Importance of increased urinary calcium excretion in the development of secondary hyperparathyroidism of patients under glucocorticoid therapy

Proton Pump Inhibitor Use and Bone Health in Patients With Rheumatic Diseases: A Cross-Sectional Study

OBJECTIVE

To assess the effect of proton pump inhibitor (PPI) use on bone mineral density (BMD) and bone microarchitecture as measured by the trabecular bone score (TBS) in patients with inflammatory rheumatic and musculoskeletal diseases (iRMDs).

METHODS

Cross-sectional data from a prospective single-center cohort (2015 to 2022) of patients with iRMDs were used to evaluate 3 co-primary outcomes: BMD of the left femoral neck and the lumbar spine (as T-scores) and the TBS. Inverse probability weighting adjusted for numerous confounders including age, sex, body mass index, current and cumulative glucocorticoid (GC) dose, C-reactive protein levels, disability, and others. Analyses were based on general linear models, following a prespecified statistical analysis plan.

RESULTS

The study included 1495 patients (75% women; mean age, 62.6±13.1 years; 49% and 63% with regular PPI and GC use, respectively). The PPI users had lower BMD at both spine (adjusted contrast -0.25; 95% CI, -0.47 to -0.04; P=.02) and femoral neck (-0.17 [-0.35 to 0.01]; P=.07). Differences between PPI users and nonusers were statistically significant only in patients concurrently using GCs at more than 7.5 mg/d prednisone equivalent. The TBS was similar in PPI users and nonusers (adjusted contrast, 0.00 [-0.04 to 0.04]; P=.97).

CONCLUSION

Our results suggest that PPIs lead to a loss of BMD rather than an impairment of bone microarchitecture in patients with iRMDs. The negative association between PPI use and BMD appears to be dependent on concurrent GC use. Clinicians should carefully review the indication for PPI use in patients with iRMDs, especially in those receiving higher dose GCs.

Efficacy of denosumab in the treatment of hypercalcemic renal dysfunction in sarcoidosis: a case report

A 70-year-old female patient was admitted for close examination and treatment of hypercalcemia (corrected serum calcium levels: 3.04 mmol/L) and renal dysfunction (serum creatinine levels: 254.59 µmol/L). The patient had a history of sarcoidosis, diagnosed based on epithelioid cell granulomas in subcutaneous nodule biopsies, uveitis, and bilateral hilar lymphadenopathy, which had spontaneously remitted 10 years before admission. Because the patient was diagnosed with hypercalcemia associated with recurrent sarcoidosis, prednisone (20 mg/day) was initiated, and its dose was tapered following the decrease in serum calcium and creatinine levels. However, the levels of these parameters increased again when the prednisone dose was reduced to ≤ 4 mg/day. We were concerned about glucocorticoid-induced osteoporosis in the patient but hesitated to use first-line bisphosphonates because of renal dysfunction. Therefore, denosumab was initiated to reduce the risk of hypercalcemia, renal dysfunction, and glucocorticoid-induced osteoporosis. Serum creatinine and corrected serum calcium levels subsequently decreased. The prednisone dose could be reduced following repeated denosumab administration.Thus, denosumab can be a multifaceted, beneficial option for sarcoidosis-induced hypercalcemia, as it alleviates renal dysfunction indirectly by normalizing serum calcium levels, facilitates reduction of the glucocorticoid dose, and ameliorates glucocorticoid-induced osteoporosis.

Glucocorticoid-induced osteoporosis: an overview with focus on its prevention and management

The widespread use of glucocorticoids (GCs) contributes to the effective management of several diseases and conditions. However, it comes at a price in the case of the bones causing glucocorticoid-induced osteoporosis (GIOP), the most common cause of secondary osteoporosis and fractures. Several scientific societies have issued comprehensive guidelines on the optimal management of patients receiving GCs with the aim of providing answers to three fundamental questions, namely, whom to treat, when to treat, and how to treat. Both common ground and different approaches exist among them. General preventive measures should start along with GC initiation, and the duration of GC therapy should be limited to the minimal effective range. A pre-existing fracture, age, gender, menopausal status, dose, and duration of GC treatment are key factors in the decision to initiate antiosteoporotic medication. Oral bisphosphonates are typically regarded as the first-line treatment choice for GIOP partly due to their cost-effectiveness. Denosumab is another valid option, but an "exit strategy" should be considered before its initiation due to the risk of rebound-associated vertebral fractures upon its discontinuation. Since impaired bone formation represents the main mechanism by which GCs negatively affect skeletal health, osteoanabolic therapies appear to be pathophysiologically the more appropriate and appealing option, although cost considerations currently limit their use to selected severe cases. Regardless of the agent selected to mitigate the impact of GCs on the skeleton, what is most crucial is that the treating physician correctly stratifies the risk and intervenes at the right time.

Bisphosphonate use for glucocorticoid-induced osteoporosis in older patients with immune thrombocytopenia: a clinical perspective

Prednisolone, used as a standard initial treatment for immune thrombocytopenia (ITP), is an important risk factor for osteoporosis. Recently, we found that prescription of bisphosphonate during initial loading of prednisolone may prevent reduction in bone mineral density and development of glucocorticoid-induced osteoporosis (GIO) in older patients with ITP receiving prolonged steroid therapy. In this review, I describe the treatment options for older patients with ITP, and present the best practices for screening, evaluating, and diagnosing ITP. I also summarize the literature from 2017 to 2022 on the treatment options for ITP, including discussions on the contraindications and side effects, with an emphasis on GIO, and the relative merits of bisphosphonates as a co-treatment for prevention of GIO. Finally, I present a perspective and an expert recommendation on how older patients with ITP would best be served in the future.

Endocrine sequelae of hematopoietic stem cell transplantation: Effects on mineral homeostasis and bone metabolism

Hematopoietic stem cell transplantation (HSCT) is an established therapeutic strategy for the treatment of malignant (leukemia and lymphoma) and non-malignant (thalassemia, anemia, and immunodeficiency) hematopoietic diseases. Thanks to the improvement in patient care and the development of more tolerable conditioning treatments, which has extended the applicability of therapy to the elderly, a growing number of patients have successfully benefited from HSCT therapy and, more importantly, HSCT transplant-related mortality has consistently reduced in recent years. However, concomitantly to long term patient survival, a growing incidence of late HSCT-related sequelae has been reported, being variably associated with negative effects on quality of life of patients and having a non-negligible impact on healthcare systems. The most predominantly observed HSCT-caused complications are chronic alterations of the endocrine system and metabolism, which endanger post-operative quality of life and increase morbidity and mortality of transplanted patients. Here, we specifically review the current knowledge on HSCT-derived side-effects on the perturbation of mineral metabolism; in particular, the homeostasis of calcium, focusing on current reports regarding osteoporosis and recurrent renal dysfunctions that have been observed in a percentage of HSC-transplanted patients. Possible secondary implications of conditioning treatments for HSCT on the physiology of the parathyroid glands and calcium homeostasis, alone or in association with HSCT-caused renal and bone defects, are critically discussed as well.

Comparison of trace element (selenium, iron), electrolyte (calcium, sodium), and physical activity levels in COVID-19 patients before and after the treatment

OBJECTIVE

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), a worldwide health problem, is the cause of 2019 coronavirus disease. This study aimed to compare the trace element (selenium and iron), electrolyte (calcium and sodium), and physical activity levels of COVID-19 patients before and after COVID-19 treatment.

METHOD

This prospective study was conducted in patients diagnosed with COVID-19 (n = 15). Trace element (selenium and iron), electrolyte (calcium and sodium), and physical activity levels of the patients were compared before and after the treatment.

RESULT

Most of patients had selenium deficiency (86.7 %), iron deficiency (73.3 %), calcium deficiency (66.7 %) and sodium deficiency (46.7 %) before COVID-19 treatment. The most important improvements were seen in iron deficiency (from 73.3 % to 26.7 %) and sodium deficiency (from 46.7 % to 13.3 %) after the treatment. Selenium, iron, calcium, and sodium levels of the patients were significantly higher after the treatment (p < 0.05). The patients had low physical activity before and after COVID-19 treatment. In addition, no statistically significant difference was found in the comparison of physical activity levels (p > 0.05).

CONCLUSION

This study indicated that selenium, iron, calcium, and sodium levels and deficiencies might improve after treating patients with COVID-19. However, the results of this study showed that the physical activity levels of COVID-19 patients might remain stable and low throughout the treatment process.

Risk for osteoporosis and fracture with glucocorticoids

Glucocorticoid use is ubiquitous and is associated with multiple adverse reactions. Among them, osteoporosis and bone fractures are of our concern. In this review, we present current evidence on the effect of glucocorticoids on bone mineral density and the risk of fractures, the mechanisms underlying those effects, and the recommendations for monitoring and treating patients who take them. The bone mineral density of the lumbar spine and total hip is lower, and the risk of fractures is higher in glucocorticoid users than non-users. These effects have a rapid onset, are dose-dependent, and improve soon after discontinuation of glucocorticoids. They also appear to occur even with non-systemic routes of administration and with low doses. Glucocorticoids reduce bone mineral density by increasing osteoclast activity and decreasing osteoblast and osteocyte activity. Calcium metabolism and parathyroid hormone activity are less important than was initially thought. Treatment decisions are on risk stratification using clinical, radiographic, and prediction tools. Our armamentarium for the treatment and prevention of glucocorticoid-induced osteoporosis includes calcium and vitamin D, bisphosphonates, recombinant parathyroid hormone, monoclonal antibodies against receptor activator of nuclear factor kappa-B ligand, and hormone treatments.

Urinary free cortisol excretion is associated with lumbar bone density in patients with adrenal Cushing's syndrome

Patients with adrenal Cushing's syndrome have a poor prognosis due to the autonomous hypersecretion of endogenous cortisol from the adrenal gland. Although several clinical examinations have been developed to manifest the autonomous hypersecretion of endogenous cortisol in this syndrome, it is unknown which parameter of cortisol overproduction is best associated with the adrenal cortisol content and bone and vascular complications of this syndrome. Therefore, the present study was undertaken to evaluate the parameter(s) associated with the adrenal cortisol content in patients with adrenal Cushing's syndrome, as well as to assess the associations between these parameters and the vascular and bone complications of this syndrome. Cardiovascular factors such as blood pressure and pulse rate, glucose metabolism, lipid metabolism, renal function, and indices of arteriosclerosis, except for diastolic blood pressure, failed to show an association with the adrenal cortisol content. Twenty-four-hour urinary free cortisol excretion (ρ = 0.893, P = 0.007) and plasma cortisol levels after the 1-mg (ρ = 0.857, P = 0.014) or 8-mg (ρ = 0.900, P = 0.037) overnight dexamethasone suppression test, but not plasma cortisol levels in the morning or late at night or indices of ¹³¹I-adosterol single-photon emission computed tomography-computed tomography, were significantly and positively associated with the adrenal cortisol content. Twenty-four-hour urinary free cortisol excretion, and not plasma cortisol levels after the 1- or 8-mg overnight dexamethasone suppression test, was significantly and negatively associated with lumbar spine bone density (lumbar spine bone mineral density, ρ = -0.786, P = 0.036; lumbar spine T score, ρ = -0.883, P = 0.009; and lumbar spine Z score, ρ = -0.883, P = 0.009). These results indicate that 24-h urinary free cortisol excretion is best associated with a decrease in bone density via increased adrenal cortisol overproduction and suggest that it could be used as a marker for osteoporosis in these patients.

Chronic Kidney Disease-Mineral Bone Disease biomarkers in kidney transplant patients

Background:

Chronic Kidney Disease associated with Mineral Bone Disease (CKD-MBD) is frequent in kidney transplant patients. Post-transplantation bone disease is complex, especially in patients with pre-existing metabolic bone disorders that are further affected by immunosuppressive medications and changes in renal allograft function. Main biochemical abnormalities of mineral metabolism in kidney transplantation (KTx) include hypophosphatemia, hyperparathyroidism (HPTH), insufficiency or deficiency of vitamin D, and hypercalcemia.

Objective:

This review aimed to summarize the pathophysiology and main biomarkers of CKD-MBD in KTx.

Methods:

A comprehensive and non-systematic search in PubMed was independently made with an emphasis on biomarkers in mineral bone disease in KTx.

Results:

CKD-MBD can be associated with numerous factors including secondary HPTH, metabolic dysregulations before KTx, and glucocorticoids therapy in post-transplant subjects. Fibroblast growth factor 23 (FGF23) reaches normal levels after KTx with good allograft function, while calcium, vitamin D and phosphorus, ultimately, result in hypercalcemia, persistent vitamin D insufficiency, and hypophosphatemia respectively. As for PTH levels, there is an initial tendency of a significant decrease, followed by a raise due to secondary or tertiary HPTH. In regard to sclerostin levels, there is no consensus in the literature.

Conclusion:

KTx patients should be continuously evaluated for mineral homeostasis and bone status, both cases with successful kidney transplantation and those with reduced functionality. Additional research on CKD-MBD pathophysiology, diagnosis, and management is essential to guarantee long-term graft function, better prognosis, good quality of life, and reduced mortality for KTx patients.

Expression of Renal Vitamin D and Phosphatonin-Related Genes in a Sheep Model of Osteoporosis

Simple Summary

Osteoporosis is a significant public health issue around the world, with post-menopausal osteoporosis due to estrogen deficiency resulting in approximately ¾ of cases. Treatment with glucocorticoids is another common cause of osteoporosis in humans. Sheep are a well-established model for osteoporosis in humans. In this study, aged sheep had their ovaries removed (ovariectomy) to simulate estrogen deficiency, and some sheep were also treated with glucocorticoids. The results showed that expression of the gene klotho in the kidney had the most marked difference in ovariectomized sheep treated with glucocorticoids for 2 months followed by a recovery period of 3 months. Klotho is known as the “anti-aging” hormone and is an important regulator of calcium and phosphorus metabolism. It may therefore be involved in the recovery of bone mineral density seen in ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months. As such, it could be an important treatment target for osteoporosis in humans.

Abstract

Osteoporosis is a significant public health issue around the world, with post-menopausal osteoporosis due to estrogen deficiency resulting in approximately ¾ of cases. In this study, 18 aged Merino ewes were ovariectomized, and 10 were controls. Three of the ovariectomized ewes were treated weekly with 400 mg of methylprednisolone for 5 months and three were treated weekly for 2 months, followed by a 3-month recovery period. At 2 months, five control animals and six ovariectomized animals were euthanized. At 5 months, all the remaining ewes were euthanized. Kidney samples were collected postmortem for qPCR analysis of NPT1, PTH1R, NPT2a, NPT2c, Klotho, FGFR1IIIc, VDR, CYP24A1, CYP27B1, TRPV5, TRPV6, CalD9k, CalD28k, PMCA and NCX1. Ovariectomized sheep had significantly greater VDR expression compared with other groups. Ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months showed significant differences in TRPV5, CYP24A1 and klotho gene expression compared to other groups. Differences in klotho expression were most marked after adjustment for repeated measures (p = 0.1). Klotho is known as the “anti-aging” hormone and is involved in calcium and phosphorus metabolism. Klotho may be involved in the recovery of bone mineral density in ovariectomized sheep treated with glucocorticoids for 2 months followed by euthanasia at 5 months. Further research on the role of klotho is recommended.

A Phase II Multicenter Trial on High-Dose Vitamin D Supplementation for the Correction of Vitamin D Insufficiency in Patients with Breast Cancer Receiving Adjuvant Chemotherapy

Breast cancer (BC) treatments induce vitamin D (VD) insufficiency and bone metabolism changes, resulting in osteoporosis and skeletal morbidity risk. We report the results of a bicentric phase II trial (ClinicalTrials.gov Identifier: NCT04091178) on the safety and efficacy of high-dose oral VD supplementation for VD deficiency correction in 44 patients with early BC treated with adjuvant chemotherapies. Patients received one dose of 100,000 IU 25-OH VD every 3 weeks from day 1 of cycle 1 to day 1 of cycle 5. The primary endpoint was the percentage of patients achieving serum 25-OH VD concentration normalization on day 1 of cycle 6 (D1C6). Secondary endpoints were safety, VD and calcium parameters at baseline and during chemotherapy, and identification of predictive biomarkers of VD normalization on D1C6. On D1C6, 21 patients (47.7%, 95% CI: 33.0–62.8) achieved VD normalization. No VD-related clinical toxicity was reported. However, 13 patients (29.5%) presented asymptomatic grade 1 hypercalciuria, leading to interruption of the high-dose oral VD supplementation in 10, followed by a rapid reduction in serum VD concentration. No baseline clinical factor was predictive of VD normalization on D1C6. This high-dose VD supplementation appears safe and efficient in patients with early BC receiving adjuvant chemotherapy.

A survey of hypercalciuria during chemotherapy in acute lymphoblastic leukemia

BACKGROUND

Urolithiasis is an extremely rare complication in childhood acute lymphoblastic leukemia (ALL), and some reports have implicated corticosteroids during chemotherapy as a risk factor for it. However, only a few reports have analyzed urinary electrolytes in this context.

METHODS

We retrospectively analyzed 55 patients with ALL who underwent chemotherapy between October 2007 and January 2019. Their median age was 9.3 years (range, 0.3-24.0 years) with 30 males and 25 females. Lineages were B-cell precursor ALL (BCP-ALL) in 42 patients, T-cell in nine and others in four patients. All patients received chemotherapy based on the Berlin-Frankfurt-Münster regimen.

RESULTS

Forty-nine out of the 55 ALL patients exhibited hypercalciuria at least once during chemotherapy. Moreover, 36 patients with BCP-ALL, who were receiving identical Berlin-Frankfurt-Münster-based regimens, exhibited significantly high urinary calcium excretion immediately following high-dose glucocorticoid administration. Among the 55 ALL patients, urolithiasis was observed in one patient, a 6-year-old boy with BCP-ALL who developed urolithiasis at reinduction chemotherapy just after cessation of high-dose dexamethasone administration.

CONCLUSIONS

Nearly 90% of the ALL patients studied developed hypercalciuria during chemotherapy in strong association with corticosteroid administration.

Glucocorticoid- and Transplantation-Induced Osteoporosis

Glucocorticoid-induced osteoporosis is the most common cause of secondary osteoporosis; nonetheless, it remains an undertreated condition. Transplantation-induced osteoporosis encompasses a broad range of unique pathogenetic features with distinct characteristics dependent on the transplanted organ. Understanding the pathogenesis of bone loss is key to recommending osteoporosis therapy in these patients. This review summarizes recent advances and addresses current issues in these fields.

Glucocorticoids dexamethasone and prednisolone suppress fibroblast growth factor 23 (FGF23)

Fibroblast growth factor 23 (FGF23) is a hormone mainly secreted by bone cells. Its most prominent effects are the regulation of renal phosphate reabsorption and calcitriol (active vitamin D, 1,25(OH)₂D₃) formation, effects dependent on its co-receptor αKlotho. Besides these actions, further paracrine and endocrine effects exist. The production of FGF23 is regulated by 1,25(OH)₂D₃, parathyroid hormone, dietary phosphate intake, iron status, as well as inflammation. Glucocorticoids are hormones with anti-inflammatory properties and are, therefore, widely used for acute and chronic inflammatory diseases, autoimmune disorders, and malignancies. The present study explored whether glucocorticoids influence the production of FGF23 in vitro as well as in mice. Fgf23 transcription was analyzed by semi-quantitative real-time PCR. Serum concentrations of FGF23 and 1,25(OH)₂D₃ were measured by ELISA. Urinary phosphate and Ca²⁺ excretion were determined in metabolic cages. As a result, in UMR106 rat osteoblast-like cells and in MC3T3-E1 cells, both, dexamethasone and prednisolone, downregulated Fgf23 transcription and FGF23 protein synthesis. Dexamethasone increased Dmp1 and Phex (encoding FGF23-regulating genes) as well as Nfkbia (encoding NFκB inhibitor IκBα) transcription in UMR106 cells. In mice, a single injection of dexamethasone or prednisolone was followed by a significant decrease of serum C-terminal and intact FGF23 concentration and bone Fgf23 mRNA expression within 12 h. These effects were paralleled by increased renal phosphate excretion and enhanced 1,25(OH)₂D₃ formation. We conclude that a single glucocorticoid treatment strongly downregulates the FGF23 plasma concentration. KEY MESSAGES: Glucocorticoids dexamethasone and prednisolone suppress the formation of bone-derived hormone fibroblast growth factor 23 (FGF23) in vitro. The effect is accompanied by an upregulation of Dmp1, Phex, and IκBα, negative regulators of FGF23, in UMR106 osteoblast-like cells. Glucocorticoid receptor antagonist RU-486 attenuates the effect of dexamethasone on FGF23, Dmp1, and Phex. In mice, a single glucocorticoid dose suppresses FGF23 and enhances 1,25(OH)₂D₃ (active vitamin D).

CKD-MBD post kidney transplantation

Complications of chronic kidney disease-associated mineral and bone disorders (CKD-MBD) are frequently observed in pediatric kidney transplant recipients and are associated with high morbidity, including growth failure, leg deformities, bone pain, fractures, osteonecrosis, and vascular calcification. Post-transplant CKD-MBD is mainly due to preexisting renal osteodystrophy and cardiovascular changes at the time of transplantation, glucocorticoid treatment, and reduced graft function. In addition, persistent elevated levels of parathyroid hormone (PTH) and fibroblast growth factor 23 may cause hypophosphatemia, resulting in impaired bone mineralization. Patient monitoring should include assessment of growth, leg deformities, and serum levels of calcium, phosphate, magnesium, alkaline phosphatase, 25-hydroxyvitamin D, and PTH. Therapy should primarily focus on regular physical activity, preservation of transplant function, and steroid-sparing immunosuppressive protocols. In addition, adequate monitoring and treatment of vitamin D and mineral metabolism including vitamin D supplementation, oral phosphate, and/or magnesium supplementation, in case of persistent hypophosphatemia/hypomagnesemia, and treatment with active vitamin D in cases of persistent secondary hyperparathyroidism. The latter should be done using the minimum PTH-suppressive dosages aiming at the recommended CKD stage-dependent PTH target range. Finally, treatment with recombinant human growth hormone should be considered in patients lacking catch-up growth within the first year after transplantation.

Fractal-Based Analysis of Bone Microstructure in Crohn's Disease: A Pilot Study

Crohn's disease (CD) is associated with bone loss and increased fracture risk. TX-Analyzer™ is a new fractal-based technique to evaluate bone microarchitecture based on conventional radiographs. The aim of the present study was to evaluate the TX-Analyzer™ of the thoracic and lumbar spine in CD patients and healthy controls (CO) and to correlate the parameters to standard imaging techniques. 39 CD patients and 39 age- and sex-matched CO were analyzed. Demographic parameters were comparable between CD and CO. Bone structure value (BSV), bone variance value (BVV) and bone entropy value (BEV) were measured at the vertebral bodies of T7 to L4 out of lateral radiographs. Bone mineral density (BMD) and trabecular bone score (TBS) by dual energy X-ray absorptiometry (DXA) were compared to TX parameters. BSV and BVV of the thoracic spine of CD were higher compared to controls, with no difference in BEV. Patients were further divided into subgroups according to the presence of a history of glucocorticoid treatment, disease duration > 15 years and bowel resection. BEV was significantly lower in CD patients with these prevalent risk factors, with no differences in BMD at all sites. Additionally, TBS was reduced in patients with a history of glucocorticoid treatment. Despite a not severely pronounced bone loss in this population, impaired bone quality in CD patients with well-known risk factors for systemic bone loss was assessed by TX-Analyzer™.

Risk Factors and Management of Osteoporosis Post-Transplant

Bone and mineral disorders are common after organ transplantation. Osteoporosis post transplantation is associated with increased morbidity and mortality. Pathogenesis of bone disorders in this particular sub set of the population is complicated by multiple co-existing factors like preexisting bone disease, Vitamin D deficiency and parathyroid dysfunction. Risk factors include post-transplant immobilization, steroid usage, diabetes mellitus, low body mass index, older age, female sex, smoking, alcohol consumption and a sedentary lifestyle. Immunosuppressive medications post-transplant have a negative impact on outcomes, and further aggravate osteoporotic risk. Management is complex and challenging due to the sub-optimal sensitivity and specificity of non-invasive diagnostic tests, and the underutilization of bone biopsy. In this review, we summarize the prevalence, pathophysiology, diagnostic tests and management of osteoporosis in solid organ and hematopoietic stem cell transplant recipients.

Exercise Alleviates Osteoporosis in Rats with Mild Chronic Kidney Disease by Decreasing Sclerostin Production

Chronic kidney disease–mineral bone disorder (CKD–MBD), comprising mineral, hormonal, and bone metabolic imbalance, is a major CKD-related issue; it causes osteoporosis prevalence in CKD patients. Osteocyte-derived sclerostin inhibits the osteogenic Wnt/β-catenin signaling pathway; its levels rise when kidney function declines. Exercise modulates the physiological functions of osteocytes, potentially altering sclerostin production. It may aid bone and mineral electrolyte homeostasis in CKD. Mild CKD was induced in rats by partial nephrectomy. They were divided into: sham (no CKD), CKD, and CKD + exercise (8 weeks of treadmill running) groups. Micro-CT scanning demonstrated that the CKD + exercise-group rats had a higher bone mineral density (BMD) of the spine and femoral metaphysis and higher femoral trabecular bone volume than the CKD-group rats. Bone formation rates were not significantly different. The CKD + exercise-group rats had lower serum sclerostin (157.1 ± 21.1 vs 309 ± 38.1 pg/mL, p < 0.05) and CTX-1 (bone resorption marker) levels. Immunohistochemistry revealed higher tibial β-catenin concentrations in the CKD + exercise-group rats. Serum FGF-23, intact parathyroid hormone (iPTH), alkaline phosphatase (ALP), calcium, and phosphate levels showed no significant differences between these groups. Thus, exercise improves BMD and bone microstructure in mild CKD by inhibiting sclerostin production, but does not alter serum minerals.

Acute hypocalcaemia following denosumab in heart and lung transplant patients with osteoporosis

BACKGROUND

Osteoporosis is highly prevalent in the heart and lung transplant population. Given high rates of concurrent renal impairment, there is increasing use of denosumab in this population. However, denosumab may be associated with hypocalcaemia, particularly in patients with chronic kidney disease (CKD).

AIM

To explore the risk of hypocalcaemia in a heart and lung transplant cohort prescribed denosumab for osteoporosis.

METHODS

We performed a retrospective database review of all surviving heart and lung transplant patients who had received denosumab for osteoporosis between January 2012 and November 2015. We assessed the rates of hypocalcaemia in this cohort and collected baseline clinical data to determine associated factors.

RESULTS

Ten patients received denosumab and had laboratory results available within 3 months of the dose. Of these, three patients developed severe (grade 4) hypocalcaemia, while two patients developed mild (grade 1) hypocalcaemia. In comparison to the five patients who remained normocalcaemic, patients with hypocalcaemia had significantly lower baseline mean estimated glomerular filtration rate but similar baseline mean corrected serum calcium. Unexpectedly, patients developing hypocalcaemia had non-significantly higher levels of 25-hydroxyvitamin D and lower baseline doses of prednisone.

CONCLUSIONS

In heart and lung transplant patients, denosumab should be used judiciously in patients with advanced renal disease due to the risk of hypocalcaemia.

Effects of alendronate for treatment of glucocorticoid-induced osteoporosis: A meta-analysis of randomized controlled trials

BACKGROUND

Alendronate has been used to prevent or treat glucocorticoid-induced osteoporosis (GIO), data regarding its efficacy are inconsistent. We conducted the current systematic review and meta-analysis to evaluate both efficacy and safety of alendronate in the treatment of GIO.

METHODS

PubMed, Embase, the Cochrane Controlled Trials Registry, and the China Academic Journal Network Publishing Databases were searched up through March 1, 2018. Randomized controlled trials (RCTs) involving patients which received alendronate treatment were included. Outcome measures were bone mineral density (BMD) changes, bone fractures, and adverse reactions. Data from the individual studies were pooled using random or fixed effect models based on heterogeneity. Effect size was reported as standardized mean differences (SMD) for continuous outcomes and pooled odds ratios (OR) for dichotomous outcomes, with 95% confidence interval (CI).

RESULTS

Overall, 10 studies involving 1002 patients were included in the present investigation. Alendronate treatment significantly increased BMD of the lumbar spine and femoral neck during 6 to 24 months. These beneficial effects were apparent at 12 months after treatment for the lumbar spine but not the femoral neck BMD. Alendronate treatment did not significantly change fracture risk nor induce significant differences in adverse gastrointestinal effects.

CONCLUSION

Alendronate significantly increases BMD of the lumbar spine and femoral neck in patients with GIO, but does not appear to reduce the risk of fractures. As relatively insufficient data regarding the GIO fracture incidence has been reported, more RCTs need to be carried out to determine the efficacy of alendronate in the prevention of GIO fracture.

Assessment of Risk Factors for Bone Disease in Renal Transplant Recipients

Background

Renal allograft recipients are at increased risk of osteoporosis and fractures because of their multiple risk factors for reduced bone mineral density (BMD).

Objective

To retrospectively assess the risk factors that may predispose renal transplant recipients to reduced BMD.

Methods

Thirty-one consecutive renal allograft recipients who had their hip and spine BMD measured by dual energy X-ray absorptiometry were evaluated. Individual patient medical records were reviewed for risk factors including demographics, laboratory parameters, glucocorticoid use, medical history, physical activity, and gonadal status. Fisher's exact test and Kruskal-Wallis chi-square approximations were used to compare BMD groups (p < 0.05). Analysis of variance with a Bonferroni adjustment was used to compare differences between BMD groups (p = 0.01) Linear regression analysis was used to correlate BMD with clinical parameters.

Results

A trend for younger patients (mean 43 y) to have osteoporosis and older patients (mean 54 y) to be osteopenic (p = 0.056) was seen. Higher body weight (p = 0.003) and higher creatinine clearance (p = 0.008) were associated with normal BMD results. Linear regression analysis showed a strong correlation between hip and spine BMD and creatinine clearance. Our data failed to show a statistical relationship between cumulative glucocorticoid dose or daily doses of greater than 7.5 mg and lower BMD. Neither male gender nor premenopausal status seemed to provide protection from reduced BMD.

Conclusions

These results suggest that all renal allograft recipients, regardless of age, gender, or hormonal status, may be at risk for the development of osteoporosis.

The biochemical and histological analysis of subcutaneous calcitonin and intramedullary methylprednisolone on bone repair after bone marrow ablation: an experimental comparative study in rats

Background

Although, glucocorticoid (GC) and calcitonin-induced changes in bone repair have been studied previously, the exact effects of these on fracture healing remain controversial. Hence, the purpose of this experimental study is to determine biochemical and histological effects of locally administrated GC and systemically administrated calcitonin on the kinetics of healing response after bone marrow ablation in rats.

Methods

After having undergone marrow ablation, a steroid-treated group of rats (n = 24) received a single dose of intramedullary methylprednisolone (2 mg/kg), a calcitonin-treated group (n = 24) received intermittently administrated subcutaneous salmon calcitonin (16 IU/kg), and a control group (n = 24) received intramedullary saline (25 μl).

Results

Blood samples taken on days 1, 3, 7, 9, and 15 after ablation showed an increase in serum calcium, alkaline phosphatase (ALP), and phosphate levels in the Calcitonin and Control groups. Levels of calcium and ALP peaked on day 7 after ablation. However, an increase in phosphate levels indicated a biphasic reaction that peaked on the third and ninth day after ablation. Hypercalcemia was not observed in Steroid group because of the inhibition of osteoclastic bone resorption. In that group, the serum levels of ALP and phosphate were lower than baseline levels. The levels of urinary calcium excretion peaked 3 to 7 days after marrow ablation in the control group and 7 to 9 days after that procedure in the steroid group. Histologic evaluation showed that the rats in the control group demonstrated the expected healing period according to the histological grades and that a delay in healing occurred in the calcitonin group after day 9 because of the inhibition of osteoclastic bone resorption. All rats in the steroid group exhibited a decrease and delayed healing response.

Conclusion

Total serum calcium, phosphate, and ALP levels increased after bilateral tibial bone marrow ablation and urine calcium and hydroxyproline excretion also increased as a factor of bone resorption. Subcutaneously administrated salmon calcitonin did not affect biochemical changes after marrow ablation. Single-dose intramedullary methylprednisolone inhibited extra-tibial bone resorption induced by cytokines after bone marrow ablation.

Accentuated hyperparathyroidism in type II Bartter syndrome

BACKGROUND

Bartter syndrome (BS) may be associated with different degrees of hypercalciuria, but marked parathyroid hormone (PTH) abnormalities have not been described.

METHODS

We compared clinical and laboratory data of patients with either ROMK-deficient type II BS (n = 14) or Barttin-deficient type IV BS (n = 20).

RESULTS

Only BS-IV patients remained mildly hypokalemic in spite of a higher need for potassium supplementation. Estimated glomerular filtration rate (eGFR) was mildly decreased in only four BS-IV patients. Average PTH values were significantly higher in BS-II (160.6 ± 85.8 vs. 92.5 ± 48 pg/ml in BS-IV, p = 0.006). In both groups, there was a positive correlation between age and log(PTH). Levels of 25(OH) vitamin D were not different. Total serum calcium was lower (within normal limits) and age-related serum phosphate (Pi)-SDS was increased in BS-II (1.19 ± 0.71 vs. 0.01 ± 1.04 in BS-IV, p < 0.001). The GFR threshold for Pi reabsorption was higher in BS-II (5.63 ± 1.25 vs. 4.36 ± 0.98, p = 0.002). Spot urine calcium/creatinine ratio and nephrocalcinosis rate (100 vs. 16 %) were higher in the BS-II group.

CONCLUSIONS

PTH, serum Pi levels, and urinary threshold for Pi reabsorption are significantly elevated in type II vs. type IV BS, suggesting a PTH resistance state. This may be a response to more severe long-standing hypercalciuria, leading to a higher rate of nephrocalcinosis in BS-II.

Vitamin D Signaling Modulators in Cancer Therapy

The antiproliferative and pro-apoptotic effects of 1α,25-dihydroxycholecalciferol (1,25(OH)2D3, 1,25D3, calcitriol) have been demonstrated in various tumor model systems in vitro and in vivo. However, limited antitumor effects of 1,25D3 have been observed in clinical trials. This may be attributed to a variety of factors including overexpression of the primary 1,25D3 degrading enzyme, CYP24A1, in tumors, which would lead to rapid local inactivation of 1,25D3. An alternative strategy for improving the antitumor activity of 1,25D3 involves the combination with a selective CYP24A1 inhibitor. The validity of this approach is supported by numerous preclinical investigations, which demonstrate that CYP24A1 inhibitors suppress 1,25D3 catabolism in tumor cells and increase the effects of 1,25D3 on gene expression and cell growth. Studies are now required to determine whether selective CYP24A1 inhibitors+1,25D3 can be used safely and effectively in patients. CYP24A1 inhibitors plus 1,25D3 can cause dose-limiting toxicity of vitamin D (hypercalcemia) in some patients. Dexamethasone significantly reduces 1,25D3-mediated hypercalcemia and enhances the antitumor activity of 1,25D3, increases VDR-ligand binding, and increases VDR protein expression. Efforts to dissect the mechanisms responsible for CYP24A1 overexpression and combinational effect of 1,25D3/dexamethasone in tumors are underway. Understanding the cross talk between vitamin D receptor (VDR) and glucocorticoid receptor (GR) signaling axes is of crucial importance to the design of new therapies that include 1,25D3 and dexamethasone. Insights gained from these studies are expected to yield novel strategies to improve the efficacy of 1,25D3 treatment.

Distal convoluted tubule

The distal convoluted tubule (DCT) is a short nephron segment, interposed between the macula densa and collecting duct. Even though it is short, it plays a key role in regulating extracellular fluid volume and electrolyte homeostasis. DCT cells are rich in mitochondria, and possess the highest density of Na+/K+-ATPase along the nephron, where it is expressed on the highly amplified basolateral membranes. DCT cells are largely water impermeable, and reabsorb sodium and chloride across the apical membrane via electroneurtral pathways. Prominent among this is the thiazide-sensitive sodium chloride cotransporter, target of widely used diuretic drugs. These cells also play a key role in magnesium reabsorption, which occurs predominantly, via a transient receptor potential channel (TRPM6). Human genetic diseases in which DCT function is perturbed have provided critical insights into the physiological role of the DCT, and how transport is regulated. These include Familial Hyperkalemic Hypertension, the salt-wasting diseases Gitelman syndrome and EAST syndrome, and hereditary hypomagnesemias. The DCT is also established as an important target for the hormones angiotensin II and aldosterone; it also appears to respond to sympathetic-nerve stimulation and changes in plasma potassium. Here, we discuss what is currently known about DCT physiology. Early studies that determined transport rates of ions by the DCT are described, as are the channels and transporters expressed along the DCT with the advent of molecular cloning. Regulation of expression and activity of these channels and transporters is also described; particular emphasis is placed on the contribution of genetic forms of DCT dysregulation to our understanding.

Steroid-induced hypocalcaemia with tetany in a patient with hypoparathyroidism

Although glucocorticoids have a known negative effect on calcium balance, they do not normally cause clinically significant hypocalcaemia. A young woman with post-surgical hypoparathyroidism developed symptomatic hypocalcaemia on two occasions following treatment with intravenous hydrocortisone for allergic reactions. Oral calcium and vitamin D supplementation could not prevent the development of hypocalcaemia. She was treated successfully with intravenous calcium gluconate infusions and discontinuation of glucocorticoids. In patients with hypoparathyroidism, impaired parathyroid hormone response to steroid-induced negative calcium balance may result in severe symptomatic hypocalcaemia requiring hospitalisation.

Moderate zinc supplementation during prolonged steroid therapy exacerbates bone loss in rats

The present study was conducted to understand the influence of zinc on bone mineral metabolism in prednisolone-treated rats. Disturbance in bone mineral metabolism was induced in rats by subjecting them to prednisolone treatment for a period of 8 weeks. Female rats aged 6-8 weeks weighing 150 to 200 g were divided into four treatment groups, viz., normal control, prednisolone-treated (40 mg/kg body weight orally, thrice a week), zinc-treated (227 mg/L in drinking water, daily), and combined prednisolone + zinc-treated groups. Parameters such as changes in mineral levels in the bone and serum, bone mineral density (BMD), bone mineral content (BMC), and bone 99m-technetium-labeled methylene diphosphonate ((99m)Tc-MDP) uptake were studied in various treatment groups. Prednisolone treatment caused an appreciable decrease in calcium levels both in the bone and serum and also in bone dry weight, BMC, and BMD in rats. Prednisolone-treated rats when supplemented with zinc showed further reduction in calcium levels, bone dry weight, BMD, and BMC. The study therefore revealed that moderate intake of zinc as a nutritional supplement during steroid therapy could enhance calcium deficiency in the body and accelerate bone loss.

Metabolic bone disease after renal transplantation

PURPOSE OF THE REVIEW

Posttransplantation mineral and bone disorder (MBD) is an important issue in the care of children after kidney transplantation (KTx) resulting in increased comorbidity, for example, bone pain, fractures, growth failure, and vascular calcifications. It is distinctly different from common forms of osteoporosis and mainly due to preexisting renal osteodystrophy at the time of KTx, glucocorticoid treatment, and reduced graft function. The purpose of this review is to give an overview of the pathogenesis and treatment of posttransplant MBD in children.

RECENT FINDINGS

Recent studies underline the impact of elevated levels of the phosphaturic hormone fibroblast growth factor-23 on posttransplant MBD. Glucocorticoid treatment results in impairment of bone strength, increased fracture risk, and lack of significant catch up, whereas steroid-sparing protocols allow for a normal adult height in the majority of patients. Whether the latter also improves bone strength remains to be elucidated.

SUMMARY

Therapeutic efforts to reduce MBD after KTx should focus on steroid-sparing immunosuppressive protocols, adequate treatment of alterations of calcium, phosphate and vitamin D metabolism, maintenance of regular physical activity, and preservation of transplant function. Preemptive KTx, that is with no prior dialysis, can prevent progressive vascular calcifications.

Hypocalcemia immediately after renal transplantation

BACKGROUND

After renal transplantation (RTX), hypercalcemia, mainly due to persistent hyperparathyroidism, and hypophosphatemia, caused by the improved ability to excrete phosphorus in the renal tubules, are expected. However, immediately after RTX, a transient reduction in serum calcium (Ca) levels has been previously reported, the reason for which is not clear.

PATIENTS AND METHODS

In 21 patients receiving ABO compatible living donor kidney transplants, serum levels of Ca, phosphorus, intact parathyroid hormone (iPTH), 1,25-dihydroxyvitamin D, and tacrolimus were measured within three wk after RTX, along with urinary Ca and phosphorus excretion. The immunosuppressive regimen consisted of a three-drug combination including a glucocorticoid, a calcineurin inhibitor, and an antimetabolite agent.

RESULTS

Serum Ca levels declined significantly during the first post-operative week. Urinary Ca excretion increased immediately after RTX and gradually normalized. Increased urinary Ca excretion did not correlate with serum levels of iPTH and tacrolimus.

CONCLUSIONS

Immediately after RTX, regardless of serum iPTH and tacrolimus levels, transient increases in urinary Ca excretion and hypocalcemia were observed. Administration of glucocorticoids is one potential cause of inappropriate urinary Ca wasting.

Primary male osteoporosis is associated with enhanced glucocorticoid availability

OBJECTIVE

While systemic glucocorticoids compromise bone metabolism, altered intracellular cortisol availability may also contribute to the pathogenesis of primary male osteoporosis (MO). The objective of this study was to assess whether intracellular cortisol availability is increased in MO due to a distorted local cortisol metabolism.

METHODS

Forty-one patients with MO were compared with age- and BMI-matched non-osteoporotic subjects after excluding overt systemic hypercortisolism (N = 41). Cortisol, cortisone and the respective tetrahydro-, 5α-tetrahydro- and total cortisol metabolites were analysed by GC-MS in 24 h urine. Apparent 11β-hydroxysteroid dehydrogenase (11β-HSD) enzyme activities, excretion of cortisol metabolites and calcium, and fractional urinary calcium excretion were assessed and related to BMD.

RESULTS

Fractional and total urinary calcium excretion negatively correlated with BMD at all (P < 0.05) and at three of five (P < 0.05) measurement sites, respectively. While systemic cortisol was unchanged, apparent 11β-HSD enzyme activity in MO patients (P < 0.01) suggested increased intracellular cortisol availability. Total and fractional urinary calcium excretion was higher, with apparent 11β-HSD enzyme activities consistent with an enhanced intracellular cortisol availability (P < 0.05).

CONCLUSION

Apparent 11β-HSD enzyme activities consistent with increased intracellular cortisol availability correlated with urinary calcium loss and reduced bone mineral density in MO. The changes in 11β-HSD activity were associated with both the fractional calcium excretion, suggesting altered renal calcium handling, and the absolute urinary calcium excretion. Both mechanisms could result in a marked bone calcium deficiency if insufficiently compensated for by intestinal calcium uptake.

Inflammatory bowel disease has a small effect on bone mineral density and risk for osteoporosis

BACKGROUND & AIMS

A high prevalence of osteoporosis has been reported among individuals with inflammatory bowel disease (IBD). We performed a population-based analysis to determine whether IBD is itself a risk factor for low bone mineral density (BMD) or whether low BMD results from other factors associated with IBD.

METHODS

We identified 1230 subjects with IBD in the Manitoba BMD Database, which contains results of BMD tests performed on all Manitobans since 1997 (n = 45,714). BMD was assessed at the lumbar spine (mean value, L1-L4), hip (total), femoral neck, and trochanter. Multivariate linear and logistic regression analyses were performed to determine the independent effects of IBD, Crohn's disease (CD), or ulcerative colitis (UC) on T score and the presence of osteoporosis (a low T score was equal to or less than -2.5) at any site; we controlled for age, sex, body mass index, hormone replacement therapy, osteoprotective medications, and corticosteroid use. We also performed regression analysis within the IBD population to determine the effect of IBD-specific factors on T score and osteoporosis.

RESULTS

IBD was associated with a statistically significant but small effect on T score; IBD did not increase the risk for osteoporosis at any site measured. CD was associated with an increased risk of osteoporosis at the lumbar spine and trochanter, but UC was not associated with an increased risk of osteoporosis or low T score. No IBD-specific variables were associated with increased risk of osteoporosis or low T score.

CONCLUSIONS

IBD has a small effect on BMD; CD poses a greater risk than UC. The risk of osteoporosis in patients with IBD appears to be related to other known osteoporosis risk factors.

Corticosteroid-induced osteoporosis: an update for dermatologists

Long-term corticosteroid treatment is the most common secondary cause of bone loss. Patients treated with long-term corticosteroid therapy may develop osteopenia or osteoporosis, and many have fractures. It is difficult to predict which corticosteroid-treated patients will develop significant skeletal complications because of variability in the underlying diseases treated with corticosteroids, and because of variation in corticosteroid dose over time. Corticosteroid therapy causes an alteration in the ratio between osteoprotegerin (OPG) and receptor activator of nuclear factor κ B (RANK) ligand (RANKL), which leads to early increased bone resorption for the first 3-6 months, with long-term treatment leading primarily to suppression of bone formation. Recently published recommendations advise the use of bisphosphonates or teriparatide in high-risk patients, depending on fracture risk assessed by bone mineral density testing. This article gives an update of current knowledge regarding the pathophysiology, clinical presentation and evaluation, and prevention and treatment of patients with corticosteroid-induced osteoporosis.

Osteoporosis after transplantation

Transplantation is an established therapy for end-stage diseases of kidney, lung, liver, and heart among others. Osteoporosis and fragility fractures are serious complications of organ transplantation, particularly in the first post-transplant year. Many factors contribute to the pathogenesis of osteoporosis following organ transplantation. This review addresses the mechanisms of bone loss that occurs both in the early and late post-transplant periods, including the contribution of the immunosuppressive agents as well as the specific features to bone loss after kidney, lung, liver, cardiac, and bone marrow transplantation. Prevention and treatment for osteoporosis in the transplant recipient are also discussed.

The course of hypercalciuria and related markers of bone metabolism parameters associated with corticosteroid treatment

BACKGROUND AND OBJECTIVE

Prolonged corticosteroid (CS) use induces osteoporosis; the pathogenesis of this condition is multifactorial and includes CS-induced hypercalciuria. We investigated the course of hypercalciuria and related markers of bone metabolism parameters during and after the CS treatment.

MATERIALS AND METHODS

We recruited 42 patients who were taking at least 10 mg/day of methylprednisolone or an equivalent dose of CSs for at least 30 days. The 24-h urinary calcium and sodium, a spot urinary calcium/creatinine ratio, and urinary deoxypyridinoline were measured prior to the treatment, at day 7, at days 30-60, and after the cessation of the treatment. Additionally, the serum levels of phosphorus, calcium, alkaline phosphatase (ALP), albumin, creatinine, osteocalcin, and parathyroid hormone (PTH) were analyzed.

RESULTS

The 24-h urinary calcium excretion was significantly increased at day 7 (182.2 ± 158.6 mg/day; p < 0.001) and at days 30-60 (196.9 ± 167.8 mg/day; p < 0.001) compared with baseline (98.7 ± 88.1 mg/day) and returned to basal level after the cessation of the CSs (118.9 ± 90.2 mg/day; p = 0.725). The urinary deoxypyridinoline level was significantly higher at days 30-60 compared with basal level. The serum osteocalcin level was decreased at days 30-60 when compared with day 7. No significant changes were detected in the PTH, phosphorus, creatinine, and ALP levels.

CONCLUSIONS

CS treatment induces hypercalciuria just after starting the treatment until the end of it. CS-induced hypercalciuria promptly improved after cessation of the treatment. By days 30-60, the excretion of urinary deoxypyridinoline was accompanied by hypercalciuria. The serum osteocalcin level was decreased at days 30-60 when compared with day 7.

Vitamin D status before and after hypophysectomy in dogs with pituitary-dependent hypercortisolism

Both spontaneous hypercortisolism and chronic glucocorticoid treatment are associated with osteoporosis and low circulating concentrations of 1,25-dihydroxy-vitamin D in humans. Pituitary-dependent hypercortisolism (PDH) is a common disorder in dogs, but little is known about the vitamin D status of affected dogs. Pituitary-dependent hypercortisolism in dogs can be treated effectively by hypophysectomy and subsequent hormone supplementation. Because hormone supplementation does not include GH, dogs that have undergone hypophysectomy have low circulating concentrations of GH and IGF-1, which may result in low plasma 1,25-dihydroxy-vitamin D concentrations and consequently increased parathyroid hormone secretion. The aim of this study was to determine whether dogs with PDH need vitamin D supplementation before and/or after hypophysectomy. To this end, we measured plasma concentrations of GH, IGF-1, parathyroid hormone, calcium, phosphate, and vitamin D metabolites in 12 dogs with PDH before and 8 wk after hypophysectomy and in 12 control dogs. Although plasma GH concentrations were lower in dogs with PDH than in control dogs both before and after hypophysectomy, the vitamin D status was similar. In conclusion, there is no need for vitamin D supplementation in dogs with PDH, either before or after hypophysectomy.

[Mechanisms and therapeutics of glucocorticoid-induced osteoporosis]

Mechanisms of glucocorticoid-induced osteoporosis (GIOP) are categorized into local and systemic effects. In the local mechanisms, direct inhibitory effect of glucocorticoid on bone formation is thought to be one of the important mechanisms of GIOP. In contrast, secondary hyperparathyroidism induced by negative balance of calcium due to inhibition of absorption and increase of excretion is an important systemic mechanism of GIOP. Other mechanisms of GIOP are also shown in this review. From clinical points of view, serum markers for evaluation of GIOP have been discussed. Osteocalcin, procollagen type I N-terminal peptide, and bone-specific alkaline phosphatase as markers of bone formation are decreased in GIOP. Collagen I N-terminal telopeptide and tartrate resistent acid phosphatase isoform 5b as markers of bone resorption are increased in GIOP. Clinical guidelines have recommended that bisphosphonate is the first choice for the treatment of GIOP. Teriparatide is recombinant human parathyroid hormone 1-34, which should be considered as a therapeutic option for those at high risk of bone fracture. Denosumab, an anti receptor activator of nuclear factor-β ligand approved as a drug for postmenopausal osteoporosis was also effective for GIOP in clinical trials.

Skeletal health of children and adolescents with inflammatory bowel disease

Current evidence points to suboptimal bone health in children and adolescents with inflammatory bowel disease (IBD) when compared with their healthy peers. This compromise is evident from diagnosis. The clinical consequences and long-term outcome of this finding are still unknown. The mechanism of suboptimal bone health in children and adolescents with IBD lays mainly in reduced bone formation, but also reduced bone resorption, processes necessary for bone growth. Factors contributing to this derangement are inflammation, delayed growth and puberty, lean mass deficits, and use of glucocorticoids. We recognize that evidence is sparse on the topic of bone health in children and adolescents with IBD. In this clinical guideline, based on current evidence, we provide recommendations on screening and monitoring bone health in children and adolescents with IBD, including modalities to achieve this and their limitations; monitoring of parameters of growth, pubertal development, and reasons for concern; evaluation of vitamin D status and vitamin D and calcium intake; exercise; and nutritional support. We also report on the current evidence of the effect of biologics on bone health in children and adolescents with IBD, as well as the role of bone active medications such as bisphosphonates. Finally, we summarize the existing numerous gaps in knowledge and potential subjects for future research endeavors.

Osteoporosis following organ transplantation: pathogenesis, diagnosis and management

Organ transplantation has become popular for the management of various chronic illnesses. With the advent of modern immunosuppressive treatments, the longevity of transplant recipients has increased. Consequently, morbid complications such as osteoporosis and bone fractures are seen at an increasing frequency in this population. In most transplant recipients, bone mineral density (BMD) falls shortly after transplantation. However, bone fracture rate plateaus in all except for post-renal transplant patients. Although the underlying pathophysiologic mechanism for this difference is not fully understood, potential mechanisms for sustained bone loss in renal transplant recipients may be persistent phosphorus wasting and defective bone mineralization. Current treatment regimens are based on studies in a small numbers of subjects with BMD as the primary outcome. Although BMD is recognized as a gold standard in the assessment of bone fracture risk, to date, its association with bone fracture risk in the general post-transplant population is not robust. Therefore, randomized controlled trials with bone fracture as the primary end point are crucial. The development of noninvasive bone markers in distinguishing bone turnover and bone mineralization status is also pivotal since skeletal lesions are heterogeneous in various organ transplantations. The elucidation of these underlying skeletal lesions is necessary for the consideration of selective treatment in this population.