Bisphosphonates Maintain BMD after Sequential Teriparatide and Denosumab in Premenopausal Women with Idiopathic Osteoporosis.

CONTEXT: We previously reported that sequential teriparatide followed by denosumab substantially increases BMD in premenopausal idiopathic osteoporosis (PremenIOP). OBJECTIVE: To determine whether administration of bisphosphonates after denosumab cessation is associated with stable BMD in PremenIOP. DESIGN: Open-label extension study. PARTICIPANTS: 24 PremenIOP Teriparatide-Denosumab Study participants. INTERVENTIONS: Oral alendronate (ALN), 70mg weekly, or IV zoledronic acid (ZOL), 5mg once (patient choice), was administered 7 months (M) after final denosumab dose. OUTCOMES: BMD by DXA and serum C-telopeptide (CTX) q6M; vertebral fracture assessment (VFA) and HR-pQCT q12M. RESULTS: 24 women with PremenIOP (aged 43 ± 8 years), severely affected with low trauma adult fractures (range 0-12; 9 with vertebral fractures) and/or very low BMD, had large BMD increases on sequential teriparatide-denosumab (spine: 25 ± 9%; total hip: 11 ± 6%). During the Bisphosphonate Extension, mean BMD and CTX changes in the entire group were small and not statistically significant at 6 or 12M.Women choosing ZOL (n = 6) versus ALN (n = 18) did not differ by baseline age, BMI, fractures, BMD, or CTX. On ZOL, there were small LSBMD declines and CTX increases, particularly between 6M and 12M, while greater stability was observed on ALN.Changes in BMD and CTX did not differ by duration of denosumab (36M vs <36M) or between 20 women who remained premenopausal and 4 who transitioned into menopause. Higher pre-teriparatide CTX, likely reflecting baseline remodeling status, predicted more spine and hip bone loss. No new vertebral (clinical or VFA screening) or non-vertebral fractures occurred. CONCLUSION: BMD remained stable in women with PremenIOP who received bisphosphonates after sequential teriparatide-denosumab therapy.

Reference ranges for body composition indices by dual energy X-ray absorptiometry from the Bone Mineral Density in Childhood Study Cohort.

BACKGROUND: Body composition assessment aids evaluation of energy stores and the impact of diseases and interventions on child growth. Current United States pediatric reference ranges from the National Health and Nutrition Examination Survey (NHANES) include 20% of children with obesity, body mass index of ≥95th percentile. OBJECTIVES: This study aimed to develop dual energy X-ray absorptiometry (DXA) based reference ranges in a diverse cohort with low-obesity prevalence from the Bone Mineral Density in Childhood Study (BMDCS). METHODS: This is a secondary analysis of a longitudinal, prospective, observational cohort. Healthy children (height and BMI within 3rd to 97th percentiles, ages 5-19 y at enrollment), from 5 United States centers were measured annually for ≤7 visits. Whole body scans were acquired using Hologic scanners. A subsample underwent repeat measurements to determine precision. We generated reference ranges for appendicular and total lean soft tissue mass index (LSTM Index), fat mass index (FMI), and other body composition measures. Resulting curves were compared to NHANES and across subgroups. Sex and age-specific equations were developed to adjust body composition Z-scores for height Z score. RESULTS: We obtained 9846 scans of 2011 participants (51% female, 22% Black, 17% Hispanic, 48% White, 7% Asian/Pacific Islander, and 6% with obesity). Precision (percent coefficient of variation) ranged from 0.7% to 1.96%. Median and-2 standard deviation curves for BMDCS and NHANES were similar, but NHANES +2 standard deviation LSTM Index and FMI curves were distinctly greater than the respective BMDCS curves. Subgroup differences were more extreme for appendicular LSTM Index-Z (mean ± SD: Asian -0.52 ± 0.93 compared with Black 0.77 ± 0.87) than for FMI-Z (Hispanic 0.29 ± 0.98 compared with Black -0.14 ± 1.1) and were smaller for Z-scores adjusted for height Z-score. CONCLUSIONS: These reference ranges add to sparse normative data regarding body composition in children and adolescents and are based on a cohort with an obesity prevalence similar to current BMI charts. Awareness of subgroup differences aids in interpreting results.

Bone intrinsic material and compositional properties in postmenopausal women diagnosed with long-term Type-1 diabetes.

The incidence of diabetes mellitus and the associated complications are growing worldwide, affecting the patients' quality of life and exerting a considerable burden on health systems. Yet, the increase in fracture risk in type 1 diabetes (T1D) patients is not fully captured by bone mineral density (BMD), leading to the hypothesis that alterations in bone quality are responsible for the increased risk. Material/compositional properties are important aspects of bone quality, yet information on human bone material/compositional properties in T1D is rather sparse. The purpose of the present study is to measure both the intrinsic material behaviour by nanoindentation, and material compositional properties by Raman spectroscopy as a function of tissue age and microanatomical location (cement lines) in bone tissue from iliac crest biopsies from postmenopausal women diagnosed with long-term T1D (N = 8), and appropriate sex-, age-, BMD- and clinically-matched controls (postmenopausal women; N = 5). The results suggest elevation of advanced glycation endproducts (AGE) content in the T1D and show significant differences in mineral maturity / crystallinity (MMC) and glycosaminoglycan (GAG) content between the T1D and control groups. Furthermore, both hardness and modulus by nanoindentation are greater in T1D. These data suggest a significant deterioration of material strength properties (toughness) and compositional properties in T1D compared with controls.

Teriparatide Followed by Denosumab in Premenopausal Idiopathic Osteoporosis: Bone Microstructure and Strength by HR-pQCT.

Premenopausal women with idiopathic osteoporosis (PreMenIOP) have marked deficits in skeletal microstructure. We have reported that sequential treatment with teriparatide and denosumab improves central skeletal bone mineral density (BMD) by dual-energy X-ray absorptiometry and central QCT in PreMenIOP. We conducted preplanned analyses of high-resolution peripheral quantitative computed tomography (HR-pQCT) scans from teriparatide and denosumab extension studies to measure effects on volumetric BMD (vBMD), microarchitecture, and estimated strength at the distal radius and tibia. Of 41 women enrolled in the parent teriparatide study (20 mcg daily), 34 enrolled in the HR-pQCT study. HR-pQCT participants initially received teriparatide (N = 24) or placebo (N = 10) for 6 months; all then received teriparatide for 24 months. After teriparatide, 26 enrolled in the phase 2B denosumab extension (60 mg q6M) for 24 months. Primary outcomes were percentage change in vBMD, microstructure, and stiffness after teriparatide and after denosumab. Changes after sequential teriparatide and denosumab were secondary outcomes. After teriparatide, significant improvements were seen in tibial trabecular number (3.3%, p = 0.01), cortical area and thickness (both 2.7%, p < 0.001), and radial trabecular microarchitecture (number: 6.8%, thickness: 2.2%, separation: -5.1%, all p < 0.02). Despite increases in cortical porosity and decreases in cortical density, whole-bone stiffness and failure load increased at both sites. After denosumab, increases in total (3.5%, p < 0.001 and 3.3%, p = 0.02) and cortical vBMD (1.7% and 3.2%; both p < 0.01), and failure load (1.1% and 3.6%; both p < 0.05) were seen at tibia and radius, respectively. Trabecular density (3.5%, p < 0.001) and number (2.4%, p = 0.03) increased at the tibia, while thickness (3.0%, p = 0.02) increased at the radius. After 48 months of sequential treatment, significant increases in total vBMD (tibia: p < 0.001; radius: p = 0.01), trabecular microstructure (p < 0.05), cortical thickness (tibia: p < 0.001; radius: p = 0.02), and whole bone strength (p < 0.02) were seen at both sites. Significant increases in total vBMD and bone strength parameters after sequential treatment with teriparatide followed by denosumab support the use of this regimen in PreMenIOP. © 2022 American Society for Bone and Mineral Research (ASBMR).

A pilot study on the nanoscale properties of bone tissue near lacunae in fracturing women.

The goal of this study is to investigate the causes of osteoporosis-related skeletal fragility in postmenopausal women. We hypothesize that bone fragility in these individuals is largely due to mineral, and/or intrinsic material properties in the osteocyte lacunar/peri-lacunar regions of bone tissue. Innovative measurements with nanoscale resolution, including scanning electron microscope (SEM), an atomic force microscope that is integrated with infrared spectroscopy (AFM-IR), and nanoindentation, were used to characterize osteocyte lacunar and peri-lacunar properties in bone biopsies from fracturing (Cases) and matched (Age, BMD), non-fracturing (Controls) postmenopausal healthy women. In the peri-lacunar space, the nanoindentation results show that the modulus and hardness of the Controls are lower than the Cases. The AFM-IR results conclusively show that the mineral matrix, maturity (peak) (except in outer/far regions in Controls) were greater in Controls than in Cases. Furthermore, these results indicate that while mineral-to-matrix area ratio tend to be greater, the mineral maturity and crystallinity peak ratio "near" lacunae is greater than at regions "far" or more distance from lacunae in the Controls only. Due to the heterogeneity of bone structure, additional measurements are needed to provide more convincing evidence of altered lacunar characteristics and changes in the peri-lacunar bone as mechanisms related to postmenopausal women and fragility. Such findings would motivate new osteocyte-targeted treatments to reduce fragility fracture risks in these groups.

Spine Volumetric BMD and Strength in Premenopausal Idiopathic Osteoporosis: Effect of Teriparatide Followed by Denosumab.

CONTEXT: Premenopausal women with idiopathic osteoporosis (PreMenIOP) have marked deficits in bone density, microstructure, and strength. OBJECTIVE: To define effects of treatment with teriparatide followed by denosumab on lumbar spine (LS) volumetric bone mineral density (vBMD) and stiffness by finite element analysis assessed on central quantitative computed tomography (cQCT) scans. DESIGN, SETTINGS, AND PARTICIPANTS: Ancillary analysis of baseline, post-teriparatide, and post-denosumab cQCT scans from a randomized trial of 41 women allocated to teriparatide (20 mcg daily; n = 28) or placebo (n = 11). After 6 months, those on teriparatide continued for 18 months, and those on placebo switched to teriparatide for 24 months. After completing teriparatide, 33 enrolled in a Phase 2B extension with denosumab (60 mg every 6 months) for 12 months. MAIN OUTCOME MEASURES: Primary outcomes were percentage change from baseline in LS trabecular vBMD and stiffness after teriparatide and between end of teriparatide and completing denosumab. Percentage change from baseline in LS trabecular vBMD and stiffness after sequential teriparatide and denosumab were secondary outcomes. FINDINGS: There were large increases (all Ps < 0.001) in trabecular vBMD (25%), other vBMD parameters, and stiffness (21%) after teriparatide. Statistically significant increases in trabecular vBMD (10%; P < 0.001) and other vBMD parameters (P = 0.03-0.001) were seen after denosumab, while stiffness increased by 7% (P = 0.068). Sequential teriparatide and denosumab led to highly significant (all Ps < 0.001) increases LS trabecular vBMD (43%), other vBMD parameters (15-31%), and stiffness (21%). CONCLUSIONS: The large and statistically significant increases in volumetric density and stiffness after sequential treatment with teriparatide followed by denosumab are encouraging and support use of this regimen in PreMenIOP.

Trabecular Bone Score Reference Values for Children and Adolescents According to Age, Sex, and Ancestry.

Trabecular bone score (TBS) is used for fracture prediction in adults, but its utility in children is limited by absence of appropriate reference values. We aimed to develop reference ranges for TBS by age, sex, and population ancestry for youth ages 5 to 20 years. We also investigated the association between height, body mass index (BMI), and TBS, agreement between TBS and lumbar spine areal bone mineral density (aBMD) and bone mineral apparent density (BMAD) Z-scores, tracking of TBS Z-scores over time, and precision of TBS measurements. We performed secondary analysis of spine dual-energy X-ray absorptiometry (DXA) scans from the Bone Mineral Density in Childhood Study (BMDCS), a mixed longitudinal cohort of healthy children (n = 2014) evaluated at five US centers. TBS was derived using a dedicated TBS algorithm accounting for tissue thickness rather than BMI. TBS increased only during ages corresponding to pubertal development with an earlier increase in females than males. There were no differences in TBS between African Americans and non-African Americans. We provide sex-specific TBS reference ranges and LMS values for calculation of TBS Z-scores by age and means and SD for calculation of Z-scores by pubertal stage. TBS Z-scores were positively associated with height Z-scores at some ages. TBS Z-scores explained only 27% and 17% of the variance of spine aBMD and BMAD Z-scores. Tracking of TBS Z-scores over 6 years was lower (r = 0.47) than for aBMD or BMAD Z-scores (r = 0.74 to 0.79), and precision error of TBS (2.87%) was greater than for aBMD (0.85%) and BMAD (1.22%). In sum, TBS Z-scores provide information distinct from spine aBMD and BMAD Z-scores. Our robust reference ranges for TBS in a well-characterized pediatric cohort and precision error estimates provide essential tools for clinical assessment using TBS and determination of its value in predicting bone fragility in childhood and adolescence. © 2022 American Society for Bone and Mineral Research (ASBMR).

Whole exome sequencing reveals potentially pathogenic variants in a small subset of premenopausal women with idiopathic osteoporosis.

Osteoporosis in premenopausal women with intact gonadal function and no known secondary cause of bone loss is termed idiopathic osteoporosis (IOP). Women with IOP diagnosed in adulthood have profound bone structural deficits and often report adult and childhood fractures, and family history of osteoporosis. Some have very low bone formation rates (BFR/BS) suggesting osteoblast dysfunction. These features led us to investigate potential genetic etiologies of bone fragility. In 75 IOP women (aged 20-49) with low trauma fractures and/or very low BMD who had undergone transiliac bone biopsies, we performed Whole Exome Sequencing (WES) using our variant analysis pipeline to select candidate rare and novel variants likely to affect known disease genes. We ran rare-variant burden analyses on all genes individually and on phenotypically-relevant gene sets. For particular genes implicated in osteoporosis, we also assessed the frequency of all (including common) variants in subjects versus 6540 non-comorbid female controls. The variant analysis pipeline identified 4 women with 4 heterozygous variants in LRP5 and PLS3 that were considered to contribute to osteoporosis. All 4 women had adult fractures, and 3 women also had multiple fractures, childhood fractures and a family history of osteoporosis. Two women presented during pregnancy/lactation. In an additional 4 subjects, 4 different relevant Variants of Uncertain Significance (VUS) were detected in the genes FKBP10, SLC34A3, and HGD. Of the subjects with VUS, 2 had multiple adult fractures, childhood fractures, and presented during pregnancy/lactation, and 2 had nephrolithiasis. BFR/BS varied among the 8 subjects with identified variants; BFR/BS was quite low in those with variants that are likely to have adverse effects on bone formation. The analysis pipeline did not discover candidate variants in COL1A1, COL1A2, WNT, or ALPL. Although we found several novel and rare variants in LRP5, cases did not have an increased burden of common LRP5 variants compared to controls. Cohort-wide collapsing analysis did not reveal any novel disease genes with genome-wide significance for qualifying variants between controls and our 75 cases. In summary, WES revealed likely pathogenic variants or relevant VUS in 8 (11%) of 75 women with IOP. Notably, the genetic variants identified were consistent with the affected women's diagnostic evaluations that revealed histological evidence of low BFR/BS or biochemical evidence of increased bone resorption and urinary calcium excretion. These results, and the fact that the majority of the women had no identifiable genetic etiology, also suggest that the pathogenesis of and mechanisms leading to osteoporosis in this cohort are heterogeneous. Future research is necessary to identify both new genetic and non-genetic etiologies of early-onset osteoporosis.

Bone-loading exercises versus risedronate for the prevention of osteoporosis in postmenopausal women with low bone mass: a randomized controlled trial.

PURPOSE: This randomized controlled trial compared changes in bone mineral density (BMD) and bone turnover in postmenopausal women with low bone mass randomized to 12 months of either risedronate, exercise, or a control group. METHODS: Two hundred seventy-six women with low bone mass, within 6 years of menopause, were included in analysis. Treatment groups were 12 months of (a) calcium and vitamin D supplements (CaD) (control), (b) risedronate + CaD (risedronate), or (c) bone-loading exercises + CaD (exercise). BMD and serum markers for bone formation (Alkphase B) and resorption (Serum Ntx) were analyzed at baseline, 6, and 12 months. RESULTS: Using hierarchical linear modeling, a group by time interaction was found for BMD at the spine, indicating a greater improvement in the risedronate group compared to exercise (p ≤ .010) or control groups (p ≤ .001). At 12 months, for women prescribed risedronate, changes in BMD at the spine, hip, and femoral neck from baseline were + 1.9%, + 0.9%, and + .09%; in exercise group women, + 0.2%, + 0.5%, and - 0.4%; and in control group women, - 0.7%, + 0.5%, and - 0.5%. There were also significant differences in reductions in Alkphase B (RvsE, p < .001, RvsC, p < .001) and Serum Ntx (RvsE, p = .004, RvsC, p = .007) in risedronate women compared to exercise and control groups. For risedronate, 12-month changes in Alkphase B and Serum Ntx were - 20.3% and - 19.0%; for exercise, - 6.7% and - 7.0%; and for control, - 6.3% and - 9.0%. CONCLUSION: Postmenopausal women with low bone mass should obtain adequate calcium and vitamin D and participate in bone-loading exercises. Additional use of BPs will increase BMD, especially at the spine.

Denosumab After Teriparatide in Premenopausal Women With Idiopathic Osteoporosis.

CONTEXT: We have previously reported that teriparatide is associated with substantial increases in bone mineral density (BMD) at the lumbar spine (LS), total hip (TH), and femoral neck (FN) and small declines at the distal radius in 41 premenopausal women with idiopathic osteoporosis (IOP), all severely affected with low trauma fractures and/or very low BMD. Effects of teriparatide dissipate if not followed by antiresorptives. OBJECTIVE: To assess the effects of 12 and 24 months of denosumab in premenopausal women with IOP completing 24 months of teriparatide. METHODS: This was a preplanned phase 2B extension study. Premenopausal women with IOP who had completed a course of teriparatide received denosumab 60 mg every 6 months over 24 months. The main outcome measure was within-group change in BMD at the LS at 12 months. Secondary outcomes include change in 12-month BMD at other sites, 24-month BMD at all sites, trabecular bone score (TBS), and bone turnover markers (BTMs). RESULTS: After completing teriparatide, 32 participants took denosumab for 12 months and 29 for 24 months, with statistically significant increases in BMD at the LS (5.2 ± 2.6% and 6.9 ± 2.6%), TH (2.9 ± 2.4% and 4.6 ± 2.8%), and FN (3.0 ± 3.8% and 4.7 ± 4.9%). Over the entire 24-month teriparatide and 24-month denosumab treatment period, BMD increased by 21.9 ± 7.8% at the LS, 9.8 ± 4.6% at the TH, and 9.5 ± 4.7% at the FN (all P < .0001). TBS increased by 5.8 ± 5.6% (P < .001). Serum BTM decreased by 75% to 85% by 3 months and remained suppressed through 12 months of denosumab. Denosumab was generally well tolerated. CONCLUSION: These data support the use of sequential teriparatide and denosumab to increase BMD in premenopausal women with severe osteoporosis.

CYP11B1 variants influence skeletal maturation via alternative splicing.

We performed genome-wide association study meta-analysis to identify genetic determinants of skeletal age (SA) deviating in multiple growth disorders. The joint meta-analysis (N = 4557) in two multiethnic cohorts of school-aged children identified one locus, CYP11B1 (expression confined to the adrenal gland), robustly associated with SA (rs6471570-A; ß = 0.14; P = 6.2 × 10-12). rs6410 (a synonymous variant in the first exon of CYP11B1 in high LD with rs6471570), was prioritized for functional follow-up being second most significant and the one closest to the first intron-exon boundary. In 208 adrenal RNA-seq samples from GTEx, C-allele of rs6410 was associated with intron 3 retention (P = 8.11 × 10-40), exon 4 inclusion (P = 4.29 × 10-34), and decreased exon 3 and 5 splicing (P = 7.85 × 10-43), replicated using RT-PCR in 15 adrenal samples. As CYP11B1 encodes 11-ß-hydroxylase, involved in adrenal glucocorticoid and mineralocorticoid biosynthesis, our findings highlight the role of adrenal steroidogenesis in SA in healthy children, suggesting alternative splicing as a likely underlying mechanism.

Altered collagen chemical compositional structure in osteopenic women with past fractures: A case-control Raman spectroscopic study.

Incidences of low-trauma fractures among osteopenic women may be related to changes in bone quality. In this blinded, prospective-controlled study, compositional and heterogeneity contributors of bone quality to fracture risk were examined. We hypothesize that Raman spectroscopy can differentiate between osteopenic women with one or more fractures (cases) from women without fractures (controls). This study involved the Raman spectroscopic analysis of cortical and cancellous bone composition using iliac crest biopsies obtained from 59-cases and 59-controls, matched for age (62.0 ± 7.5 and 61.7 ± 7.3 years, respectively, p = 0.38) and hip bone mineral density (BMD, 0.827 ± 0.083 and 0.823 ± 0.072 g/cm3, respectively, p = 0.57). Based on aggregate univariate case-control and odds ratio based logistic regression analyses, we discovered two Raman ratiometric parameters that were predictive of past fracture risk. Specifically, 1244/1268 and 1044/959 cm-1 ratios, were identified as the most differential aspects of bone quality in cortical cases with odds ratios of 0.617 (0.406-0.938 95% CI, p = 0.024) and 1.656 (1.083-2.534 95% CI, p = 0.020), respectively. Both 1244/1268 and 1044/959 cm-1 ratios exhibited moderate sensitivity (59.3-64.4%) but low specificity (49.2-52.5%). These results suggest that the organization of mineralized collagen fibrils were significantly altered in cortical cases compared to controls. In contrast, compositional and heterogeneity parameters related to mineral/matrix ratios, B-type carbonate substitutions, and mineral crystallinity, were not significantly different between cases and controls. In conclusion, a key outcome of this study is the significant odds ratios obtained for two Raman parameters (1244/1268 and 1044/959 cm-1 ratios), which from a diagnostic perspective, may assist in the screening of osteopenic women with suspected low-trauma fractures. One important implication of these findings includes considering the possibility that changes in the organization of collagen compositional structure plays a far greater role in postmenopausal women with osteopenic fractures.

Promoting adherence to bone-loading exercises in postmenopausal women with low bone mass.

BACKGROUND: We recently completed a parent study (Bone Loading Exercises versus Risedronate on Bone Health in Post-menopausal Women [NIH# R01NR015029]) examining bone-loading exercises to prevent bone loss in postmenopausal women with low bone mass. Forty-three million US women have low bone mass and increased risk for fractures. Bone-loading exercises (weight-bearing and resistance training) can preserve bone mass and decrease risk of fractures. However, multiple barriers prevent women from exercising and adherence rates are low. PURPOSE: This secondary analysis of the parent study (a) examined barriers specific to women participating in bone-loading exercises; (b) described effectiveness of self-efficacy strategies used in the parent study for increasing confidence in knowledge and reducing barriers; and (c) applied study findings and principles of self-efficacy and self-regulation in development of guidelines for promoting adherence to exercises. METHODS: Seventy-two women were randomized to the exercise group and completed 12 months of exercises. Instruments for self-efficacy were completed at 2 weeks and barriers interference at 6 months. Percent adherence was measured as the number of exercise sessions attended divided by the number prescribed. RESULTS: In the 12-month study, average adherence to exercises was 58.9%. Lower adherers reported lack of self-regulation skills such as "lack of time" as the most frequent barriers to exercise. IMPLICATIONS FOR PRACTICE: Guidelines developed included promotion of skills for self-regulation (such as regulation of time) as well as self-efficacy to improve adherence rates. Nurse practitioners may be the most motivated of all providers to use guidelines promoting exercise for women in their clinical practice.

Genome-wide association study implicates novel loci and reveals candidate effector genes for longitudinal pediatric bone accrual.

BACKGROUND: Bone accrual impacts lifelong skeletal health, but genetic discovery has been primarily limited to cross-sectional study designs and hampered by uncertainty about target effector genes. Here, we capture this dynamic phenotype by modeling longitudinal bone accrual across 11,000 bone scans in a cohort of healthy children and adolescents, followed by genome-wide association studies (GWAS) and variant-to-gene mapping with functional follow-up. RESULTS: We identify 40 loci, 35 not previously reported, with various degrees of supportive evidence, half residing in topological associated domains harboring known bone genes. Of several loci potentially associated with later-life fracture risk, a candidate SNP lookup provides the most compelling evidence for rs11195210 (SMC3). Variant-to-gene mapping combining ATAC-seq to assay open chromatin with high-resolution promoter-focused Capture C identifies contacts between GWAS loci and nearby gene promoters. siRNA knockdown of gene expression supports the putative effector gene at three specific loci in two osteoblast cell models. Finally, using CRISPR-Cas9 genome editing, we confirm that the immediate genomic region harboring the putative causal SNP influences PRPF38A expression, a location which is predicted to coincide with a set of binding sites for relevant transcription factors. CONCLUSIONS: Using a new longitudinal approach, we expand the number of genetic loci putatively associated with pediatric bone gain. Functional follow-up in appropriate cell models finds novel candidate genes impacting bone accrual. Our data also raise the possibility that the cell fate decision between osteogenic and adipogenic lineages is important in normal bone accrual.

Effect of Teriparatide on Bone Remodeling and Density in Premenopausal Idiopathic Osteoporosis: A Phase II Trial.

CONTEXT: Premenopausal women with idiopathic osteoporosis (IOP) have abnormal skeletal microarchitecture and variable tissue-level bone formation rate (BFR). OBJECTIVES: Compare 6 months (M) of teriparatide versus placebo on areal bone mineral density (aBMD) by dual-energy x-ray absorptiometry (DXA), bone turnover markers (BTMs) and BFR at 3M by quadruple-labeled transiliac biopsy. Characterize 12M and 24M effects of teriparatide on aBMD and whether BTMs and BFR predict response. DESIGN: 6M phase 2 randomized controlled trial (RCT) followed by open extension. SETTING: Tertiary referral centers. PATIENTS: Premenopausal women with IOP. INTERVENTIONS: A total of 41 women were randomized to either teriparatide 20 mcg (n = 28) or placebo (n = 13). After 6M, those on placebo switched to teriparatide for 24M; those on teriparatide continued for 18M. MAIN OUTCOME MEASURES: 6M RCT: Between-group differences in lumbar spine (LS) aBMD (percent change from baseline), 3M BFR, and hypercalcemia. Open-label extension: Within-group change in LS aBMD over 12M and 24M. Secondary outcomes included aBMD change at other sites and relationship between BTMs, BFR, and changes in aBMD. FINDINGS: Over 6M, LS aBMD increased by 5.5% (95% CI: 3.83, 7.19) in teriparatide and 1.5% (95% CI: -0.73, 3.83) in placebo (P = 0.007). There were increases in 3M BTMs, and BFR (cancellous and endocortical BFR: between-groups P = 0.004). Over 24M, teriparatide increased LS aBMD by 13.2% (95% CI: 10.3, 16.2), total hip by 5.2% (95% CI: 3.7, 6.7) and femoral neck by 5.0% (95% CI: 3.2, 6.7; all P ≤ 0.001). Serum N-terminal propeptides of procollagen type 1 (P1NP) and 3M endocortical BFR were moderately associated with LS aBMD response. Teriparatide was well-tolerated. CONCLUSIONS: Teriparatide increased BFR and formation markers and was associated with marked aBMD improvements in most premenopausal women (82%) with IOP.

Pediatric Reference Ranges for Ultradistal Radius Bone Density: Results from the Bone Mineral Density in Childhood Study.

CONTEXT: The ultradistal (UD) radius is rich in trabecular bone and is easily measured by dual energy X-ray absorptiometry (DXA). UD radius areal bone mineral density (aBMD) may help identify trabecular bone deficits, but reference data are needed for research and clinical interpretation of this measure. OBJECTIVE: We developed age-, sex-, and population ancestry-specific reference ranges for UD radius aBMD assessed by DXA and calculated Z-scores. We examined tracking of UD radius aBMD Z-scores over 6 years and determined associations between UD radius aBMD Z-scores and other bone measures by DXA and peripheral quantitative computed tomography. DESIGN: Multicenter longitudinal study. PARTICIPANTS: A total of 2014 (922 males, 22% African American) children ages 5 to 19 years at enrollment who participated in the Bone Mineral Density in Childhood Study. MAIN OUTCOME MEASURE: UD radius aBMD. RESULTS: UD radius aBMD increased nonlinearly with age (P < 0.001) and tended to be greater in males versus females (P = 0.054). Age-, sex-, and ancestry-specific UD radius aBMD reference curves were constructed. UD radius aBMD Z-scores positively associated with Z-scores at other skeletal sites (r = 0.54-0.64, all P < 0.001) and peripheral quantitative computed tomography measures of distal radius total volumetric BMD (r = 0.68, P < 0.001) and trabecular volumetric BMD (r = 0.70, P < 0.001), and was weakly associated with height Z-score (r = 0.09, P = 0.015). UD radius aBMD Z-scores tracked strongly over 6 years, regardless of pubertal stage (r = 0.66-0.69; all P < 0.05). CONCLUSION: UD radius aBMD Z-scores strongly associated with distal radius trabecular bone density, with marginal confounding by stature. These reference data may provide a valuable resource for bone health assessment in children.

Women With Pregnancy and Lactation-Associated Osteoporosis (PLO) Have Low Bone Remodeling Rates at the Tissue Level.

Pregnancy and lactation-associated osteoporosis (PLO) is a rare, severe, early form of osteoporosis in which young women present with fractures, usually multiple vertebral fractures, during late pregnancy or lactation. In studies of idiopathic osteoporosis (IOP) in premenopausal women, we enrolled 78 women with low-trauma fractures and 40 healthy controls, all with normal menses and no secondary cause of bone loss. In 15 of the affected women, the PLO subgroup, fractures had occurred during late pregnancy or lactation. We hypothesized that clinical, bone structural, and metabolic characteristics would differ between women with PLO and those with (non-PLO) IOP and controls. All were evaluated > 12 months postpartum, when structural and remodeling characteristics would be expected to reflect baseline premenopausal status rather than transient postpartum changes. As previously reported, affected subjects (PLO and IOP) had BMD and microarchitectural deficiencies compared to controls. Women with PLO did not differ from those with IOP in terms of age, BMI, body fat, menarcheal age, parity, or age at first pregnancy. However, women with PLO had a more severe clinical presentation than those with IOP: more fractures (5.5 ± 3.3 versus 2.6 ± 2.1; p = 0.005); more vertebral fractures (80% versus 17%; p < 0.001); and higher prevalence of multiple fractures. BMD deficits were more profound and cortical width tended to be lower in PLO. PLO subjects also had significantly lower tissue-level mineral apposition rate and bone formation rates (0.005 ± 0.005 versus 0.011 ± 0.010 mm2 /mm/year; p = 0.006), as well as lower serum P1NP (33 ± 12 versus 44 ± 18 µg/L; p = 0.02) and CTX (257 ± 102 versus 355 ± 193 pg/mL; p = 0.01) than IOP. The finding that women with PLO have a low bone remodeling state assessed more than a year postpartum increases our understanding of the pathogenic mechanism of PLO. We conclude that women with PLO may have underlying osteoblast functional deficits which could affect their therapeutic response to osteoanabolic medications. © 2019 American Society for Bone and Mineral Research.

Approaches to Recruitment of Postmenopausal Women for a Community-Based Study.

BACKGROUND: Few researchers have focused on the challenges of recruiting postmenopausal women for community-based research. Researchers have reported that multiple methods may be needed to recruit the required number of subjects. One contemporary approach to recruitment is use of Facebook. More studies are needed examining Facebook as a recruitment strategy. OBJECTIVE: The aim of the study was to examine which recruitment methods were most successful and cost-effective in recruiting postmenopausal women for a randomized controlled trial on bone loss. METHODS: Subjects were 276 postmenopausal women who had osteopenia and were within 5 years of menopause. Multiple methods were used to recruit women. To determine which methods were successful, women were asked how they learned about the study. Descriptive data were used to examine recruitment numbers as well as to determine the cost-effectiveness and enrollment efficiency of recruitment methods. RESULTS: Healthcare provider letters yielded the highest number of enrolled subjects (n = 58), followed by postcard mailings (n = 47), and Facebook posts (n = 44). Eleven subjects were referred by family and friends, five subjects were from newspaper or television, and two were from digital ads. Cost of recruitment per subject enrolled was highest with digital ads and postcard mailings. DISCUSSION: Recruitment could be more costly and time-consuming than anticipated. Recruitment using direct-targeted mailings, such as provider letters and postcards, was successful in our study and has been effective in previous studies reviewed. Facebook was successful for recruitment in our study and may continue to be useful for recruitment in the future, as the number of women accessing Facebook continues to increase.

Postmenopausal osteoporotic fracture-associated COLIA1 variant impacts bone accretion in girls.

Over the past two decades, a low frequency variant (rs1800012) within the first intron of the type I collagen alpha 1 (COLIA1) gene has been implicated in lower areal BMD (aBMD) and increased risk of osteoporotic fracture. This association is particularly strong in postmenopausal women, in whom net bone loss arises in the context of high bone turnover. High bone turnover also accompanies childhood linear growth; however, the role of rs1800012 in this stage of net bone accretion is less well understood. Thus, we assessed the association between rs1800012 and aBMD and bone mineral content (BMC) Z-scores for the 1/3 distal radius, lumbar spine, total hip, and femoral neck total body less head in the Bone Mineral Density in Childhood Study, a mixed-longitudinal cohort of children and adolescents (total n = 804 girls and 771 boys; n = 19 girls and 22 boys with the TT genotype). Mixed effects modeling, stratified by sex, was used to test for associations between rs1800012 and aBMD or BMC Z-scores and for pubertal stage interactions. Separately, SITAR growth modeling of aBMD and BMC in subjects with longitudinal data reduced the complex longitudinal bone accrual curves into three parameters representing a-size, b-timing, and c-velocity. We tested for differences in these three parameters by rs1800012 genotype using t-tests. Girls with the TT genotype had significantly lower aBMD and BMC Z-scores prior to puberty completion (e.g. spine aBMD-Z P-interaction = 1.0 × 10-6), but this association was attenuated post-puberty. SITAR models revealed that TT girls began pubertal bone accrual later (b-timing; e.g. total hip BMC, P = 0.03). BMC and aBMD Z-scores also increased across puberty in TT homozygous boys. Our data, along with previous findings in post-menopausal women, suggest that rs1800012 principally affects female bone density during periods of high turnover. Insights into the genetics of bone gain and loss may be masked during the relatively quiescent state in mid-adulthood, and discovery efforts should focus on early and late life.

Lumbar Spine Bone Mineral Apparent Density in Children: Results From the Bone Mineral Density in Childhood Study.

CONTEXT: Dual-energy X-ray absorptiometry (DXA) is a cornerstone of pediatric bone health assessment, yet differences in height-for-age confound the interpretation of areal bone mineral density (aBMD) measures. To reduce the confounding of short stature on spine bone density, use of bone mineral apparent density (BMAD) and height-for-age Z-score (HAZ)‒adjusted aBMD (aBMDHAZ) are recommended. However, spine BMAD reference data are sparse, and the degree to which BMAD and aBMDHAZ account for height-related artifacts in bone density remains unclear. OBJECTIVE: We developed age-, sex-, and population ancestry‒specific spine BMAD reference ranges; compared height-adjustment methods in accounting for shorter stature; and assessed the stability of these measures over time. DESIGN: Secondary analysis of data from a previous longitudinal study. PARTICIPANTS: Children and adolescents aged 5 to 19 years at baseline (n = 2014; 922 males; 22% black) from the Bone Mineral Density in Childhood Study. MAIN OUTCOME MEASURES: Lumbar spine BMAD and aBMDHAZ from DXA. RESULTS: Spine BMAD increased nonlinearly with age and was greater in blacks and females (all P < 0.001). Age-specific spine BMAD z-score reference curves were constructed for black and non‒black males and females. Overall, both BMAD and aBMDHAZz scores reduced the confounding influence of shorter stature, but neither was consistently unbiased across all age ranges. Both BMAD and aBMDHAZz scores tracked strongly over 6 years (r = 0.70 to 0.80; all P < 0.001). CONCLUSION: This study provided robust spine BMAD reference ranges and demonstrated that BMAD and aBMDHAZ partially reduced the confounding influence of shorter stature on bone density.