[Update 2017 of the KDIGO guidelines on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD). What are the real changes?]

Guidelines for the assessment, diagnosis and therapy of the alterations that characterize the CKD-MBD are an important support in the clinical practice of the nephrologist. Compared to the KDIGO guidelines published in 2009, the 2017 update made changes on some topics on which there was previously no strong evidence both in terms of diagnosis and therapy. The recommendations include the diagnosis of bone anomalies in CKD-MBD and the treatment of mineral metabolism abnormalities with particular regard to hyperphosphataemia, calcium levels, secondary hyperparathyroidism and anti-resorptive therapies. The Italian Study Group on Mineral Metabolism, in reviewing the 2017 recommendations, aimed to assess the weight of the evidence that led to this update. In fact, on some topics there has not been a substantial difference on the degree of evidence compared to the previous guidelines. The Italian Study Group emphasizes the points that may still reserve critical issues, including interpretation, and invites an evaluation that is articulated and personalized for each patient.

Association of Severity of Coronary Lesions with Bone Mineral Density in Postmenopausal Women.

BACKGROUND: Coronary artery disease (CAD) and osteoporosis (OP) are common diseases in postmenopausal women. In both cross-sectional and longitudinal epidemiologic studies, low bone mass has been related to increased frequency of CAD. However, available data on the relationship between bone mineral density (BMD) and severity of coronary lesions is limited. OBJECTIVE: To investigate association between the BMD and severity of coronary lesions assessed by Gensini score in postmenopausal women. METHODS: This study included 122 postmenopausal women who were diagnosed with CAD. These patients were divided into two groups according to the severity of coronary lesions assessed by the Gensini score - patients with mild coronary lesions (Gensini score < 25) and patients with severe coronary lesions (Gensini score ≥ 25). Femoral neck mineral density was measured with dual energy X-ray absorptiometry (DXA). RESULTS: The study included postmenopausal women aged 64.31 ± 4.71 years, 85 of whom (69.7%) exhibited severe coronary lesions. Participants with severe coronary lesions had a significantly higher T score than did those with mild coronary lesions at the femoral neck (p < 0.05). The mean T-score was -0.84 ± 1.01 in mild coronary lesions group, -1.42 ± 1.39 in severe coronary lesions group (p < 0.05). Multivariable logistic regression analysis showed that osteopenia-osteoporosis at the Femoral neck (odds ratio 2.73; 95% confidence interval 1.06 to 6.13) was associated with an increased risk of developing severe coronary lesions. The multiple regression model showed that T-scores (b = -0.407, SE = 0.151, p=0.007) were the independent predictors of Gensini score. CONCLUSION: The relationship between severity of coronary lesions and BMD was significant in postmenopausal women. BMD, a low-cost technique involving minimal radiation exposure, widely used for osteoporosis screening, is a promising marker of severity of coronary lesions.

Association of Severity of Coronary Lesions with Bone Mineral Density in Postmenopausal Women / Associação entre Gravidade das Lesões Coronarianas e Densidade Mineral Óssea em Mulheres Pós-Menopausa

Abstract Background: Coronary artery disease (CAD) and osteoporosis (OP) are common diseases in postmenopausal women. In both cross-sectional and longitudinal epidemiologic studies, low bone mass has been related to increased frequency of CAD. However, available data on the relationship between bone mineral density (BMD) and severity of coronary lesions is limited. Objective: To investigate association between the BMD and severity of coronary lesions assessed by Gensini score in postmenopausal women. Methods: This study included 122 postmenopausal women who were diagnosed with CAD. These patients were divided into two groups according to the severity of coronary lesions assessed by the Gensini score - patients with mild coronary lesions (Gensini score < 25) and patients with severe coronary lesions (Gensini score ≥ 25). Femoral neck mineral density was measured with dual energy X-ray absorptiometry (DXA). Results: The study included postmenopausal women aged 64.31 ± 4.71 years, 85 of whom (69.7%) exhibited severe coronary lesions. Participants with severe coronary lesions had a significantly higher T score than did those with mild coronary lesions at the femoral neck (p < 0.05). The mean T-score was −0.84 ± 1.01 in mild coronary lesions group, −1.42 ± 1.39 in severe coronary lesions group (p < 0.05). Multivariable logistic regression analysis showed that osteopenia-osteoporosis at the Femoral neck (odds ratio 2.73; 95% confidence interval 1.06 to 6.13) was associated with an increased risk of developing severe coronary lesions. The multiple regression model showed that T-scores (b = −0.407, SE = 0.151, p=0.007) were the independent predictors of Gensini score. Conclusion: The relationship between severity of coronary lesions and BMD was significant in postmenopausal women. BMD, a low-cost technique involving minimal radiation exposure, widely used for osteoporosis screening, is a promising marker of severity of coronary lesions.

Resumo Fundamento: A doença arterial coronariana (DAC) e a osteoporose são doenças comuns em mulheres pós-menopausa. Tanto em estudos transversais como em estudos epidemiológicos longitudinais, a massa óssea diminuída foi relacionada à frequência aumentada de DAC. No entanto, dados disponíveis sobre a relação entre densidade mineral óssea (DMO) e gravidade das lesões coronarianas são limitados. Objetivo: Investigar a associação entre DMO e gravidade das lesões coronarianas avaliadas pelo escore de Gensini em mulheres pós-menopausa. Métodos: Este estudo incluiu 122 mulheres pós-menopausa diagnosticadas com DAC. As pacientes foram divididas em dois grupos de acordo com a gravidade das lesões coronarianas avaliada pelo escore de Gensini - pacientes com lesões coronarianas leves (escore de Gensini < 25) e pacientes com lesões coronarianas graves (escore de Gensini ≥ 25). A densidade mineral do colo femoral foi medida por absorção de raios-X de dupla energia (DXA). Resultados: O estudo incluiu mulheres pós-menopausa com idade de 64,31 ± 4,71 anos, 85 delas (69,7%) com lesões coronarianas graves. Pacientes com lesões coronarianas graves apresentaram um escore T mais elevado que aquelas com lesões coronarianas leves no colo femoral (p < 0,05). O escore T médio foi -0,84 ± 1,01 no grupo com lesões leves, e -1,42 ± 1,39 no grupo com lesões graves (p < 0,05). A análise de regressão logística multivariada mostrou que a osteopenia-osteoporose no colo femoral (odds ratio 2,73; intervalo de confiança de 95% 1,06 - 6,13) esteve associada com um risco aumentado de se desenvolver lesões coronarianas graves. O modelo de regressão múltipla mostrou que os escores T (b = -0,407; EP= 0,151; p = 0,007) foram preditores independentes do escore de Gensini. Conclusão: Encontrou-se uma relação significativa entre a gravidade das lesões coronarianas e a DMO em mulheres pós-menopausa. DMO, uma técnica de baixo custo que envolve mínima exposição à radiação, e amplamente utilizada no rastreamento de osteoporose, é um marcador promissor da gravidade de lesões coronarianas graves.

TDF and quantitative ultrasound bone quality in African patients on second line ART, ANRS 12169 2LADY sub-study.

BACKGROUND: Bone demineralization, which leads to osteoporosis and increased fracture risk, is a common metabolic disorder in HIV-infected individuals. In this study, we aimed to assess the change in bone quality using quantitative ultrasound (QUS) over 96 weeks of follow-up after initiation of second-line treatment, and to identify factors associated with change in bone quality. METHODS AND FINDINGS: In a randomized trial (ANRS 12169), TDF and PI-naïve participants failing standard first-line treatment, from Burkina Faso, Cameroon, and Senegal were randomized to receive either TDF/FTC/LPVr, ABC/ddI/LPVr or TDF/FTC/DRVr. Their bone quality was assessed using calcaneal QUS at baseline and every 24 weeks until week 96. Stiffness index (SI) was used to measure bone quality. Out of 228 participants, 168 (74%) were women. At baseline, median age was 37 years (IQR: 33-46 years) and median T-CD4 count was 199 cells/µl (IQR: 113-319 cells/µl). The median duration of first-line antiretroviral treatment (ART) was 52 months (IQR: 36-72 months) and the median baseline SI was 101 (IQR: 87-116). In multivariable analysis, factors associated with baseline SI were sex (ß = -10.8 [-18.1,-3.5] for women), age (ß = -8.7 [-12.4,-5.1] per 10 years), body mass index (BMI) (ß = +0.8 [0.1,1.5] per unit of BMI), and study site (ß = +12.8 [6.5,19.1] for Cameroon). After 96 weeks of second-line therapy, a reduction of 7.1% in mean SI was observed, as compared with baseline. Factors associated with SI during the follow-up were similar to those found at baseline. Exposure to TDF was not associated with a greater loss of bone quality over time. CONCLUSION: Bone quality decreased after second-line ART initiation in African patients independently of TDF exposure. Factors associated with bone quality include age, sex, baseline BMI, study site, and duration of follow-up.

Bone mineral density loss in clinically suspect arthralgia is associated with subclinical inflammation and progression to clinical arthritis.

OBJECTIVE: Peripheral bone mineral density (BMD) may be decreased in early rheumatoid arthritis (RA) but it is unknown whether BMD loss emerges before arthritis is clinically apparent. We aimed to study whether BMD loss occurs in patients with clinically suspect arthralgia (CSA), and whether it is associated with progression to clinical arthritis and magnetic resonance imaging (MRI)-detected subclinical inflammation. METHOD: Patients with CSA had arthralgia for <1 year and were at risk of progressing to RA according to their rheumatologists. At baseline, a 1.5 T MRI was performed of unilateral metacarpophalangeal, wrist, and metatarsophalangeal joints, and scored on synovitis, bone marrow oedema, and tenosynovitis;. summing these features yielded the total MRI inflammation score. Digital X-ray radiogrammetry (DXR) was used to estimate BMD on two sequential conventional hand radiographs (mean interval between radiographs 4.4 months). The change in BMD was studied; BMD loss was defined as a decrease of ≥2.5 mg/cm2/month. Patients were followed for arthritis development for a median of 18.4 months. RESULTS: In CSA patients (n = 108), change in BMD was negatively associated with age (ß = -0.03, p = 0.007). BMD loss in CSA patients was associated with arthritis development [adjusted for age hazard ratio (HR) = 6.1, 95% confidence interval (CI) 1.7 to 21.4] and was most frequently estimated in the months before clinical arthritis development. The total MRI inflammation scores were associated with the change in BMD (adjusted for age ß = -0.05, p = 0.047). The total MRI inflammation score and BMD loss were both independently associated with arthritis development (HR = 1.1, 95% CI 1.1 to 1.2, and HR = 4.6, 95% CI 1.2 to 17.2, respectively). CONCLUSION: In CSA patients, severe BMD loss is associated with MRI-detectable subclinical inflammation and with progression to clinical arthritis.

Osteoporosis: A Future Public Health Problem for Israel? Medical and Legal Obligations.

BACKGROUND: Starvation in early life can lead to premature metabolic syndrome and bone demineralization. Osteoporosis in the Jewish population may not yet be a recognized syndrome, but the harsh conditions to which Holocaust survivors were exposed may have increased the incidence of the condition. Immigrants and refugees who came to Israel from East Africa and Yemen - whether decades ago or more recently - may have been at increased risk of under-nutrition during pregnancy, affecting both the mother and consequently the offspring. This malnutrition may be further exacerbated by rapid overfeeding in the adopted developed country. This problem was also recognized at the turn of the 21st century in poor and underdeveloped countries and is becoming a global public health issue. In this review, the risks for premature metabolic syndrome and bone demineralization are enumerated and preventive measures outlined.

Accelerated bone turnover identifies hemiplegic patients at higher risk of demineralization.

Immobilization osteoporosis represents a severe complication in hemiplegic patients (HPs), causing fragility fractures, which may occur during rehabilitation reducing functional recovery and survival. The aim of the study was to investigate determinants of bone loss, independent from length of immobilization, which may be useful in early identification of HPs at higher risk of demineralization. Forty-eight HPs of both sexes underwent anthropometric measurements, evaluation of scores of spasticity and of lower limb motory capacity. Laboratory tests were performed. On serum: calcium; phosphorus; creatinine; ALP; iPTH; 25(OH) vitamin-D; sex hormones; Δ4-androstenedione; DHEA-S; insulin; IGF-1; FT3; FT4; TSH; c-AMP. On urine: c-AMP and calcium/creatinine ratio. Two bone turnover markers were measured: serum osteocalcin (BGP) and urinary deoxypyridinoline (DPD). Bone mineral density was determined at both femoral necks, defining a percentage difference in bone loss between paretic and non-paretic limb, thus controlling for the complex cofactors involved. Only bone turnover markers significantly and directly correlated with the entity of demineralization, controlling for age, sex and length of immobilization in the multivariate analysis (BGP coefficient estimate=0.008; SE=0.003; p=0.020; DPD coefficient estimate=0.005; SE=0.002; p=0.036). BGP and DPD are not dependent on anthropometric and endocrine-metabolic parameters, disability patterns and duration of immobilization, thus represent independent determinants of the degree of demineralization. A cutoff was defined for BGP and DPD above which subjects show significantly greater risk of demineralization. The immobilization event generates more severe bone loss when it occurs in subjects with higher bone turnover. BGP and DPD measurements may be of primary importance for early identification of HPs at risk, with relevant preventive implications.

Osteocyte-directed bone demineralization along canaliculi.

The mammalian skeleton stores calcium and phosphate ions in bone matrix. Osteocytes in osteocyte lacunae extend numerous dendrites into canaliculi less than a micron in diameter and which are distributed throughout bone matrix. Although osteoclasts are the primary bone-resorbing cells, osteocytes also reportedly dissolve hydroxyapatite at peri-lacunar bone matrix. However, robust three-dimensional evidence for peri-canalicular bone mineral dissolution has been lacking. Here we applied a previously reported Talbot-defocus multiscan tomography method for synchrotron X-ray microscopy and analyzed the degree of bone mineralization in mouse cortical bone around the lacuno-canalicular network, which is connected both to blood vessels and the peri- and endosteum. We detected cylindrical low mineral density regions spreading around canaliculi derived from a subset of osteocytes. Transmission electron microscopy revealed both intact and demineralized bone matrix around the canaliculus. Peri-canalicular low mineral density regions were also observed in osteopetrotic mice lacking osteoclasts, indicating that osteoclasts are dispensable for peri-canalicular demineralization. These data suggest demineralization can occur from within bone through the canalicular system, and that peri-canalicular demineralization occurs not uniformly but directed by individual osteocytes. Blockade of peri-canalicular demineralization may be a therapeutic strategy to increase bone mass and quality.

A pilot study of change in fracture risk in patients with acute respiratory distress syndrome.

INTRODUCTION: Acute skeletal muscle wasting is a major contributor to post critical illness physical impairment. However, the bone response remains uncharacterized. We prospectively investigated the early changes in bone mineral density (BMD) and fracture risk in critical illness. METHODS: Patients were prospectively recruited ≤24 hours following intensive care unit (ICU) admission to a university teaching or a community hospital (August 2009 to April 2011). All were aged >18 years and expected to be intubated for >48 hours, spend >7 days in critical care and survive ICU admission. Forty-six patients were studied (55.3% male), with a mean age of 54.4 years (95% confidence interval (CI): 49.1 to 59.6) and an APACHE II score of 23.9 (95% CI: 22.4 to 25.5). Calcaneal dual X-ray absorptiometry (DXA) assessment of BMD was performed on day 1 and 10. Increase in fracture risk was calculated from the change in T-score. RESULTS: BMD did not change between day 1 and 10 in the cohort overall (0.434 (95% CI: 0.405 to 0.463) versus 0.425 g/cm(2) (95% CI: 0.399 to 0.450), P = 0.58). Multivariable logistical regression revealed admission corrected calcium (odds ratio (OR): 1.980 (95% CI: 1.089 to 3.609), P = 0.026) and admission PaO2-to-FiO2 ratio (OR: 0.916 (95% CI: 0.833 to 0.998), P = 0.044) to be associated with >2% loss of BMD. Patients with acute respiratory distress syndrome had a greater loss in BMD than those without (-2.81% (95% CI: -5.73 to 0.118%), n = 34 versus 2.40% (95% CI: 0.204 to 4.586%), n = 12, P = 0.029). In the 34 patients with acute respiratory distress syndrome, fracture risk increased by 19.4% (95% CI: 13.9 to 25.0%). CONCLUSIONS: Patients with acute respiratory distress syndrome demonstrated early and rapid bone demineralisation with associated increase in fracture risk.

Identifying sex-specific risk factors for low bone mineral density in adolescent runners.

BACKGROUND: Adolescent runners may be at risk for low bone mineral density (BMD) associated with sports participation. Few prior investigations have evaluated bone health in young runners, particularly males. PURPOSE: To characterize sex-specific risk factors for low BMD in adolescent runners. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Training characteristics, fracture history, eating behaviors and attitudes, and menstrual history were measured using online questionnaires. A food frequency questionnaire was used to identify dietary patterns and measure calcium intake. Runners (female: n = 94, male: n = 42) completed dual-energy x-ray absorptiometry (DXA) to measure lumbar spine (LS) and total body less head (TBLH) BMD and body composition values, including android-to-gynoid (A:G) fat mass ratio. The BMD was standardized to Z-scores using age, sex, and race/ethnicity reference values. Questionnaire values were combined with DXA values to determine risk factors associated with differences in BMD Z-scores in LS and TBLH and low bone mass (defined as BMD Z-score ≤-1). RESULTS: In multivariable analyses, risk factors for lower LS BMD Z-scores in girls included lower A:G ratio, being shorter, and the combination of (interaction between) current menstrual irregularity and a history of fracture (all P < .01). Later age of menarche, lower A:G ratio, lower lean mass, and drinking less milk were associated with lower TBLH BMD Z-scores (P < .01). In boys, lower body mass index (BMI) Z-scores and the belief that being thinner improves performance were associated with lower LS and TBLH BMD Z-scores (all P < .05); lower A:G ratio was additionally associated with lower TBLH Z-scores (P < .01). Thirteen girls (14%) and 9 boys (21%) had low bone mass. Girls with a BMI ≤17.5 kg/m(2) or both menstrual irregularity and a history of fracture were significantly more likely to have low bone mass. Boys with a BMI ≤17.5 kg/m(2) and belief that thinness improves performance were significantly more likely to have low bone mass. CONCLUSION: This study identified sex-specific risk factors for impaired bone mass in adolescent runners. These risk factors can be helpful to guide sports medicine professionals in evaluation and management of young runners at risk for impaired bone health.

Comparison of peripheral forearm DXA and clinical risk factor screening using FRAX® to assess the risk of HIV-associated low bone mass: a cross-sectional study.

UNLABELLED: There is growing awareness that HIV infection is associated with low bone mass and fracture. DXA is a relatively scarce resource. Therefore, we evaluated two tools: peripheral DXA (pDXA) at the forearm and Fracture Risk Assessment Tool (FRAX®) to see which performed best at identifying men who should undergo DXA. In this setting, neither pDXA nor FRAX® showed good sensitivity and specificity for DXA. PURPOSE: Infection with human immunodeficiency virus (HIV) is associated with an increased risk of low bone mineral density (BMD) and fractures. European guidance advocates screening using the FRAX® tool at diagnosis, on initiation of antiretroviral therapy and biannually thereafter in order to decide the need for DXA scanning. This cross-sectional study evaluates the performance of FRAX® and compares its sensitivity and specificity with that of another screening tool, peripheral forearm DXA (pDXA). METHODS: HIV-infected men with varying exposure to antiretroviral therapies were recruited. FRAX® scores were calculated for all participants and everybody underwent pDXA scanning. Femoral neck and lumbar spine BMD was acquired on a Hologic QDR machine by an assessor blinded to the results of the FRAX® and pDXA. RESULTS: One hundred and sixty-eight men (median age 45 years) were recruited with a median duration since HIV diagnosis of 74 months. In total, 21 % of subjects had either osteoporosis (aged ≥50 years) or BMD lower than expected for age (aged <50 years), according to axial DXA. Using a pDXA screening threshold of T ≤ -0.9, sensitivity was high (91 %) in defining those with the worst BMD on axial DXA but with poorer specificity (33 %). Alternately, using a threshold of T ≤ -2.7 reduced sensitivity (34 %) with an increase in specificity (91 %). FRAX® with HIV included as a secondary risk factor had poor sensitivity (31 %) and specificity (74 %) for detecting those with the poorest BMD on axial DXA. CONCLUSION: In this setting, neither pDXA scanning nor FRAX® was sensitive and specific for low bone mass on DXA and neither was performance much improved by using both screening tools. Prospective studies with fracture as an outcome are required in HIV.

Strain-induced optical changes in demineralized bone.

Bone "stress-whitens," becoming visibly white during mechanical loading, immediately prior to failure. Stress-whitening is known to make materials tougher by dissipating mechanical energy. A greater understanding of stress-whitening, both an optical and mechanical phenomenon, may help explain age-related increases in fracture risk that occur without changes in bone mineralization. In this work, we directly measure the optical properties of demineralized bone as a function of deformation and immersing fluid (with different hydrogen-bonding potentials, water, and ethanol). The change in refractive index of demineralized bone was linear: with deformation and not applied force. Changes in refractive index were likely due to pushing low-refractive-index fluid out of specimens and secondarily due to changes in the refractive index of the collagenous phase. Results were consistent with stress-whitening of demineralized bone previously observed. In ethanol, the refractive index values were lower and less sensitive to deformation compared with deionized water, corroborating the sensitivity to fluid hydration. Differences in refractive index were consistent with structural changes in the collagenous phase such as densification that may also occur under mechanical loading. Understanding bone quality, particularly stress-whitening investigated here, may lead to new therapeutic targets and noninvasive methods to assess bone quality.

Stress-whitening occurs in demineralized bone.

INTRODUCTION: The incidence of age-related bone fracture is increasing with average population age. Bone scatters more light (stress-whitens) during loading, immediately prior to failure, in a manner visually similar to polymer crazing. We wish to understand the stress-whitening process because of its possible effect on bone toughness. The goals of this investigation were a) to establish that stress-whitening is a property of the demineralized organic matrix of bone rather than only a property of mineralized tissue and that stress whitening within the demineralized bone is dependent upon both b) hydrogen bonding and, c) the orientation of loading. METHODS: Demineralized cortical bone specimens were loaded in tension to failure (0.08 strain/s). The effect of hydrogen bonding on mechanical properties and the stress-whitening process was probed by altering the Hansen's hydrogen bonding parameter (δh) of the immersing solution. RESULTS: Stress-whitening occurred in the demineralized bone. Stress-whitening was negatively correlated with δh (R(2)=0.81, p<0.0001). Stress-whitening was significantly lower (p<0.0001) in specimens loaded orthogonally compared to those loaded parallel to the long (strong) axis. CONCLUSION: The stress-whitening observed was consistent with increased Mie scattering. We suggest that the change in Mie scattering was due to collagen fibril dehydration driven by the externally applied stress. The presence of stress-whitening in demineralized bone suggests that this process may be a property of the collagenous matrix and hence may be present in other collagenous tissues rather than an emergent property of the bone composite.

The relationship between intact PTH and biointact PTH (1-84) with bone and mineral metabolism in pre-dialysis chronic kidney disease (CKD).

OBJECTIVES: Abnormalities in PTH are implicated in the pathogenesis of bone abnormalities in chronic kidney disease (CKD)-mineral bone disorder (CKD-MBD). PTH concentrations are important in clinical decision and management. This emphasises the importance of providing an assay which measures biologically active PTH. We compared concentrations of intact PTH with biointact PTH (1-84) in CKD and end stage renal disease (ESRD) and investigated the relationship between the 2 PTH assays with bone and mineral laboratory parameters and bone mineral density (BMD) in CKD. DESIGN AND METHODS: We assessed 140 patients (61 in ESRD and 79 with CKD stages 1-4) in this cross-sectional study. We measured biointact PTH (1-84) as well as routine biochemical parameters on all subjects. In the CKD cohort, bone turnover markers; bone alkaline phosphatase (BAP) and tartrate resistant acid phosphatase (TRACP)-5b and bone mineral density (BMD) were also determined. RESULTS: In ESRD, intact PTH concentration was significantly higher compared to biointact PTH (1-84) (422 [443] v/s 266 [251] pg/mL, (p<0.001) with an average bias of 60%. In CKD, intact PTH concentration was also higher compared to biointact PTH (1-84) (79[55] v/s 68[49] pg/mL p<0.001) with an average bias of 18%. Only the biointact PTH (1-84) assay showed any significant correlation with serum calcium concentrations (r=-0.26, p<0.05) and phosphate (r=0.25, p<0.05) in CKD. Following multilinear regression analysis and adjustment for all significant co-variables, only eGFR, BAP and 25 (OH)vitamin remained significantly associated with intact PTH and biointact PTH (1-84). The strength of association was stronger between BAP and biointact PTH (1-84) (biointact PTH (1-84): p=0.007, intact PTH: p=0.01). In adjusted analyses, only biointact PTH (1-84) was significantly associated with BMD at the fore-arm (FARM) (p=0.049). CONCLUSIONS: The study confirms the differences between intact PTH and biointact PTH (1-84) in ESRD. Whilst there may be similarities in the diagnostic ability of both intact and biointact PTH (1-84), our data suggest that biointact PTH (1-84) assay may better reflect bone metabolism and BMD in CKD. Further longitudinal studies are needed.

Vitamin D, parathyroid hormone, and bone mineral density status in kidney transplant recipients.

INTRODUCTION: Bone disease and bone fractures are common among kidney transplant recipients. The aim of this study was to investigate the prevalence of vitamin D deficiency, hyperparathyroidism, and osteoporosis kidney transplant patients. MATERIALS AND METHODS: A total of 113 kidney transplant recipients (58 women and 55 men) were selected consecutively from the transplant clinic between January and April 2010. A serum sample from each patient was analyzed for creatinine, calcium, phosphorus, 25-hydroxyvitamin D, and intact parathyroid hormone levels. Bone mineral density was measured by the dual energy x-ray absorptiometry method and classified according to the classification of the World Health Organization. Risk factors of bone mineral density outcomes were evaluated in univariable and multivariable analyses. RESULTS: Forty-five percent of the patients had vitamin D deficiency and 76.2% had hyperparathyroidism. There was a significant correlation between vitamin D deficiency and high serum parathyroid hormone (P = .04) and serum creatinine levels (P = .001). However, there were no significant associations of serum calcium and phosphorus with vitamin D or parathyroid hormone levels. The osteoporosis and osteopenia were reported in 12.4% and 52.2% of the recipients in the lumbar spine and 45.1% and 36.3% of the patients in the femoral neck, respectively. Multivariable analyses showed that there were significant correlations between patients' age and body mass index and femoral neck osteoporosis. Risk factors for lumbar spine osteoporosis were end-stage renal disease duration, serum calcium, and body mass index. CONCLUSIONS: Vitamin D deficiency, hyperparathyroidism, and osteoporosis are very common in our kidney transplant recipients. Early diagnosis and treatment of these abnormalities should be included in the posttransplant follow-up of patients in order to prevent severe bone diseases and bone fractures.

Bone density and cortical structure after pediatric renal transplantation.

The impact of renal transplantation on trabecular and cortical bone mineral density (BMD) and cortical structure is unknown. We obtained quantitative computed tomography scans of the tibia in pediatric renal transplant recipients at transplantation and 3, 6, and 12 months; 58 recipients completed at least two visits. We used more than 700 reference participants to generate Z-scores for trabecular BMD, cortical BMD, section modulus (a summary measure of cortical dimensions and strength), and muscle and fat area. At baseline, compared with reference participants, renal transplant recipients had significantly lower mean section modulus and muscle area; trabecular BMD was significantly greater than reference participants only in transplant recipients younger than 13 years. After transplantation, trabecular BMD decreased significantly in association with greater glucocorticoid exposure. Cortical BMD increased significantly in association with greater glucocorticoid exposure and greater decreases in parathyroid hormone levels. Muscle and fat area both increased significantly, but section modulus did not improve. At 12 months, transplantation associated with significantly lower section modulus and greater fat area compared with reference participants. Muscle area and cortical BMD did not differ significantly between transplant recipients and reference participants. Trabecular BMD was no longer significantly elevated in younger recipients and was low in older recipients. Pediatric renal transplant associated with persistent deficits in section modulus, despite recovery of muscle, and low trabecular BMD in older recipients. Future studies should determine the implications of these data on fracture risk and identify strategies to improve bone density and structure.

Analysis of bone demineralization due to the use of exoprosthesis by comparing Young's modulus of the femur in unilateral transfemoral amputees.

BACKGROUND: There is a relation between Hounsfield units obtained from computed tomography (CT) scans and bone density. The density of the bones can be used to establish its mechanical properties and therefore to assess the bone mechanical condition using CT images. OBJECTIVES: To identify the effect of the transfemoral amputation and the use of external lower limb prosthesis in the bone properties, by comparing Young's modulus. STUDY DESIGN: Young's modulus comparison. METHODS: Comparison of bone density between the healthy femur and the amputated bone of 20 unilateral transfemoral amputees was done by generating three histograms of the Hounsfield units at different parts of the femur. The histograms were created based on images obtained by CT and the Hounsfield units were translated to Young's modulus to establish the comparison. RESULTS: The results show a significant difference (p-value <0.05) between the mean value of Young's modulus of healthy and amputated bone. CONCLUSIONS: There is clearly a direct association between the use of external prosthesis and the bone demineralization due the stress shielding phenomenon. The Young's modulus comparison using information from CT images can be a suitable tool to analyze the bone demineralization due to the use of exoprosthesis.

Patterns of bone mineral acquisition in children with epidermolysis bullosa: a longitudinal study.

BACKGROUND: Reduced bone mass and fractures are known complications of generalized forms of epidermolysis bullosa (EB). However, the aetiology - inadequate bone acquisition, premature bone loss, or a combination - is unclear. OBJECTIVES: To determine patterns of bone mineral acquisition in children with EB and to identify clinical and laboratory correlates of change in areal bone mineral density (aBMD). METHODS: Seventeen subjects ≥ 6 years of age with generalized EB were studied at two visits at least 12 months apart with clinical and laboratory evaluations and dual energy X-ray absorptiometry scans of the lumbar spine. Wilcoxon signed-rank tests were used to determine if changes from baseline to follow-up were significant. Wilcoxon rank-sum tests were used to compare subjects with gains in aBMD Z-score with those who experienced no change or decreases to determine if baseline laboratory or clinical characteristics differed between the two groups. RESULTS: Subjects gained height and weight at follow-up, but there was no significant improvement in mean Z-scores for height, weight or body mass index. Laboratory values did not change significantly. Mean bone mineral content and aBMD of the lumbar spine increased significantly at follow-up, but mean aBMD Z-scores remained static. No differences in clinical characteristics or laboratory values were seen between subjects with increased aBMD Z-scores vs. those whose scores decreased or did not change. CONCLUSIONS: Low bone mass in children with generalized EB is due primarily to inadequate gains in aBMD. Interventions to improve overall health and to help build bone mass in this patient population are warranted.