Dual-energy X-ray Absorptiometry Scans Research Articles

Opportunistic Screening for Osteoporosis by CT as Compared with DXA

Background: Osteoporosis is commonly evaluated using dual-energy X-ray absorptiometry (DXA) for bone mineral density (BMD). Non-contrast computed tomography (CT) scans provide an alternative for opportunistic osteoporosis assessment. This study aimed to evaluate screening thresholds for osteoporosis based on CT attenuation values in Hounsfield units (HU) of L1–L4 vertebrae from CT scans of the abdominal region, compared to DXA assessments of the lumbar spine and hips. Methods: Conducted retrospectively over approximately two years, the analysis included 109 patients who had both CT and DXA scans within 12 months, excluding those with metal artifacts affecting the vertebrae. CT attenuation values in the trabecular region of the vertebrae were measured and compared among three groups based on the lowest T-score from DXA. Results: In a predominantly female cohort (mean age 66.3 years), the lowest CT attenuation values for L1–L4 vertebrae showed a moderate correlation with the lowest T-score, with a Pearson correlation coefficient of 0.542 (95% CI: 0.388, 0.667). A HU threshold of ≤142 at the L1 vertebra showed 91.9% sensitivity and 48.4% specificity, while a threshold of ≤160 HU showed 97.3% sensitivity and 31.3% specificity for screening osteoporosis. Conclusions: This study supports the use of non-contrast CT with these HU thresholds as an opportunistic tool for osteoporosis assessment.

Impact of different antiretroviral therapy regimens on bone mineral density in people living with HIV: a retrospective and longitudinal study in China

BackgroundHIV infection and antiretroviral therapy (ART) are associated with bone loss of people living with HIV (PLWH), but limited studies exist on the impacts of ART regimens on bone mineral density (BMD) in China. This study evaluated BMD changes with three common ART regimens: tenofovir disoproxil fumarate (TDF) + lamivudine (3TC) + efavirenz (EFV), tenofovir alafenamide (TAF)-containing, and dolutegravir (DTG)-containing (non-TDF/non-TAF) therapies.MethodsIn this retrospective study, the prevalence of low BMD was analyzed in PLWH who underwent dual-energy X-ray absorptiometry (DXA) before ART initiation. BMD changes were assessed in participants who had follow-up DXA scans after ≥ 1 year of ART with TDF + 3TC + EFV, TAF-containing, or DTG-containing regimens. We used multivariate logistic regression to evaluate the impact of different ART regimens on > 3% BMD reduction, adjusting for demographic and clinical variables that were significant in univariate analysis (P < 0.10).Results22.99% (630/2740) of PLWH before ART initiation had low BMD. Among 571 individuals followed up for over 1 year, BMD at the femoral neck (FN) and total hip (TH) decreased significantly in the TDF + 3TC + EFV [FN: -0.03(-0.07, 0.00) g/cm2, TH: -0.02(-0.05, 0.00) g/cm2, P < 0.001 for both] and TAF-containing regimens [FN: -0.02(-0.05, 0.01) g/cm2, TH: -0.02(-0.04, 0.01) g/cm2, P < 0.001 for both]. Lumbar spine (LS) BMD decreased significantly only with TDF + 3TC + EFV [-0.02(-0.05, 0.01) g/cm2, P < 0.001]. TDF + 3TC + EFV caused greater BMD loss at the FN and LS than the TAF-containing regimen[FN: -3.66% (-8.05%, 0.34%) vs. -2.38% (-5.44%, 1.12%), P = 0.044; LS: -2.11% (-4.50%, 0.62%) vs.-0.06% (-2.05%, 2.57%), P < 0.001]. Compared to TDF + 3TC + EFV, DTG-containing regimens showed smaller BMD reductions across all sites [FN: -1.49% (-4.65%, 3.83%), TH: 0.00% (-3.98%, 3.18%), LS: 0.59% (-2.73%, 3.09%), P = 0.004, 0.008 and 0.004, respectively]. TAF-containing and DTG-containing regimens showed no significant differences in BMD changes. Multivariable logistic regression showed that TDF + 3TC + EFV, compared to DTG-containing regimens, had higher odds of > 3% FN and LS BMD reduction (FN: OR 2.91, 95% CI: 1.33 to 6.37, P = 0.009; LS: OR 2.93, 95% CI: 1.17 to 7.32, P = 0.022), while TAF-containing regimens were not independently linked to > 3% BMD loss (P > 0.05).ConclusionsTAF-containing and DTG-containing regimens caused less bone loss than TDF + 3TC + EFV, offering safer options for preserving bone health in Chinese PLWH.

Investigating the triglyceride–glucose index in postmenopausal osteoporosis

Objective This retrospective study aims to assess the association of the triglyceride–glucose index (TyG index) with postmenopausal osteoporosis and investigate longitudinal changes in TyG index levels in relation to osteoporosis risk. Methods Out of 704 women, after excluding those with osteopenia, a total of 517 patients who met the inclusion criteria were included. Participants were categorized based on T-scores derived from lumbar spine dual-energy X-ray absorptiometry scans. Demographic data, biochemical parameters and TyG index levels were analyzed. Logistic regression, correlation analysis and receiver operating characteristic (ROC) curve analysis were employed for statistical evaluation. Results The osteoporosis group (n = 254) exhibited significantly higher TyG index and triglyceride levels compared to controls (n = 263). Longitudinal analysis revealed significant increases in TyG index levels among women developing osteoporosis over time. ROC analysis demonstrated the TyG index’s accuracy for osteoporosis (first TyG area under the curve [AUC]: 0.767, second TyG AUC: 0.818, p < 0.001). Regression analyses identified the TyG index as a significant factor associated with osteoporosis (odds ratio: 39.468, 95% confidence interval: 12.884–120.903, p < 0.001). Conclusions The TyG index emerges as a valuable indicator for postmenopausal osteoporosis. These results emphasize the need for integrating metabolic health indicators into osteoporosis management strategies, warranting further research into targeted interventions.

Biological Heterogeneity in Susceptibility to Glucocorticoid-Induced Bone Loss: Short- and Long-Term Hip BMD Trajectories.

Glucocorticoids (GCs) are widely used for their anti-inflammatory and immunosuppressive properties. Their effect on bone health is predominantly negative by decreasing bone formation and increasing risk of fractures. This work aimed to quantify the short- and long-term changes in total hip bone mineral density (THBMD) after initiating systemic GC treatment in previously GC treatment-naive adults without bone protective agents. An observational study was conducted using THBMD data from dual-energy x-ray absorptiometry (DXA). Individuals were stratified by sex and tertiles of GC exposure. Individuals not GC-exposed served as a reference group. Routine-care DXA scans were obtained from the main public hospitals servicing the Island of Funen in Denmark. A total of 15 099 adults underwent routine DXA at Odense University Hospital between 2006 and 2021. Data were enriched with Danish national registers. Intervention included systemic GCs (observational data). The short-term outcome included annualized THBMD changes between first 2 DXA scans. The long-term outcome included greater than 5% annualized THBMD loss over a 10-year follow-up. Strong associations between GC exposure and THBMD loss was found for both outcomes, with larger losses in the middle and upper tertiles of GC exposure. The risk of experiencing greater than 5% annualized THBMD loss was elevated, especially in the first 2 years of initiating GC treatment. There is significant heterogeneity in THBMD responses, with approximately 1 in 5 patients experiencing no nominal bone loss despite receiving upper tertile levels of GC exposure. The findings confirm the association between initial GC exposure and significant bone loss. The heterogeneity in individual responses emphasizes the need for early monitoring and personalized approaches in managing bone health for patients undergoing GC treatment.

Prevalence of incomplete atypical femoral fractures using single energy absorptiometry after long term anti-resorptive therapy.

Atypical femur fractures (AFFs) have been reported with long term use of anti-resorptive drugs. Early identification is crucial because it allows early intervention to stop the progression to complete fracture, thus potentially reducing the ensuing burden. It has been shown that extending the scan image to take a full-length image of the femur (FFI) using single energy (SE) X-rays at the time of a dual-energy X-ray absorptiometry (DXA) scan can detect findings in the spectrum of AFF. Following the International Society for Clinical Densitometry (ISCD) recommendations, FFI by SE X-ray is being performed for all patients who present to the Calcium Metabolism and Osteoporosis program at AUBMC for BMD measurement by DXA, if they have received anti-resorptive drug for, a cumulative period of 3years or more. Patients can be currently on anti-resorptive drug or have discontinued it within the past 5years prior to scan, instead of the 1year, as recommended by the ISCD. The primary aim of this retrospective study was to assess the prevalence of findings in the spectrum of AFF using FFI by SE X-rays. We collected data on demographic factors, clinical risk factors for osteoporosis, and bone densitometry parameters. Out of the 948 patients, 18 patients were found to have findings in the spectrum of AFF, 14 underwent subsequent imaging studies to investigate and confirm these abnormalities. One patient out of 948 patients was found to have an incomplete AFF confirmed by CT scan. Studying the prevalence of the signs of AFF on FFI in other studies and assessing the specificity of this technique by comparing its findings to more established methods, is important. Future ISCD task forces may need to re-assess efficacy and cost effectiveness of its recommended guidance on using SE femur in patients to prevent adverse outcomes.

Shoulder Arthroplasty Patients Are Underscreened for Osteoporosis.

Osteoporosis screening and subsequent treatment has been shown to be efficacious in decreasing the rates of fragility fractures and periprosthetic fractures (PPF). However, current screening and treatment rates are low. This study aims to determine (1) the prevalence of total shoulder arthroplasty (TSA) patients who meet criteria for osteoporosis screening, (2) the prevalence of those screened, and (3) the 5-year cumulative incidence of fragility fracture (FF) and periprosthetic fractures (PPF). The PearlDiver database was used to identify all patients older than 50 years who underwent TSA. Guidelines from the American Association of Clinical Endocrinologists were used to stratify patients into "high risk" and "low risk" of osteoporosis cohorts using International Classification of Disease codes for various risk factors. The prevalence of osteoporosis screening using dual-energy x-ray absorptiometry (DXA) scan was analyzed, and the 5-year cumulative incidence of FF and PPF was calculated between the "low-risk" and "high-risk" groups using Kaplan-Meier analysis. In total, 66,140 (65.5%) who underwent TSA were considered "high risk" for osteoporosis. Of the "high-risk" patients, 11.7% patients received routine osteoporosis screening preoperatively. Within 5 years, "high-risk" TSA patients had markedly higher cumulative incidence for PPF (HR: 1.4; 95% CI: 1.0-1.9; P = 0.037) and FF (HR: 2.42; 95% CI: 2.1-2.8; P < 0.001) when compared with those at "low risk". There is a high prevalence of osteoporosis among patients undergoing TSA but a low rate of routine osteoporosis screening in this cohort. Patients with osteoporosis who are categorized as "high risk" have an increased rate of fragility fractures and PPF. Therefore, there is an opportunity to increase appropriate osteoporosis screening and management in this cohort, which may affect future risk of FF and periprosthetic fracture. III.

Assessing Practice Patterns Regarding Use of Norethindrone Acetate in Adolescents.

Norethindrone acetate (NETA) is commonly used in adolescent patients for management of heavy menstrual bleeding, menstrual suppression, and endometriosis. Clinical guidelines do not address specific dosing strategies, clinical indications, contraindications, or monitoring. We sought to survey current prescribers of NETA to assess practice patterns of use among adolescent patients. An anonymous cross-sectional survey was sent via email list-serv to members of the North American Society for Pediatric and Adolescent Gynecology Providers (NASPAG). Participants were asked about their own demographics, patterns of use and monitoring of NETA. Seventy-one providers participated in the survey including 46 gynecologists and 22 adolescent medicine trained clinicians. The most common indications for use were menstrual suppression and treatment of endometriosis. Most providers (n=51) used NETA in patients with estrogen contraindications, with over half limiting the maximum dose used (n=24). While 14%(n=9) of providers surveyed had concerns about effects on bone mineral density with prolonged NETA use, only 1 participant routinely obtained dual-energy X-ray absorptiometry (DEXA) scans. 43% of participants using NETA felt there were no absolute contraindications (n=27); others cited liver disease (n=15), active or prior venous thromboembolism (n=7), and inherited thrombophilia or increased clotting risk (n=3) as strict contraindications. NETA is commonly prescribed for adolescents by study participants. Despite widespread use, practice patterns vary regarding eligibility, monitoring, and perceived risks. This likely reflects limited data and highlights the need for further investigations of NETA use. Our study was limited by low response rate that may not be reflective of general clinical practice.

Bone strain index for fracture risk assessment in older men-the prospective STRAMBO study.

Bone strain index (BSI) is a noninvasive index of bone strength assessed on lumbar spine and femur dual energy X-ray absorptiometry scans using the finite-element method. In this study, we assess the link of the lumbar spine and hip BSI with fracture risk in older men. Prospective cohort study. A cohort of 825 men aged ≥60 was followed up for 12 years. Lumbar spine and hip bone mineral density, BSI, Fracture Risk Assessment Tool (FRAX) for major osteoporotic fractures (MOPFx), and lumbar spine trabecular bone score (TBS) were assessed at baseline. Overall, 159 men had 198 incident fractures. After adjustment for FRAX and prior falls, a higher BSI was associated with a higher fracture risk, eg, trochanter BSI: (HR = 1.34 per standard deviation (SD) increase, 95% CI: 1.14-1.58, P < .001). Patterns were similar for MOPFx, vertebral, nonvertebral, and multiple fractures. The fracture risk was higher in the highest vs the lowest BSI quartiles. The associations were the strongest for the BSI of the lumbar spine and trochanter. When the TBS and BSI were analyzed jointly, their respective contributions to fracture prediction varied according to the fracture and the site of the BSI, eg, both the TBS and the trochanter BSI contributed to the MOPFx prediction (TBS: HR = 1.38/SD decrease, 95%CI: 1.04-1.84, P < .05; BSI: HR = 1.49/SD increase, 95% CI: 1.16-1.91, P < .005). The BSI at both the lumbar and the femoral sites was associated with a higher fracture risk independently of FRAX and prior falls in older men followed prospectively for 12 years.

Tenofovir Disoproxil Fumarate/Emtricitabine Prophylaxis Has No Effect on Bone Mineral Density and Bone Mineral Content in African Breastfeeding Women Receiving Pre-Exposure Prophylaxis for HIV.

Tenofovir disoproxil fumarate (TDF) when used as preexposure prophylaxis (PrEP) in pregnancy is considered safe overall however there is insufficient evidence of its effect on maternal bone. We compared bone mineral density (BMD) and content (BMC) at the lumbar spine (LS) and hip of African breastfeeding women exposed and not exposed to TDF-containing PrEP in a randomized control trial (RCT). This is a secondary data analysis of an RCT where pregnant women were randomized to initiating PrEP in pregnancy or delayed initiation of PrEP until breastfeeding cessation. BMD and BMC at the LS and hip were measured using dual-energy x-ray absorptiometry (DXA) at 6, 26, 50, and 74 weeks postpartum. In an exploratory analysis, BMD at the hip and LS were evaluated against varying Tenofovir (TFV) levels during pregnancy. Of 300 women in the RCT who had a DXA at 6 weeks postpartum, 102 (66%) women in the Immediate PrEP arm and 105 (72%) in the Delayed PrEP arm had a 74-week DXA scan. Adjusting for breastfeeding duration and body mass index (BMI), there were no significant differences in BMD or BMC at the hip and LS between treatment arms. There was no consistent dose-effect of TFV-DP detected during pregnancy on BMD at the hip (p=0.231) or the LS (p=0.277). After adjusting for breastfeeding and BMI, TDF when given as oral preexposure prophylaxis during pregnancy had no deleterious effect on BMD and BMC at the hip and LS of African breastfeeding women.

Sarcopenic obesity in survivors of childhood acute lymphoblastic leukemia: prevalence, risk factors, and implications for cancer survivors.

Sarcopenic obesity, characterized by increased adiposity with low skeletal muscle mass, contributes to frailty and the development of chronic disease. Data on sarcopenic obesity in survivors of childhood acute lymphoblastic leukemia (cALL) is limited. A cross-sectional study on 65 cALL survivors (7-18years, > 2years from treatment completion) was conducted on cALL survivors with the primary outcome to determine the prevalence of sarcopenic obesity. Sarcopenic obesity was defined as patients with a positive Fat Mass Index (FMI) z-score with a negative Skeletal Muscle Index (SMI) z-score, measured using a Dual-Energy Xray Absorptiometry (DXA) scan. In addition, we assessed the factors associated with sarcopenic obesity by multivariable regression analysis. The mean (± SD) age was 12.9 (± 3.2) years, the median (Interquartile Range) time since diagnosis was 6.5 (5.9;8) years, and 66% received cranial radiotherapy. Central obesity, insulin resistance, and metabolic syndrome were seen in 21.5%, 23.1%, and 21% respectively. DXA-derived body composition variables revealed higher fat percentage despite normal body mass index (BMI) and lower muscle mass compared to the general population. Sarcopenic obesity was seen in 21 (34%) of survivors. On multivariable regression analysis, age at diagnosis (OR: 0.95 (95% CI: 0.92-0.98), p = 0.02), central obesity (OR: 18.99 (95% 2.32-155.5), p = 0.006) and insulin resistance (OR: 10.2 (95% CI: 1.75-59.09), p = 0.01) were associated with sarcopenic obesity. Sarcopenic obesity, an early clinical indicator for metabolic disease despite normal BMI, was significantly worse in children diagnosed with ALL at a younger age and was associated with central obesity and insulin resistance, which may contribute to adverse outcomes later in life.

Assessing bone quality in hounsfield units using computed tomography: what value should be used to classify bone as normal or osteoporotic?

The purpose of this study was to investigate threshold values for classifying bone as normal or osteoporotic based on Computed Tomography (CT) Hounsfield Units (HU) and to determine if clinically applicable values could be derived to aid spine surgeons evaluating bone quality using CT. This literature review was completed using PubMed and Ovid (MedLine), using syntax specific to bone quality and CT. The included articles were original clinical studies assessing bone quality and utilized composite L1-L4 HU values compared against dual-energy X-ray absorptiometry (DEXA) values. Extracted data study descriptors, CT measurement technique, and CT threshold values. CTs were measured from L1-L4 using either axial or sagittal images, and must classify their bone quality findings for any of the following 3 categories: normal, osteopenia, or osteoporosis. This review located 34 studies measuring bone density using CT with threshold values, of which, 10 were included in the final review. Number of patients ranged from 74 to 283 and cohort ages from 20s to 70.6 years. CT threshold values for assessing normal and osteoporotic bone quality ranged from 150 to 179 and 87 to 155, respectively. From combining values across studies, a HU value of ≥ 170 HU was associated with normal bone and ≤ 115 HU with osteoporosis. There is variation in HU values used to differentiate normal from compromised bone quality, even after limiting studies. For patients with HU values between or near 170 or 115 HU, a DEXA scan may be warranted for further evaluation. With ongoing investigation in this area, threshold values for classifying bone quality using CT will be continually refined.

Utility of fat-free adipose tissue correction formula for tracking body composition changes with dual-energy X-ray absorptiometry.

Fat loss is often the target of weight loss interventions; however, preservation of lean soft tissue (LST) may be more important for health and weight maintenance. Though some LST loss may be inevitable when tracking body composition changes using dual-energy X-ray absorptiometry (DXA), correcting for the fat-free component of adipose tissue (FFAT) in DXA-derived LST (DXALST) has been proposed. This analysis sought to evaluate differences between DXALST and FFAT-corrected LST (FFATLST) amongst varied populations and interventions to understand application of the correction formula on LST outcomes. 226 subjects were analyzed across five prior studies. Three studies evaluated combined nutrition and exercise (high-intensity interval training [HIIT] or high-intensity resistance training [HIRT]) interventions, including HIIT + HIRT with pre- and post-nutrient timing (HIITRT), HIIT + essential amino acids (HIITAA), and HIRT + protein (HIRTPRO). Remaining studies evaluated HIIT (HIITOW) and protein following bariatric surgery (BARPRO). Pre and post total body DXA scans were used to measure DXALST, body mass, and fat mass (FM). The correction formula was applied to calculate FFATLST. Paired sample t-tests were used to evaluate differences between DXALST and FFATLST change scores (Δ) across all subjects, within each study and intervention. Significant differences between ΔDXALST and ΔFFATLST were observed for BARPRO (mean difference [MD; ΔDXALST-ΔFFATLST] ± standard error [SE]: -3.5 ± 1.2 kg, p < 0.001), as well as HIRTPRO (-0.1 ± 0.2 kg, p = 0.004). When evaluating LST, the FFAT correction may be specifically applicable to cases of significant weight loss (>10% of original weight) or body recomposition (≥2% FM loss and ≥2% LST gain).

Abstract 4136678: Detecting Myosteatosis-Related Low Physical Function in Heart Failure Patients Using Abdominal Computed Tomography and Plasma Amino Acid Profile

Background: Evaluation of sarcopenia requires quantifying appendicular skeletal muscle mass and functional capacity, but resource constraints often limit feasibility. Alterations in muscle quality, especially intramuscular lipid infiltration (i.e., myosteatosis), and systemic metabolic derangements are associated with disability. Hypothesis: Opportunistic CT imaging and plasma amino acid profiling could identify low physical function in patients with heart failure (HF). Methods: We retrospectively examined 220 HF patients (74 ± 13 years old; 59% male) who underwent plasma amino acid profiling, abdominal CT imaging, and dual-energy X-ray absorptiometry (DXA) scan within two months. Myosteatosis was evaluated using single-slice CT imaging at the L3/4 level and quantified as mean muscle attenuation (MMA). Physical function was assessed by the short physical performance battery (SPPB), with low physical function defined as SPPB ≤9. Results: CT-derived single-slice areas of skeletal muscle and adipose tissue were highly correlated with DXA-derived appendicular skeletal muscle mass and total fat mass. Logistic regression analyses revealed that higher age and lower MMA, but not skeletal muscle area, were significantly associated with low physical function independently of NT-proBNP. Subjects with MMA below the median value (32.0 HU for males and 23.7 HU for females) had higher odds of low physical function (adjusted OR 2.04, 95% CI 1.04-3.96). Ten amino acids and the Fischer ratio were significantly correlated with MMA levels. Multivariate regression analyses, adjusted for potential confounders including age, gender, and body mass index, demonstrated that serum albumin and Fischer ratio were independent determinants of MMA levels. When serum albumin and Fischer ratio were dichotomized by their median values (3.6 mg/dL and 3.23, respectively), the prevalence of low physical function was significantly higher in subjects with low albumin and low Fischer ratio, but not in those with low levels of only either parameter, compared to those with high albumin and high Fischer ratio (adjusted OR 2.36, 95% CI 1.02-5.49). Conclusions: Myosteatosis assessed by single-slice abdominal CT imaging is an independent determinant of low physical function in HF patients. Combined with an assessment of serum albumin and Fischer ratio, these simple biomarkers could facilitate the early detection of patients at risk for developing frailty.

Accreditation of in-abattoir Dual Energy X-ray Absorptiometry scanning apparatus to predict lamb carcass composition in Australia

Dual Energy X-ray Absorptiometry (DXA) scanners operating at abattoir processing speeds are currently installed in six sheep meat abattoirs around Australia, predicting carcass composition as estimates of computed tomography (CT) determined fat %, lean %, and bone %. This study tested an updated bone-detection algorithm for these DXA scanners. This algorithm improved the precision of prediction for carcass fat% and lean%, but most notably for bone % (R2 = 0.92, RMSE = 0.61 %), compared to the previous algorithm (R2 = 0.51, RMSE = 1.57 %). This was due to improved allocation of bone-containing pixels, resulting from the inclusion of tissue thickness in the bone-detection equation. In a second experiment, the predictions from this new algorithm, along with an automated phantom calibration technique, were assessed relative to their ability to meet the AUS-MEAT accreditation accuracy standards required for predicting CT determined carcass fat%, lean%, and bone%. The DXA met these standards for predicting fat % (range 10.9 % - 37.1 %), lean % (range 49.0 % - 66.2 %), and bone % (range 11.6 % - 25.0 %), across three weight bands of light carcasses (<22 kg), mid-weight carcasses (22-28 kg), and heavy carcasses (>28 kg). This work allowed for the accreditation of DXA, enabling its predictions of carcass composition to be used for trading sheep carcasses in Australia. The accuracy of these predictions far exceed those provided by the historical industry measure of GR tissue depth, and hot carcass weight.

Fat Distribution and Urolithiasis Risk Parameters in Uric Acid Stone Formers and Patients with Type 2 Diabetes Mellitus.

Key Points Under a controlled diet, uric acid stone formers (UASFs) and diabetic patients have higher endogenous net acid production.Under a controlled diet, UASFs have lower ammonium-to-net acid excretion ratio.Body fat inversely correlates with urine buffer capacity in normal individuals, but this relationship is lost in diabetic patients and UASFs. Background Uric acid (UA) nephrolithiasis affects approximately 10% of kidney stones, with a greater preponderance among patients with obesity and diabetes mellitus (DM). UA lithogenicity is driven by abnormally acidic urine pH. Distinguishing the contribution of intrinsic (e.g., body adiposity) versus external (e.g., dietary) factors to UA stone propensity is challenging because of uncontrolled diets in outpatients in previously published studies. Methods This compilation of metabolic studies with body composition examined by dual-energy x-ray absorptiometry scan and blood and urine biochemistry collected under a controlled metabolic diet was conducted across three distinct populations: 74 UA stone formers (UASF group), 13 patients with type 2 DM without kidney stones (DM group), and 51 healthy volunteers (HV group). Results Compared with HVs, both UASFs and patients with DM exhibited higher levels of net acid excretion (NAE) and significantly lower urine pH and lower proportion of NAE excreted as ammonium (NH4 +/NAE), all under controlled diets. UASFs exhibited significantly lower NH4 +/NAE compared with patients with DM. UASFs also showed higher total body and truncal fat compared with HVs. Among the HVs, lower NH4 +/NAE ratio correlated with higher truncal and total fat. However, this association was abolished in the UASF and DM groups who exhibit a fixed low NH4 +/NAE ratio across a range of body and truncal fat. Conclusions The findings suggest a dual defect of diet-independent increase in acid production and impaired kidney NH4 + excretion as major contributors to the risk of UA stone formation. There is an inverse physiologic association between body fat content and NH4 +/NAE in HVs, whereas NH4 +/NAE is persistently low in UASFs and patients with DM, regardless of body fat, representing pathophysiology.

Prescribing Blood Flow Restricted Exercise: Limb Composition Influences the Pressure Required to Create Arterial Occlusion.

As blood flow restriction gains popularity across different populations (eg,young and older adults) and settings (eg,clinical and sports rehabilitation), the accuracy of blood flow restricted percentage becomes crucial. We aimed to compare manually measured arterial occlusion pressure (AOP) among young adults to understand whether lower limb composition affects the pressure required to achieve AOP. The results will shed light on the adequacy of published calculations used to estimate AOP in practical and research settings. An observational cross-sectional study design was implemented to examine the relationship between lower limb composition, lower limb circumference, and measured AOP. Twenty-two participants (12 males, 26 [4]y, 1.74 [0.07]m, 73.2 [12.5]kg) underwent a whole-body Dual-energy X-ray Absorptiometry scan before AOP (in millimeters of mercury) and lower limb circumference (in centimeters) were determined. In a supine position, a 10-cm wide cuff was manually inflated on the dominant leg to the point where a pulse could no longer be detected by a Doppler ultrasound of the posterior tibial artery to determine AOP. Lower limb composition (fat, muscle, and bone mass [in grams]) was obtained from the Dual-energy X-ray Absorptiometry scan. Lower limb muscle mass had a moderate negative relationship with AOP (r2 = .433, β = -0.004) and a moderate positive relationship with lower limb circumference (r2 = .497, β = 0.001). Lower limb circumference had the weakest relationship with AOP (r2 = .316, β = 0.050) of all measures. The reported relationships between lower limb muscle mass, lower limb circumference, and AOP suggest that as muscle mass increases, lower limb circumference also increases, yet AOP decreases. This implies that limb circumference should not be used as the primary measure for calculating AOP within the sampled population. We recommend individually measuring AOP when implementing blood flow restriction in all exercise modalities.

Trabecular Bone Score in Individuals with Chronic Spinal Cord Injury: A Cross-Sectional Study.

To describe lumbar spine (LS) trabecular bone score (TBS) values after SCI, and to explore the differences in fractures risk assessment between FRAX® and TBS-adjusted FRAX® in individuals living with chronic SCI. Baseline dual-energy x-ray absorptiometry (DXA) scans from an established cohort were acquired using a Hologic Discovery QDR 4500. TBS measurements were performed using the TBS iNsightTM software version 2.1.2.0. A Welch's t-test was performed to explore differences in TBS, FRAX®, and TBS-adjusted FRAX® between men and women, between participants ≤49 years and ≥50 years, and between subgroups with and without history of fracture and with complete and incomplete injury. We analyzed 37 scans; the mean TBS was 1.336 ± 0.107. The mean 10-year fracture risk was 8.8% ± 11.4% for major osteoporotic fracture and 4.0% ± 10.8% for hip fracture according to FRAX®, and 6.6% ± 2.8% for major osteoporotic fracture and 2.8% ± 6.7% for hip fractures according to TBS-adjusted FRAX®. The 10-year fracture risk for major osteoporotic fractures was higher in individuals with a prior fragility fracture compared to those without, according to FRAX® (p = .033) and TBS-adjusted FRAX® (p = .001). Over a half of our sample presented a partially degraded bone microarchitecture based on TBS. TBS was not different between people with motor complete and motor incomplete injury or with and without prior fragility fracture. Future studies are needed to define the clinical relevance of TBS and TBS-adjusted FRAX® in people with chronic SCI.

Evaluating the Importance of Practice-Level Factors on Adherence to Prostate Cancer Treatment Guidelines in Urology

ObjectiveTo evaluate adherence to treatment guideline recommendations across the continuum of prostate cancer care by US community urologists using several prostate cancer (PCa) specific performance indicators (PIs). Additionally, to determine which practice-related factors, such as having a designated PCa patient champion, active patient management in a patient portal, and in-office dispensing of medications, were associated with improved PI performance. MethodsElectronic medical record data was collected retrospectively from the PPS Analytics Patient Population Health Management Platform. The cohort consisted of adult patients with a PCa-related service visit during the period 7/1/2019 to 6/30/2022. Five PIs were reviewed: dual-energy x-ray absorptiometry (DEXA) scanning with androgen deprivation therapy (ADT), systemic therapy in metastatic PCa, external beam radiation therapy (EBRT) concurrent with ADT, image monitoring, and regular testosterone testing and monitoring. ResultsA total of 101,186 patients were identified from 95 urology practices. PI adherence rates ranged from a low of 13.6% for a DEXA scan within 6-months of ADT initiation to a high of 72.3% for EBRT concurrent with ADT in intermediate/high risk localized PCa. The results also demonstrated that several practice-related features were associated with better PI adherence. ConclusionsThe findings suggest there exists a wide range in PI adherence rates for urologists in the delivery of community urology care in the Unites States compared to clinical guideline recommendations. Future research should examine the factors associated with PI nonadherence and promote implementation of interventions that enhance guideline concordant care.

In-utero exposure to tenofovir-containing pre-exposure prophylaxis and bone mineral content in HIV-unexposed infants in South Africa.

Tenofovir disoproxil fumarate (TDF) is a common drug of choice for pre-exposure prophylaxis (PrEP) or as a combination HIV treatment for pregnant women. In-utero exposure to TDF was found to be associated with lower bone mineral content (BMC) in HIV-exposed uninfected neonates. Data for infants born to women taking TDF-PrEP are lacking. The CAP016 randomized control trial was conducted in South Africa between September 2017 and August 2021 and pregnant women either initiated TDF/FTC PrEP in pregnancy (Immediate PrEP arm-IP) or at cessation of breastfeeding (Deferred PrEP arm-DP). In a secondary data analysis, we evaluated BMC in HIV-unexposed infants in the CAP016 trial in the first 18 months of life in association with maternal TDF-PrEP use during pregnancy. Infants born to women randomized to the IP arm or DP arm in the CAP016 clinical trial had BMC measurements of the whole body with head (WBH) and lumbar spine (LS) by dual energy X-ray absorptiometry (DXA) at 6, 26, 50 and 74 weeks. Of 481 infants born to women enrolled in the CAP016 clinical trial, 335 (69.6%) infants had a minimum of one DXA scan of the WBH and LS between 6 and 74 weeks of age (168 IP and 167 DP). Women in the IP arm received TDF-FTC PreP for a median of 19 weeks between initiation in pregnancy and delivery. Using a mixed linear regression model and adjusted for gestational age, sex and ever-breastfed, the mean difference (95% CI) for BMC of the WBH between IP and DP arms were -0.74 (-8.69 to 7.20), -1.26 (-10.75 to 8.23), -9.17 (-20.02 to 1.69) and 5.02 (-6.74 to 16.78) g at 6, 26, 50 and 74 weeks (p = 0.283). Mean differences in BMC of the LS were 0.07 (-0.10 to 0.23), 0.02 (-0.18 to 0.22), -0.14 (-0.36 to 0.09) and 0.14 (-0.11 to 0.38) g at 6, 26, 50 and 74 weeks, respectively (p = 0.329). In a randomized controlled trial, there were no differences in BMC of the WBH and LS between infants exposed to in-utero TDF-FTC PrEP and unexposed infants in the first 18 months of life.

Biometric Changes Up to 2 Years After Hip Arthroscopy in National Collegiate Athletic Association Division I Athletes.

Patients who undergo hip arthroscopy for femoroacetabular impingement (FAI) require lower extremity immobilization for an extended period of time. Periods of immobilization combined with surgery have been associated with decreased muscle mass and bone mineral density (BMD). The purpose of this study was to characterize postoperative body composition and BMD changes after arthroscopy for FAI. It was hypothesized that both lean mass and BMD would decrease postoperatively and then normalize over time. Case series; Level of evidence, 4. This was a retrospective review of 23 National Collegiate Athletic Association Division I athletes who underwent hip arthroscopy between 2017 and 2019 and had a dual-energy x-ray absorptiometry scan preoperatively and at 3, 6, 12, or 24 months postoperatively. Linear mixed-effects models were used to compare pre- with postoperative lean and fat mass values for the total body and total leg (both operative and nonoperative sides) as well as trunk, pelvic, and spinal BMD. For total-leg, femur, and femoral BMD, linear mixed-effects models were used to evaluate the influence of time, side (operative vs nonoperative), and their interaction on each outcome measure. Regarding pelvic BMD, compared with baseline (mean, 1.41 g/cm2 [95% CI, 1.33-1.49]), significant decreases were seen at postoperative 3 months (mean, 1.36 g/cm2 [95% CI, 1.28-1.45 g/cm2]; P < .001) and 6 months (mean, 1.39 g/cm2 [95% CI, 1.27-1.52 g/cm2]; P < .01) but not at 12 months (mean, 1.42 g/cm2 [95% CI, 1.33-1.51 g/cm2]; P = .319). Total-leg BMD for the operative side increased significantly from baseline (mean, 1.52 g/cm2 [95% CI, 1.43-1.61 g/cm2]) to ≥2 years postoperatively (mean, 1.56 g/cm2 [95% CI, 1.47-1.65 g/cm2]) (P = .005). Combined leg fat mass was increased from baseline (mean, 6427 g [95% CI, 4855-7999 g]) to ≥2 years (mean, 11645 g [95% CI, 7845-15,446 g]) (P < .01). There were no significant differences in total-body fat or lean mass or combined-leg lean mass. In this patient population, a postoperative decrease in pelvic BMD that resolved by 12 months and an increase in total-leg BMD on the operative side at ≥2 years were observed. While hip arthroscopy for FAI may have significant benefits for long-term body composition and bone mass, clinicians should be aware of the potential implications of decreased bone mass for up to 12 months postoperatively.