Serum Phosphate Is Associated With Fracture Risk: The Rotterdam Study and MrOS

Prevalence and risk factors predisposing low bone mineral density in patients with thalassemia

Background

A common complication of thalassemia is secondary osteoporosis. This study aimed to assess the prevalence and factors associated with low BMD in thalassemic patients.

Method

This is a cross-sectional study. Eligible patients were males aged within 18-49 years or premenopausal women diagnosed with thalassemia in Chiang Mai University Hospital between July 2021 and July 2022. The diagnosis of low BMD by dual-energy x-ray absorptiometry (DXA) was defined as a Z-score of -2.0 SD or lower in either the lumbar spine or femoral neck. Clinical factors associated with low BMD were analyzed using a logistic regression model.

Results

Prevalence of low BMD was 62.4% from 210 patients with a mean age of 29.7 ± 7.6 years. The predominant clinical characteristics of low BMD thalassemia patients were being female, transfusion-dependent (TDT) and a history of splenectomy. From multivariable analysis, the independent variables associated with low BMD were transfusion dependency (odds ratio, OR 2.36; 95%CI 1.28 to 4.38; p=0.006) and body mass index (BMI) (OR 0.71; 95%CI 0.61 to 0.82; p<0.001). Among patients with low BMD, we observed a correlation between a Z-score with low IGF-1 levels (β=-0.42; 95% CI -0.83 to -0.01; p=0.040), serum phosphate levels (β=0.40; 95% CI 0.07 to 0.73; p=0.016) and hypogonadism (β=-0.48, 95% CI -0.91 to -0.04, p=0.031).

Conclusion

This study found a prevalence of low BMD in 62.4% of subjects. Factors associated with low BMD were TDT and BMI. Within the low BMD subgroup, hypogonadism, serum phosphate and low serum IGF-1 levels were associated with a lower Z-score.

Organic phosphate but not inorganic phosphate regulates Fgf23 expression through MAPK and TGF-ꞵ signaling

One of the main regulators of phosphate homeostasis is fibroblast growth factor 23 (FGF23), secreted by osteocytes. The effects of organic versus inorganic dietary phosphate on this homeostasis are unclear. This study used MC3T3-E1 FGF23-producing cells to examine the transcriptomic responses to these phosphates. Most importantly, the expression and secretion of FGF23 were only increased in response to organic phosphate. Gene ontology terms related to a response to environmental change were only enriched in cells treated with organic phosphate while cells treated with inorganic phosphate were enriched for terms associated with regulation of cellular phosphate metabolism. Inhibition of MAPK signaling diminished the response of Fgf23 to organic phosphate, suggesting it activates FGF23. TGF-β signaling inhibition increased Fgf23 expression after the addition of organic phosphate, while the negative TGF-β regulator Skil decreased this response. In summary, the observed differential response of FGF23-producing to phosphate types may have consequences for phosphate homeostasis.

Features of patients and fracture risk in hypoparathyroidism; a single center study

PURPOSE

Patients with hypoparathyroidism (hypoPT) have low bone turnover and high bone mineral density (BMD). However, data on fracture risk are conflicting. The objectives of this study were: 1. To describe clinical/biochemical characteristics of hypoPT patients followed at a single medical center. 2. To identify postsurgical hypoPT patients and investigate their fracture rate compared with gender/age-matched post-surgical normocalcemic patients.

METHODS

Retrospective analysis of patient's medical records treated at the tertiary medical center in 2010-2021 identified by computerized medical database search.

RESULTS

The cohort included 133 patients (91% women, mean age 64 ± 13 years) of whom 105 (79%) had post-thyroidectomy hypoparathyroidism and the remainder had an autoimmune/idiopathic/other etiology. Mean follow-up time was 21 ± 12 and 27 ± 12 years, respectively. The control group included 142 post-thyroidectomy patients without hypoparathyroidism. Patients in the postsurgical hypoparathyroidism group were older and had higher calcium and PTH levels at diagnosis than the non-surgical hypoPT patients. Comparing the postsurgical hypoPT and postsurgical normocalcemic control patients revealed a significantly higher BMD in the hypoPT group. Yet, fracture rates were 31% in the postsurgical hypoparathyroidism group and 21% in the control group (P = 0.1) over a similar median follow-up period (17 and 18.4 years, respectively). In both groups the most common fracture site was the spine (50% and 70%, respectively; p = 0.33), mainly nonclinical morphometric fractures. Higher phosphorus blood level was associated with increased fracture risk.

CONCLUSIONS

The relatively high BMD in patients with postsurgical hypoparathyroidism is not associated with lower fracture risk. Silent morphometric fractures are quite common in this group of patients.

Impact of Intravenous Iron Substitution on Serum Phosphate Levels and Bone Turnover Markers-An Open-Label Pilot Study

The association between intravenous iron substitution therapy and hypophosphatemia was previously reported in patients with iron deficiency anemia. However, the extent of hypophosphatemia is thought to depend on the type of iron supplementation. We hypothesized that the intravenous application of ferric carboxymaltose and iron sucrose leads to a different longitudinal adaptation in serum phosphate levels. In this open-label pilot study, a total of 20 patients with inflammatory bowel diseases or iron deficiency anemia were randomly assigned to one of two study groups (group 1: ferric carboxymaltose, n = 10; group 2: iron sucrose, n = 10). Serum values were controlled before iron substitution therapy, as well as 2, 4, and 12 weeks after the last drug administration. The primary objective of the study was the longitudinal evaluation of serum phosphate levels after iron substitution therapy with ferric carboxymaltose and iron sucrose. The secondary objective was the longitudinal investigation of calcium, 25-hydroxyvitamin D (25(OH)D), intact parathyroid hormone, procollagen type 1 amino-terminal propeptide (P1NP), beta-CrossLaps (CTX), hemoglobin (Hb), iron, ferritin, and transferrin saturation levels. Two weeks after drug administration, phosphate levels were significantly lower (p < 0.001) in group 1 and ferritin levels were significantly higher (p < 0.001) in group 1. Phosphate levels (0.8-1.45 mmol/L) were below the therapeutic threshold and ferritin levels (10-200 ng/mL for women and 30-300 ng/mL for men) were above the therapeutic threshold in group 1. P1NP (15-59 µg/L) and CTX (<0.57 ng/mL) levels were above the therapeutic threshold in group 2. Four weeks after drug administration, significant differences were still observed between both study groups for phosphate (p = 0.043) and ferritin (p = 0.0009). All serum values except for Hb were within the therapeutic thresholds. Twelve weeks after drug administration, no differences were observed in all serum values between both study groups. Hb values were within the therapeutic threshold in both study groups. Serum 25(OH)D levels did not differ between both study groups throughout the whole study period and remained within the therapeutic threshold.

Factors influencing the bone mineral density in Duroc boars

BACKGROUND

Leg weakness affects animal welfare and is one of the primary reasons for culling of boars. Low bone mineral density (BMD) is one of the primary factors contributing to leg weakness. Low BMD also appeared to be associated with severe bone pain and has the highest risk of skeletal fragility. Surprisingly, few studies have been performed on the factors influencing BMD in pigs. Therefore, the primary aim of this study was to identify the influencing factors on boar BMD. Herein, the BMD data were determined through the use of ultrasonography from 893 Duroc boars. Logistic regression model was utilized in the analysis of BMD, in which the explanatory variables in the model were lines, ages, body weights, backfat thicknesses and serum mineral element concentrations (Ca, P, Mg, Cu, Fe, Zn, Mn, Se, Pb and Cd).

RESULTS

Results showed that factors significantly influencing BMD included serum Ca, P concentrations, ages and backfat thicknesses (P < 0.05), in which serum Ca concentrations were positively correlated with BMD (P < 0.01), whereas increasing concentrations of serum P decreased BMD (P < 0.01). The serum Ca/P ratio showed significant quadratic effects on BMD (r = 0.28, P < 0.01), and the Ca/P ratio to achieve the best BMD was determined to be 3.7. Furthermore, BMD also changed with age quadratically (r = 0.40, P < 0.01), and reached a peak value around 47 months. Interestingly, a quadratic (r = 0.26, P < 0.01) increase in the BMD was observed as backfat thickness increased, and the inflection point was calculated at around 17 mm.

CONCLUSION

In conclusion, BMD characteristics of boars could be detected by ultrasonic method, and serum Ca, serum P, age, and backfat thickness contributed to the greatest effect on BMD.

Evocalcet Rescues Secondary Hyperparathyroidism-driven Cortical Porosity in CKD Male Rats

To elucidate the effect of evocalcet, a new oral calcimimetic to bone of secondary hyperparathyroidism (SHPT) with chronic kidney disease (CKD), the rats were 5/6 nephrectomized and fed on a high-phosphate diet. The treated rats were then divided into vehicle groups and evocalcet administered groups. The rats in the vehicle groups exhibited increased levels of serum PTH and inorganic phosphate (Pi) levels, high bone turnover, and severe cortical porosity, mimicking SHPT (CKD-SHPT rats). The cortical bone of the CKD-SHPT rats showed broad demineralization around the osteocytes, suppression of Phex/small integrin-binding ligand N-linked glycoprotein-mediated mineralization in the periphery of the osteocytic lacunae, and increased levels of osteocytic cell death, all of which were considered as the first steps of cortical porosity. In contrast, evocalcet ameliorated the increased serum PTH levels, the enlarged osteocytic lacunae, and the cortical porosity of the CKD-SHPT rats. Osteocytes of CKD-SHPT rats strongly expressed PTH receptor and Pit1/Pit2, which sense extracellular Pi, indicating that PTH and Pi affected these osteocytes. Cell death of cultured osteocytes increased in a Pi concentration-dependent manner, and PTH administration rapidly elevated Pit1 expression and enhanced osteocytic death, indicating the possibility that the highly concentrated serum PTH and Pi cause severe perilacunar osteolysis and osteocytic cell death. It is likely therefore that evocalcet not only decreases serum PTH but also reduces the exacerbation combined with PTH and Pi to the demineralization of osteocytic lacunae and osteocytic cell death, thereby protecting cortical porosity in CKD-SHPT rats.

Risk factors for subchondral insufficiency fracture of the femoral head in renal transplant patients

INTRODUCTION

Risk factors associated with subchondral insufficiency fracture (SIF) of the femoral head have not been established. The aim of the present study was to determine the incidence and risk factors for SIF of the femoral head following renal transplantation (RT).

MATERIALS AND METHODS

We analyzed the cases of 681 RT patients (mean age at surgery: 49.5 ± 13.6 years, 249 women, 432 men) to determine the incidence of SIF. Hip magnetic resonance imaging (MRI) was performed 6 months post-RT. The following potential predictors of SIF were evaluated: (1) patient's condition at RT: bone mineral density (BMD), pre-RT laboratory values including calcium (Ca), phosphorus (P), calcium-phosphorus product (Ca × P), and intact parathyroid hormone; the patient and donor's blood relationship; and mismatching number of human leukocyte antigens (HLAs), and (2) post-RT dosage(s) of steroid(s), the immunosuppressive regimen, and the incidence of acute rejection.

RESULTS

SIF was observed in 15 hips (13 patients, 1.9%). We successfully matched 39 patients without SIF. A multivariate logistic regression analysis adjusted for cumulative dosages of steroids, revealed the following were risk factors for SIF: osteoporosis (OR: 11.4, p = 0.046), lumbar BMD (OR: 0.003, p = 0.038), pre-RT serum P (OR 2.68, p = 0.004), and pre-RT serum Ca × P (OR: 1.11, p = 0.005).

CONCLUSION

Since osteoporosis, the lumbar BMD, serum P, and serum Ca × P were identified as risk factors for a post-RT SIF, these factors should be evaluated before RT for the prediction of the SIF risk.

Reduced trabecular bone mineral density and thinner cortices in men with distal forearm fractures

Men with distal forearm fractures have reduced bone density, an increased risk of osteoporosis and of further fractures. The aim of the study was to investigate the structural determinants of these observations using quantitative CT (qCT). Ninety six men with low-trauma distal forearm fracture and 101 age-matched healthy control subjects were recruited. All subjects underwent a quantitative CT on a standard 64-slice whole body CT scanner. These were analysed on Mindways QCT PRO™ Software to generate volumetric and geometric data at the lumbar spine, femoral neck and total hip, ultra-distal and distal 33 % radius. Biochemical investigations, health questionnaires and measurements of bone turnover were made. Men with fracture had significantly lower total and trabecular vBMD at all sites. The greatest percentage reduction was at the ultra-distal radius (13.5 % total and 11.7 % trabecular vBMD). In the fracture group cortical vBMD was significantly higher in the femoral neck (p < 0.001) and maintained at the ultra-distal radius compared with control subjects. However, cortical cross-sectional area (CSA) and thickness were significantly reduced at the femoral neck (p < 0.001 and p = 0.002 respectively) and forearm sites (CSA ultradistal radius p = 0.001, cortical thickness p = 0.002, CSA distal one third radius p = 0.045 and cortical thickness p = 0.005). Cross sectional moment of inertia (CSMI) and section moduli were significantly reduced at the femoral neck (CSMI1 p = 0.002, CSMI2 p = 0.012 and section moduli Z1 p < 0.001, Z2 p = 0.004) and the ultra-distal radius (CSMI1 p = 0.008 and section moduli Z1 p = 0.018, Z2 p = 0.007). In stepwise logistic regression analysis distal forearm fracture showed the strongest association with a model comprising ultra-distal forearm trabecular vBMD (negative), procollagen type I N-terminal propeptide (PINP, positive) and sex hormone binding globulin (SHBG, negative). In conclusion, these observations explain the structural reasons for the increased fracture risk in men with distal forearm fractures.

High phosphate-induced progressive proximal tubular injury is associated with the activation of Stat3/Kim-1 signaling pathway and macrophage recruitment

Dietary phosphate intake in the Western population greatly exceeds the recommended dietary allowance and is linked to enhanced cardiovascular and all-cause mortality. It is unclear whether a chronic high phosphate diet (HPD) causes kidney injury in healthy individuals. Here, we show that feeding a 2% HPD in C57BL/6N mice for one up to six months resulted in hyperphosphatemia, hyperphosphaturia, increased plasma levels of fibroblast growth factor (FGF) 23, and parathyroid hormone (PTH) compared to mice on a 0.8% phosphate diet. Kidney injury was already noted after two months of HPD characterized by loss of proximal tubular (PT) cell polarity, flattened epithelia, disruption of brush border membranes, vacuolization, increased PT cell proliferation, marked interstitial mononuclear infiltration, and progressive accumulation of collagen fibers. HPD increased Stat3 activation and Kim-1 expression in PT epithelial cells and enhanced renal synthesis of chemokines recruiting monocytes and macrophages as well as macrophage related factors. Enhanced recruitment of F4/80⁺ macrophages around injured PT lesions was timely associated with increased Kim-1 synthesis, tubular MCP-1 expression, and degree of PT injury score. Likewise, tubulointerstitial fibrosis was associated with activation of Stat3/Kim-1 signaling pathway. The stimulation of human proximal tubular cells with high phosphate activated Stat3 signaling and induced HAVCR1 and CCL2 expression. We conclude that high phosphate results in progressive proximal tubular injury, indicating that high dietary phosphate intake may affect kidney health and therefore represents an underestimated health problem for the general population.

Anemia is associated with increased risk of non-vertebral osteoporotic fractures in elderly men: the MrOS Sweden cohort

This study includes 1005 men from the Gothenburg part of the Osteoporotic Fracture in Men Study (MrOS). Included are 66 men with anemia (hemoglobin < 130 g/L). The follow-up time was up to 16 years, and the main results are that anemia is associated with all fractures and non-vertebral osteoporotic fractures.

INTRODUCTION

Anemia and osteoporotic fractures are conditions that are associated with increased morbidity and mortality. Clinical studies have suggested that anemia can be used as a predictor of future osteoporotic fractures.

METHOD

Men from the Osteoporotic Fractures in Men Study (MrOS) Sweden, Gothenburg, with available hemoglobin (Hb) values (n = 1005, median age 75.3 years (SD 3.2)), were included in the current analyses. Of these, 66 suffered from anemia, defined as Hb < 130 g/L. Median follow-up time for fracture was 10.1 years and the longest follow-up time was 16.1 years.

RESULTS

Men with anemia had, at baseline, experienced more falls and had a higher prevalence of diabetes, cancer, prostate cancer, hypertension, and stroke. Anemia was not statistically significantly associated with bone mineral density (BMD). Men with anemia had higher serum levels of fibroblast growth factor 23 (iFGF23) (p < 0.001) and phosphate (p = 0.001) and lower serum levels of testosterone (p < 0.001) and estradiol (p < 0.001). Moreover, men with anemia had an increased risk of any fracture (hazard ratio (HR) 1.97, 95% CI 1.28-3.02) and non-vertebral osteoporotic fracture (HR 2.15, 95% CI 1.18-3.93), after adjustment for age and total hip BMD, in 10 years. The risk for any fracture was increased in 10 and 16 years independently of falls, comorbidities, inflammation, and sex hormones. The age-adjusted risk of hip fracture was increased in men with anemia (HR 2.32, 95% CI 1.06-5.12), in 10 years, although this was no longer statistically significant after further adjustment for total hip BMD.

CONCLUSIONS

Anemia is associated with an increased risk for any fracture and non-vertebral osteoporotic fracture in elderly men with a long follow-up time. The cause is probably multifactorial and our results support that anemia can be used as a predictor for future fracture.

FGF23-Klotho Axis and Fractures in Patients Without and With Early CKD: A Case-Cohort Analysis of CARTaGENE

CONTEXT

Whether fibroblast growth factor-23 (FGF23) and α-Klotho are associated with fractures, especially in chronic kidney disease (CKD), remains controversial.

OBJECTIVE

We evaluated how FGF23, α-Klotho, and traditional mineral parameters predict fractures in individuals with and without early CKD.

METHODS

We conducted a stratified case-cohort analysis using CARTaGENE, a population-based survey from Quebec, Canada. Individuals aged 40 to 69 years were selected according to outcome and CKD status (non-CKD: eGFR > 60 mL/min/1.73 m2; CKD stage 3: eGFR 30-60 mL/min/1.73 m2]). Baseline levels of c-terminal FGF23 (cFGF23), α-Klotho, parathyroid hormone (PTH), phosphate, and calcium were analyzed for associations with osteoporotic fracture incidence from recruitment (2009-2010) through March 2016. Adjusted Cox models were used, and predictors were treated linearly or flexibly using splines.

RESULTS

A total of 312 patients (159 non-CKD; 153 CKD) were included; 98 had ≥ 1 fracture at any site during a median follow up of 70 months. Compared with non-CKD, CKD patients had increased levels of cFGF23 but similar levels of α-Klotho. cFGF23 was linearly associated with increased fracture incidence (adjusted HR = 1.81 [1.71, 1.93] per doubling for all participants). The association of α-Klotho with fracture followed a U-curve (overall P = 0.019) but was attenuated by adjustment for potential mediators (bone mineral density, phosphate, PTH). PTH and phosphate also had U-shaped associations with fracture. Associations were mostly similar between non-CKD and CKD. Adjustment for cFGF23 strongly attenuated the association between CKD status and fractures.

CONCLUSION

cFGF23 is associated linearly with fracture incidence while α-Klotho, PTH, and phosphate levels have a U-shaped association.

Prevalence, Characteristics, and Associated Risk Factors of Wrist Fractures in Americans Above 50: The Cross-Sectional NHANES Study

SUMMARY

By analyzing data from NHANES, we aimed to evaluate the prevalence, characteristics, and associated factors of wrist fractures in Americans aged 50 and above.

INTRODUCTION

Wrist fractures, whose prevalence increases with age, are one of the most common fractures in the United States. However, epidemiological studies on the prevalence of wrist fractures of certain ages were limited.

METHODS

The data of Americans aged 50 or above from 2013-2014 and 2017-2018 in NHANES were extracted and analyzed.

RESULTS

The prevalence of wrist fractures among Americans whose age was 50 or above was 12%, which was similar between men and women (men 12.8% vs. women 11.4%, p = 0.267). Among those who had experienced their first wrist fracture, 17.8% of the population experienced a second wrist fracture. The top two causes of the first wrist fracture were a fall from a standing height (56%) or a hard fall (34.8%). The prevalence of wrist fractures was higher in men than in women (13.7% versus 8.7%, p = 0.023) aged < 60, but higher in women than in men aged ≥ 60 (11.8% versus 14.3%, p = 0.007). Multivariate analysis showed that obesity, frequent drinking, current smoking, high serum phosphate level, non-Hispanic white women, and osteoporosis were independently associated with wrist fractures. Stratified by race, osteoporosis, frequent drinking, and high serum phosphate level were risk factors for wrist fractures in all races. As for Mexican Americans, non-Hispanic whites, and other races including multi-racial, current smoking was a risk factor of wrist factures. Furthermore, obesity was positively associated with wrist fractures in Mexican Americans, other Hispanics, and non-Hispanic whites.

CONCLUSION

The prevalence of wrist fractures in Americans aged 50 and above was 12%. Falling from a standing height was the main cause of the first wrist fracture. Frequent drinking, current smoker, high serum phosphate level, osteoporosis, obesity, and non-Hispanic women were more likely to experience wrist fractures.

Use of Micro-CT Imaging to Assess Ventral Mandibular Cortical Thickness and Volume in an Experimental Rodent Model With Chronic High-Phosphorus Intake

Adverse effects of high dietary phosphorus on bone health have been observed in both animal and human studies. The aim of the investigation was to examine chronic effects of high phosphorus diet on the apical mandibular cortical thickness and volume in a hystricomorph rodent (Octodon degus) using microcomputed tomography. Male degus were randomly divided into two groups fed by different mineral contents from the age of 12 weeks till the age of 17 months. The micro-CT scanning and wall thickness analysis were applied on the region of the mandible exactly under the apices of the 4th premolar tooth, first molar tooth, and second molar tooth in two animals from each group. General overview and mapping of the ventral mandibular bone thickness revealed pronounced bony mandibular protrusions in all the animals fed a high-phosphorus diet with obvious bone thinning apically to the 4th premolar and first and second molar tooth apices. Mandibular bone volume and thickness located apically to the premolar and molars were statistically significantly smaller/thinner in the group fed by a high phosphorus diet. The thinnest bone measured 0.004 mm, where the mandibular 4th premolar tooth almost perforated the mandibular cortex. Similar studies of metabolic bone disease and its influence on alveolar bone were also published in rats and mice. The influence of different environmental, infectious, or metabolic factors on the growing tooth, alveolar bone formation, and bone pathologies must be done experimentally on growing animals. In contrast, degus have continuously growing dentition, and the effect of any of the above listed factors can be studied in this animal model at any age and for longer time periods.

Pathophysiology of Vascular Calcification and Bone Loss: Linked Disorders of Ageing?

Vascular Calcification (VC), low bone mass and fragility fractures are frequently observed in ageing subjects. Although this clinical observation could be the mere coincidence of frequent age-dependent disorders, clinical and experimental data suggest that VC and bone loss could share pathophysiological mechanisms. Indeed, VC is an active process of calcium and phosphate precipitation that involves the transition of the vascular smooth muscle cells (VSMCs) into osteoblast-like cells. Among the molecules involved in this process, parathyroid hormone (PTH) plays a key role acting through several mechanisms which includes the regulation of the RANK/RANKL/OPG system and the Wnt/ß-catenin pathway, the main pathways for bone resorption and bone formation, respectively. Furthermore, some microRNAs have been implicated as common regulators of bone metabolism, VC, left ventricle hypertrophy and myocardial fibrosis. Elucidating the common mechanisms between ageing; VC and bone loss could help to better understand the potential effects of osteoporosis drugs on the CV system.

A review and perspective on the assessment, management and prevention of fragility fractures in patients with osteoporosis and chronic kidney disease

This article aims to review the methods used for the assessment of fracture risk and the use of osteoporosis medications for fracture prevention in the population with CKD, and highlights the difficulties faced by clinicians in the management of these patients and the latest recommendations and guidelines. Chronic kidney disease (CKD) and osteoporosis often co-exist in older adults, and they present a major healthcare challenge. CKD mineral and bone disorder (CKD-MBD) occurs as renal function declines and this syndrome affects most patients in CKD stages 4 and 5. The biochemical abnormalities of CKD-MBD, renal bone disease and risk factors associated with age-related bone loss and osteoporosis lead to a cumulative effect on fracture risk and mortality. There is a need for routine evaluation of fracture risk and fracture prevention in this population. Measurement of bone mineral density (BMD) and the use of the FRAX tool have predictive value for incident fractures in the general population and in CKD. This enables physicians to identify CKD patients most at risk of sustaining a fragility fracture and allows a more targeted approach to fracture prevention. Data analysis from the pivotal trials of therapeutic agents used in osteoporosis show that these drugs can be considered in mild and moderate CKD (stages 1-3 CKD). Off-label drug use in patients with CKD-MBD and more severe renal impairment (CKD stages 4 and 5) could offer significant benefits to sub-groups of patients when carefully tailored to each individual's bone turnover and calcium and phosphate balance. However, this requires a selective approach and treatment decisions based on inference from pathophysiology while we await further trials. Guidelines advocate the correction and/or reduction of the biochemical abnormalities of CKD-MBD before initiation of treatment with osteoporosis drugs and close monitoring during treatment.

Bone Quality in Chronic Kidney Disease Patients: Current Concepts and Future Directions - Part II

Background

Patients with chronic kidney disease (CKD) have an increased risk of osteoporotic fractures, which is due not only to low bone volume and mass but also poor microarchitecture and tissue quality. The pharmacological and nonpharmacological interventions detailed, herein, are potential approaches to improve bone health in CKD patients. Various medications build up bone mass but also affect bone tissue quality. Antiresorptive therapies strikingly reduce bone turnover; however, they can impair bone mineralization and negatively affect the ability to repair bone microdamage and cause an increase in bone brittleness. On the other hand, some osteoporosis therapies may cause a redistribution of bone structure that may improve bone strength without noticeable effect on BMD. This may explain why some drugs can affect fracture risk disproportionately to changes in BMD.

Summary

An accurate detection of the underlying bone abnormalities in CKD patients, including bone quantity and quality abnormalities, helps in institution of appropriate management strategies. Here in this part II, we are focusing on advancements in bone therapeutics that are anticipated to improve bone health and decrease mortality in CKD patients.

Key Messages

Therapeutic interventions to improve bone health can potentially advance life span. Emphasis should be given to the impact of various therapeutic interventions on bone quality.

Phosphate and bone fracture risk in chronic kidney disease patients

In chronic kidney disease (CKD), phosphate homoeostasis plays a central role in the development of mineral and bone disorder (MBD) together with decreased serum calcium and elevated serum parathyroid hormone, fibroblast growth factor 23 and sclerostin levels. Today there are only a few data exploring the direct role of abnormal phosphate homoeostasis and hyperphosphataemia in the development of CKD-MBD. On the other hand, several studies have looked at the link between hyperphosphataemia and cardiovascular morbidity and mortality in CKD, but there is a lack of evidence to indicate that lowering phosphate levels improves cardiovascular outcomes in this population. Furthermore, the impact of liberalizing phosphate targets on CKD-MBD progression and bone fracture is currently not known. In this review we discuss the central role of phosphate in the pathogenesis of CKD-MBD and how it may be associated with fracture risk, both in hyper- and hypophosphataemia.

The Importance of Phosphate Control in Chronic Kidney Disease

A series of problems including osteopathy, abnormal serum data, and vascular calcification associated with chronic kidney disease (CKD) are now collectively called CKD-mineral bone disease (CKD-MBD). The pathophysiology of CKD-MBD is becoming clear with the emerging of αKlotho, originally identified as a progeria-causing protein, and bone-derived phosphaturic fibroblast growth factor 23 (FGF23) as associated factors. Meanwhile, compared with calcium and parathyroid hormone, which have long been linked with CKD-MBD, phosphate is now attracting more attention because of its association with complications and outcomes. Incidentally, as the pivotal roles of FGF23 and αKlotho in phosphate metabolism have been unveiled, how phosphate metabolism and hyperphosphatemia are involved in CKD-MBD and how they can be clinically treated have become of great interest. Thus, the aim of this review is reconsider CKD-MBD from the viewpoint of phosphorus, its involvement in the pathophysiology, causing complications, therapeutic approach based on the clinical evidence, and clarifying the importance of phosphorus management.

Traditional and Non-traditional Risk Factors for Osteoporosis in CKD

Osteoporosis is a state of bone fragility with reduced skeletal resistance to trauma, and consequently increased risk of fracture. A wide range of conditions, including traditional risk factors, lifestyle choices, diseases and their treatments may contribute to bone fragility. It is therefore not surprising that the multi-morbid patient with chronic kidney disease (CKD) is at a particularly high risk. CKD is associated with reduced bone quantity, as well as impaired bone quality. Bone fragility in CKD is a composite of primary osteoporosis, accumulation of traditional and uremia-related risk factors, assaults brought on by systemic disease, and detrimental effects of drugs. Some risk factors are modifiable and represent potential targets for intervention. This review provides an overview of the heterogeneity of bone fragility in CKD.

Bone Fragility Fractures in CKD Patients

Chronic kidney diseases (CKD) are associated with mineral and bone diseases (MBD), including pain, bone loss, and fractures. Bone fragility related to CKD includes the risk factors observed in osteoporosis in addition to those related to CKD, resulting in a higher risk of mortality related to fractures. Unawareness of such complications led to a poor management of fractures and a lack of preventive approaches. The current guidelines of the Kidney Disease Improving Global Outcomes (KDIGO) recommend the assessment of bone mineral density if results will impact treatment decision. In addition to bone density, circulating biomarkers of mineral, serum bone turnover markers, and imaging techniques are currently available to evaluate the fracture risk. The purpose of this review is to provide an overview of the epidemiology and pathogenesis of CKD-associated bone loss. The contribution of the current tools and other techniques in development are discussed. We here propose a current view of how to better predict bone fragility and the therapeutic options in CKD.

Sevelamer Use, Vitamin K Levels, Vascular Calcifications, and Vertebral Fractures in Hemodialysis Patients: Results from the VIKI Study

Hyperphosphatemia is a risk factor for vascular calcifications (VCs), which are part of the chronic kidney disease-mineral and bone disorders (CKD-MBD). Vitamin K-dependent proteins such as matrix Gla protein (MGP) and bone Gla proteins (BGP, or osteocalcin) can inhibit VCs and regulate bone mineralization. In this analysis of the Vitamin K Italian (VIKI) study, the relationship between vitamin K status, vertebral fractures (VFs) and VCs in 387 hemodialysis (HD) patients with (N = 163; 42.1%) or without N = 224; 57.9%) sevelamer was evaluated. Levels of vitamin K vitamers K1 and K2 or menaquinones (MK; MK4-7), total and undercarboxylated (uc) forms for both BGP and MGP were determined. Although no differences in clinical characteristics were noted, lower levels of MK4 (0.45 versus 0.6 ng/mL, p = .01) and a greater MK4 deficiency was observed in sevelamer-treated patients (13.5% versus 5.4%, p = .005). Multivariate logistic regression revealed that MK4 deficiency was associated with sevelamer use (odds ratio [OR] = 2.64, 95% confidence interval [CI] 1.25-5.58, p = .011) and aortic calcification (OR = 8.04, 95% CI 1.07-60.26, p = .04). In the same logistic model, sevelamer amplified the effect of total BGP levels on the odds of VFs in patients with total BGP <150 μg/L compared with those with total BGP ≥150 μg/L (OR = 3.15, 95% CI 1.46-6.76, p = .003). In contrast, there was no such effect in those untreated (total BGP <150 μg/L versus total BGP ≥150 μg/L: OR = 1.21, 95% CI 0.66-2.23, p = .54]; p = .049 for effect modification by sevelamer). Sevelamer may interfere with MK4 levels in HD patients and interact with low BGP levels to increase bone fractures in CKD patients. © 2020 American Society for Bone and Mineral Research (ASBMR).

Control of phosphorus and prevention of fractures in the kidney patient

Patients with chronic kidney disease have a higher risk of fractures than the general population due to the added factor of uraemia. Although the mechanisms behind uraemia-associated fractures are not fully understood, it is widely accepted that the decrease in bone mineral content and alteration in bone architecture both increase bone fragility. As chronic kidney disease progresses, the risk of fracture increases, especially once the patient requires dialysis. Among the many causes of the increased risk are advanced age, amenorrhoea, steroid exposure, decreased vitamin D, increased PTH, malnutrition and chronic inflammation. Serum phosphorus, whether high or very low, seems to correlate with the risk of fracture. Moreover, increased serum phosphate is known to directly and indirectly affect bone metabolism through the development of adaptive hormonal mechanisms aimed at preventing hyperphosphataemia, such as the increase in PTH and FGF23 and the reduction in calcitriol. These adaptive mechanisms are less intense if the intestinal absorption of phosphorus is reduced with the use of phosphorus captors, which seem to have a positive impact in reducing the risk of fractures. We describe here the possible mechanisms associating serum phosphorus levels, the adaptive mechanisms typical in kidney disease and the use of drugs to control hyperphosphataemia with the risk of fractures. We found no studies in the literature providing evidence on the influence of different treatments on the risk of fractures in patients with chronic kidney disease. We suggest that control of phosphorus should be an objective to consider.

Control of phosphorus and prevention of fractures in the kidney patient

Patients with chronic kidney disease have a higher risk of fractures than the general population due to the added factor of uraemia. Although the mechanisms behind uraemia-associated fractures are not fully understood, it is widely accepted that the decrease in bone mineral content and alteration in bone architecture both increase bone fragility. As chronic kidney disease progresses, the risk of fracture increases, especially once the patient requires dialysis. Among the many causes of the increased risk are advanced age, amenorrhoea, steroid exposure, decreased vitamin D, increased parathyroid hormone (PTH), malnutrition and chronic inflammation. Serum phosphorus, whether high or very low, seems to correlate with the risk of fracture. Moreover, increased serum phosphate is known to directly and indirectly affect bone metabolism through the development of adaptive hormonal mechanisms aimed at preventing hyperphosphataemia, such as the increase in PTH and fibroblast growth factor 23 (FGF23) and the reduction in calcitriol. These adaptive mechanisms are less intense if the intestinal absorption of phosphorus is reduced with the use of phosphorus captors, which seem to have a positive impact in reducing the risk of fractures. We describe here the possible mechanisms associating serum phosphorus levels, the adaptive mechanisms typical in kidney disease and the use of drugs to control hyperphosphataemia with the risk of fractures. We found no studies in the literature providing evidence on the influence of different treatments on the risk of fractures in patients with chronic kidney disease. We suggest that control of phosphorus should be an objective to consider.

Effect of long-term use of unfractionated or low-molecular-weight heparin on bone mineral density in maintenance hemodialysis patients

Introduction

Long‐term use of unfractionated heparin (UFH) or low‐molecular‐weight heparin (LMWH) causes bone loss and osteoporosis in patients not receiving hemodialysis. This study aimed to investigate the effect of UFH and LMWH on bone mineral density (BMD) in patients undergoing maintenance hemodialysis (MHD).

Methods

Patients undergoing MHD using UFH or LMWH as anticoagulants were enrolled. BMD (in g/cm²), T‐score and Z‐score (BMDs) were measured at the lumbar spine and femur neck using dual‐energy X‐ray absorptiometry (DXA) at baseline and 2 years later. Patient demographics and clinical indices were collected. Correlation analysis was used to identify significant predictors of bone loss. Multiple linear regression was used to explore the relationship between heparin type and bone loss progression.

Findings

A total of 104 patients were enrolled and completed the baseline BMD test; 72 completed the test again 2 years later. Six patients were excluded because they used both UFH and LMWH. Although BMD decreased in some patients in the UFH group, a slight increase in the BMD was observed on an average in the LMWH group after 2 years. The mean change in BMD (in g/cm²) [0(−0.03,0.04) vs. 0.04(0,0.06), P = 0.023], T‐score [0(−0.40,0.30) vs. 0.35(−0.03,0.53), P = 0.038], and Z‐score [0.10(−0.30,0.40) vs. 0.45(0.08,0.63), P = 0.031] in the lumbar spine in the UFH group was lower than those in the LMWH group. Femur neck BMD did not change significantly. In a linear regression model, after adjusting for diabetes mellitus, parathyroid hormone, and serum phosphate, we did not find an association between heparin substances and BMD.

Discussion

UFH might be associated with loss of lumbar spine BMD in patients undergoing MHD.

FRAX prognostic and intervention thresholds in the management of major bone fractures in hemodialysis patients: A two-year prospective multicenter cohort study

PURPOSE

The usefulness of FRAX in predicting major bone fractures in patients with end-stage kidney disease on maintenance hemodialysis treatment has been confirmed in previous studies. For meaningful clinical use, the prognostic and intervention FRAX thresholds need to be established.

METHODS

The primary aim of our study was to calculate the optimal cut-off point of FRAX for the best prediction of an increased bone fracture risk in dialysis patients and additionally, to propose its intervention threshold, indicating the need for antifracture pharmacological treatment. The study included 718 hemodialysis patients, who were followed up for two years. Thirty low-energy major bone fractures were diagnosed during the study period. We used the Polish version of FRAX (without the DXA examination) and some particular variables of the FRAX calculator. The optimal cut-off point for prediction of an increased major bone fracture risk was based on the analysis of the sensitivity and specificity curves of FRAX.

RESULTS

The analysis revealed FRAX >5% (sensitivity of 70.0%, specificity of 69.8%) as the prognostic threshold for major bone fractures. Its sensitivity for bone fracture prediction was significantly higher, but specificity lower than those of FRAX ≥10%, used in general Polish population. The reason for this can be an underestimation of bone fracture risk with FRAX in dialysis patients.

CONCLUSIONS

We conclude that the FRAX prognostic threshold for identification of an increased risk of major bone fractures in hemodialysis patients is >5%. We propose to use this specific value of FRAX as an intervention threshold for pharmacological antifracture treatment in hemodialysis patients.

Neuropeptide Y1 Receptor Antagonist Alters Gut Microbiota and Alleviates the Ovariectomy-Induced Osteoporosis in Rats

A plethora of evidence has suggested that gut microbiota is involved in the occurrence and development of postmenopausal osteoporosis (PMO). It has been suggested that neuropeptide Y (NPY) modulates the bone metabolism through Y1 receptor (Y1R), and might be associated with gut microbiota. The present study aims to evaluate the anti-osteoporotic effects of Y1R antagonist and to investigate the potential mechanism by which Y1R antagonist regulates gut microbiota. In this study, eighteen female rats were randomly divided into three groups: the sham surgery (SHAM) group, the ovariectomized (OVX) group, and OVX+BIBO3304 group. After 6 weeks following surgery, Y1R antagonist BIBO3304 was administered to the rats in OVX+BIBO3304 group for 7 days. The bone microstructure and serum biochemical parameters were measured at 12 weeks after operation. The differences in the gut microbiota were analyzed by 16S rDNA gene sequencing. Heat-map and Spearman's correlation analyses were constructed to investigate the correlations between microbiota and bone metabolism-related parameters. The results indicated that OVX+BIBO3304 group showed significantly higher BMD, BV/TV, Tb.Th, Tb.N, Conn.D, and serum Ca²⁺ level than those in OVX group. Additionally, Y1R antagonist changed the gut microbiota composition with lower Firmicutes/Bacteroidetes ratio and higher proportions of some probiotics, including Lactobacillus. The correlation analysis showed that the changes of gut microbiota were closely associated with bone microstructure and serum Ca²⁺ levels. Our results suggested that Y1R antagonist played an anti-osteoporotic effect and regulated gut microbiota in OVX rats, indicating the potential to utilize Y1R antagonist as a novel treatment for PMO.

Effect of continuous long-term treatment for 10 years with bisphosphonate on Japanese osteoporosis patients

INTRODUCTION

In terms of the balance between benefits and risks of long-term treatment with bisphosphonate, uncertainties remain regarding the optimal treatment duration. We investigated effects of continuous long-term treatment for 10 years with bisphosphonate in postmenopausal osteoporosis patients.

MATERIALS AND METHODS

Fifty five patients in the outpatient clinic of our hospital have been continuously treated with alendronate or risedronate for 10 years. All data were retrospectively collected. The age, height, weight, total muscle volume, total fat volume, and BMD at the lumbar spine, total hip and distal 1/3 radius, alkaline phosphatase (ALP), urinary type I collagen cross-linked N-telopeptide (uNTX) and tartrate-resistant acid phosphatase-5b (TRAP5b), calcium (Ca) and phosphate (P) levels were measured pre- and after the start of 10-year continuous treatment.

RESULTS

BMD at the lumbar spine increased continuously over the 10-year period, while BMD at the total hip slightly but significantly decreased, and that at the 1/3 radius did not show any significant change over the 10 years. Serum Ca value was significantly decreased after the start of treatment, and became stable within the reference range from the second year. Bone resorption markers such as uNTX and TRAP5b significantly decreased from the second year after the start of treatment and no significant changes were observed thereafter. There were no serious medical adverse events including atypical femoral fractures and osteonecrosis of the jaw.

CONCLUSION

We believe that the continuous use of alendronate and risedronate for 10 years could be an option for the treatment of postmenopausal osteoporosis patients.

Linear and Non-linear Correlations Between Serum Phosphate Level and Bone Mineral Density in Type 2 Diabetes

Introduction: Serum phosphate plays an important role in bone mineralization and might be a risk factor for many bone diseases. Patients with T2D usually have low serum phosphate level due to diet control, osmotic diuresis, and insulin stimulation. Current studies have discussed the linear association between serum phosphate and bone mineral density (BMD). Objective: We aimed to analyze both the linear and non-linear correlations between serum phosphate and BMD in patients with type 2 diabetes (T2D). Methods: We included 1,469 patients with T2D and obtained their basic information, laboratory measurements, and BMD data. Multivariate adjusted linear regression was used to analyze the linear associations, and we applied a two-piecewise linear regression model using a smoothing function to examine the non-linear association. Results: No linear correlation was found between serum phosphate and BMD in patients with T2D. In women with T2D, we found a non-linear correlation between serum phosphate level and femur neck or total hip BMD. When serum phosphate was <1.3 mmol/L, it was positively associated with femur neck and total hip BMD, whereas when phosphate was >1.3 mmol/L, it was negatively associated with femur neck BMD. Conclusions: In men with T2D, serum phosphate level was not associated with BMD. However, in women with T2D, we found a non-linear correlation between serum phosphate and femur neck or total hip BMD.

Re-evaluation of phosphoric acid-phosphates - di-, tri- and polyphosphates (E 338-341, E 343, E 450-452) as food additives and the safety of proposed extension of use

The Panel on Food Additives and Flavourings added to Food (FAF) provided a scientific opinion re-evaluating the safety of phosphates (E 338-341, E 343, E 450-452) as food additives. The Panel considered that adequate exposure and toxicity data were available. Phosphates are authorised food additives in the EU in accordance with Annex II and III to Regulation (EC) No 1333/2008. Exposure to phosphates from the whole diet was estimated using mainly analytical data. The values ranged from 251 mg P/person per day in infants to 1,625 mg P/person per day for adults, and the high exposure (95th percentile) from 331 mg P/person per day in infants to 2,728 mg P/person per day for adults. Phosphate is essential for all living organisms, is absorbed at 80-90% as free orthophosphate excreted via the kidney. The Panel considered phosphates to be of low acute oral toxicity and there is no concern with respect to genotoxicity and carcinogenicity. No effects were reported in developmental toxicity studies. The Panel derived a group acceptable daily intake (ADI) for phosphates expressed as phosphorus of 40 mg/kg body weight (bw) per day and concluded that this ADI is protective for the human population. The Panel noted that in the estimated exposure scenario based on analytical data exposure estimates exceeded the proposed ADI for infants, toddlers and other children at the mean level, and for infants, toddlers, children and adolescents at the 95th percentile. The Panel also noted that phosphates exposure by food supplements exceeds the proposed ADI. The Panel concluded that the available data did not give rise to safety concerns in infants below 16 weeks of age consuming formula and food for medical purposes.

Bone microarchitecture and bone turnover in hepatic cirrhosis

Liver cirrhosis leads to bone loss. To date, information on bone quality (three-dimensional microarchitecture) and, thus, bone strength is scarce. We observed decreased bone quality at both assessed sites, independent of disease severity. Therefore, all patients should undergo early-stage screening for osteoporosis.

INTRODUCTION

Recent studies found low bone mineral density in cirrhosis, but data on bone microstructure are scarce. This study assessed weight-bearing and non-weight-bearing bones in patients with cirrhosis and healthy controls. The primary objective was to evaluate trabecular and cortical microarchitecture.

METHODS

This was a single-center study in patients with recently diagnosed hepatic cirrhosis. Thirty-two patients and 32 controls participated in this study. After determining the type of cirrhosis, the parameters of bone microarchitecture were assessed by high-resolution peripheral quantitative computed tomography.

RESULTS

Both cortical and trabecular microarchitectures showed significant alterations. At the radius, trabecular bone volume fraction was 17% lower (corrected p = 0.028), and, at the tibia, differences were slightly more pronounced. Trabecular bone volume fraction was 19% lower (p = 0.024), cortical bone mineral density 7% (p = 0.007), and cortical thickness 28% (p = 0.001), while cortical porosity was 32% higher (p = 0.023), compared to controls. Areal bone mineral density was lower (lumbar spine - 13%, total hip - 11%, total body - 9%, radius - 17%, and calcaneus - 26%). There was no correlation between disease severity and microarchitecture. Areal bone mineral density (aBMD) measured by dual-energy X-ray absorptiometry (DXA) correlated well with parameters of cortical and trabecular microarchitecture.

CONCLUSIONS

Hepatic cirrhosis deteriorates both trabecular and cortical microarchitecture, regardless of disease severity. Areal bone mineral density is diminished at all sites as a sign of generalized affection. In patients with hepatic cirrhosis, regardless of its origin or disease severity, aBMD measurements are an appropriate tool for osteologic screening.

Effect of dietary phosphorus intake and age on intestinal phosphorus absorption efficiency and phosphorus balance in male rats

Intestinal phosphorus absorption is an important component of whole-body phosphorus metabolism, and limiting dietary phosphorus absorption is particularly of interest as a therapeutic target in patients with chronic kidney disease to manage mineral bone disorders. Yet, mechanisms and regulation of intestinal phosphorus absorption have not been adequately studied and discrepancies in findings exist based on the absorption assessment technique used. In vitro techniques show rather consistent effects of dietary phosphorus intake level and age on intestinal sodium-dependent phosphate transport. But, the few studies that have used in vivo techniques conflict with these in vitro studies. Therefore, we aimed to investigate the effects of dietary phosphorus intake level on phosphorus absorption using the in situ ligated loop technique in three different aged rats. Male Sprague-Dawley rats (n = 72), were studied at 10-, 20-, and 30-weeks-of-age on a low (0.1%), normal (0.6%), or high (1.2%) phosphorus diet in a 3x3 factorial design (n = 8/group). Rats were fed their assigned diet for 2-weeks prior to absorption testing by jejunal ligated loop as a non-survival procedure, utilizing 33P radioisotope. Metabolic cages were used for determination of calcium and phosphorus balance over the final four days prior to sacrifice, and blood was collected at the time of sacrifice for biochemistries. Our results show that phosphorus absorption was higher in 10-week-old rats compared with 20- and 30-week-olds and this corresponded to higher gene expression of the major phosphate transporter, NaPi-2b, as well as higher whole-body phosphorus balance and net phosphorus absorption. Dietary phosphorus intake level did not affect jejunal phosphorus absorption or NaPi-2b gene expression. Our results contrast with studies utilizing in vitro techniques, but corroborate results of other rodent studies utilizing in situ or in vivo methods. Thus, there is need for additional studies that employ more physiological methods of phosphorus absorption assessment.

Predictors of bone fractures in a single-centre cohort of hemodialysis patients: a 2-year follow-up study

PURPOSE

Bone involvement represents one of the complications of end-stage chronic kidney disease, with fractures being its major risk. The aim of our study was to assess the frequency and predictors of low-trauma fractures in a cohort of maintenance hemodialysis patients followed-up on for 2 years.

METHODS

59 patients (67.6 ± 13.1 years, 43 males) treated with hemodiafiltration underwent initially laboratory (markers of calcium-phosphate metabolism and bone turnover markers) and densitometry examination with TBS assessment (Lunar Prodigy, TBS software 2.1.2). During 24-month follow-up, the frequency of low-trauma fractures was assessed and possible predictors of increased fracture risk were identified using product-moment correlation matrices.

RESULTS

Altogether 7 (11.9%) low-trauma fractures were observed. In the whole group, age (P = 0.047), T-score in proximal femur (P = 0.04), low vitamin D, low BMI (P = 0.03 for both), and higher FRAX for major osteoporotic fracture (P = 0.01) were connected with fractures, but in multi-variate analysis only BMI remained significantly negatively associated with fractures (P = 0.047). TBS and bone turnover markers failed to predict fractures. However, women with fractures had significantly lower serum phosphate (P = 0.03) and higher parathyroid hormone (P = 0.04). Parameters of hip structure analysis significantly correlated with FRAX, but not with fractures.

CONCLUSIONS

In a group of hemodialysis patients from one centre, T-score in proximal femur, low vitamin D, low BMI, and high FRAX for major osteoporotic fracture were associated with low-trauma fractures, however, in multi-variate analysis only low BMI remained a significant predictor of fracture risk.

The physiology of endocrine systems with ageing

During ageing, the secretory patterns of the hormones produced by the hypothalamic-pituitary axis change, as does the sensitivity of the axis to negative feedback by end hormones. Additionally, glucose homoeostasis tends towards disequilibrium with increasing age. Along with these endocrine alterations, a loss of bone and muscle mass and strength occurs, coupled with an increase in fat mass. In addition, ageing-induced effects are difficult to disentangle from the influence of other factors that are common in older people, such as chronic diseases, inflammation, and low nutritional status, all of which can also affect endocrine systems. Traditionally, the decrease in hormone activity during the ageing process has been considered to be detrimental because of the related decline in bodily functions. The concept of hormone replacement therapy was suggested as a therapeutic intervention to stop or reverse this decline. However, clearly some of these changes are a beneficial adaptation to ageing, whereas hormonal intervention often causes important adverse effects. In this paper, we discuss the effects of age on the different hypothalamic-pituitary-hormonal organ axes, as well as age-related changes in calcium and bone metabolism and glucose homoeostasis.

Long-Term Effects of Severe Burn Injury on Bone Turnover and Microarchitecture

Severe burn injury triggers massive alterations in stress hormone levels with a dose-dependent hypermetabolic status including increased bone resorption. This study evaluated bone microarchitecture measured by noninvasive high-resolution peripheral quantitative computed tomography (HR-pQCT). Changes of serum bone turnover markers (BTM) as well as regulators of bone signaling pathways involved in skeletal health were assessed. Standardized effect sizes as a quantitative measure regarding the impact of serum changes and the prediction of these changes on bone microarchitecture were investigated. In total, 32 male patients with a severe burn injury (median total body surface area [TBSA], 40.5%; median age 40.5 years) and 28 matched male controls (median age 38.3 years) over a period of 24 months were included. In patients who had sustained a thermal injury, trabecular and cortical bone microstructure showed a continuous decline, whereas cortical porosity (Ct.Po) and pore volume increased. Initially, elevated levels of BTM and C-reactive protein (CRP) continuously decreased over time but remained elevated. In contrast, levels of soluble receptor activator of NF-κB ligand (sRANKL) increased over time. Osteocalcin, bone-specific alkaline phosphatase (BALP), intact N-terminal type 1 procollagen propeptide (P1NP), and cross-linked C-telopeptide (CTX) acutely reflected the increase of Ct.Po at the radius (R²  = 0.41), followed by the reduction of trabecular thickness at the tibia (R²  = 0.28). In adult male patients, early and sustained changes of markers of bone resorption, formation and regulators of bone signaling pathways, prolonged inflammatory cytokine activities in conjunction with muscle catabolism, and vitamin D insufficiency were observed. These alterations are directly linked to a prolonged deterioration of bone microstructure. The probably increased risk of fragility fractures should be of clinical concern and subject to future interventional studies with bone-protective agents. © 2017 American Society for Bone and Mineral Research.

Effects of Excessive Dietary Phosphorus Intake on Bone Health

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of dietary phosphorus, its sources, recommended intakes, and its absorption and metabolism in health and in chronic kidney disease and to discuss recent findings in this area with a focus on the effects of inorganic phosphate additives in bone health.

RECENT FINDINGS

Recent findings show that increasing dietary phosphorus through inorganic phosphate additives has detrimental effects on bone and mineral metabolism in humans and animals. There is new data supporting an educational intervention to limit phosphate additives in patients with chronic kidney disease to control serum phosphate. The average intake of phosphorus in the USA is well above the recommended dietary allowance. Inorganic phosphate additives, which are absorbed at a high rate, account for a substantial and likely underestimated portion of this excessive intake. These additives have negative effects on bone metabolism and present a prime opportunity to lower total phosphorus intake in the USA. Further evidence is needed to confirm whether lowering dietary phosphorus intake would have beneficial effects to improve fracture risk.

The Rotterdam Study: 2018 update on objectives, design and main results

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. Since 2016, the cohort is being expanded by persons aged 40 years and over. The findings of the Rotterdam Study have been presented in over 1500 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.