58 %), users of bone-specific medication (10.5 %) and cancer (7.6 %), 466 women were classified as having a screening DXA. Forty of these women had osteoporosis at the lumbar spine (n = 32, 6.9 %) or femoral neck (n = 17, 3.6 %). Three predictors of osteoporosis (postmenopausal, nonuse of hormonal therapy and body mass index) were identified and incorporated into the Monash Osteoporosis Risk Score for women at midlife (MORS). In the screened study population, the MORS had a sensitivity of 70 % and specificity of 66 %, with a positive predictive value of 16.2 % and negative predictive value of 95.9 % for osteoporosis. Very few women referred for a screening DXA scan will be found to have osteoporosis. The MORS, a simple decision tool, would have identified 70 % of the women in our screening DXA study population and would have eliminated over 60 % of the screening DXA studies. Hence, use of the MORS may reduce unnecessary DXA scans and facilitate identification of the majority of cases of osteoporosis in women aged 40 to 65 years.

Bone mineral density status in urolithiasis patients with vitamin D inadequacy followed at a tertiary stone centre.

We assessed abnormalities in bone mineral density (BMD) and the risk of hip and major osteoporotic fractures in urolithiasis patients with vitamin D inadequacy (VDI) followed at a tertiary stone centre. Stone-free patients with VDI were invited to undergo dual-energy x-ray absorptiometry (DXA) scans to assess for BMD abnormalities at the femoral neck and lumbar spine. The World Health Organization's validated Fracture Risk Assessment Tool (FRAX) was used to calculate the risk of hip and major osteoporotic fractures within 10 years. Patients with primary hyperparathyroidism or hypercalcemia were excluded. In total, 50 consecutive patients were included between June 2011 and August 2012, including 26 (52%) males. The median age was 51 years and the median 25-hydroxyl vitamin D (25[OH] D) was 18.8 ng/mL. Thirty patients (60%) had abnormal T-scores on DXA studies. This decreased to 22 (44%) when age-matched Z-scores were used; 36% had osteopenia and 8% had osteoporosis. Femoral neck and lumbar spines were affected in 24% and 32% of patients, respectively. Recurrent stone-formers had significantly lower BMD when compared with first-time stone formers. Median serum 25(OH)D was comparable between patients with normal and abnormal DXA scans (18.6 vs. 18.8 ng/mL; p = 0.91). Five patients (10%) were at high risk (≥3%) of hip fractures within 10 years. A high prevalence of abnormal DXA scans was found in urolithiasis patients with VDI, including 5 patients (10%) at high risk of hip fractures. Future studies need to assess the economic impact of obtaining DXA scans on urolithiasis patients with VDI, especially in recurrent stone-formers.

Appropriateness of referrals to a tertiary referral centre for bone mineral density testing

Evidence-based guidelines for who should have a dual-energy X-ray absorptiometry (DXA) scan are well established. Much attention has been appropriately focussed on increasing the proportion of persons at high risk for fracture who are being referred for such investigation. Little literature exists on the extent of inappropriate referrals for DXA. In this cross-sectional study we assessed the prevalence of inappropriate referrals for DXA studies at our centre using modified International Society for Clinical Densitometry (ISCD) guidelines. All DXA referrals were vetted for appropriateness and priority using established ISCD criteria. We evaluated the reasons for DXA referral on all subjects and studied the prevalence of missing information, and the number of referrals for DXA deemed to be inappropriate at our institution. Two thousand and twenty-five DXA referrals were reviewed. Information was missing on many requests (e.g., menopausal status, body mass index), and 33% of the referrals were deemed as inappropriate. Compared to those deemed appropriate, inappropriate referrals were more likely to be younger females, had no risk factors for osteoporosis, had an inappropriate referral reason, and had less/missing information. In this study we have noted a concerning number of DXA referrals with limited information or no appropriate indication for such an examination. Education of referring physicians should focus on not only improving referrals for subjects at high risk, but also inappropriate referrals for subjects at low risk.

Impact of adding distal forearm DXA to hip and spine measurements on DXA report

Dual energy X-ray absorptiometry (DXA) is the gold standard modality for non-invasive diagnosis of osteoporosis but controversy exists about the optimal site (s) for bone mineral density (BMD) measurement. The objective was to find out impact of adding distal forearm BMD to hip and spine measurements on final diagnosis of a DXA study. This prospective study recruited 279 consecutive patients [female 256 (92%); male 23 (8%)] with a mean age of 63.25 ± 10.62 years from April 2011 to April 2012. The BMD was measured over hip (total hip and femoral neck), spine and distal forearm in all patients. Based on T-Score values of hip and spine (2 sites), diagnosis was normal in 34%, low bone mass in 40% and osteoporosis in 26% patients. However, adding distal forearm BMD and T-score (3 sites), diagnosis was normal in 28%, low bone mass in 37% and osteoporosis in 35%. Therefore, distal forearm BMD has upstaged the diagnosis from normal to low bone mass in 14%, from normal to osteoporosis in 2% and from low bone mass to osteoporosis in 18% patients. We conclude that combining distal forearm BMD with spine and hip can identify more patients with low bone mass or osteoporosis.

65 BONE DENSITY RESULTS OF VITAMIN-D INADEQUATE PATIENTS PRESENTING WITH UROLITHIASIS TO A TERTIARY STONE CENTER

You have accessJournal of UrologyGeneral & Epidemiological Trends & Socioeconomics: Evidence-Based Medicine & Outcomes (II)1 Apr 201365 BONE DENSITY RESULTS OF VITAMIN-D INADEQUATE PATIENTS PRESENTING WITH UROLITHIASIS TO A TERTIARY STONE CENTER Mohamed Elkoushy, Terence Lee, and Sero Andonian Mohamed ElkoushyMohamed Elkoushy Montreal, Canada More articles by this author , Terence LeeTerence Lee Montreal, Canada More articles by this author , and Sero AndonianSero Andonian Montreal, Canada More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.1443AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Vitamin-D Inadequacy (VDI) and its associated metabolic abnormalities are prevalent in patients presenting with urolithiasis. Vitamin D plays a vital role in bone health and stone-formers are at risk of premature bone loss that may be exaggerated by VDI. Therefore, the aim of the present study was to assess abnormalities in bone density studies for patients with VDI presenting with urolithiasis to a tertiary stone clinic. METHODS A retrospective review of prospectively collected data was performed for patients presenting to stone clinic from November, 2009 to August, 2012. Demographic and clinical data were collected together with metabolic stone work-up and bone density studies. VDI was defined as VD levels < 30 ng/ml. A Dual-energy X-ray Absorptiometry (DXA) scan was used to evaluate the Bone Mineral Density (BMD) at the femoral neck and lumbar spine. The World Health Organization (WHO) criteria were used to define patients with abnormal BMD; normal (within ±1 SD), osteopenia (−1 to −2.5 SD), and osteoporosis (<−2.5 SD). Patients with primary hyperparathyroidism or hypercalcemia were excluded. RESULTS A total of 49 patients with VDI with DXA studies were included; 26 (53.1%) were males. Mean age (95%CI) was 51.5 (42.5-58.3) years, mean BMI (95%CI) was 27.9 (21.6- 31.2) kg/m2 and mean serum VD (95%CI) was 18.4 (16.4-26.2) ng/ml. Twenty-nine patients (59.2%) had abnormal DXA studies where 23 (46.9%) had osteopenia and 6(12.3%) had osteoporosis in the femoral neck and/or lumbar spine. Femoral neck was affected in 42.8% of patients (36.7% osteopenia and 6.1% osteoporosis) while lumbar spine was affected in 40.8% of patients (32.6% osteopenia and 8.2% osteoporosis; one patient had severe osteoporosis with history of osteoporotic fractures). Median serum VD (95%CI) was not significantly different between patients with normal and abnormal DXA scans [19.2 (8-29) vs. 17.2 (6-28) ng/ml, p=0.10). Similarly, median serum VD (95%CI) did not significantly differ between osteopenics and osteoporotics [17.6 (6-28) vs. 15.6 (6.8-23.6) ng/ml, p=0.64]. Of interest, 61.3% of those with abnormal DXA scans were males. CONCLUSIONS A high prevalence of abnormal DXA scans was found in patients presenting with urolithiasis and vitamin D inadequacy. These findings need to be taken into account during evaluation and replacement of vitamin D in this population. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e27 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Mohamed Elkoushy Montreal, Canada More articles by this author Terence Lee Montreal, Canada More articles by this author Sero Andonian Montreal, Canada More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

Proximal humerus cortical bone thickness correlates with bone mineral density and can clinically rule out osteoporosis

Bone mineral density measurements with dual-energy x-ray absorptiometry (DXA) are commonly used to diagnose osteoporosis and assess fracture risk. This study describes the association between radiographic measures of proximal humeral cortical bone thickness and bone mineral density measured by DXA. The study also assesses the discriminative capability of clinical cortical bone thickness measurements at the proximal humerus to differentiate patients with osteoporosis. Patients (N = 108) with shoulder radiographs and DXA studies were evaluated. Cortical bone thickness was assessed with 2 techniques, the gauge method and the average method. Pearson correlations were used to describe the relationship between cortical bone thickness measurement techniques and femoral and lumbar DXA. Sensitivity, specificity, and negative predictive value for predicting osteoporosis were determined for several cortical bone thickness thresholds. Rater reliability of measures was assessed with intraclass correlation coefficients. The intra-rater and inter-rater reliability of measures was excellent (intraclass correlation coefficient > 0.85). Average cortical bone thickness measurements at the proximal humerus strongly correlated with DXA femur measurements (r = 0.64, P < .0001) and moderately correlated with DXA lumbar measurements (r=0.49, P < .0001). Gauge cortical thickness measurements also correlated with DXA femur measurements (R = 0.53, P < .0001) and DXA lumbar measurements (R = 0.35, P < .001). An average proximal humerus cortical thickness measurement of 6 mm was identified as a potential threshold value for predicting osteoporosis, with a sensitivity of 93%, specificity of 52%, and negative predictive value of 95%. Average cortical bone thickness measurements obtained from standard anteroposterior shoulder radiographs are correlated with DXA. Furthermore, they provide a clinically relevant, rapid, sensitive, and inexpensive method for ruling out osteoporosis.

The Role of Distal Third Radius Dual Energy X-ray Absorptiometry (DXA) and Central DXA in Evaluating for Osteopenia and Osteoporosis in Men Receiving Androgen Deprivation Therapy for Prostate Cancer

The authors assessed the use of distal third radius dual energy X-ray absorptiometry (DXA) concomitantly with central (hip and lumbar spine) DXA to identify men with osteopenia or osteoporosis receiving androgen deprivation therapy (ADT) for prostate cancer. Initial classification with central DXA demonstrated 60 (17%) normal, 187 (55%) osteopenic, and 96 (28%) osteoporotic patients. Sixteen of 60 (27%) normal patients were reclassified as osteopenic (14) or osteoporotic (2), and 20 of 187 (11%) osteopenic patients were reclassified as osteoporotic with the combination of central DXA plus distal third radius DXA. The difference in reclassification was statistically significant. The addition of distal third radius to central DXA scanning in men with bone loss associated with ADT identifies a statistically significant number of men being reclassified as having osteopenia or osteoporosis. Combined central and distal third radius DXA scanning should be considered routine in the evaluation of all men suspected of bone loss associated with ADT. This has specific significant clinical relevance because of the large number of men with nonevaluable central DXA studies. Fracture risk prediction and treatment recommendations based on this reclassification will need to be determined by follow-up studies.

Adherence to the U.S. Preventive Services Task Force 2002 Osteoporosis Screening Guidelines in Academic Primary Care Settings

Osteoporosis is very common in older women in the United States. Osteoporotic fractures cause significant morbidity and mortality, as well as high healthcare costs. Since 2002, the United States Preventive Services Task Force (USPSTF) has recommended screening for osteoporosis of all women aged ≥65. Our objective was to determine adherence to osteoporosis screening guidelines by primary care internists in a large academic medical center and to assess if adherence varies based on provider gender or practice location. This was a retrospective electronic medical record (EMR) review. All women aged ≥65 who were seen in the General Internal Medicine Center (GIMC) or the Women's Health Care Center (WHCC) at the University of Washington Medical Center by internal medicine attending physicians between January 1, 2006, and February 2, 2008, were included in the study. We determined if the patient had a dual energy x-ray absorptiometry (DEXA) study in the EMR database. We calculated the percentage of patients screened per provider and also compared the rate of screening for male vs. female providers and for GIMC vs. WHCC providers. Of the 1363 women included in the study, 70% had documentation of a DEXA study. Adherence to screening recommendations for individual providers varied from 33% to 100%. Screening was more likely to occur in the WHCC than in the GIMC (79.2% vs. 66.7%, p<0.001). Although women providers were more likely to screen than their male counterparts (72.2% vs. 66.1%, p=0.023), this relationship did not hold true after excluding women providers from the WHCC. We found good adherence to the USPSTF 2002 guidelines for osteoporosis screening in women aged ≥65 years by primary care physicians in a large urban academic medical center. The practice site and not gender of the provider resulted in significantly different screening rates.

Multivariate Analysis of Morphometric Characteristics to Evaluate Risk Factors for Cranial Cruciate Ligament Deficiency in Labrador Retrievers

To determine the combination of conformation characteristics of the pelvic limbs of Labrador Retrievers that best discriminates between limb at risk to develop cranial cruciate ligament (CCL) disease and limbs at low risk using radiographs, computerized tomography (CT) images, and dual-energy X-ray absorptiometry (DEXA). Cross-sectional clinical study. Twelve clinically normal and 9 unilaterally CCL-deficient Labrador Retrievers. The pelvic limbs of normal dogs were considered as non-predisposed to CCL disease and the contralateral limbs of CCL-deficient dogs as predisposed. Conformation variables, obtained from femur and tibial radiographs, pelvic limb CT images and DEXA studies, of predisposed pelvic limbs were compared with the conformation variables from pelvic limbs of the low-risk group. An ROC curve analysis was used to assess the discriminating properties of conformation variables for several combinations. We determined that a combination of tibial plateau angle (TPA) and femoral anteversion angle (FAA) measured on radiographs was optimal for discriminating predisposed and non-predisposed limbs for CCL disease in Labrador Retrievers. Assessing predisposition to CCL disease with a combination of conformational measurements is better than using univariate parameters. In the future, TPA and FAA may be used to screen dogs suspected of being susceptible to CCL disease.

Bone remodeling around stable uncemented titanium stems during the second decade after total hip arthroplasty: a DXA study at 12 and 17 years

In a cohort study, bone mineral density (BMD) around uncemented femoral components after total hip arthroplasty (THA) was evaluated. The results suggest that there are no clinically relevant changes in overall periprosthetic BMD in the second decade. However, continuous remodeling with limited proximal bone loss (stress-shielding) occurs, predominantly in female patients. Progressive periprosthetic bone loss and stress-shielding are a major concern in THA. Little is known about the extent and pattern of periprosthetic bone remodeling around uncemented stems in the second decade. In a cohort study, periprosthetic BMD was measured in 131 patients with 146 uncemented CLS stems using dual-energy X-ray absorptiometry (DXA) at a mean of 12years postoperatively (t1). Patients were followed clinically and radiographically, and a second DXA was performed at a mean of 17years postoperatively (t2) using the identical protocol. We obtained a complete set of two consecutive DXA measurements for 88 hips (78 patients, 35 male, 43 female). On radiographic evaluation at t1 and t2, regular bone ongrowth was present in all cases and no signs of radiographic loosening, severe bone loss or diaphyseal cortical hypertrophy were detected. There was no clinically relevant change in overall periprosthetic BMD (netavg) between t1 and t2 for both male and female patients. We analyzed the differences in BMD in the periprosthetic regions of interest (ROIs) according to Gruen and found a slight decrease in periprosthetic BMD in ROI 7 in male patients and in ROIs 1, 4, 6 and 7 in female patients. The study suggests that there are no clinically relevant changes in overall periprosthetic BMD around stable, straight uncemented stems between 12 and 17years postoperatively. However, continuous remodeling with limited proximal bone loss occurs, predominantly in female patients. After secondary osteointegration of this implant, stress-shielding remains minimal in the second decade.

Some Physical and Clinical Factors Influencing the Measurement of Precision Error, Least Significant Change, and Bone Mineral Density in Dual-Energy X-Ray Absorptiometry

Dual-energy X-ray absorptiometry (DXA) is the standard method of measuring bone mineral density (BMD) at highly trabecular bone, which can be statistically linked to the risk of fracture. For DXA, precision error (PE) and phantom-based accuracy studies are among the most important routine quality control procedures. A precision study was performed at our institution using International Society for Clinical Densitometry guidelines. Comparing our results with those reported by other investigators, we draw the following general conclusions: the PE was higher for the spine than the hip, which we attribute to the better geometric reproducibility at the hip. The hypothesis that the DXA calculates BMD relative to water was validated. Whether follow-up measurements are performed by the same technologist on the same day—or different technologists on subsequent days—does not appear to have a clinically significant impact on PE or least significant change (LSC). Mixing beam types (i.e., fan and pencil) may affect lumbar PE and LSC measurements more significantly than those of the hip. The use of a single technologist may reduce the PE for the lumbar spine but appears to increase it for the hip. Restricting the patient population to the female gender has the apparent effect of narrowing the gap between lumbar and hip PEs. Finally, the degree of BMD measurement accuracy can be affected by the type of phantom being used (e.g., European Spine Phantom vs Lunar phantom) and the faults in specific DXA edge detection algorithms.

Of small bones and big mistakes; bone densitometry in children revisited

In this paper we discuss the bone densitometry systems available and their applicability in children and adolescents. Based on the knowledge that the majority of bone densitometry studies in children are performed using dual-energy X-ray absorptiometry (DXA), we focus attention on the sources of errors in interpretation of DXA studies in children and adolescents.

Adolescent exercise associated with long-term superior measures of bone geometry: a cross-sectional DXA and MRI study

Objective:To investigate whether childhood sports participation, particularly weight-bearing sports, has any effect on bone mineral content (BMC), areal bone mineral density (aBMD) and bone geometric characteristics in middle-aged postmenopausal women.Design/setting:In...

Five-year DEXA study of 88 hips with cemented femoral stem

We performed repeated dual-energy X-ray absorptiometry (DEXA) measurements over five years in a homogeneous patient population to study the effect of a cemented stem on proximal femoral bone remodelling. Data from 88 patients (88 hips) implanted with total hip arthroplasty (THA) prostheses were extracted from three randomised studies. Femoral bone mineral density (BMD) was measured using a Lunar DPX-IQ densitometer for five years postoperatively. At one year the BMD changes had decreased between -2.0% [region of interest (ROI) 1] and -11.5% (ROI 7). During the follow-up period the BMD initially increased during the second year and thereafter decreased again in ROIs 5, 6 and 7. The loss of BMD at five years was more pronounced in region 7 (12.9%) and decreased with increasing age, total hip replacement (THR) on the right side and decreasing weight of the patient. We found that after the initial phase of early bone loss a period of recovery follows. Thereafter the BMD decreases again, which probably reflects the normal ageing of bone after uncomplicated cemented THA.

Osteoporosis After Kidney Transplantation: Preliminary Report From a Single Center

Objective One of the major adverse effects of kidney transplantation is osteoporosis, which is mainly related to steroid use. Only limited data are available on calcitonin therapy for posttransplantation osteoporosis. Method From March 2007 to August 2007, 67 kidney recipients agreed to enter this study. Dual energy X-ray absorptiometry (DEXA) was performed to evaluate bone mineral density (BMD) in the lumbar (L) spine and left femoral neck. We prescribed calcitonin nasal spray to osteoporosis patients (DEXA T <−2.5 SD) who agreed with the treatment. A second and a third DEXA were performed at 3-month subsequent intervals later to evaluate the therapeutic effects. Results The incidence of osteoporosis in our kidney recipients was 46.26% (31/67 patients). Osteopenia accounted for 38.81% (26/67 patients) and only 14.93% (10/67 patients) were normal. Calcitonin inhalation seemed to improve the BMD with 61% showing improvement on the second DEXA study in our preliminary data. Conclusion Our preliminary data suggested that calcitonin may help to restore bone mass in kidney recipients with osteoporosis. Steroid elimination may prevent the onset of osteoporosis and might even enhance calcitonin efficacy. In the future we need a longer study period to confirm the results and compare it with the outcomes of bisphosphonates therapy.

DXA scanning in clinical practice

Dual-energy X-ray absorptiometry (DXA) is recognized as the reference method to measure bone mineral density (BMD) with acceptable accuracy errors and good precision and reproducibility. The World Health Organization (WHO) has established DXA as the best densitometric technique for assessing BMD in postmenopausal women and based the definitions of osteopenia and osteoporosis on its results. DXA allows accurate diagnosis of osteoporosis, estimation of fracture risk and monitoring of patients undergoing treatment. However, when DXA studies are performed incorrectly, it can lead to major mistakes in diagnosis and therapy. This article reviews the fundamentals of positioning, scan analysis and interpretation of DXA in clinical practice.

Vertebral Morphometry by DXA: A Comparison of Supine Lateral and Decubitus Lateral Densitometers

Identification of vertebral fracture has become increasingly important in the diagnosis and management of osteoporosis. This study compares the morphometric techniques on a fan beam dual-energy X-ray absorptiometry (DXA) GE-Lunar Expert system (Expert) using a supine lateral position and a narrow fan beam GE-Lunar Prodigy system (Prodigy; GE Lunar, Madison, WI) that requires lateral decubitus positioning. Patient acceptability, image quality, observer, and equipment variability were determined. Study subjects were recruited from clinical referrals sent for a routine DXA study that included vertebral morphometry. Twenty-five patients underwent lateral vertebral assessment on both machines and completed a questionnaire on comfort and tolerability. Analysis was undertaken by two trained observers. Vertebral height, anterior/posterior height (A/P) and mid/posterior height (M/P) ratios, image quality, and prevalent fractures were assessed. There were no significant differences in patient comfort or image quality scores. More upper thoracic vertebrae could be assessed on the Expert, and good radiographic positioning was easier to achieve on the Expert. Inter-observer coefficients of variance percentage (CV%) of vertebral height was lower on the Prodigy (3.5% in the lumbar spine rising to 12.8% in the thoracic spine) than the Expert (4.2% to 16.9%). Inter-observer CV% for A/P and M/P ratios varied from 2.5% to 10.5% on the Prodigy compared with 3.5% to 12.3% on the Expert, depending on vertebral level. The variation between instruments was similar to the inter-observer CV% (anterior height: -0.11+/-1.65 mm; mid height: 0.54+/-1.51 mm; posterior height: 0.43+/-1.46 mm). There was good agreement between observers and between the Expert and Prodigy in identifying severe fractures, but lack of agreement in identifying moderate fractures. In conclusion, there was no clinically significant difference in patient comfort and image quality between the Expert and the Prodigy. The inter-observer variations in vertebral height and A/P and M/P ratios are similar to the variations between instruments. In making the change from the supine lateral to the decubitus lateral positioning, measurements of vertebral height are reproducible and patient comfort is not compromised.

QCT versus DXA in 320 survivors of childhood cancer: Association of BMD with fracture history

To assess agreement on diagnosis of diminished bone mineral density (BMD) and correlation between BMD values obtained by dual-energy X-ray absorptiometry (DXA) and quantitative computed tomography (QCT) in childhood cancer survivors. We retrospectively reviewed lumbar spine QCT and DXA studies for BMD in patients who underwent both imaging studies within a 24-hr period. We determined correlation between BMD values and agreement on diagnosis of diminished BMD obtained by both modalities. Diminished BMD was defined as two or more SDs below mean for age- and gender-matched reference values. We evaluated the relationship of BMD values determined by each modality to self-reported fracture history in the 160 (50%) patients with available reports. Of 320 patients, 56% (178) were male; 87% (277) were white. Median age was 16.4 (range, 5.1-36.0) years. Median BMD Z-score was -1.43 (range, -5.96 to 3.20) by QCT and -1.30 (range, -5.50 to 2.80) by DXA. Correlation between QCT- and DXA-determined BMD values was significant but low, and agreement on diminished BMD was fair (kappa = 0.32). There was no association between BMD measured by either QCT or DXA and self-reported traumatic fracture history. Male gender was associated with doubling the traumatic fracture risk (P = 0.0499). Quantitative computed tomography and DXA may give discrepant results when used to assess bone health in childhood cancer survivors, especially in those of non-white race. This inconsistency in indicators of BMD deficiency may complicate clinical decision-making. Consecutive use of a single modality is recommended to provide reliable longitudinal information.