Severe Osteoporosis With Pathogenic LRP5 Variant

A 24-year-old female patient was diagnosed with osteoporosis after presenting with numerous fractures throughout her childhood and adolescence. Risk factors included chronic constipation, severe vitamin D deficiency, and long-term high-dose steroid use for severe eczema. Metabolic bone disorder clinical exome screening (limited panel of metabolic bone disorders and gastrointestinal disorders) was undertaken and revealed a class 4 likely pathogenic variant in the LRP5 gene known to cause osteoporosis. Optimal treatment for patients with this variant is not well defined. A literature review of the condition and potential treatment options is discussed.

Femora of women with premature ovarian insufficiency exhibit reduced strength and misalignment with the transmitted vertical forces from the upper body

BACKGROUND

Women with premature ovarian insufficiency (POI) lack oestrogen, which is a key determinant of bone growth, epiphyseal closure, and bone tissue organisation. Although dual-energy X-ray absorptiometry (DXA)-derived areal bone mineral density (BMD) remains the gold standard for fracture risk evaluation, it does not fully characterise the skeletal abnormalities present in these women. Hence, we aimed to assess hip/femur anatomy, strength, and geometry and femoral alignment using advanced hip analysis (AHA).

METHODS

We conducted a cross-sectional, case-control study including 89 women with spontaneous normal karyotype POI (s-POI) or iatrogenic POI (i-POI), aged 20-50 years compared with 89 age- and body mass index (BMI)-matched population-based female controls. Hip anatomy, strength, geometrical parameters, and femur alignment were measured using hip DXA images and Lunar AHA software. Femoral orientation angle (FOA) was quantified as the overall orientation of the femur with respect to the axis of the forces transmitted from the upper body.

RESULTS

The median age of POI diagnosis was 35 (18-40) years; the mean POI duration at the time of DXA was 2.07 (range 0-13) years, and 84% of POI women received oestrogen therapy. Areal BMD at all sites was significantly lower in the POI group (all P < .05). Indices of compressive and bending strength were lower in women with POI compared with controls, specifically the cross-sectional area (CSA, mm2) and section modulus (SM, mm3) (139.30 ± 29.08 vs 157.29 ± 22.26, P < .001 and 665.21 ± 129.54 vs 575.53 ± 150.88, P < .001, respectively). The FOA was smaller (124.99 ± 3.18) in women with POI as compared with controls (128.04 ± 3.80; P < .001) at baseline and after adjusting for height and femoral neck BMD.

CONCLUSION

Alongside lower BMD at multiple sites, the femora of women with POI demonstrate reduced strength and a misalignment with forces transmitted from the upper body. Further research is needed to establish the role of these newly identified features and their role in fracture risk prediction in this population.

Chronic kidney disease-related sarcopenia as a prognostic indicator in elderly haemodialysis patients

BACKGROUND

The mortality of dialysis patients greatly exceeds that of the general population and identifying predictive factors for mortality may provide opportunities for earlier intervention. This study assessed the influence of sarcopenia on mortality in patients on haemodialysis.

METHODS

This prospective, observational study enrolled 77 haemodialysis patients aged 60 years and over, of whom 33 (43%) were female, from two community dialysis centres. Baseline demographic and laboratory data were collected, and sarcopenia was diagnosed using grip strength, muscle mass by bioimpedance analysis (BIA) and muscle function by timed up-and-go according to European Working Group on Sarcopenia in Older People criteria. Nutritional status was assessed using a subjective nutritional assessment score, comprising functional changes in weight, appetite, gastrointestinal symptoms and energy.. A comorbidity score (maximum 7 points) was derived from the presence or absence of hypertension, ischaemic heart disease, vascular disease (cerebrovascular disease, peripheral vascular disease, and abdominal aortic aneurysm), diabetes mellitus, respiratory disease, a history of malignancy and psychiatric disease. Outcomes over six years were linked to the Australian and New Zealand Dialysis and Transplant Registry.

RESULTS

The median participant age was 71 years (range 60-87). Probable and confirmed sarcopenia was present in 55.9% and severe sarcopenia with reduced functional testing in 11.7%. Over 6 years, overall mortality was 50 of the 77 patients (65%), principally from cardiovascular events, dialysis withdrawal and infection. There were no significant survival differences between patients with no, probable, confirmed, or severe sarcopenia, or between tertiles of the nutritional assessment score. After adjustment for age, dialysis vintage, mean arterial pressure (MAP) and the total comorbidity score, no sarcopenia category predicted mortality. However, the total comorbidity score [Hazard Ratio (HR) 1.27, Confidence Intervals (CI) 1.02, 1.58, p = 0.03] and MAP (HR 0.96, CI 0.94, 0.99, P = < 0.01) predicted mortality.

CONCLUSION

Sarcopenia is highly prevalent in elderly haemodialysis patients but is not an independent predictor of mortality. Haemodialysis patients have multiple competing risks for mortality which, in this study, was predicted by a lower MAP and a higher total comorbidity score.

TRIAL REGISTRATION

Recruitment commenced December 2011. The study was registered 10.01.2012 with the Australian New Zealand Clinical Trials Registry (ACTRN12612000048886).

DXA-derived advanced hip analysis and the trabecular bone score in end-stage kidney disease secondary to type 1 diabetes

OBJECTIVE

Patients with end-stage kidney disease (ESKD) caused by type 1 diabetes mellitus (T1DM) have a heightened fracture risk. Bone mineral density (BMD) may predict fracture less accurately in ESKD than in patients with chronic kidney disease (CKD) stages 1-3b or the general population. Alternate, readily available imaging modalities are needed to improve ESKD fracture risk assessment. This study aimed to assess dual-energy X-ray absorptiometry (DXA)-derived BMD, the trabecular bone score (TBS) and advanced hip analysis parameters in patients with ESKD due to T1DM and to compare their results with those of patients with ESKD from other causes.

METHODS

We compared the DXA-derived TBS, hip cortical thickness (CT) and femoral neck (FN) buckling ratio (BR), an index of FN stability, of patients with T1DM and ESKD undergoing simultaneous pancreas kidney transplantation, patients with ESKD from other causes receiving kidney transplants and population reference ranges.

RESULTS

Of 227 patients with ESKD, 28% had T1DM and 65% were male. Compared with other ESKD patients, patients with T1DM were younger (42 ± 7.7 vs 51 ± 13.8 years), had shorter dialysis duration (24.4 ± 21 vs 42.6 ± 40 months), had higher HbA1c (7.9 ± 1.57% vs 5.4 ± 0.95%) and had lower BMI (25 ± 6 vs 27 ± 5 kg/m2). They had lower spine, hip and UD radius BMD Z-scores (all P ≤ 0.001), TBS (1.33 ± 0.12 vs 1.36 ± 0.12; P = 0.05), CT at the FN (P = 0.03), calcar (P = 0.006) and shaft (P < 0.001) and higher BR (10.1±7.1 vs 7.7±4; P = 0.006). All ESKD parameters were lower than population-based reference ranges (P < 0.001). Adjusting for age, sex, dialysis vintage and weight, prevalent vertebral fractures in patients with T1DM and ESKD were associated with higher BR (odds ratio (OR): 3.27 (95% CI: 1.19-8.92), P = 0.002) and lower FN CT (OR: 3.70 (95% CI: 1.13-12.50)).

CONCLUSION

Patients with ESKD and T1DM have reduced TBS, reduced CT and increased BR compared with other ESKD patients. Prospective study of these parameters is warranted to determine their utility in fracture risk prediction and management.

SIGNIFICANCE STATEMENT

Patients with ESKD and T1DM have an elevated fracture risk due to decreased bone strength. As an adjunct to BMD, evaluating dual-energy X-ray absorptiometry parameters that incorporate structural change may have greater value in patients with ESKD and T1DM than in the general population. In this study, patients with ESKD due to T1DM had lower BMD, lower trabecular bone scores, more severe loss of CT and higher BR than other patients with ESKD and people from the general population. Both lower CT and higher BR were associated with prevalent vertebral fractures in patients with T1DM and ESKD. Changes to these parameters should be evaluated for incident fracture prediction.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

Patients with end-stage kidney disease have markedly abnormal cortical hip parameters by dual-energy X-ray absorptiometry

BACKGROUND

Patients with end-stage kidney disease (ESKD) have higher fracture rates and post-fracture mortality than the general population, but bone mineral density by dual-energy X-ray absorptiometry (DXA) is less predictive of fracture in this patient group. Bone biopsy and high-resolution imaging indicate that cortical thickness (CT) is reduced and cortical porosity is increased in ESKD. The aim of this study was to assess cortical parameters using DXA in patients with ESKD. It was hypothesized that these parameters would show deterioration and be associated with fracture.

METHODS

Using advanced hip analysis, normal age-related ranges were determined from 752 female and 861 male femur scans and were compared with scans of 226 patients with ESKD at the time of transplantation.

RESULTS

Compared with controls, female patients had lower mean±SD CT (mms) at the femoral neck (FN) (2.59 ± 1.42 versus 5.23 ± 1.85), calcar (3.46 ± 1.07 versus 5.09 ± 1.30) and shaft (4.42 ± 1.21 versus 7.44 ± 2.07; P < 0.001 for each), and buckling ratios were higher (8.21 ± 4.6 versus 3.63 ± 1.42; P < 0.001), indicating greater FN instability. All findings were similar for men. Prevalent fracture was documented in 28.8% of patients; 12.4% vertebral only, 8.4% non-vertebral only and 8% vertebral plus non-vertebral. In adjusted models, each 1 SD reduction in FN CT and increase in the buckling ratio was associated with a respective 1.73 (1.22-2.46)- and 1.82 (1.49-2.86)-fold increase in the risk of prevalent vertebral fracture.

CONCLUSIONS

In patients with ESKD, DXA-derived cortical parameters are markedly abnormal compared with age- and sex-matched controls. These parameters should be assessed for incident fracture prediction and targeting treatment.

Bone health in chronic kidney disease-mineral and bone disorder: a clinical case seminar and update

The metabolic abnormalities affecting bone in the setting of chronic kidney disease (CKD) are complex with overlapping and interacting aetiologies and have challenging diagnostic and management strategies. Disturbances in calcium, phosphate, fibroblast growth factor 23, parathyroid hormone concentrations and vitamin D deficiency are commonly encountered and contribute to the clinical syndromes of bone disorders in CKD, including hyperparathyroidism, osteomalacia, osteoporosis and adynamic bone disease. Mineral and bone abnormalities may also persist or arise de novo post-renal transplantation. The Kidney Disease Improving Global Outcomes organisation describes these mineral metabolism derangements and skeletal abnormalities as 'CKD Mineral and Bone Disorder'. Patients with this disorder have an increased risk of fracture, cardiovascular events and overall increased mortality. In light of the recently updated 2017 guidelines from the Kidney Disease Improving Global Outcomes, we present a clinical case-based discussion to highlight the complexities of investigating and managing the bone health of patients with CKD with a focus on these updates.

Gonadal Hormones in the Pathogenesis and Treatment of Bone Health in Patients with Chronic Kidney Disease: a Systematic Review and Meta-Analysis

PURPOSE OF REVIEW

Patients with chronic kidney disease (CKD) have a greatly increased fracture risk compared with the general population. Gonadal hormones have an important influence on bone mineral density (BMD) and fracture risk, and hormone therapies can significantly improve these outcomes. Gonadal dysfunction is a frequent finding in patients with CKD; yet, little is known about the impact of gonadal hormones in the pathogenesis and treatment of bone health in patients with CKD. This systematic review and meta-analysis aimed to examine the effects of gonadal hormones and hormone therapies on bone outcomes in men and women with CKD.

METHODS

EMBASE, MEDLINE, SCOPUS, and clinical trial registries were systematically searched from inception to February 14, 2018 for studies that assessed gonadal hormones or hormone treatments with bone outcomes in patients with CKD stage 3-5D. Two independent reviewers screened the titles and abstracts of search results according to inclusion criteria and assessed study quality and risk of bias using validated assessment tools.

RECENT FINDINGS

Thirteen studies met the inclusion criteria. Six moderate-to-high quality observational studies showed inconsistent association between any gonadal hormone and bone outcomes, limited by significant study heterogeneity. Five moderate-high risk of bias interventional studies examined treatment with selective oestrogen receptor modulators in post-menopausal women (four using raloxifene and one bazedoxifene) and demonstrated variable effects on BMD and fracture outcomes. Meta-analysis of raloxifene treatment in post-menopausal women demonstrated improvement in lumbar spine (SMD 3.30; 95% CI 3.21-3.38) and femoral neck (SMD 3.29; 95% CI 3.21-3.36) BMD compared with placebo. Transdermal oestradiol/norethisterone in pre-menopausal women receiving dialysis (n = 1 study), demonstrated BMD improvement over 12 months. Testosterone treatment for 6 months in dialysis-dependant men (n = 1 study) did not improve BMD. There is evidence that raloxifene treatment may be beneficial in improving BMD in post-menopausal women with CKD. There is insufficient evidence for other hormone treatments in men or women. Despite high fracture rates and frequent gonadal dysfunction in patients with CKD, significant evidence gaps exist, and well-designed studies are required to specifically assess the impact of gonadal status in the pathogenesis of CKD-related bone fragility and its treatment.

Aortic vascular calcification is inversely associated with the trabecular bone score in patients receiving dialysis

INTRODUCTION

Progressive chronic kidney disease (CKD) confers a marked increase in risk for vascular calcification, cardiovascular disease, fracture and mortality, with likely contributing factors including dysregulated bone metabolism and mineral homeostasis. In general population studies, increased vascular calcification is directly related to mortality and inversely related to bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA). In patients with CKD, abnormalities in turnover, mineralization and bone volume reduce the ability of DXA to predict fracture. The trabecular bone score (TBS) obtained from lumbar spine DXA images, provides a surrogate measure of microarchitectural integrity not captured by BMD. This study aimed to examine the association of the TBS to prevalent abdominal aortic calcification (AAC) in patients with CKD receiving dialysis.

METHODS

We performed a cross-sectional study of dialysis patients awaiting transplantation. All patients underwent laboratory testing, lateral spinal radiographs including the abdominal aorta, DXA imaging and TBS assessment. AAC scores were determined using the Kauppila method. Correlations and linear regression models were used to determine predictors of AAC scores.

RESULTS

146 patients (60% male, mean age 48 ± 13 years) were included, of whom 49% had prevalent calcification with an AAC score ≥ 1. Of those with calcification, the mean AAC score was 7 ± 5.5 and 42 patients had scores ≥ 6, considered to indicate severe AAC. TBS values corresponding to intermediate or high risk for fracture (<1.31) were present in 35% of patients. TBS values correlated inversely to AAC scores (β = -0.206, p = 0.013) and remained significant in multivariable linear regression, adjusting for age, BMI and time on dialysis (-0.160, p = 0.031). There was no significant correlation of AAC scores to any BMD parameter.

CONCLUSION

There is a high prevalence of AAC in relatively young dialysis patients awaiting transplantation and their AAC scores are inversely related to the TBS but not to DXA-derived BMD parameters. In patients with CKD on dialysis, TBS assessment reflects microarchitectural abnormalities of bone not captured by DXA. The inverse relationship of TBS to vascular calcification may provide insights into bone-vascular interactions in CKD.

The trabecular bone score is associated with bone mineral density, markers of bone turnover and prevalent fracture in patients with end stage kidney disease

Fracture risk increases in end-stage kidney disease (ESKD), but bone mineral density (BMD) measurement is less predictive of risk than in the general population. In this study of patients with ESKD, a lower trabecular bone score (TBS), indicative of microarchitectural deterioration, was associated with higher bone turnover markers and prevalent non-vertebral fracture.

INTRODUCTION

Declining renal function carries increased fracture risks, but BMD is less predictive of fracture for dialysis patients than the general population. The TBS, obtained from lumbar spine dual-energy X-ray absorptiometry (DXA) images, provides information on microarchitectural integrity not captured by BMD. The aim of this study was to assess associations of the TBS to clinical, DXA, radiological, and laboratory measures in patients with ESKD undergoing kidney and simultaneous pancreas kidney (SPK) transplantation.

METHODS

A total of 147 patients with ESKD underwent pre-transplant laboratory testing, DXA, lateral spine X-ray, and structured history within 4 weeks of transplantation. Associations of the TBS to demographic data, prevalent fracture, BMD, and laboratory variables were assessed.

RESULTS

Of 147 patients (60% male, mean age 48 ± 13 years), 36% had diabetes mellitus (DM) and 54 patients had fractures: 21 prevalent vertebral fractures only, 22 non-vertebral fractures only, and 11 had both. The mean TBS (1.345 ± 0.125) was lower in patients undergoing SPK than kidney-only transplants (1.292 vs. 1.364, p = 0.001). The TBS correlated to spine and total hip BMD, body mass index and inversely to parathyroid hormone, alkaline phosphatase and procollagen 1 N-propeptide. By multivariable logistic regression, lower TBS was significantly associated to prior non-vertebral fracture (p = 0.026).

CONCLUSIONS

A lower TBS, suggestive of increased microarchitectural damage, was associated with type 1 DM, markers of higher bone turnover, and prevalent fracture. These data support the need for prospective studies to evaluate whether TBS inclusion improves fracture prediction in patients with ESKD.

Serum phosphorus levels and fracture following renal transplantation

PURPOSE

Increased fracture rates are observed in renal transplant recipients (RTRs) compared with the general population. Risk factors include age, diabetes, dialysis vintage, immunosuppression and mineral and bone disorders.¹ Low serum phosphorus levels occur post-transplantation; however, its relationship with fracture risk has not been evaluated. The purpose of this study was to evaluate risk factors for fracture in RTRs at a single tertiary referral centre.

METHODS

A retrospective cross-sectional analysis of 146 patients (75 M, 71 F) who had been referred for dual energy X-ray densitometry (DXA) post-renal transplantation was performed. Aetiology of end stage kidney disease (ESKD), duration of dialysis, parathyroidectomy history, immunosuppression regimen, bone mineral density (BMD), biochemistry and fractures were documented. Statistical analyses included univariable and multivariable regression.

RESULTS

The mean age of patients was 54 years and mean time post-transplantation 6.7 years. A total of 79 fractures occurred in 52 patients (35%), with 40 fractures occurring post-transplantation. Ankle/foot fractures were most common (48%). Lower serum phosphorus levels and declining femoral neck (FN) T-score and were associated with fractures in both univariable and multivariable regression analyses after adjusting for age, gender, weight, estimated glomerular filtration rate and pre-transplant history of fracture (P=.011 and P=.042 respectively). The relationship between serum phosphorus and fracture remained significant independent of FN T-score, parathyroid hormone levels, parathyroidectomy status and prednisolone use.

CONCLUSION

Fracture was common post-renal transplantation. Lower serum phosphorus levels and declining FN T-scores were associated with fractures. The mechanism of this previously unreported observation requires further evaluation in prospective studies.

Glucocorticoids did not reverse type 1 diabetes mellitus secondary to pembrolizumab in a patient with metastatic melanoma

Immune checkpoint inhibitors offer patients with advanced melanoma substantial improvements in survival. Unlike chemotherapy, immune checkpoint inhibitors such as ipilimumab and pembrolizumab cause unique immune-related adverse events (irAEs), including the development of endocrinopathies. We report a case of a man aged 60 years who developed diabetic ketoacidosis (DKA) following the use of pembrolizumab for the treatment of metastatic melanoma. He received four cycles of ipilimumab, before proceeding to pembrolizumab. Five weeks after initiating pembrolizumab, he presented in DKA with a pH of 7.0, bicarbonate of 7 mmol/L, blood glucose of 27 mmol/L and serum ketones of 5.9 mmol/L. Antibodies to glutamic acid decarboxylase (anti-GAD) and Islet antigen 2 (IA-2) were negative and C-peptide was low at 57 pmol/L (300-2350 pmol/L). There was no personal or family history of autoimmune conditions. Standard immunosuppression for irAEs was started using prednisolone in an attempt to salvage β cell function but was unsuccessful. To the best of our knowledge, this is the first reported attempt at reversing pembrolizumab-induced type 1 diabetes using glucocorticoids.

Vinclozolin exposure in utero induces postpubertal prostatitis and reduces sperm production via a reversible hormone-regulated mechanism

Vinclozolin is an endocrine-disrupting chemical (EDC) that binds with high affinity to the androgen receptor (AR) and blocks the action of gonadal hormones on male reproductive organs. An alternative mechanism of action of Vinclozolin involves transgenerational effects on the male reproductive tract. We previously reported in utero Vinclozolin exposure-induced prostatitis (prostate inflammation) in postpubertal rats concurrent with down-regulation of AR and increased nuclear factor-kappaB activation. We postulated the male reproductive abnormalities induced by in utero Vinclozolin exposure could be reversed by testosterone supplementation, in contrast to the permanent modifications involving DNA methyltransferases (Dnmts) described by others. To test this hypothesis, we administered high-dose testosterone at puberty to Vinclozolin-treated rats and determined the effect on anogenital distance (AGD); testicular germ cell apoptosis, concentration of elongated spermatids, and the onset of prostatitis. Concurrently we examined Dnmt1, -3A, -3B, and -3L mRNA expression. Consistent with previous reports, in utero exposure to Vinclozolin significantly reduced AGD, increased testicular germ cell apoptosis 3-fold, reduced elongated spermatid number by 40%, and induced postpubertal prostatitis in 100% of exposed males. Administration of high-dose testosterone (25 mg/kg) at puberty normalized AGD, reduced germ cell apoptosis, and restored elongated spermatid number. Testosterone restored AR and nuclear factor-kappaB expression in the prostate and abolished Vinclozolin-induced prostatitis. Altered Dnmt expression was evident with in utero Vinclozolin exposure and was not normalized after testosterone treatment. These data demonstrate in utero Vinclozolin-induced male reproductive tract abnormalities are AR mediated and reversible and involve a mechanism independent of Dnmt expression.