Dual X-ray Absorptiometry Results Research Articles

Prevalence and Risk Factors of Discordance Between Hip and Spinal Bone Mineral Density Among Saudi Subjects.

BackgroundDiscordance between hip and spine on dual-energy x-ray absorptiometry is a well-known problem in diagnosing osteoporosis. The prevalence and risk factors of this problem have not been studied in the Saudi population. The objective of this study was to document this discordance in our population and its possible risk factors.Materials and methodsWe analyzed data obtained from subjects who had dual x-ray absorptiometry (DXA) between January 2021 and December 2021 at King Khalid University Hospital, Riyadh, Saudi Arabia. Subjects with the following conditions were excluded: secondary osteoporosis, patients taking anti-osteoporotic agents, patients on steroids or hormonal replacement therapy, hyperparathyroidism, hypoparathyroidism, and chronic renal disease. A total of 1388 patients satisfied our inclusion criteria. World Health Organization (WHO) criteria for diagnosis were implemented. Major discordance was defined as osteoporosis in one site and normal in the other. Minor discordance was defined as a difference of no more than one World Health Organization diagnostic class between two sites. Bivariate statistical analysis was achieved using appropriate statistical tests (chi-square, student’s t-test, one-way analysis of variance, and Pearson’s correlation), based on the type of study and outcome variables. A p-value of < 0.05 and 95% CI were used to report the statistical significance and precision of results.ResultsA total of 1388 subjects were analyzed, of which, 1196 (86%) were females with a mean age of 58.8 (13.8 SD) and 192 were males with a mean age of 58 (18.0 SD). Lumbar osteoporosis was found in 312 (22.5%) participants while hip osteoporosis was reported in 73 (5.3%) of the participants. Major discordance was documented in 85 (6.1%) of all participants (6.3% of the male and 6.1% of the female patients). All of these subjects had lumbar spine osteoporosis with normal hip bone mineral density (BMD). Minor discordance was found in 591 patients (42.6%). Obesity (BMI > 30) was found to be a risk factor for both major (2.10-11.6, 95% CI) and minor (2.5-11.4, 95% CI) discordance.ConclusionDiscordance between hip and spine BMD is common among Saudi subjects. Lumbar spine osteoporosis with normal hip BMD caused this discordance in our subjects. Obesity could be responsible for the occurrence of this discordance. Mechanisms may include higher rate of turnover in spine, technical artifacts in the measurements of lumbar spine BMD, or due to the effects of weight loading. Caution should be exercised when interpreting DXA results, especially in obese subjects.

Quantitative Ultrasound of Phalanx in Primary and Secondary Osteoporosis: Mini-review and Practical Experience

Objective: Dual x-ray absorptiometry (DXA) is gold standard of bone densitometry, but quantitative ultrasound (QUS) of bone is less expensive and portable. This study was designed to assess its usefulness in secondary osteoporosis diagnosis. Materials and Methods: There were 200 secondary osteoporosis cases (rheumatoid arthritis, hemodialysis, kidney transplant patients, and levothyroxine users) and of those, their phalanx QUS results were compared with normal controls. Also, the QUS and DXA results were compared to find any correlation of these methods for diagnosing osteoporosis. Results: There was not significantly different results compared with normal controls, except for those of hemodialysis patients ( P = .00). Also, the comparison of QUS with DXA results showed no significant correlation except in hemodialysis patients, in both spinal and femoral regions ( P = .023 and .21, respectively), as well as the levothyroxine group’s spinal region ( P = .005). Conclusion: These results suggest that QUS of phalanx may be useful in screening secondary osteoporosis but for establishment of diagnosis, DXA measurements are still needed.

Comparison of Anthropometric Equations and Dual X-ray Absorptiometry to Determine Body Composition in Active Breast Cancer Survivors

Objective The purpose of this study was to 1) compare the body composition values of an active group of breast cancer survivors (BCS) determined by dual X-ray absorptiometry (DXA) and anthropometry, and 2) compare the bone mineral density of the upper thoracic region to assess the effect of tumor burden on bone health. Design and Methods Forty (n=40) breast cancer survivors from a local competitive Dragon Boat Team were measured as part of team assessments. ANOVA with Dunn’s post-hoc testing was used to compare results of DXA, body density, and body composition estimated from anthropometry. Bland-Altman testing and correlational analysis were calculated. Results Percentage of fat measure by DXA was significantly higher than values used to estimate body fat from skinfold measures or from body density equations (DXA 41.1±6.0% vs. 3-site skinfolds 28.8±4.9%, 4-site skinfolds, 22.1±4.1%, skinfold and body density, 31.8±9.4%, respectively, p&lt;0.05). Post-hoc testing revealed that all values were significantly different and the strongest correlation with DXA was skinfolds at three sites was r=0.81. Regional (upper thoracic) bone mineral density was not significantly different based on tumor side diagnosis (breast cancer diagnosis side versus healthy, 0.971±0.198 vs. 0.988±0.190 gm*cc-1). Anthropometry and bilateral bone mineral density characteristics are presented to serve as a comparative sample of BCS for future studies. Conclusion As body composition is an important factor in long-term cancer survivorship, we found the use of skinfold measures inadequate to accurately determine percentage of fat in this group of active female BCS. As a result, recommendations aimed at achieving an ideal body composition based solely on anthropometry would have grossly underestimated fat mass, which may lead to overall clinically poorer outcomes.

SUN-397 The Osteosee System Measurements, Based on Parametric Electrical Impedance Tomography, Correlate with Dual X-Ray Absorptiometry Results for the Diagnosis of Osteoporosis

Introduction: Dual X-Ray Absorptiometry (DXA) is the gold standard for the diagnosis of osteoporosis, but it has its pitfalls. The OsteoSee @Clinic is a novel portable and user-friendly system, which uses parametric Electrical Impedance Tomography (pEIT), being developed to allow screening and diagnosis of osteoporosis at the primary care clinic Aim: To test the new system and compare its results to those of the DXA system. Methods and Subjects: This prospective study was conducted between 01/01/2019 and 01/06/2019. Subjects who presented for a routine DXA scan (lumbar spine and proximal femur with Lunar Prodigy GE healthcare system) were enrolled. After signing an informed consent form, they were scanned with the OsteoSee @Clinic system (OsteoSee Ltd., Israel) using 5 electrodes placed around the left distal forearm and around the pelvis. Results: OsteoSee @Clinic data were compared to DXA total hip bone mineral density (BMD). Correlations were examined between pEIT-index of the pelvis versus DXA total hip BMD. Sensitivity and specificity were calculated according to the diagnosis obtained by DXA based on the total hip T-score. An analysis based on 182 subjects (35 healthy, 115 osteopenia, 32 osteoporosis) scanned on the wrist showed an R-value of 0.795 (p-value < 0.001) representing the correlation between the pEIT-wrist index and DXA results. From the ROC plot, we obtained a sensitivity of 84% and specificity of 71% to diagnose osteoporotic vs osteopenic & normal subjects, and a sensitivity of 82% and specificity of 86% for identifying osteopenic & osteoporotic vs normal subjects. An analysis of 98 subjects (17 healthy, 66 osteopenic, 15 osteoporosis) scanned on the pelvis showed an R-value of 0.740 (p-value < 0.001), representing the correlation between the pEIT-pelvis index and DXA BMD. From the ROC plot, we obtained a sensitivity of 80% and specificity of 81% to diagnose osteoporotic vs osteopenic & normal subjects, and a sensitivity of 70% and specificity of 76% for identifying osteopenic & osteoporotic Vs normal subjects. Conclusions: The OsteoSee @Clinic system results correlate well with DXA measurements, especially when taking into account clinical interpolations. Sensitivity and specificity values indicate that the OsteoSee @Clinic system can provide screening and diagnosis of osteoporosis. With the DXA system being costly to operate and inaccessible to many patients, the OsteoSee @Clinic system may address the unmet need for diagnosing and treating osteoporosis, and offer an alternative for a broader screening of the population at risk of fractures.Disclosure: The study was funded by OsteoSee Ltd., Israel

Motor Competence and Body Composition in young adults: An exploratory study

BackgroundThe association between obesity and physical inactivity strongly and independently predict overall obesity in young adulthood. Physical inactivity and increasing obesity in our society is multifaceted, but on key factor to promote physical activity is motor competence (MC). PurposeThis study aimed to analyse a physically active group of young adults by investigating the correlations between MC, adiposity and body mineral density by using dual X-ray absorptiometry (DXA). MethodsForty-four young men (22,1 ± years; 69,0 ± kg; 173,7 ± meters) and 21 young women (20,2 ± years; 63,8 ± kg; 169,6 ± meters) participated in this study and completed anthropometrics; DXA; Motor Competence assessment battery that comprise two tests for each of the three constructs: locomotor, manipulative and stability. Descriptive statistics were considered and Spearman's correlation test to examine the association between MC scores and DXA results. The Mann-Whitney test was used to compare males to females for p < 0,05. ResultsMotor Competence (MC) variables and body composition in female revealed significant associations only between shuttle run and total fat (r = −0,648). In males, demonstrate several positive statistically associations with MC Stability and Locomotor tasks and constructs (p < 0,05). ConclusionsIn very active young adults, MC positive influences weight status, particularly in locomotor and stability tasks.

Is it possible to predict a risk of osteoporosis in patients with juvenile idiopathic arthritis? A study of serum levels of bone turnover markers.

Low bone mineral density is a common finding in children with systemic connective tissue diseases, including juvenile idiopathic arthritis (JIA). The influence of the ongoing process of bone remodeling on the disease course merits further investigation. The aim of this study was to assess the clinical relevance of markers of bone turnover and their potential role as predictors of higher fracture risk and, by extension, risk of osteoporosis. Blood samples were collected from 59 patients diagnosed with JIA in order to determine serum levels of the following markers of bone turnover: Beta-Crosslaps, osteocalcin, bone alkaline phosphatase, osteoprotegerin and receptor activator for nuclear factor kappa-B ligand. The values were analyzed with laboratory parameters and results of dual X-ray absorptiometry (DXA). Osteoprotegerin and bone alkaline phosphatase levels were age-dependent. Beta-Crosslaps values were significantly higher in patients with positive JADAS27 score (p=0.0410). Osteoprotegerin levels were higher in patients treated with biological agents than only with disease-modifying anti-rheumatic drugs (p=0.0273). There was no relation between markers of bone turnover and sex, DXA results, dosage of glucocorticosteroids and disease duration. The authors postulate performing DXA measurements every 6 months in patients with higher disease activity. The potential lower fracture risk in children with JIA within biological treatment needs further assessment. Age- and sex-adjusted reference rates of bone turnover markers need to be developed for Central European patients in order to assess individual values properly.

Osteoporotic alterations in a group of different ethnicity Brazilian postmenopausal women: An observational study.

To compare peripheral bone mineral density alterations among Brazilian postmenopausal women from three ethnic groups considering age and body mass index influence; to correlate their bone mineral density with the mandibular cortical index (MCI); and to evaluate the influence of age, body mass index and ethnicity in the MCI using risk factor analysis. Osteoporosis risk is known to have ethical influences. However, little is known about the differences in ethnicity in radiomorphometric indices. A total of 150 postmenopausal women with different ethnicities (Caucasian, Asian and Afro-descendant) who underwent peripheral dual X-ray absorptiometry and panoramic examination were included. Bone mineral density and MCI were assessed. Adjusted odds ratio analyses were performed on bone density and MCI considering the effect of age, ethnicity and body mass index. The correlations between the MCI and the dual X-ray absorptiometry results were made. Old age, low body mass index and non-Afro-descendant were associated with low bone density. Compared with Afro-descendants, Asians and Caucasians have higher chances of having decreased bone mass. For the MCI, statistical analysis showed that age is the only variable associated with osteoporotic alterations in the mandible. Furthermore, an inverse correlation was found between the MCI and the T-scores. Bone density is higher in Brazilian Afro-descendant women than in Caucasians and Asians. Patient's age is associated with bone density and the MCI. The mandibular cortical index is inversely correlated with the peripheral densitometry results within the study ethnic population.

Understanding the Variation in Use of Screening DXA Scans in Pediatric Patients with Celiac Disease

Celiac disease (CD) is an immune-mediated genetic disorder occurring secondary to gluten exposure and increasing the likelihood of low bone mineral density (BMD). As there are no published guidelines for dual-x-ray absorptiometry (DXA) scanning in pediatric CD patients, we characterized current practices of pediatric gastroenterologists in ordering screening DXA scans for pediatric CD patients. To accomplish this, A REDCap survey was distributed to the NASPGHAN listserv. There was a total of 231 (11%) responses. The majority (60%) of clinicians do not order screening DXA scans because they don’t believe it is clinically necessary. Patient factors influenced ordering screening DXA scans with fracture history driving ordering and tissue transglutaminase (tTG) level not affecting practice. Physician factors such as practice type and experience were not associated with ordering screening DXA scans. Case scenarios, showed wide variation in management based on DXA results.

Measurement of Distal Ulnar Hounsfield Units Accurately Predicts Bone Mineral Density of the Forearm.

Hounsfield unit (HU) measurement obtained from computed tomography (CT) scans of the wrist is a potential new screening method for low bone mineral density (BMD). We hypothesized that HU measurements of the ulnar head obtained from CT scans would correlate with BMD assessed with dual x-ray absorptiometry (DXA) scans of the forearm. Patients with both upper-extremity CT and DXA scans performed at a single institution were included in the study. Hounsfield units were manually measured in the distal part of the ulna by 1 author blinded to the DXA results. Average values were then compared with forearm BMD values as determined with a DXA scan. Seventy-seven CT scans of 74 patients were included. Average HU values were significantly lower in the osteoporotic and osteopenic groups in comparison with the normal BMD group. The upper limit of the 95% confidence interval for osteopenic patients was 145.9 HU. The average forearm T-score for patients with an HU value at or below the cutoff of 146 was significantly lower than the average T-score for those with an HU value of >146 HU (p < 0.0001). Sensitivity and negative predictive value for low BMD using this cutoff value were calculated to be 91% and 89%, respectively. Distal ulnar HU measurements accurately reflect the BMD of the forearm as diagnosed with a DXA scan. Our results suggest that distal ulnar HU measurements of ≤146 HU are strongly associated with low BMD and that values above this cutoff accurately rule out low forearm BMD with a high degree of sensitivity and negative predictive value. Utilizing this technique may improve the capture of at-risk patients and streamline the screening process for osteoporosis. Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Assessment of osteoporotic alterations in type 2 diabetes: a retrospective study.

To analyze the influence of Type 2 diabetes on bone mineral density (BMD) and panoramic radiomorphometry in postmenopausal females, comparing with results from non-diabetic postmenopausal females. A total of 228 postmenopausal females (mean age: 59.51 ± 11.08 years) were included in this study. Demographics, T scores and Z scores from peripheral dual X-ray absorptiometry (DXA) and mandibular cortical index (MCI) from panoramic radiographs were assessed. Mean comparison between results for diabetics and non-diabetics was carried out with the Student's t-test. In addition, non-parametric correlations between MCI and DXA results were carried out with Spearman's test, at a level of significance of 5%. Mean Z score values were significantly higher in diabetics than in non-diabetics (p = 0.001). T and Z score values were also significantly correlated with MCI (r = 0.428, p = 0.001, and r = 0.356, p = 0.022, respectively). Within the limitations of this study, the present results suggest that Type 2 diabetes might increase BMD in postmenopausal females.

Estimation of femoral neck bone mineral density by ultrasound scanning: Preliminary results and feasibility

Abstract Aim of this paper was to assess the diagnostic accuracy of a novel ultrasound (US) approach for femoral neck densitometry. A total of 173 female patients (56–75 years) were recruited and all of them underwent a dual X-ray absorptiometry (DXA) of the proximal femur and an US scan of the same anatomical district. Acquired US data were analysed through a novel algorithm that performed a series of spectral and statistical analyses in order to calculate bone mineral density employing an innovative method. Diagnostic accuracy of US investigations was quantitatively assessed through a direct comparison with DXA results. The average diagnostic agreement resulted pretty good (85.55%), with a maximum (88.00%) in correspondence of the youngest investigated patients (56–60 y). Overall, diagnostic accuracy showed only minimal variations with patient age, indicating that the proposed approach has the potential to be effectively employable for osteoporosis diagnosis in the whole considered age interval.

Cortical Bone Thickness of the Distal Part of the Tibia Predicts Bone Mineral Density.

Poor bone density may affect surgical planning, treatment outcome, and postoperative protocols. Many patients with foot and ankle problems have not undergone a dual x-ray absorptiometry (DXA) scan, which is currently the gold standard for determining bone density. The purpose of this study was to determine if the cortical bone thickness (CBT) of the distal part of the tibia measured on radiographs correlated with bone mineral density. After exclusion criteria were applied, 167 consecutive adult patients (mean age and standard deviation [SD], 62 ± 11.62 years) who had had standardized ankle radiographs and a DXA scan within 6 months of each other were included in this retrospective study. The CBT was measured with both the gauge and the average method on standardized anteroposterior, lateral, and hindfoot alignment radiographs. The relationship between CBT in the distal part of the tibia and DXA findings in the hip, proximal part of the femur, and lumbar spine was assessed with Pearson correlations. The interrater and intrarater reliability of CBT measurements was assessed with intraclass correlation coefficients. Subgroup analysis was performed to determine the ability of CBT thresholds to predict osteoporosis. Average CBT measurements on the anteroposterior, lateral, and hindfoot alignment views strongly correlated with DXA findings in the proximal part of the femur (r = 0.70, 0.64, and 0.55, respectively; p < 0.0001), the hip (r = 0.74, 0.67, and 0.53; p < 0.0001), and the lumbar spine (r = 0.61, 0.60, and 0.47; p < 0.0001). The interrater and intrarater reliability of the CBT measurements was excellent. Use of a 3.5-mm average CBT of the distal part of the tibia on the anteroposterior view as the threshold value for predicting osteoporosis (T score less than -2.5) had a sensitivity of 100%, a specificity of 25%, an accuracy of 33%, a positive predictive value of 19%, and a negative predictive value of 100%. Measurement of the average CBT of the distal part of the tibia is a quick and reliable method for obtaining information on bone quality. CBT measured on standard ankle radiographs correlated strongly with DXA results and may prove to be a useful screening tool for osteoporosis. Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Innovative ultrasound approach to estimate spinal mineral density: diagnostic assessment on overweight and obese women

The aim of this study is to assess the accuracy of a novel ultrasound (US) approach for lumbar spine densitometry on overweight and obese women of variable age through a clinical validation study. The US method was originally developed in women with body mass index (BMI) 25 kg/m2) and underwent dual X-ray absorptiometry (DXA) of lumbar spine (L1–L4) and an US scan of the same vertebrae L1–L4, performed with a dedicated device providing both echographic images and ‘raw’ radiofrequency signals. Acquired US data were analysed through a novel automatic algorithm that performed a series of spectral and statistical analyses to calculate bone mineral density employing an innovative method. Diagnostic accuracy of US investigations was quantitatively assessed through a direct comparison with DXA results. The average agreement between US and DXA diagnoses was acceptable for patients aged 45–65 years (81.5%), while a slight decrement was observed for older patients (69.6%), which can be partially due to a decrease in DXA accuracy because of age-related degenerations. The adopted method has a potential for early osteoporosis diagnosis in people younger than 65 years, independent of their BMI.

Evaluation of osteoporosis in jaw bones using cone beam CT and dual-energy X-ray absorptiometry.

The aim of this study was to evaluate changes in jaw bones due to osteoporosis using cone beam computed tomography (CBCT) images. Subjects that had undergone CBCT for various oral conditions and demonstrating clinical findings of osteoporosis were invited to participate in the study. Dual X-ray absorptiometry (DXA) was performed on 90 patients aged over 30 years who underwent CBCT. The study groups were based on DXA results, and included 26 osteoporosis patients (mean age ± standard deviation; 58.52 ± 5.91), 33 osteopenia patients (52.67 ± 8.61) and 31 healthy controls (49.81 ± 10.47). CBCT images of jaw bones were evaluated using radiomorphometric indexes, CT values, histogram analysis (HA) and fractal dimension (FD) analysis. Right and left mandibular radiomorphometric indexes, CT values and HA measurements in osteoporosis patients were significantly lower than measurements in osteopenia patients and control subjects (P ≤ 0.05). Positive correlations were observed between measurements of spine bone mineral density (BMD) and right and left mandibular CT values (P ≤ 0.01) and HA (P ≤ 0.01) measurements. Left maxilla FD measurements in osteoporosis patients were significantly lower than in the control (P ≤ 0.05) and osteopenia (P ≤ 0.05) groups. Osteoporosis caused significant changes in radiomorphometric indexes, CT values, and HA and FD measurements in the jaw bones. (J Oral Sci 58, 185-194, 2016).

Skeletal muscle abnormalities and exercise capacity in adults with a Fontan circulation

ObjectivesThe peripheral muscle pump is key in promoting cardiac filling during exercise, especially in subjects who lack a subpulmonary ventricle (the Fontan circulation). A muscle-wasting syndrome exists in acquired heart...

AB0624 High correlation between a new ultrasonic method for spinal densitometry and dual x-ray absorptiometry

BackgroundOsteoporosis is a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue leading to increased fragility and augmented fracture risk. Bone densitometry performed through dual...

Health care for osteoporosis in inflammatory bowel disease: Unmet needs in care of male patients?

Background and aimsOsteoporosis is a frequent complication of inflammatory bowel disease (IBD). It may be related to IBD itself or to its therapy. In this study, the quality of care regarding diagnosis and treatment of osteoporosis was examined. MethodsIn this retrospective, monocentric study 293 consecutive patients with IBD (98 ulcerative colitis, 195 Crohn's disease) were included. Information on age, gender, weight, nicotine abuse, course, disease pattern and medication was assessed, results of dual X-ray absorptiometry (DEXA-scan) were evaluated. ResultsDEXA-scan was performed in 174 patients (59 male, 115 female). Bone mineral density (BMD) was impaired in 38.5% of these patients. Male patients were diagnosed more often with osteopenia or osteoporosis than females (55.9% vs. 29.6%, p=0.03) and had a risk of bone disease comparable to postmenopausal women. Additionally, duration of corticosteroid treatment and IBD were identified as risk factors for osteoporosis. Follow up DEXA-scan demonstrated an overall deterioration of BMD in patients with normal baseline results. ConclusionsWhile in general, women are considered at higher risk for osteoporosis, male patients had a higher risk of impaired BMD, especially when under treatment with corticosteroids. The high incidence of reduced BMD supports the recommendation to screen patients with IBD at an early stage of disease, although a possible bias has to be considered for patients at a tertial referral centre for IBD. Patients with normal baseline DEXA-scan were still at risk to develop bone disease and it seems advisable to monitor patients with IBD for reduced BMD continually.

Evaluation of vertebral bone marrow fat content by chemical-shift MRI in osteoporosis

To quantitatively evaluate vertebral bone marrow fat content and investigate its association with osteoporosis with chemical-shift magnetic resonance imaging (CS-MRI). Fifty-six female patients (age range 50-65 years) with varying bone mineral densities as documented with dual x-ray absorptiometry (DXA) were prospectively included in the study. According to the DXA results, the patients were grouped as normal bone density, osteopenic, or osteoporotic. In order to calculate fat content, the lumbar region was visualized in the sagittal plane by CS-MRI sequence. "Region of interest" (ROI)s were placed within L3 vertebral bodies and air (our reference point) at different time points by different radiologists. Fat content was calculated through "signal intensity (SI) suppression rate" and "SI Index". The quantitative values were compared statistically with those obtained from DXA examinations. Kruskal-Wallis, and Mann-Whitney U tests were used for comparisons between groups. The reliability of the measurements performed by two radiologists was evaluated with the "intraclass correlation coefficient". This study was approved by an institutional review board and all participants provided informed consent to participate in the study. Eighteen subjects with normal bone density (mean T score, 0.39 ± 1.3 [standard deviation]), 20 subjects with osteopenia (mean T score, -1.79 ± 0.38), and 18 subjects with osteoporosis (mean T score, -3 ± 0.5) were determined according to DXA results. The median age was 55.9 (age range 50-64 years) in the normal group, 55.5 (age range 50-64 years) in the osteopenic group, and 55.1 (age range 50-65 years) in the osteoporotic group (p = 0.872). In the CS-MRI examination, the values of "SI suppression ratio" and "SI Index" (median [min:max]) were calculated by the first and second reader, independently. There was no statistically significant difference between the groups with regard to vertebral bone marrow fat content (p > 0.05). According to the "intraclass correlation coefficient", the measurements were reliable (0.55 and 0.60). Vertebral bone marrow fat content calculated with CS-MRI is not a reliable parameter for predicting bone mineral density in female patients aged between 50 and 65 years.

Bone Mineral Content in Patients with Anaphylactic Reactions, Signs of Mastocytosis and Elevated Basal Serum Tryptase Levels

Introduction: To examine the relationship between elevated basal serum tryptase levels (BST), a marker of total mast cell mass, and bone mineral density (BMD) in patients with anaphylactic reactions and signs of mastocytosis. Methods: Retrospective evaluation of patient charts at an allergy unit. Patients with BST levels above 20 ng/ml were eligible if clinical and follow-up data and results of dual X-ray absorptiometry (DXA) were available. Patients with previous use of anti-osteoporotic medications and with osteoporosis not caused by mastocytosis were excluded. Spearman’s rank correlation, Mann-Whitney test and receiver operating characteristic curve (ROC) was used for analysis. Results: 24 patients were included. The main presenting symptom (17 of 24 patients) was anaphylactic reactions to insect stings. BST levels ranged between 21 and 158 ng/ml (median 48 ng/ml). Study participants with Z-score values below - 1.0 had a median BST level of 46 ng/ml, the patients with Z-score values above or equal to -1.0 had a median BST level of 27 ng/ml. ROC analysis of the patient group with BST values between 30 and 100 ng/ml revealed a best cut-off value of BST to detect a low BMD when BST level would be at least 27 ng/ml resulting in a sensitivity of 92% and a specificity of 70%. Conclusion: Patients with moderately elevated BST levels seem to be at increased risk for low BMD.

RESPONSE

Dear Editor-in-Chief: We are grateful for the encouraging comments by Dr. Ducher and coworkers. Indeed, our study shows that bones are structurally stronger in the arms and legs of master track cyclists, in particular in sprinters. This contradicts the common notion that cycling per se would be detrimental to bone health (3). It suggests that fractures, frequently experienced in the extremities by cyclists, may be unrelated to poor bone strength, but simply be caused by falls. However, as stated in the original manuscript, some points have to be considered. First, our study is based on a genuine elite sample, with several current and former world record holders and even an Olympic champion. With one exception (4), all other studies in the field were less selective regarding their participants. Second, we have applied extremely rigorous and stringent inclusion criteria for control participants to ascertain that they were truly sedentary (7). The study by Nichols et al. (5), conversely, included recreational exercisers as control participants, and some participants were doing heavy physical labor in their jobs. This will have contributed to the discrepancy between both studies, with Nichols et al. reporting reduced and our study finding enhanced bone strength estimators in cyclists. Third, participants in our study were specialized in track cycling, and mostly in sprinting events, whereas all other studies in the field have involved road cyclists. The differences between both types of cycling are obvious. For example, starting on a track involves very large forces within the body. Moreover, track cycles do not have brakes, and kinetic energy, therefore, has to be absorbed by the musculature. These, and other, less obvious differences may be crucially involved in bone adaptive processes and thus cause differences between track and road cyclists' bones. Finally, it cannot be ruled out that bones in the extremities respond differently to cycling than the hip and the axial skeleton. Unfortunately, the latter skeletal sites have mainly been studied by dual x-ray absorptiometry (DXA). DXA results are given in terms of "areal bone mineral density" (aBMD) and have to be interpreted with great care, as they amalgamate bone structure, volume-to-tissue ratio, and bone material properties, with the latter being least variable in human bone (1). For example, the same amount of bone distributed with a wider diameter in a long bone will yield lower aBMD values as assessed by DXA, but greater torsional and bending strength (2,6). In consequence, it would be consistent with the literature and theoretically possible if cyclists had greater bone mineral content and section modulus in their hip bones, but reduced aBMD values. Future studies ought to address this question with appropriate methods. In conclusion, more qualified work is needed to study the axial skeleton in cyclists. However, it seems to be clear from our study that impact forces are not strictly required to grow strong bones. Likewise, it seems that the term "weight-bearing," which is a somewhat fuzzy concept in relation to cycling anyway, may be a dispensable term when discussing bone biology. Jörn Rittweger, MD, PhD Sally F. Gilliver, PhD Institute for Biomedical Research into Human Movement and Health Manchester Metropolitan University Manchester, United Kingdom Désirée C. Wilks, BSc MRC Human Nutrition Research Cambridge, United Kingdom