Bone mineralization defects and vitamin D deficiency: histomorphometric analysis of iliac crest bone biopsies and circulating 25-hydroxyvitamin D in 675 patients

Alterations of bone material properties in adult patients with X-linked hypophosphatemia (XLH)

X-linked hypophosphatemia (XLH) caused by PHEX mutations results in elevated serum FGF23 levels, renal phosphate wasting and low 1,25-dihydroxyvitamin D. The glycophosphoprotein osteopontin, a potent inhibitor of mineralization normally degraded by PHEX, accumulates within the bone matrix. Conventional therapy consisting of supplementation with phosphate and vitamin D analogs is burdensome and the effects on bone material poorly characterized. We analyzed transiliac bone biopsies from four adult patients, two of them severely affected due to no diagnosis and no treatment until adulthood. We used light microscopy, qBEI and FTIRI to study histology, histomorphometry, bone mineralization density distribution, properties of the organic matrix and size of hypomineralized periosteocytic lesions. Non-treatment resulted in severe osteomalacia, twice the amount of mineralized trabecular volume, multiple osteon-like perforations, continuity of lamellae from mineralized to unmineralized areas and distinctive patches of woven bone. Periosteocytic lesions were larger than in treated patients. The latter had nearly normal osteoid thicknesses, although surface was still elevated. The median calcium content of the matrix was always within normal range, although the percentage of lowly mineralized bone areas was highly increased in non-treated patients, resulting in a marked heterogeneity in mineralization. Divalent collagen cross-links were evident independently of the mineral content of the matrix. Broad osteoid seams lacked measurable pyridinoline, a mature trivalent cross-link and exhibited considerable acidic lipid content, typically found in matrix vesicles. Based on our results, we propose a model that possibly integrates the relationship between the observed mineralization disturbances, FGF23 secretion and the known osteopontin accumulation in XLH.

Association of 25-hydroxy vitamin D level with the blood pressure response to a maximum exercise test among professional indoor athletes

Purpose

Low vitamin D levels have been associated with elevated blood pressure (BP) in the general population. However, whether there is an association of vitamin D insufficiency with BP changes during maximum exercise in athletes is currently unclear.

Methods

A total of 120 male professional indoor athletes (age 26 ± 5 years) were examined. BP was measured at rest and during a graded cycling test. We assessed the BP response (BPR) during maximum exercise and the respective load. BP and BPR (peak-baseline BP) were analysed with respect to 25-OH vitamin D levels, with levels < 30 ng/mL defining vitamin D insufficiency.

Results

35 athletes were classified as being vitamin D insufficient. BP was not different between sufficient and insufficient vitamin D groups (122 ± 10/75 ± 7 vs. 120 ± 12/77 ± 9 mmHg). At maximum exercise, however, systolic BP (198 ± 17 vs. 189 ± 19, p = 0.026) and the pulse pressure (118 ± 18 vs. 109 ± 21 mmHg, p = 0.021) were higher in the sufficient group; the BPR was not different between groups (76 ± 20/5 ± 6 vs. 69 ± 22/3 ± 6 mmHg, p = 0.103). Athletes with sufficient levels had a higher maximum power output (3.99 ± 0.82 vs. 3.58 ± 0.78 W/kg, p = 0.015) and achieved higher workloads (367 ± 78 vs. 333 ± 80 W, p = 0.003). The workload-adjusted BPR (maximum systolic BP/MPO) was not different between athletes with sufficient and insufficient vitamin D levels (51 ± 10 vs. 56 ± 14 mmHg × kg/W, p = 0.079).

Conclusion

Athletes with sufficient vitamin D achieved a higher maximum systolic BP and a higher maximum power output. The workload-adjusted BPR was not different between groups, which suggests that this finding reflects a better performance of athletes with sufficient vitamin D.

Standardized Histomorphometric Evaluation of Osteoarthritis in a Surgical Mouse Model

One of the most prevalent joint disorders in the United States, osteoarthritis (OA) is characterized by progressive degeneration of articular cartilage, primarily in the hip and knee joints, which results in significant impacts on patient mobility and quality of life. To date, there are no existing curative therapies for OA able to slow down or inhibit cartilage degeneration. Presently, there is an extensive body of ongoing research to understand OA pathology and discover novel therapeutic approaches or agents that can efficiently slow down, stop, or even reverse OA. Thus, it is crucial to have a quantitative and reproducible approach to accurately evaluate OA-associated pathological changes in the joint cartilage, synovium, and subchondral bone. Currently, OA severity and progression are primarily assessed using the Osteoarthritis Research Society International (OARSI) or Mankin scoring systems. In spite of the importance of these scoring systems, they are semiquantitative and can be influenced by user subjectivity. More importantly, they fail to accurately evaluate subtle, yet important, changes in the cartilage during the early disease states or early treatment phases. The protocol we describe here uses a computerized and semiautomated histomorphometric software system to establish a standardized, rigorous, and reproducible quantitative methodology for the evaluation of joint changes in OA. This protocol presents a powerful addition to the existing systems and allows for more efficient detection of pathological changes in the joint.

Serum PTH is not a good marker for defining a threshold for vitamin D deficiency

OBJECTIVE

In addition to its skeletal effects, vitamin D may also be important for health in general. It is uncertain what level of serum 25-hydroxyvitamin D (25(OH)D), marker of vitamin D status, is sufficient for these effects. With decreasing serum 25(OH)D levels there is an increase in serum PTH. The point at which this occurs has been considered as a threshold for vitamin D sufficiency. The thresholds found have varied widely and have mainly been based on observational studies. However, to truly establish a threshold for vitamin D effects, this has to be based on randomized controlled trials (RCTs).

METHODS

The study included 2803 subjects from a general health survey, the Tromsø study, and pooled individual person data from five vitamin D intervention studies (n = 1544). Serum parathyroid hormone (PTH) and change in PTH after vitamin D supplementation were related to serum 25(OH)D levels in steps of 25 nmol/L (<24, 25-49, 50-74, 75-99, and >99 nmol/L).

RESULTS

In the Tromsø study, in the females there was a gradual decrease in serum PTH with increasing serum 25(OH)D with no apparent plateau, whereas in the males the decrease in PTH in subjects with serum 25(OH)D >74 nmol/l was marginal. In pooled RCTs, there was a significant reduction in serum PTH by vitamin D supplementation regardless of baseline serum 25(OH)D level.

CONCLUSIONS

The use of the serum PTH-25(OH)D relation from observational studies to determine a threshold for vitamin D sufficiency is highly questionable.

Osteoidosis leads to altered differentiation and function of osteoclasts

In patients with osteomalacia, a defect in bone mineralization leads to changed characteristics of the bone surface. Considering that the properties of the surrounding matrix influence function and differentiation of cells, we aimed to investigate the effect of osteoidosis on differentiation and function of osteoclasts. Based on osteomalacic bone biopsies, a model for osteoidosis in vitro (OIV) was established. Peripheral blood mononuclear cells were differentiated to osteoclasts on mineralized surfaces (MS) as internal control and on OIV. We observed a significantly reduced number of osteoclasts and surface resorption on OIV. Atomic force microscopy revealed a significant effect of the altered degree of mineralization on surface mechanics and an unmasking of collagen fibres on the surface. Indeed, coating of MS with RGD peptides mimicked the resorption phenotype observed in OIV, suggesting that the altered differentiation of osteoclasts on OIV might be associated with an interaction of the cells with amino acid sequences of unmasked extracellular matrix proteins containing RGD sequences. Transcriptome analysis uncovered a strong significant up‐regulation of transmembrane glycoprotein TROP2 in osteoclastic cultures on OIV. TROP2 expression on OIV was also confirmed on the protein level and found on the bone surface of patients with osteomalacia. Taken together, our results show a direct influence of the mineralization state of the extracellular matrix surface on differentiation and function of osteoclasts on this surface which may be important for the pathophysiology of osteomalacia and other bone disorders with changed ratio of osteoid to bone.

Weaker bones and white skin as adaptions to improve anthropological "fitness" for northern environments

The vitamin D paradox relates to the lower risk of osteoporosis in people of sub-Saharan African ancestry (Blacks) compared with people of European ancestry (Whites). The paradox implies that for bone health, Blacks require less vitamin D and calcium than Whites do. Why should populations that migrated northward out of Africa have ended up needing more vitamin D than tropical Blacks? Human skin color became lighter away from the tropics to permit greater skin penetration of the UVB light that generates vitamin D. Lack of vitamin D impairs intestinal calcium absorption and limits the amount of calcium that can deposit into the protein matrix of bone, causing rickets or osteomalacia. These can cause cephalopelvic disproportion and death in childbirth. Whiter skin was more fit for reproduction in UV-light restricted environments, but natural selection was also driven by the phenotype of bone per se. Bone formation starts with the deposition of bone-matrix proteins. Mineralization of the matrix happens more slowly, and it stiffens bone. If vitamin D and/or calcium supplies are marginal, larger bones will not be as fully mineralized as smaller bones. For the same amount of mineral, unmineralized or partially mineralized bone is more easily deformed than fully mineralized bone. The evidence leads to the hypothesis that to minimize the soft bone that causes pelvic deformation, a decrease in amount of bone, along with more rapid mineralization of osteoid improved reproductive fitness in Whites. Adaptation of bone biology for reproductive fitness in response to the environmental stress of limited availability of vitamin D and calcium came at the cost of greater risk of osteoporosis later in life.

Hypovitaminosis D and Aging: Is There a Role in Muscle and Brain Health?

The older-adult population is constantly increasing, hence aging and mechanisms leading to aging are a topic raising increasing interest. Hypovitaminosis D is common amongst old patients and has been proposed as causative of several chronic diseases. Here we review the role of hypovitaminosis D and vitamin D supplementation in sarcopenia and dementia, from bench to bedside.

Vitamin D nutritional status in the adult population in Colombia - An analytical cross-sectional study

Background

The key role of Vitamin D is to maintain an adequate calcium and phosphorus metabolism. Vitamin D plays an antagonistic role with the parathyroid hormone. 25 OH Vitamin D is the major circulating form and the best indicator to monitor Vitamin D levels.

Methods

A cross-sectional study was conducted in 1339 individuals ≥18 years old. The main objective was to establish the nutritional status of Vitamin D and its association with PTH and ionized calcium levels. Other objectives were to compare the levels of 25 OH Vitamin D based on sun exposure habits, and to identify the minimum cut-off point for the levels of 25 OH Vitamin D that could give rise to a concomitant increase in PTH and ionized calcium levels.

Results

14.2% of participants presented Vitamin D deficiency, and 28.8% presented insufficiency; ≥89% of the participants with deficiency or insufficiency were exposed to sunlight <30 minutes per week. A value of 25 OH Vitamin D >30 ng/mL was associated with a more stable and "flat" PTH value. The median of 25 OH Vit-D associated with hypercalcemia was <10 ng/mL.

Conclusion

In Colombia, low 25 OH Vitamin D values are highly prevalent; this may be accounted for by poor sun-exposure habits and frequent use of sunscreen. Just as in other similar trials, the lower the levels of 25 OH Vit-D, the higher the effect on PTH and ionized calcium elevation.

Vitamin D, and Maternal and Child Health

Vitamin D has important roles in calcium metabolism and in the prevention of rickets and osteomalacia; low levels of 25-hydroxyvitamin D are common in the general population and amongst pregnant women. Whilst there is a wealth of observational evidence linking vitamin D deficiency to a wide range of disease outcomes, there are currently few high-quality randomised controlled trials to confirm any causal associations, although many are currently in progress. Furthermore, currently, the vast majority of published guidelines recommend standard supplemental vitamin D doses for children and pregnant women, yet there is increasing recognition that individual characteristics and genetic factors may influence the response to supplementation. As such, future research needs to concentrate on documenting definite beneficial clinical outcomes of vitamin D supplementation, and establishing personalised dosing schedules and demonstrating effective approaches to optimising initiation and adherence.

Serum 25-hydroxyvitamin D concentrations in Japanese postmenopausal women with osteoporotic fractures

Objectives

To assess the vitamin D status in postmenopausal women with osteoporotic fractures, determine its concentration by fracture site at the clinical setting, and compare the proportion of vitamin D deficiency with that reported in literature.

Methods

The prospective study included 317 postmenopausal women with osteoporotic fractures who were treated consecutively from 2016 to 2018. After obtaining informed consent for participation in the seamless treatment of osteoporosis against fractures study, which is our initiative to prevent secondary osteoporotic fractures, we registered the patients, examined bone mineral density (BMD) at the unfractured femoral neck and lumbar spine, serum 25-hydroxyvitamin D (25(OH)D) concentration, blood chemistry, and bone turnover markers.

Results

The mean age of the patients was 80.7 years. Moreover, 78% of patients of all fractures had 25(OH)D concentration < 20 ng/mL, whereas 12% of patients had 25(OH)D concentration ≥ 30 ng/mL 25(OH)D concentration in hip fractures was significantly lower than that in vertebral or distal radius fractures (P < 0.05). Multiple regression analysis revealed that 25(OH)D concentration is significantly associated with femoral neck BMD (β = 0.16; 95% confidence interval [CI], 0.78–12.17, P = 0.03) and serum albumin concentration (β = 0.21; 95% CI, 0.62–2.96, P < 0.001) in patients with 25(OH)D concentration < 30 ng/mL.

Conclusions

The results of this study show that the proportion of postmenopausal women with osteoporotic fractures who had vitamin D deficiency was higher than the proportion in previous reports that examined general postmenopausal women (35.2%–52.0%).

Effectiveness of Native Vitamin D Therapy in Patients with Chronic Kidney Disease Stage 3 and Hypovitaminosis D in Colombia, South America

Introduction: In a high percentage of patients with chronic kidney disease (CKD) low levels of vitamin D are detected. The purpose of this study was to evaluate if the native vitamin D therapy (cholecalciferol) in the patients with stage 3 and hypovitaminosis D allows to modify markers of bone and mineral metabolism once normal serum levels have been achieved.

MATERIALS AND METHODS

From an initial base of 297 patients with CKD and hypovitaminosis D, those with normal or high levels of PTH were chosen for therapy with native vitamin D. The initial administered dose was 1000 IU/day, with adjustments every 4 months of 1000 IU (maximum 4000 IU/day, according to RDA and IOM), until achieving serum levels of 25 hydroxyvitamin D greater than 30 ng/mL and lower than 80 ng/mL. The variables calcium, phosphorus, intact parathormone (iPTH), creatinine and glomerular filtration rate (GFR) were also evaluated every 4 months.

RESULTS

The total number of patients included in this study was 170. Seventy-three patients were excluded along the follow-up: 17 non-responders (never achieved the projected serum levels of vitamin D), and 56 for not completing one year of follow-up. A total of 97 patients were finally included. In 82 patients, follow-up was achieved for 12 months (G1) and in 38 patients for 24 months (G2). In 15 patients despite achieving satisfactory levels of vitamin D at 12 months, it was not possible to obtain adequate levels of iPTH for their GFR according to K/DOQI 2003 guidelines and they were called refractory to therapy (G3). In both groups 1 and 2, a non-significant tendency to increase calcium and serum phosphorus was observed. iPTH decreased significantly at 12 and 24 months follow-up. In group 3, we opted at 12 months for conversion to calcitriol, with a significant reduction in iPTH values. In this group, the initial value of GFR was close to 30 mL/min, and its fall in time more significant than the other two groups to CKD stage 4.

CONCLUSION

Cholecalciferol with adjustment in its dose, and obtaining normal serum levels is an excellent therapeutic alternative for the treatment of patients with CKD stage 3, and hypovitaminosis D. In the group of patients with GFR close to 30 mL/min, or lower values (stage 4), and with the presence of secondary hyperparathyroidism, the use of active form of vitamin D (calcitriol, paricalcitol) is recommended as the first therapeutic alternative.

Vitamin D and cardiovascular disease in chronic kidney disease

Chronic kidney disease (CKD) is considered an independent risk factor for cardiovascular disease, with increased cardiovascular morbidity and mortality seen even in the early stages of CKD. Several studies have shown a high prevalence of vitamin D deficiency in individuals with CKD. Low vitamin D levels upregulate the renin-angiotensin-aldosterone system (RAAS), cause endothelial dysfunction, and increase inflammation. Epidemiological studies show an association between vitamin D deficiency and risk factors for cardiovascular disease, but a causal relationship has not been established. The high cardiovascular morbidity and mortality associated with CKD in adults requires therapies to decrease this elevated risk. However, results from several meta-analyses and randomized clinical trials in adults have not shown convincing evidence for the use of vitamin D therapy in improving cardiovascular outcomes. Lack of high-quality evidence from randomized clinical trials in children regarding the effectiveness and long-term safety of vitamin D treatment precludes any recommendations on its use to mitigate the cardiovascular burden of CKD.

Burosumab Improved Histomorphometric Measures of Osteomalacia in Adults with X-Linked Hypophosphatemia: A Phase 3, Single-Arm, International Trial

In adults with X-linked hypophosphatemia (XLH), excess FGF23 impairs renal phosphate reabsorption and suppresses production of 1,25-dihydroxyvitamin D, resulting in chronic hypophosphatemia and persistent osteomalacia. Osteomalacia is associated with poor bone quality causing atraumatic fractures, pseudofractures, delayed fracture healing, and bone pain. Burosumab is a fully human monoclonal antibody against FGF23. UX023-CL304 is an ongoing, open-label, single-arm, phase 3 study investigating the efficacy of subcutaneous burosumab, 1.0 mg/kg administered every 4 weeks, in improving osteomalacia in adults with XLH who have not been treated for at least 2 years before enrollment. The primary endpoint was improvement in osteoid volume/bone volume assessed by transiliac bone biopsies obtained at baseline and week 48. Additional assessments included serum phosphorus, markers of bone turnover, fracture/pseudofracture healing, and safety. Fourteen subjects enrolled, 13 completed 48 weeks, and 11 completed paired biopsies. All osteomalacia-related histomorphometric measures improved significantly at week 48 (mean percent change: osteoid volume/bone volume, -54%, osteoid thickness, -32%, osteoid surface/bone surface, -26%, [median] mineralization lag time, -83%). Mean serum phosphorus concentration averaged across the mid-point of the dose cycle between weeks 0 and 24 was 3.3 mg/dL, a 50% increase from 2.2 mg/dL at baseline. Markers of bone formation and resorption increased at week 48 (least squares [LS] mean increase: P1NP, +77%; CTx, +36%; both p < 0.0001). All subjects had one or more treatment-emergent adverse event (AE). Most AEs were mild to moderate in severity. Two subjects experienced serious AEs (migraine; paresthesia) that were unrelated to treatment and resolved. Eleven subjects had 18 biopsy procedure-related AEs: 14 for pain, two for itch, and one each for headache and bandage irritation. No deaths or incidents of hyperphosphatemia occurred. In conclusion, by normalizing phosphate homeostasis, burosumab significantly improved osteomalacia in adults with XLH, which likely explains the improved fracture healing and amelioration of skeletal complications. © 2019 The Authors. Journal of Bone and Mineral Research published by American Society for Bone and Mineral Research.

Wnt1 is an Lrp5-independent bone-anabolic Wnt ligand

WNT1 mutations in humans are associated with a new form of osteogenesis imperfecta and with early-onset osteoporosis, suggesting a key role of WNT1 in bone mass regulation. However, the general mode of action and the therapeutic potential of Wnt1 in clinically relevant situations such as aging remain to be established. Here, we report the high prevalence of heterozygous WNT1 mutations in patients with early-onset osteoporosis. We show that inactivation of Wnt1 in osteoblasts causes severe osteoporosis and spontaneous bone fractures in mice. In contrast, conditional Wnt1 expression in osteoblasts promoted rapid bone mass increase in developing young, adult, and aged mice by rapidly increasing osteoblast numbers and function. Contrary to current mechanistic models, loss of Lrp5, the co-receptor thought to transmit extracellular WNT signals during bone mass regulation, did not reduce the bone-anabolic effect of Wnt1, providing direct evidence that Wnt1 function does not require the LRP5 co-receptor. The identification of Wnt1 as a regulator of bone formation and remodeling provides the basis for development of Wnt1-targeting drugs for the treatment of osteoporosis.

Low Vitamin D Status Is Associated With Impaired Bone Quality and Increased Risk of Fracture-Related Hospitalization in Older Australian Women

The vitamin D debate relates in part to ideal public health population levels of circulating 25-hydroxyvitamin D (25OHD) to maintain bone structure and reduce fracture. In a secondary analysis of 1348 women aged 70 to 85 years at baseline (1998) from the Perth Longitudinal Study of Aging in Women (a 5-year calcium supplementation trial followed by two 5-year extensions), we examined the dose-response relations of baseline plasma 25OHD with hip DXA BMD at year 1, lumbar spine BMD, and trabecular bone score (TBS) at year 5, and fracture-related hospitalizations over 14.5 years obtained by health record linkage. Mean baseline plasma 25OHD was 66.9 ± 28.2 nmol/L and 28.5%, 36.4%, and 35.1% of women had levels <50, 50 to 74.9, and ≥75 nmol/L, respectively. Generalized additive models showed that total hip and femoral neck BMD and TBS, but not spine BMD, were higher with increasing plasma 25OHD up to 100 nmol/L. Compared with those with 25OHD <50 nmol/L, women with 25OHD ≥75 nmol/L had significantly higher total hip and femoral neck BMD at year 1 (3.3% to 3.9%) and TBS at year 5 (2.0%), all P < 0.05. During the follow-up, 27.6% of women experienced any fracture-related hospitalization and 10.6% hip fracture-related hospitalization. Penalized spline regression models showed a decrease in risk with increased 25OHD levels up to 65 nmol/L and 75 nmol/L for hip fracture and any fracture-related hospitalization, respectively. Cox regression grouped analyses showed that compared with women with 25OHD <50 nmol/L, those with 25OHD levels 50 to 74.9 and ≥75 nmol/L had significantly lower risk for hip fracture [HR 0.60 (95% CI, 0.40 to 0.91) and 0.61 (95% CI, 0.40 to 0.92), respectively], and any fracture-related hospitalization [HR 0.77 (95% CI, 0.59 to 0.99) and 0.70 (95% CI, 0.54 to 0.91), respectively]. In older white women, 25OHD levels >50 nmol/L are a minimum public health target and 25OHD levels beyond 75 nmol/L may not have additional benefit to reduce fracture risk. © 2019 American Society for Bone and Mineral Research.

Benefit-risk balance of native vitamin D supplementation in chronic hemodialysis: what can we learn from the major clinical trials and international guidelines?

For some years, there has been a great renewal of interest in native vitamin D and its major involvement in osseous and non-osseous effects in the organism. Patients in chronic hemodialysis (CHD) constitute a specific population with different physiopathologic characteristics and needs, since morbidity and mortality are strongly correlated with vitamin D insufficiency. Vitamin D supplementation raises very pertinent questions for which we have only partial answers and we lack solid scientific proof to establish certain truths. Thus, we try through this mini-review to analyze the results of the main randomized clinical trials conducted during the last decade, and to discuss international guidelines concerning native vitamin D supplementation in CHD patients. Seven double-blind randomized clinical trials have evaluated native Vitamin D supplementation in CHD patients. These clinical trials began between 2007 and 2013 and studied relatively small samples of patients with an average of 50. All of these trials are important, but do not provide sufficient scientific proof concerning the advantages, consequences, and secondary effects of native vitamin D supplementation in CHD. None of the European, American, English, Asian, Australian, or Canadian recommendations have specified the targets, doses, duration, or the molecule of vitamin D supplementation in the patient on CHD. In 2017, the long-awaited KDIGO recommendations were published and despite the results of clinical trials conducted, the recommendations on native vitamin D supplementation in CHD were very imprecise and sparse, limited to suggesting correction of any state of vitamin D insufficiency or deficiency.

Spontaneous bilateral femoral neck fractures in a young male adult: a case report and literature review

Background

Simultaneous bilateral femoral neck fracture is a very rare condition, even in osteoporotic elderly individuals. We report an atypical case of a young male adult who developed simultaneous bilateral femoral neck fractures without previous trauma or overuse.

Case presentation

A 33-year-old man presented with discomfort in the bilateral groin, which had started 2 weeks previously. Bilateral femoral neck fractures were observed on a radiograph, and in addition, a fracture line was seen at the right subchondral region of the acetabulum using magnetic resonance imaging (MRI). Although the patient had no obvious risk factors associated with bone fragility, his bone mineral density measured using dual X-ray absorptiometry indicated severe osteoporosis (lumber spine: T score − 3.4 standard deviation [SD]; femoral neck: T score − 2.8 SD). Serum 25-hydroxyvitamin D level was deficient (19 ng/mL), which was considered to be partly due to non-sunlight exposure for 3 years owing to social withdrawal. Bilateral osteosynthesis was performed, considering his young age, although more than 2 weeks had passed since the onset of the fracture. Bone union and non-occurrence of osteonecrosis of the femoral head were confirmed via radiography and MRI 8 months after the surgery.

Conclusions

Our case suggests that simultaneous non-traumatic bilateral femoral neck fractures can occur in healthy young men.

From Osteoclast Differentiation to Osteonecrosis of the Jaw: Molecular and Clinical Insights

Bone physiology relies on the delicate balance between resorption and formation of its tissue. Bone resorption depends on a process called osteoclastogenesis in which bone-resorbing cells, i.e., osteoclasts, are produced by the differentiation of more undifferentiated progenitors and precursors. This process is governed by two main factors, monocyte-colony stimulating factor (M-CSF) and receptor activator of NFκB ligand (RANKL). While the former exerts a proliferating effect on progenitors/precursors, the latter triggers a differentiation effect on more mature cells of the same lineage. Bone homeostasis requires a perfect space–time coordination of the involved signals. When osteoclastogenesis is poorly balanced with the differentiation of the bone forming counterparts, i.e., osteoblasts, physiological bone remodelling can turn into a pathological state, causing the systematic disruption of bone tissue which results in osteopenia or osteolysis. Examples of these conditions are represented by osteoporosis, Paget’s disease, bone metastasis, and multiple myeloma. Therefore, drugs targeting osteoclastogenesis, such as bisphosphonates and an anti-RANKL monoclonal antibody, have been developed and are currently used in the treatment of such diseases. Despite their demonstrated therapeutic efficacy, these agents are unfortunately not devoid of side effects. In this regard, a condition called osteonecrosis of the jaw (ONJ) has been recently correlated with anti-resorptive therapy. In this review we will address the involvement of osteoclasts and osteoclast-related factors in the pathogenesis of ONJ. It is to be hoped that a better understanding of the biological mechanisms underlying bone remodelling will help in the design a medical therapeutic approach for ONJ as an alternative to surgical procedures.

Recovery of bone mineralization and quality during asfotase alfa treatment in an adult patient with infantile-onset hypophosphatasia

Hypophosphatasia (HPP) is a hereditary musculoskeletal disorder characterized by low serum alkaline phosphatase (ALP) activity leading to poor bone mineralization. On a micro-morphological level, this may not only be reflected by an enrichment of osteoid but also a degradation of bone quality. Asfotase alfa is an enzyme replacement therapy that was recently demonstrated to improve bone mineralization as well as clinical status (e.g. growth, muscle strength and quality of life). However, the underlying changes of bone quality parameters on asfotase alfa treatment are currently not known. In the present study, we report a 24-year-old woman with genetically confirmed infantile-onset HPP and recurrent fractures. While the initiated asfotase alfa treatment was followed by rapid clinical improvements (i.e., disappearance of bone marrow edema, increase of muscle strength), the BMD assessed by DXA at the hip and spine increased moderately at two years follow-up. A detailed skeletal assessment using high-resolution peripheral quantitative computed tomography (HR-pQCT) and a high-resolution analysis of two consecutive iliac crest bone biopsies revealed only minor improvements of bone microarchitecture but a remarkable reduction of osteoid parameters. Furthermore, the high mineralization heterogeneity at baseline assessed by quantitative backscattered electron imaging (qBEI) decreased after 2 year of asfotase alfa treatment. Finally, we found an increase in mineral maturation reflected by higher mineral-to-matrix and carbonate-to-phosphate ratios using Fourier transform infrared spectroscopy (FTIR) imaging as well as increased local mechanical properties using reference point indentation (RPI). Taken together, our findings provide evidence for an improvement of bone quality indices beyond the mere reduction of osteoid indices and thereby contribute to the understanding of fracture risk reduction in HPP patients on asfotase alfa treatment.

[Osteomalacia-Clinical aspects, diagnostics and treatment]

Osteomalacia is a bone disease caused by impaired skeletal mineralization. Vitamin D dependent types have to be distinguished from hypophosphatemic forms. Typical signs and symptoms include diffuse bone pain, muscle weakness and fragility fractures. The fracture pattern in osteomalacia is typically different from that of osteoporosis. Fragility fractures of the pelvis, sacrum, distal parts of the foot, proximal tibia and ribs are indicators for osteomalacia, whereas femoral neck and vertebral fractures (wedged vertebra, fish vertebra, vertebra plana and cover plate impression fractures) are typical for osteoporosis. Unspecific clinical features may be the reason for a delayed diagnosis. The correct classification of the complaint is dependent on the knowledge of the pathophysiology of osteomalacia and performance of additional bone-specific examinations. Determination of specific laboratory parameters should follow a rational algorithm, supplemented by imaging methods and a bone biopsy.

Ultra-high matrix mineralization of sperm whale auditory ossicles facilitates high sound pressure and high-frequency underwater hearing

The auditory ossicles-malleus, incus and stapes-are the smallest bones in mammalian bodies and enable stable sound transmission to the inner ear. Sperm whales are one of the deepest diving aquatic mammals that produce and perceive sounds with extreme loudness greater than 180 dB and frequencies higher than 30 kHz. Therefore, it is of major interest to decipher the microstructural basis for these unparalleled hearing abilities. Using a suite of high-resolution imaging techniques, we reveal that auditory ossicles of sperm whales are highly functional, featuring an ultra-high matrix mineralization that is higher than their teeth. On a micro-morphological and cellular level, this was associated with osteonal structures and osteocyte lacunar occlusions through calcified nanospherites (i.e. micropetrosis), while the bones were characterized by a higher hardness compared to a vertebral bone of the same animals as well as to human auditory ossicles. We propose that the ultra-high mineralization facilitates the unique hearing ability of sperm whales. High matrix mineralization represents an evolutionary conserved or convergent adaptation to middle ear sound transmission.

Outcome of Teriparatide Treatment on Fracture Healing Complications and Symptomatic Bone Marrow Edema in Four Adult Patients With Hypophosphatasia

The response to teriparatide has been described in very few cases of hypophosphatasia (HPP). In this cross‐sectional study, we report the prevalence of symptomatic bone marrow edema (BME) and fracture healing complications in a large cohort of childhood and adult HPP patients and discuss the results of teriparatide treatment in four cases. From 2016 to 2018, 51 patients with a diagnosis of HPP were seen at our institution. The diagnosis of HPP was established by low serum alkaline phosphatase (ALP), elevated serum pyridoxal‐5‐phosphate (PLP), at least one typical clinical symptom of HPP and supported by ALPL mutation analysis. In this study cohort, 28 (56%) and 14 (27%) patients had a history of fracture or a history of BME, respectively. Four patients, including middle‐aged to elderly women and men who all presented with persistent symptomatic BME or fracture healing complications, were treated with teriparatide. DXA was performed prior to treatment and laboratory values were measured on a regular basis during treatment. Treatment with teriparatide showed variable effects in terms of clinical and biochemical response. Although all four patients displayed a temporary increase in ALP activity, only two patients with a mild form of adult HPP and moderately increased PLP levels showed definite clinical and radiological improvement after teriparatide treatment. In conclusion, fracture healing complications and BME occur frequently in HPP patients. Teriparatide shows variable clinical and biochemical effects depending on the severity of the disease. PLP levels and the number of ALPL alleles might be good parameters to predict treatment outcomes. © 2019 The Authors. JBMR Plus Published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research

Elite athletes as research model: vitamin D insufficiency associates with elevated central blood pressure in professional handball athletes

PURPOSE

Low vitamin D levels have been associated with elevated blood pressure in the general population. Prospective studies, however, have produced conflicting evidence about the blood pressure-lowering effects of vitamin D supplementation. Cardiorespiratory fitness may modulate the vitamin D-blood pressure association. We therefore examined this association in professional athletes, whose high training load serves as a biological control for physical fitness.

METHODS

50 male professional handball players (age 26 ± 5 years) were examined. We assessed the central aortic pressure parameters using transfer function-based analysis of oscillometrically obtained peripheral arterial waveforms. Serum 25-OH vitamin D concentrations were determined by chemiluminescent immunoassay. The threshold for insufficiency was set at values of < 30 ng/mL.

RESULTS

Central blood pressure (cBP) was 98 ± 7/60 ± 10 mmHg. The aortic pulse wave velocity (PWV) was 6.3 ± 1.0 m/s. Nine athletes (18%) displayed insufficient 25-OH vitamin D levels and had a significantly (p < 0.01) higher cBP compared with the 41 (82%) athletes with sufficient 25-OH vitamin D levels (106 ± 5/68 ± 8 vs. 97 ± 7/58 ± 9 mmHg). Central systolic blood pressure (cSBP) in vitamin D-sufficient athletes was significantly lower in comparison to the healthy reference population (97 mmHg vs. 103 mmHg, p < 0.001). This significance of difference was lost in vitamin D-insufficient athletes (106 mmHg vs. 103 mmHg, p = 0.12).

CONCLUSION

Significantly raised central systolic and diastolic blood pressure in vitamin D-insufficient elite athletes implicates vitamin D as a potential modifier of vascular functional health.

Skeletal and Extraskeletal Actions of Vitamin D: Current Evidence and Outstanding Questions

The etiology of endemic rickets was discovered a century ago. Vitamin D is the precursor of 25-hydroxyvitamin D and other metabolites, including 1,25(OH)2D, the ligand for the vitamin D receptor (VDR). The effects of the vitamin D endocrine system on bone and its growth plate are primarily indirect and mediated by its effect on intestinal calcium transport and serum calcium and phosphate homeostasis. Rickets and osteomalacia can be prevented by daily supplements of 400 IU of vitamin D. Vitamin D deficiency (serum 25-hydroxyvitamin D <50 nmol/L) accelerates bone turnover, bone loss, and osteoporotic fractures. These risks can be reduced by 800 IU of vitamin D together with an appropriate calcium intake, given to institutionalized or vitamin D-deficient elderly subjects. VDR and vitamin D metabolic enzymes are widely expressed. Numerous genetic, molecular, cellular, and animal studies strongly suggest that vitamin D signaling has many extraskeletal effects. These include regulation of cell proliferation, immune and muscle function, skin differentiation, and reproduction, as well as vascular and metabolic properties. From observational studies in human subjects, poor vitamin D status is associated with nearly all diseases predicted by these extraskeletal actions. Results of randomized controlled trials and Mendelian randomization studies are supportive of vitamin D supplementation in reducing the incidence of some diseases, but, globally, conclusions are mixed. These findings point to a need for continued ongoing and future basic and clinical studies to better define whether vitamin D status can be optimized to improve many aspects of human health. Vitamin D deficiency enhances the risk of osteoporotic fractures and is associated with many diseases. We review what is established and what is plausible regarding the health effects of vitamin D.

La-Doped mesoporous calcium silicate/chitosan scaffolds for bone tissue engineering

Trace rare earth elements such as lanthanum (La) regulated effectively bone tissue performances; however, the underlying mechanism remains unknown. In order to accelerate bone defects especially in patients with osteoporosis or other metabolic diseases, we firstly constructed lanthanum-doped mesoporous calcium silicate/chitosan (La-MCS/CTS) scaffolds by freeze-drying technology. During the freeze-drying procedure, three-dimensional macropores were produced within the La-MCS/CTS scaffolds by using ice crystals as templates, and the La-MCS nanoparticles were distributed on the macropore walls. The hierarchically porous structures and biocompatible components contributed to the adhesion, spreading and proliferation of rat bone marrow-derived mesenchymal stem cells (rBMSCs), and accelerated the in-growth of new bone tissues. Particularly, the La3+ ions in the bone scaffolds remarkably induced the osteogenic differentiation of rBMSCs via the activation of the TGF signal pathway. A critical-sized calvarial-defect rat model further revealed that the La-MCS/CTS scaffolds significantly promoted new bone regeneration as compared with pure MCS/CTS scaffolds. In conclusion, the La-MCS/CTS scaffold showed the prominent ability in osteogenesis and bone regeneration, which showed its application potential for bone defect therapy.

How To Build a Bone: PHOSPHO1, Biomineralization, and Beyond

Since its characterization two decades ago, the phosphatase PHOSPHO1 has been the subject of an increasing focus of research. This work has elucidated PHOSPHO1's central role in the biomineralization of bone and other hard tissues, but has also implicated the enzyme in other biological processes in health and disease. During mineralization PHOSPHO1 liberates inorganic phosphate (P_i) to be incorporated into the mineral phase through hydrolysis of its substrates phosphocholine (PCho) and phosphoethanolamine (PEA). Localization of PHOSPHO1 within matrix vesicles allows accumulation of P_i within a protected environment where mineral crystals may nucleate and subsequently invade the organic collagenous scaffold. Here, we examine the evidence for this process, first discussing the discovery and characterization of PHOSPHO1, before considering experimental evidence for its canonical role in matrix vesicle–mediated biomineralization. We also contemplate roles for PHOSPHO1 in disorders of dysregulated mineralization such as vascular calcification, along with emerging evidence of its activity in other systems including choline synthesis and homeostasis, and energy metabolism. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Temporal increases in 25-hydroxyvitamin D in midlife women: Longitudinal results from the Study of Women's Health Across the Nation

OBJECTIVE

25-hydroxyvitamin D (25(OH)D) is critical for bone mineralization and may prevent fractures. Understanding vitamin D deficiency trends in midlife women is particularly important given their concurrent menopausal changes that increase risk for fracture. We aimed to evaluate changes in mean 25(OH)D over time and their determinants in a racially, ethnically and socioeconomically diverse cohort of midlife women.

DESIGN

A multi-centre prospective cohort study.

PATIENTS

1585 women ages 42-52 years at baseline.

MEASUREMENTS

We measured serum 25(OH)D at 2 time points (1998-2000 and 2009-2011). Between-visit change was assessed in the whole cohort and in socioeconomic and demographic subgroups. Among those with vitamin D deficiency (25(OH)D <30 nmol/L) at baseline, we evaluated determinants of persistent deficiency at follow-up.

RESULTS

Mean 25(OH)D increased from 53.8 to 70.0 nmol/L (P < 0.001), and the prevalence of deficiency decreased from 20.4% to 9.7% (P < 0.001). While baseline 25(OH)D differed among subgroups, the changes in 25(OH)D were similar among groups. The proportion of women reporting dietary supplement use increased from 40.8% to 67.1% (P < 0.001), and the increase in 25(OH)D was significantly higher in supplement users. Among women with vitamin D deficiency at baseline, White women and supplement users were less likely to remain deficient at follow-up.

CONCLUSIONS

Among midlife women, temporal increases in 25(OH)D concentrations are driven largely by increases in supplement use. The proportion of women with 25(OH)D <30 nmol/L and thus at high risk for skeletal consequences remains substantial. Targeted screening for vitamin D deficiency in populations at risk for fragility fracture may be advisable.

Hypovitaminosis D: Is It Time to Consider the Use of Calcifediol?

Hypovitaminosis D is becoming a notable health problem worldwide. A consensus exists among several different medical societies as to the need for adequate levels of vitamin D for bone and general health. The correct method by which to restore normal vitamin D levels is still a matter of debate. Although cholecalciferol remains the most commonly distributed form of vitamin D supplementation worldwide, several drugs with vitamin D activity are available for clinical use, and making the correct selection for the individual patient may be challenging. In this narrative review, we aim to contribute to the current knowledge base on the possible and appropriate use of calcifediol-the 25-alpha-hydroxylated metabolite-in relation to its chemical characteristics, its biological properties, and its pathophysiological aspects. Furthermore, we examine the trials that have aimed to evaluate the effect of calcifediol on the restoration of normal vitamin D levels. Calcifediol is more soluble than cholecalciferol in organic solvents, due to its high polarity. Good intestinal absorption and high affinity for the vitamin-D-binding protein positively affect the bioavailability of calcifediol compared with cholecalciferol. In particular, orally administered calcifediol shows a much shorter half-life than oral cholecalciferol. Most findings suggest that oral calcifediol is about three- to five-fold more powerful than oral cholecalciferol, and that it has a higher rate of intestinal absorption. Accordingly, calcifediol can be particularly useful in treating diseases associated with decreased intestinal absorption, as well as obesity (given its lower trapping in the adipose tissue) and potentially neurological diseases treated with drugs that interfere with the hepatic cytochrome P-450 enzyme system, resulting in decreased synthesis of calcifediol. Up to now, there has not been enough clinical evidence for its use in the context of osteoporosis treatment.

Determinants of vitamin D status of healthy office workers in Sydney, Australia

Low vitamin D status, measured as 25-hydroxyvitamin D (25OHD), has been linked to increased risk of osteoporosis and other disorders. Due to the indoor nature of office work, there may be an increased risk of 25OHD deficiency in this group. The aim of the current study was to evaluate seasonal variations of 25OHD in a population of healthy office workers, and to assess the effect of sun exposure behaviour, skin pigmentation, physical activity (PA) and dietary intake on serum 25OHD concentrations. We assessed the vitamin D status of healthy office workers in Sydney, Australia, at the end of summer (n = 103) and then at the end of winter (n = 71). Data on anthropometry, PA, dietary intake, sun exposure and skin phototype were collected along with blood samples. Serum 25OHD was measured by radioimmunoassay. Mean 25OHD concentration in late summer was 68 ± 27 nmol/L (range: 24-160 nmol/L), and in late winter was 59 ± 32 nmol/L (range: 15-174 nmol/L). 25OHD deficiency (<50 nmol/L) was observed in 29% and 42% of participants at end-summer and end-winter, respectively. Almost 10% of individuals were extremely deficient (<25 nmol/L) at end-winter, particularly those with dark skin (phototypes 5 and 6). Independent predictors of end-summer 25OHD were skin phototype (p < 0.02), summer sun exposure (p < 0.001) and skin area exposed (p = 0.005). The strongest predictor of end-winter 25OHD was end-summer 25OHD concentration (p < 0.001). If this was excluded from the model, the independent predictors of end-winter 25OHD were skin phototype (p < 0.01), sun exposure in winter (p = 0.01) and oily fish consumption (p < 0.05). Sunscreen use was significantly associated with higher vitamin D status (p < 0.05) as those who used sunscreen were also more likely to spend time outdoors. We conclude that sun exposure is beneficial for vitamin D status even with sunscreen use. Vitamin D supplements should be targeted to individuals who are darker skinned or unable to obtain adequate sun exposure, particularly during the winter months.

Spot the silent sufferers: A call for clinical diagnostic criteria for solar and nutritional osteomalacia

Osteomalacia and rickets result from defective mineralization when the body is deprived of calcium. Globally, the main cause of osteomalacia is a lack of mineral supply for bone modeling and remodeling due to solar vitamin D and/or dietary calcium deficiency. Osteomalacia occurs when existing bone is replaced by unmineralized bone matrix (osteoid) during remodeling in children and adults, or when newly formed bone is not mineralized in time during modeling in children. Rickets occurs when hypomineralization affects the epiphyseal growth plate chondrocytes and adjacent bone metaphysis in growing children. Hence, osteomalacia co-exists with rickets in growing children. Several reports in the last decade highlight the resurgence of so-called "nutritional" rickets in the dark-skinned population living in high-income countries. However, very few studies have ever explored the hidden iceberg of nutritional osteomalacia in the population. Rickets presents with hypocalcaemic (seizures, tetany, cardiomyopathy), or hypophosphataemic complications (leg bowing, knock knees, rachitic rosary, muscle weakness) and is diagnosed on radiographs (cupping and fraying of metaphyses). In contrast, osteomalacia lacks distinctive, non-invasive diagnostic laboratory or imaging criteria and the clinical presentation is non-specific (general fatigue, malaise, muscle weakness and pain). Hence, osteomalacia remains largely undiagnosed, as a hidden disease in millions of dark-skinned people who are at greatest risk. Radiographs may demonstrate Looser's zone fractures in those most severely affected, however to date, osteomalacia remains a histological diagnosis requiring a bone biopsy. Biochemical features of high serum alkaline phosphatase (ALP), high parathyroid hormone (PTH) with or without low 25 hydroxyvitamin D (25OHD) concentrations are common to both rickets and osteomalacia. Here, we propose non-invasive diagnostic criteria for osteomalacia. We recommend a diagnosis of osteomalacia in the presence of high ALP, high PTH, low dietary calcium intake (<300 mg/day) and/or low serum 25OHD (<30 nmol/L). Presence of clinical symptoms (as above) or Looser's zone fractures should be used to reaffirm the diagnosis. We call for further studies to explore the true prevalence of nutritional osteomalacia in various populations, specifically the Black and Asian ethnic groups, in order to identify the hidden disease burden and inform public health policies for vitamin D/calcium supplementation and food fortification.

Is vitamin D deficiency a risk factor for osteonecrosis of the jaw in patients with cancer? A matched case-control study

PURPOSE

A previous case-control histomorphometric study showed higher odds of osteomalacia in patients with bisphosphonate-related osteonecrosis of the jaw (BRONJ). Vitamin D deficiency causes osteomalacia and may therefore be involved in the pathogenesis of BRONJ. The present case-control study aimed at testing such hypothesis.

MATERIALS AND METHODS

BRONJ+ and BRONJ- patients treated with bisphosphonates were matched by sex (same) and age (within 5 years). Serum 25-hydroxy-vitamin D (25-OH-D), parathyroid hormone, bone alkaline phosphatase, total procollagen type 1 amino-terminal propeptide, carboxy-terminal collagen crosslinks, Dickkopf WNT signaling pathway inhibitor 1 and sclerostin were measured.

RESULTS

The main outcome was vitamin D deficiency defined as 25-OH-D < 50 nmol/l. A total of 51 BRONJ+ and 73 BRONJ- patients were studied. The frequency (95% CI) of vitamin D deficiency was 59% (45%-72%) in BRONJ+ and 62% (48%-75%) in BRONJ- patients. This amounts to a difference of -3% (-22%-16%, p = 0.77) for BRONJ+ patients. Serum 25-hydroxy-vitamin D and parathyroid hormone were similar in BRONJ+ and BRONJ- patients. Among the bone metabolism markers, only sclerostin differed between the two groups, being higher in BRONJ+ patients.

CONCLUSION

The present matched case-control study suggests that vitamin D deficiency is not a risk factor for BRONJ.

Vitamin D and the Skin: A Review for Dermatologists

In recent years, the growing interest in the role played by vitamin D in skin disease has given rise to the publication of many studies of the relationship between this vitamin and certain skin conditions. As dermatologists, we need to understand, among other aspects, how vitamin D is synthesized and the main sources in humans, as well as plasma levels and the factors that can modify them. Of particular interest are the latest discoveries about the role of vitamin D in skin diseases such as lupus erythematosus, ichthyosis, atopic dermatitis, hidradenitis suppurativa, acne, alopecia areata, androgenetic alopecia, melanoma, and nonmelanoma skin cancer. Also of interest is the importance of vitamin D as adjuvant therapy in patients on long-term treatment with corticosteroids. In this review, we provide an overview of the most important and most recent information regarding the relationship between vitamin D and skin disease and discuss the importance of assessing individual vitamin D status and correcting deficiencies.

Parameters of Bone and Cardiovascular Health Related to 25-Hydroxyvitamin D Status in Emirati Nationals attending Primary Care and Diabetes services: a retrospective cohort study

Vitamin D deficiency is endemic in people living in the Gulf states. We performed a retrospective analysis of data gathered at the first attendance of 82,396 Emirati nationals to outpatient diabetes, endocrinology and general primary care services at two centres in the United Arab Emirates during 2012–2016. Our aim was to explore associations between vitamin D status and markers of cardiovascular and bone health. In the study population, 67.1% of men and 73.5% of women had serum 25(OH)D of less than 50 nmol/L, with the lowest levels being found in young adults. Among Emirati adults with type 2 diabetes, serum 25(OH)D < 50 nmol/L was associated with an increased risk of a coexisting adverse total cholesterol:HDL (TC:HDL) ratio (odds ratio 2.13 (1.60–2.84), p < 0.001). Correcting for age, sex, body mass index, HbA1c and statin therapy, an increase in 25(OH)D of 1 nmol/L was associated with a 0.01 unit reduction in TC:HDL in this population. In a subset of 1064 adult individuals, 25(OH)D < 25 nmol/L was associated with a reduction in DEXA-measured z-score of −0.29 (−0.44 to −0.15, p < 0.001) at the femoral neck and of −0.25(−0.45 to −0.05, p = 0.015) at L1–4, corrected for body mass index, compared with individuals with 25(OH)D ≥ 75 nmol/L. Our findings raise concerns regarding lifetime burden of cardiovascular disease and bone health for young Emiratis with vitamin D deficiency.

Association between Vitamin D Levels and Nonalcoholic Fatty Liver Disease: Potential Confounding Variables

Nonalcoholic fatty liver disease (NAFLD), historically considered to be the hepatic component of the metabolic syndrome, is a spectrum of fat-associated liver conditions, in the absence of secondary causes, that may progress to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Disease progression is closely associated with body weight or fatness, dyslipidemia, insulin resistance, oxidative stress, and inflammation. Recently, vitamin D deficiency has been linked to the pathogenesis and severity of NAFLD because of vitamin D "pleiotropic" functions, with roles in immune modulation, cell differentiation and proliferation, and regulation of inflammation. Indeed, several studies have reported an association between vitamin D and NAFLD/NASH. However, other studies have failed to find an association. Therefore, we sought to critically review the current evidence on the association between vitamin D deficiency and NAFLD/NASH, and to analyze and discuss some key variables that may interfere with this evaluation, such as host-, environment-, and heritability-related factors regulating vitamin D synthesis and metabolism; definitions of deficient or optimal vitamin D status with respect to skeletal and nonskeletal outcomes including NAFLD/NASH; methods of measuring 25(OH)D; and methods of diagnosing NAFLD as well as quantifying adiposity, the cardinal link between vitamin D deficiency and NAFLD.

Micronutrient deficiencies and health-related quality of life: the case of children with vitamin D deficiency

OBJECTIVE

To explore the extent to which micronutrient deficiencies (MND) affect children's health-related quality of life (HRQoL), using vitamin D deficiency (VDD) as a case study.

DESIGN

Proxy valuation study to estimate the impact of VDD on the HRQoL of younger (0-4 years) and older (>4 years) children. We used the Child Health Utility 9 Dimension (CHU9D) questionnaire to estimate HRQoL for children within six VDD-related health states: 'hypocalcaemic cardiomyopathy', 'hypocalcaemic seizures', 'active rickets', 'bone deformities', 'pain and muscle weakness' and 'subclinical VDD'.

SETTING

Sampling was not restricted to any particular setting and worldwide experts were recruited.

PARTICIPANTS

Respondents were paediatric bone experts recruited through network sampling.

RESULTS

Thirty-eight experts completed the survey. The health state with the largest detrimental impact (mean score (se)) on children's HRQoL was hypocalcaemic cardiomyopathy (0·47 (0·02)), followed by hypocalcaemic seizures (0·50 (0·02)) and active rickets (0·62 (0·02) in young children; 0·57 (0·02) in older children). Asymptomatic VDD had a modest but noticeable negative impact on HRQoL, attributed mostly to tiredness in both age groups and pain in the older paediatric population.

CONCLUSIONS

Elicitation of HRQoL from clinical experts suggests a negative impact of VDD on HRQoL, even if there is no recognizable clinical manifestation. HRQoL data from populations of patients with MND will inform public health policy decisions. In some settings, routine collection of HRQoL data alongside national nutrition surveys may help capture the full burden of MND and prioritize resources towards effective prevention.

High prevalence of vitamin D insufficiency in professional handball athletes

OBJECTIVES

Vitamin D affects multiple body functions through the regulation of gene expression. In sports medicine, its influence on musculoskeletal health and performance is of particular interest. Vitamin D insufficiency might decrease athletic performance and increase the risk of musculoskeletal injuries. Several studies have demonstrated vitamin D deficiency in professional athletes; however, the prevalence of vitamin D insufficiency in professional handball players is yet unknown.

METHODS

The study was planned as a prospective, non-interventional study. We examined 70 male elite handball athletes (first league) in a pre-competition medical assessment in July. Age, height, weight, body mass index, 25-OH vitamin D, calcium, and parathyroid hormone were evaluated, and a sun exposure score was calculated. Players were then divided into two groups of vitamin D levels: insufficient (<30 ng/mL) and sufficient (≥30 ng/mL).

RESULTS

The mean 25-OH vitamin D level of the 70 players was 33.5 ± 10.9 ng/mL (median 32.2, IQR 26.5-38.9 ng/mL). Thirty-nine (55.7%) had sufficient and 31 (44.3%) insufficient levels. Athletes with sufficient vitamin D levels had significantly lower parathyroid hormone levels than athletes with insufficiency (24.9 ± 12.1 vs. 33.5 ± 15.1 ng/mL, p = 0.02). All other parameters evaluated demonstrated no significant difference between the two groups.

CONCLUSION

Vitamin D insufficiency is a common finding in professional handball athletes even in summer, which might negatively affect physical performance. Furthermore, it might lead to an increased risk of musculoskeletal injuries and infections. This should be evaluated in further studies.

Osteological evidence of metabolic diseases from a post medieval North Italy archaeological site

Skeletal lesions related to metabolic diseases in children have been systematically investigated in paleopathological literature only in recent years. This work presents an infant pathological specimen from the post-medieval cemetery of the St. Mary's Nativity church (15th-18th centuries, Segno, Trento, Trentino, Northeast Italy). The bones belonged to an individual of 9 ± 3 months of age, estimated upon an assessment of the stage of dental eruption. Metabolic diseases were diagnosed with paleopathological criteria according to previous literature. Differential diagnosis of the osteological evidence indicates a disease that might be caused by the lack of vitamin D or C. Comorbidity of vitamin C and D deficiency has been widely studied in clinical literature, particularly in children between 3 months and 5 years of age. The study of ancient osteoarchaeological materials allows us to improve our knowledge on diseases' effects on bone development in children and, in this case, it represents additional evidence of the presence of metabolic diseases in a rural contest of the Italian post-medieval period.

Vitamin D Binding Protein and the Biological Activity of Vitamin D

Vitamin D has a long-established role in bone health. In the last two decades, there has been a dramatic resurgence in research interest in vitamin D due to studies that have shown its possible benefits for non-skeletal health. Underpinning the renewed interest in vitamin D was the identification of the vital role of intracrine or localized, tissue-specific, conversion of inactive pro-hormone 25-hydroxyvitamin D [25(OH)D] to active 1,25-dihydroxyvitamin D [1,25(OH)₂D]. This intracrine mechanism is the likely driving force behind vitamin D action resulting in positive effects on human health. To fully capture the effect of this localized, tissue-specific conversion to 1,25(OH)₂D, adequate 25(OH)D would be required. As such, low serum concentrations of 25(OH)D would compromise intracrine generation of 1,25(OH)₂D within target tissues. Consistent with this is the observation that all adverse human health consequences of vitamin D deficiency are associated with a low serum 25(OH)D level and not with low 1,25(OH)₂D concentrations. Thus, clinical investigators have sought to define what concentration of serum 25(OH)D constitutes adequate vitamin D status. However, since 25(OH)D is transported in serum bound primarily to vitamin D binding protein (DBP) and secondarily to albumin, is the total 25(OH)D (bound plus free) or the unbound free 25(OH)D the crucial determinant of the non-classical actions of vitamin D? While DBP-bound-25(OH)D is important for renal handling of 25(OH)D and endocrine synthesis of 1,25(OH)₂D, how does DBP impact extra-renal synthesis of 1,25(OH)₂D and subsequent 1,25(OH)₂D actions? Are their pathophysiological contexts where total 25(OH)D and free 25(OH)D would diverge in value as a marker of vitamin D status? This review aims to introduce and discuss the concept of free 25(OH)D, the molecular biology and biochemistry of vitamin D and DBP that provides the context for free 25(OH)D, and surveys in vitro, animal, and human studies taking free 25(OH)D into consideration.

Identification of vitamin D and other bone metabolism parameters as risk factors for primary bone marrow oedema syndrome

Background

The aetiology and pathogenesis of primary bone marrow oedema syndrome (BMES) remain unclear. This retrospective cross-sectional study in a large cohort of patients with BMES was performed to characterise the overall skeletal status and turnover in patients with BMES, with the aim of identifying risk factors for this disease.

Methods

Patients who were diagnosed with BMES on the basis of clinical and radiological (magnetic resonance imaging) findings in our outpatient clinic were identified retrospectively. Patient history, co-existing metabolic disorders, bone metabolism parameters (serum calcium, phosphate, 25-OH-D₃, bone-specific alkaline phosphatase, parathyroid hormone, and osteocalcin, and urinary deoxypyridinoline) and bone mineral density (as measured by dual-energy X-ray absorptiometry) were extracted from the medical records. Patients with secondary causes for BMES were excluded from the study.

Results

Of the 171 patients, 65 were identified without secondary cause for BMES. Of the 65 patients, 61.5% were female. The mean age was 49.5 ± 16.7 years, and age-related BMES prevalence showed two peaks, one in adolescence (11–20 years) and one at an older age (51–70 years). BMES predominantly affected the weight-bearing joints, namely, the ankle/foot (55.1%), knee (22.4%) and proximal femur (16.3%). Thyroid disorders and secondary hyperparathyroidism were highly prevalent (21.5 and 21.4%, respectively). On average, the cohort had elevated deoxypyridinoline levels and low 25-OH-D₃ levels (19.0 ± 7.5 μg/l in patients without vitamin D supplementation). Osteopenia and osteoporosis were diagnosed in 47.4 and 17.5% of patients, respectively.

Conclusions

BMES is associated with high bone turnover. Patients who are diagnosed with BMES should be screened carefully for bone metabolism disorders and their potential risk factors.

Electronic supplementary material

The online version of this article (10.1186/s12891-018-2379-x) contains supplementary material, which is available to authorized users.

Radiographically recognizable? An investigation into the appearance of osteomalacic pseudofractures

Pseudofractures, lucent bands that occur due to a build-up of osteoid, are a key feature of osteomalacia. In paleopathology, pseudofractures are often marked by small, linear cracks in the cortex of the bone surrounded by irregular, bony spicule formation. Radiography can be used to help diagnose pseudofractures, both clinically and in paleopathology. A detailed understanding of the radiographic appearance of pseudofractures and their development is, therefore, necessary to aid a diagnosis of vitamin D deficiency. The present study examined the clinical literature to determine current ideas on the appearance of pseudofractures with the aim of applying this knowledge to paleopathology. A radiographic study of the characteristics of pseudofractures was performed on five individuals with clear skeletal features of osteomalacia from archaeological sites in Canada and the United Kingdom dating to the medieval period (5th to 15th centuries) and the 18th to 19th century. Results show that the radiographic appearance of pseudofractures could potentially reveal information about the cause of the deficiency and the chronicity of pseudofractures. This type of information has the potential to further our understanding of the lived experiences of archaeological individuals with osteomalacia.

Vitamin D's role in health and disease: How does the present inform our understanding of the past?

While the role of vitamin D in supporting bone homeostasis during growth and maintenance is well substantiated, emerging evidence from ecological and observational studies suggests that a deficiency of vitamin D is associated with some cancers, immune disorders, cardiovascular disease, abnormal glucose metabolism, and neurodegenerative diseases. Biological plausibility for extraskeletal functions originated with the discovery of the vitamin D receptor in many body tissues and knowledge that the conversion of 25-hydroxyvitamin D (25(OH)D) to its active metabolite 1,25(OH)₂D occurs in many cell types in addition to the kidney. The association of vitamin D status in humans as an etiological factor in developmental programming of bone, in some chronic diseases, and in all-cause mortality, in addition to skeletal morbidity, is supported by some but not all observational studies and randomized controlled trials. These clinical observations have implications for paleopathology, both in terms of specific comorbidities and the potential role of vitamin D in individuals who display no evidence for skeletal disease. This paper outlines recent clinical research on vitamin D metabolism and its novel biological roles, and explores the possible relevance to paleopathological research designs, theoretical models, and interpretations of disease experience.

The Lysosomal Protein Arylsulfatase B Is a Key Enzyme Involved in Skeletal Turnover

Skeletal pathologies are frequently observed in lysosomal storage disorders, yet the relevance of specific lysosomal enzymes in bone remodeling cell types is poorly defined. Two lysosomal enzymes, ie, cathepsin K (Ctsk) and Acp5 (also known as tartrate-resistant acid phosphatase), have long been known as molecular marker proteins of differentiated osteoclasts. However, whereas the cysteine protease Ctsk is directly involved in the degradation of bone matrix proteins, the molecular function of Acp5 in osteoclasts is still unknown. Here we show that Acp5, in concert with Acp2 (lysosomal acid phosphatase), is required for dephosphorylation of the lysosomal mannose 6-phosphate targeting signal to promote the activity of specific lysosomal enzymes. Using an unbiased approach we identified the glycosaminoglycan-degrading enzyme arylsulfatase B (Arsb), mutated in mucopolysaccharidosis type VI (MPS-VI), as an osteoclast marker, whose activity depends on dephosphorylation by Acp2 and Acp5. Similar to Acp2/Acp5^-/- mice, Arsb-deficient mice display lysosomal storage accumulation in osteoclasts, impaired osteoclast activity, and high trabecular bone mass. Of note, the most prominent lysosomal storage accumulation was observed in osteocytes from Arsb-deficient mice, yet this pathology did not impair production of sclerostin (Sost) and Fgf23. Because the influence of enzyme replacement therapy (ERT) on bone remodeling in MPS-VI is still unknown, we additionally treated Arsb-deficient mice by weekly injection of recombinant human ARSB from 12 to 24 weeks of age. We found that the high bone mass phenotype of Arsb-deficient mice and the underlying bone cell deficits were fully corrected by ERT in the trabecular compartment. Taken together, our results do not only show that the function of Acp5 in osteoclasts is linked to dephosphorylation and activation of lysosomal enzymes, they also provide an important proof-of-principle for the feasibility of ERT to correct bone cell pathologies in lysosomal storage disorders. © 2018 The Authors. Journal of Bone and Mineral Research Published by Wiley Periodicals Inc.

Prevalence of vitamin D deficiency amongst soccer athletes and effects of 8 weeks supplementation

BACKGROUND

High prevalence of vitamin D deficiency is well known around the world in risk populations. Although less is known about the athletic population, some studies report vitamin D deficiency amongst athletic population and adequate vitamin D levels are crucial for athletic population as they can prevent injuries such as stress fractures and might even have ergogenic effects for example on muscle function. The main objectives were to evaluate the basal serum levels of 25(OH)D and calcium in professional soccer athletes on the latitude 40°N, to evaluate the effects in 25(OH)D and calcium serum levels following supplementation of 1667 IU/day of cholecalciferol during a period of 8 weeks and evaluate eventual toxicity arising from it.

METHODS

Twenty-eight professional athletes were evaluated according to the skin type. Basal serum levels of 25(OH)D and calcium were evaluated during winter months. Athletes were then supplemented with cholecalciferol 25.000 IU every two weeks. Serum levels of 25(OH)D and calcium were evaluated after supplementation.

RESULTS

25(OH)D initially ranged between 9.9 ng/mL and 32.9 ng/mL with a median of 19.2 IQR 7.24 ng/mL. A statistically significant inverse correlation exists between vitamin D deficiency and the Fitzpatrick Scale (ρ=-0.555 P=0.003). After 8 weeks, 25(OH)D ranged between 10.6 ng/mL and 43.4 ng/mL with a median of 33.2 ng/mL IQR 6.1 ng/mL. We verified a statistically significant increase of serum 25(OH) D levels (11.74±5.988; CI 95% [9,02; 14,47]; P<0.001. In addition, there was a statistically significant reduction of calcium: -0.36±0.457; CI 95% [- 0.57; -0.15]; P=0.002.

CONCLUSIONS

Professional athletes have a high prevalence of vitamin D deficiency. Supplementation with cholecalciferol in winter months during 8 weeks is safe and effective in raising 25(OH)D serum levels. However, it may not be sufficient for athletes to reach adequate vitamin D levels.

Prevention of rickets and osteomalacia in the UK: political action overdue

The consequences of vitamin D and dietary calcium deficiency have become a huge public health concern in the UK. The burden of disease from these deficiencies includes rickets, and hypocalcaemic seizures, dilated cardiomyopathy and mostly occult myopathy and osteomalacia. The increasing burden of the disease is intrinsically linked to ethnicity and the population demographic changes in the UK. Three facts have led to the resurfacing of the English disease: (1) the UK has no ultraviolet sunlight for at least 6 months of the year, (2) dark skin produces far less vitamin D than white skin per unit ultraviolet light exposure, and (3) non-European Union immigration over the last century. To date, the UK government demonstrates incomplete understanding of these three facts, and its failure to adjust its prevention programmes to changing demographics is endangering the health and life of UK residents with dark skin, of whom infants are the most vulnerable. Establishing accountability through the implementation of monitored antenatal and infantile supplementation programmes and mandatory food fortification is overdue.

Incorporation and Remodeling of Structural Allografts in Acetabular Reconstruction: Multiscale, Micro-Morphological Analysis of 13 Pelvic Explants

BACKGROUND

Total hip arthroplasty (THA) is frequently accompanied by acetabular bone loss, which constitutes a major challenge in revision procedures. Structural allografts can be implanted to restore a stable osseous foundation for the acetabular prosthesis. As previous studies were limited to clinical data or included very few cases, the extent to which the graft bone is incorporated over time has remained unclear.

METHODS

Thirteen acetabula were retrieved post mortem, and the incorporation properties of the bone allografts were analyzed using a hierarchical approach of imaging techniques including contact radiography, high-resolution peripheral quantitative computed tomography (HR-pQCT), histological analysis of undecalcified specimens, and quantitative backscattered electron imaging (qBEI). The distance between the current allograft bone and host bone borders (i.e., current overlap) as well as the distance between the original allograft bone and host bone borders (i.e., total ingrowth) were assessed.

RESULTS

In 10 of 13 cases, the complete interface (100%) was characterized by direct contact and additional overlap of the allograft bone and host bone, while the remaining 3 cases demonstrated direct contact along 25% to 80% of the interface. The allograft bone showed an intact trabecular structure and significantly higher mineralization compared with the host bone. The mean current overlap (and standard deviation) was 2.3 ± 1.0 mm, with a maximum of 5.3 ± 2.4 mm. Importantly, the total ingrowth reached much further, to a mean of 7.2 ± 2.3 mm (maximum, 10.5 ± 4.0 mm). Neither the time that the allograft was in situ nor the degree of contact between the host and allograft bone correlated with the current overlap and the time in situ did not correlate with total ingrowth.

CONCLUSIONS

This study showed bone remodeling with subsequent interconnection of the host and allograft bone along the majority of the interface, leading to adequate incorporation of the allograft. The lack of complete incorporation of the graft did not lead to graft collapse up to 22 years after revision surgery.

CLINICAL RELEVANCE

Our study provides the first systematic multiscale evaluation of successfully implanted structural allografts and forms the scientific basis for their clinical use in revision THA.

Bone Formation Parameters of the Biopsied Ilium Differ between Subtrochanteric and Diaphyseal Atypical Femoral Fractures in Bisphosphonate-Treated Patients

Atypical femoral fractures (AFFs) are defined as atraumatic or low-trauma fractures located in the subtrochanteric or diaphyseal sites. Long-term bisphosphonates (BPs) are administered to prevent fragility fractures in patients with primary osteoporosis or collagen diseases who are already taking glucocorticoids (GCs). Long-term BP use is one of the most important risk factors for AFFs. Its pathogenesis is characterized by severely suppressed bone turnover (SSBT), but whether the characteristics of patients are different regarding to location of fracture site remains unknown. In this study, we compared the characteristics and bone histomorphometric findings between subtrochanteric and diaphyseal sites in patients with BP-associated AFFs. Nine women with BP-associated AFFs were recruited, including 3 with systemic lupus erythematosus, 2 with rheumatoid arthritis, 2 with primary osteoporosis, 1 with polymyalgia rheumatica, and 1 with sarcoidosis. Patients were divided into the subtrochanteric group (n = 5; average age, 52 years; BP treatment, 5.9 years) and the diaphyseal group (n = 4; average age, 77 years; BP treatment, 2.6 years). Compared with the diaphyseal group, the subtrochanteric group had significantly higher daily GC doses (average, 10.9 vs. 2.3 mg/day) and significantly lower serum 25-hydroxyvitamin-D levels (17.8 vs. 25.6 ng/mL). Bone histomorphometry of the biopsied iliac bone showed SSBT in 3 cases (subtrochanteric, n = 1; diaphyseal, n = 2). Osteoid volume and trabecular thickness were significantly lower in the subtrochanteric group than in the diaphyseal group. Bone formation was inhibited more severely in subtrochanteric than in the diaphyseal group due to the higher GC doses used.

Cortical Matrix Mineral Density Measured Noninvasively in Pre- and Postmenopausal Women and a Woman With Vitamin D-Dependent Rickets

Reduced bone mineral density (BMD) may be due to reduced mineralized bone matrix volume, incomplete secondary mineralization, or reduced primary mineralization. Because bone biopsy is invasive, we hypothesized that noninvasive image acquisition at high resolution can accurately quantify matrix mineral density (MMD). Quantification of MMD was confined to voxels attenuation photons above 80% of that produced by fully mineralized bone matrix because attenuation at this level is due to variation in mineralization, not porosity. To assess accuracy, 9 cadaveric distal radii were imaged at a voxel size of 82 microns using high-resolution peripheral quantitative computed tomography (HR-pQCT; XtremeCT, Scanco Medical AG, Bruttisellen, Switzerland) and compared with VivaCT 40 (µCT) at 19-micron voxel size. Associations between MMD and porosity were studied in 94 healthy vitamin D-replete premenopausal women, 77 postmenopausal women, and in a 27-year-old woman with vitamin D-dependent rickets (VDDR). Microstructure and MMD were quantified using StrAx (StraxCorp, Melbourne, Australia). MMD measured by HR-pQCT and µCT correlated (R = 0.87; p < 0.0001). The precision error for MMD was 2.43%. Cortical porosity and MMD were associated with age (r²  = 0.5 and -0.4, respectively) and correlated inversely in pre- and postmenopausal women (both r²  = 0.9, all p < 0.001). Porosity was higher, and MMD was lower, in post- than in premenopausal women (porosity 40.3% ± 7.0 versus 34.7% ± 3.5, respectively; MMD 65.4% ± 1.8 versus 66.6% ± 1.4, respectively, both p < 0.001). In the woman with VDDR, MMD was 5.6 SD lower and porosity was 5.6 SD higher than the respective trait means in premenopausal women. BMD was reduced (Z-scores femoral neck -4.3 SD, lumbar spine -3.8 SD). Low-radiation HR-pQCT may facilitate noninvasive quantification of bone's MMD and microstructure in health, disease, and during treatment. © 2018 American Society for Bone and Mineral Research.

Cardiac, bone and growth plate manifestations in hypocalcemic infants: revealing the hidden body of the vitamin D deficiency iceberg

BACKGROUND

Whilst hypocalcemic complications from vitamin D deficiency are considered rare in high-income countries, they are highly prevalent among Black, Asian and Minority Ethnic (BAME) group with darker skin. To date, the extent of osteomalacia in such infants and their family members is unknown. Our aim was to investigate clinical, cardiac and bone histomorphometric characteristics, bone matrix mineralization in affected infants and to test family members for biochemical evidence of osteomalacia.

CASE PRESENTATION

Three infants of BAME origin (aged 5-6 months) presented acutely in early-spring with cardiac arrest, respiratory arrest following seizure or severe respiratory distress, with profound hypocalcemia (serum calcium 1.22-1.96 mmol/L). All infants had dark skin and vitamin D supplementation had not been addressed during child surveillance visits. All three had severely dilated left ventricles (z-scores + 4.6 to + 6.5) with reduced ejection fraction (25-30%; normal 55-70), fractional shortening (7 to 15%; normal 29-40) and global hypokinesia, confirming hypocalcemic dilated cardiomyopathy. They all had low serum levels of 25 hydroxyvitamin D (25OHD < 15 nmol/L), and elevated parathyroid hormone (PTH; 219-482 ng/L) and alkaline phosphatase (ALP; 802-1123 IU/L), with undiagnosed rickets on radiographs. One infant died from cardiac arrest. At post-mortem examination, his growth plate showed a widened, irregular zone of hypertrophic chondrocytes. Histomorphometry and backscattered electron microscopy of a trans-iliac bone biopsy sample revealed increased osteoid thickness (+ 262% of normal) and osteoid volume/bone volume (+ 1573%), and extremely low bone mineralization density. Five of the nine tested family members had vitamin D deficiency (25OHD < 30 nmol/L), three had insufficiency (< 50 nmol/L) and 6/9 members had elevated PTH and ALP levels.

CONCLUSIONS

The severe, hidden, cardiac and bone pathology described here exposes a failure of public health prevention programs, as complications from vitamin D deficiency are entirely preventable by routine supplementation. The family investigations demonstrate widespread deficiency and undiagnosed osteomalacia in ethnic risk groups and call for protective legislation.