Total and bone-specific alkaline phosphatases in haemodialysis patients with chronic liver disease

Agomelatine alleviates steroid-induced osteoporosis by targeting SIRT1/RANKL/FOXO1/OPG signalling in rats

One of the major contributors to secondary osteoporosis is long-term glucocorticoid usage. Clinically used antidepressant agomelatine also has anti-inflammatory properties. Our research aimed to inspect the probable defensive effect of agomelatine against steroid-promoted osteoporosis. There were four groups of rats; group I had saline as a negative control; rats of group II had dexamethasone (0.6 mg/kg, s.c.), twice weekly for 12 weeks; rats of group III had agomelatine (40 mg/kg/day, orally), as a positive control, daily for 12 weeks; and rats of group IV had dexamethasone + agomelatine in the same previous doses combined for 12 weeks. Finally, biochemical as well as histopathological changes were evaluated and dexamethasone treatment caused osteoporosis, as evidenced by discontinuous thin cancellous bone trabeculae, minor fissures and fractures, irregular eroded endosteal surface with elevated alkaline phosphate, tartarate resistant acid phosphate (TRACP) and osteocalcin levels. Osteoprotegerin (OPG), calcium, and phosphorus levels decreased with disturbed receptor activator of nuclear factor κ B ligand (RANKL), forkhead box O1 (FOXO1), and silent information regulator 1 (SIRT1) protein expression. However, treatment with agomelatine restored the normal levels of biochemical parameters to a great extent, supported by SIRT activation with an improvement in histopathological changes. Here, we concluded that agomelatine ameliorates steroid-induced osteoporosis through a SIRT1/RANKL/FOXO1/OPG-dependent pathway.

Different Effects of Empagliflozin on Markers of Mineral-Bone Metabolism in Diabetic and Non-Diabetic Patients with Stage 3 Chronic Kidney Disease

Background and objectives: Treatment with sodium-glucose co-transporter 2 (SGLT2) inhibitors decrease tubular reabsorption of phosphate, which may explain the reduction of bone mineral density and an excess of bone fractures observed in some studies with this class of drugs. Since an increased risk of bone fractures may also be a result of diabetes itself, our study aimed to compare the effect of empagliflozin on the markers of mineral-bone metabolism between diabetic (DKD) and non-diabetic (ND-CKD) patients with stage 3 chronic kidney disease (CKD). Materials and Methods: Forty-two patients with stage 3 CKD and A2 albuminuria, including 18 with DKD and 24 ND-CKD, were investigated. All subjects received 10 mg empagliflozin for 7 days. Serum calcium, phosphate, parathormone (PTH), calcitriol, bone alkaline phosphatase (BAP), FGF-23 and urine calcium, phosphate, albumin and the renal tubular maximum reabsorption rate of phosphate to the glomerular filtration rate (TmP-GFR) were measured before and after empagliflozin administration. Differences in biomarkers response to empagliflozin between DKD and ND-CKD were the main measures of outcome. Results: There was a significant increase of PTH, FGF-23 and phosphate in DKD but not in ND-CKD whereas BAP and TmP/GFR did not change in either group. The reduction of albuminuria was only significant in ND-CKD. Conclusions: The effect of SGLT2 inhibitor on serum mineral and bone markers and on albuminuria in patients with CKD may be differently modified by the presence of diabetes mellitus.

Bone evaluation in paediatric chronic kidney disease: clinical practice points from the European Society for Paediatric Nephrology CKD-MBD and Dialysis working groups and CKD-MBD working group of the ERA-EDTA

Mineral and bone disorder (MBD) is widely prevalent in children with chronic kidney disease (CKD) and is associated with significant morbidity. CKD may cause disturbances in bone remodelling/modelling, which are more pronounced in the growing skeleton, manifesting as short stature, bone pain and deformities, fractures, slipped epiphyses and ectopic calcifications. Although assessment of bone health is a key element in the clinical care of children with CKD, it remains a major challenge for physicians. On the one hand, bone biopsy with histomorphometry is the gold standard for assessing bone health, but it is expensive, invasive and requires expertise in the interpretation of bone histology. On the other hand, currently available non-invasive measures, including dual-energy X-ray absorptiometry and biomarkers of bone formation/resorption, are affected by growth and pubertal status and have limited sensitivity and specificity in predicting changes in bone turnover and mineralization. In the absence of high-quality evidence, there are wide variations in clinical practice in the diagnosis and management of CKD-MBD in childhood. We present clinical practice points (CPPs) on the assessment of bone disease in children with CKD Stages 2-5 and on dialysis based on the best available evidence and consensus of experts from the CKD-MBD and Dialysis working groups of the European Society for Paediatric Nephrology and the CKD-MBD working group of the European Renal Association-European Dialysis and Transplant Association. These CPPs should be carefully considered by treating physicians and adapted to individual patients' needs as appropriate. Further areas for research are suggested.

Alkaline phosphatase is a predictor of Bone Mineral Density in postmenopausal females

Objectives:

The study was planned to determine whether serum calcium, phosphate and alkaline phosphatase (ALP) are predictors of bone mineral density (BMD) in postmenopausal non-osteoporotic, osteopenic, and osteoporotic females.

Methods:

In this cross sectional study, conducted at Shaikh Zayed Hospital, Lahore in the year 2014-2015, postmenopausal females between 50-70 years of age were taken and divided into three groups non-osteoporotic (n=52), osteopenic (n=69) and osteoporotic (n=47). Serum ALP, phosphate and calcium were used in a stepwise multiple regression analysis to predict T-score in these groups.

Results:

In normal postmenopausal females, the prediction model was statistically significant, F(2, 41) = 6.041, p < 0.05 and showed a T-score variance of 22%. T-score was primarily predicted by higher levels of phosphate and calcium. In postmenopausal osteopenic females, T-score was only predicted by lower levels of ALP. The model was statistically significant, F(1, 59) = 4.995, p < 0.05, and accounted for approximately 7% of the variance of T-score. In postmenopausal osteoporotic females, the prediction model contained no predictors.

Conclusion:

Our study suggested that calcium and phosphate are the strongest predictors of T-score in postmenopausal normal females, while in postmenopausal osteopenic females ALP was the strongest predictor of T-score. Elevated serum ALP levels may help in determining loss of BMD in postmenopausal females.

Rethinking Bone Disease in Kidney Disease

Renal osteodystrophy (ROD) is the bone component of chronic kidney disease mineral and bone disorder (CKD-MBD). ROD affects bone quality and strength through the numerous hormonal and metabolic disturbances that occur in patients with kidney disease. Collectively these disorders in bone quality increase fracture risk in CKD patients compared with the general population. Fractures are a serious complication of kidney disease and are associated with higher morbidity and mortality compared with the general population. Furthermore, at a population level, fractures are at historically high levels in patients with end-stage kidney disease (ESKD), whereas in contrast the general population has experienced a steady decline in fracture incidence rates. Based on these findings, it is clear that a paradigm shift is needed in our approach to diagnosing and managing ROD. In clinical practice, our ability to diagnose ROD and initiate antifracture treatments is impeded by the lack of accurate noninvasive methods that identify ROD type. The past decade has seen advances in the noninvasive measurement of bone quality and strength that have been studied in kidney disease patients. Below we review the current literature pertaining to the epidemiology, pathology, diagnosis, and management of ROD. We aim to highlight the pressing need for a greater awareness of this condition and the need for the implementation of strategies that prevent fractures in kidney disease patients. Research is needed for more accurate noninvasive assessment of ROD type, clinical studies of existing osteoporosis therapies in patients across the spectrum of kidney disease, and the development of CKD-specific treatments. © 2018 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Alkaline Phosphatases in the Complex Chronic Kidney Disease-Mineral and Bone Disorders

Alkaline phosphatases (APs) remove the phosphate (dephosphorylation) needed in multiple metabolic processes (from many molecules such as proteins, nucleotides, or pyrophosphate). Therefore, APs are important for bone mineralization but paradoxically they can also be deleterious for other processes, such as vascular calcification and the increasingly known cross-talk between bone and vessels. A proper balance between beneficial and harmful activities is further complicated in the context of chronic kidney disease (CKD). In this narrative review, we will briefly update the complexity of the enzyme, including its different isoforms such as the bone-specific alkaline phosphatase or the most recently discovered B1x. We will also analyze the correlations and potential discrepancies with parathyroid hormone and bone turnover and, most importantly, the valuable recent associations of AP's with cardiovascular disease and/or vascular calcification, and survival. Finally, a basic knowledge of the synthetic and degradation pathways of APs promises to open new therapeutic strategies for the treatment of the CKD-Mineral and Bone Disorder (CKD-MBD) in the near future, as well as for other processes such as sepsis, acute kidney injury, inflammation, endothelial dysfunction, metabolic syndrome or, in diabetes, cardiovascular complications. However, no studies have been done using APs as a primary therapeutic target for clinical outcomes, and therefore, AP's levels cannot yet be used alone as an isolated primary target in the treatment of CKD-MBD. Nonetheless, its diagnostic and prognostic potential should be underlined.

The use of bone turnover markers in chronic kidney disease-mineral and bone disorders

Bone turnover markers assist in fracture risk prediction, management and monitoring of osteoporosis in patients without chronic kidney disease (CKD). The use in CKD-mineral bone disorder (MBD) has been limited as many of these markers and breakdown products are renally excreted, including the most commonly used and well standardized procollagen type I N propeptide and C-terminal cross-linking telopeptide of type I collagen. Of the markers unaffected by renal function, bone specific alkaline phosphatase is associated with mortality and fracture rate in CKD subjects and is now available on several automated analysers. When used in combination with PTH, bone specific alkaline phosphatase as a bone formation marker correlated well with bone biopsy histomorphometry in predicting adynamic bone disease. Tartrate-resistant acid phosphatase 5b is a resorption marker that is under development for automation. Both high and low bone turnover in CKD-MBD patients are associated with increased fracture and mortality risk. Bone biopsy as the gold standard to differentiate between adynamic bone disease and osteitis fibrosa is limited by availability and cost. Appropriate use of bone turnover markers is vital in the decision to commence anti-resorptive agents, and to monitor efficacy in order to avoid over suppression of bone turnover, which may lead to stress fractures. Further efforts are required to develop markers unaffected by renal function with standardized cut-off values and fracture as well as vascular calcification end-points.

Variations of parathyroid hormone and bone biomarkers are concordant only after a long term follow-up in hemodialyzed patients

End-stage renal disease is associated with mineral and bone disorders. Guidelines recommending therapies should be based on serial assessments of biomarkers, and thus on variations (Δ), rather than scattered values. We analyzed the correlations between ΔPTH and Δbone biomarkers such as bone-specific alkaline phosphatase (b-ALP), Beta-CrossLaps (CTX), osteocalcin, intact serum procollagen type-1 N-propeptide (P1NP), and tartrate-resistant acid phosphatase 5B (TRAP-5B) at different time-points. In this prospective observational analysis, variations of biomarkers were followed after 6-week (n = 129), 6-month (n = 108) and one-year (n = 93) period. Associations between variations were studied by univariate linear regression. Patients followed for one-year period were classified (increaser or decliner) according to variations reaching the critical difference. Over the 6-week period, only ΔCTX was correlated with ΔPTH (r = 0.38, p < 0.0001). Over the one-year period, correlations between ΔPTH and Δbone biomarkers became significant (r from 0.23 to 0.47, p < 0.01), except with ΔTRAP-5b. Correlations between Δbone biomarkers were all significant after one-year period (r from 0.31 to 0.68, p < 0.01), except between Δb-ALP and ΔTRAP-5b. In the head-to-head classifications (decliners/increasers), the percentage of concordant patients was significantly higher over the one-year than the 6-week period. A concordance between ΔPTH and Δbone biomarkers is observed in dialysis patients, but only after a long follow-up.

Serum alkaline phosphatase, a risk factor for non-alcoholic fatty liver, but only for women in their 30s and 40s: evidence from a large cohort study

BACKGROUND

Several risk factors are able to predict non-alcoholic fatty liver (NAFL) development, but the predictive value of serum alkaline phosphatase (ALP) remains uncertain. Our aim is to investigate the association between serum ALP levels and NAFL.

METHODS

21,331 NAFL-free subjects were included. Sex-specific ALP quartiles (Q1 to Q4) were defined. With Q1 used as reference, hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated across each quartile.

RESULTS

After adjusting for confounding variables, values in Q2, Q3 and Q4 had HRs (95%CIs) of 1.16 (0.94-1.43), 1.38 (1.13-1.69), 1.51 (1.24-1.83) in females and 0.99 (0.90-1.09), 1.04 (0.95-1.14), 0.96 (0.87-1.05) in males, respectively. A subgroup analysis of age factors in females, from Q2 to Q4, adjusted HRs (95%CIs) were 1.31 (0.81-1.99), 1.86 (1.23-2.81), 2.44 (1.60-3.71) in their 30 s, 1.13 (0.83-1.54), 1.17 (0.85-1.62), 1.65 (1.22-2.25) in their 40 s, and 0.95 (0.51-1.78), 0.91 (0.52-1.62), 0.89 (0.53-1.52) in their 50 s.

CONCLUSIONS

Higher serum ALP levels are considered a significant predictor for NAFL development in females aged 30 to 50.

Total and bone-specific alkaline phosphatase are associated with bone mineral density over time in end-stage renal disease patients starting dialysis

BACKGROUND

Alkaline phosphatase (ALP) and bone-specific ALP (BALP) are implicated in the abnormal skeletal mineralization and accelerated vascular calcification in chronic kidney disease (CKD) patients. Whereas ALP and BALP may predict mortality in CKD, BALP is reported to have higher sensitivity and specificity than total ALP in reflecting histological alterations in bone; however, results on their associations with bone mineral density (BMD) are inconsistent. Here we evaluated associations of total ALP and BALP with BMD during up to 24 months in end-stage renal disease (ESRD) patients.

METHODS

In this longitudinal study, 194 ESRD patients (median age 57 years, 66 % male, 32 % diabetes mellitus, mean body mass index 24.8 kg/m²) underwent measurements of total ALP and BALP and total and regional body BMD (by dual-energy X-ray absorptiometry) at dialysis initiation (n = 194), and after 12 (n = 98) and 24 months (n = 40) on dialysis.

RESULTS

At baseline, patients had median total ALP 65.4 (43.3-126.4) U/l, BALP 13.5 (7.1-27.3) µg/l and BMD 1.14 (0.97-1.31) g/cm². During the study period, serum concentrations of ALP and BALP increased significantly (p < 0.001), whereas total and regional BMD remained stable. BMD correlated inversely with total ALP (rho = -0.20, p = 0.005) and BALP (rho = -0.30, p < 0.001) at baseline, and correlations were similar also at 12 and 24 months.

CONCLUSION

ALP and BALP are equally accurate albeit weak predictors of BMD in ESRD patients, both at baseline and longitudinally. The dissociation between stable BMD and increasing ALP and BALP may possibly reflect increased soft tissue calcifications with time on dialysis.

Determinants of bone mineral density in patients on haemodialysis or peritoneal dialysis--a cross-sectional, longitudinal study

INTRODUCTION

The aim of the study was to identify biomarkers of alteration in bone mineral density (BMD) in patients on haemodialysis (HD) and peritoneal dialysis (PD).

MATERIALS AND METHODS

In a cross-sectional, longitudinal study dual-energy X-ray absorptiometry scans were performed in 146 HD-patients and 28 PD-patients. Follow-up after 14 months (mean) was conducted in 73 patients. As potential biomarkers we investigated parathyroid hormone (PTH), 25-hydroxy vitamin-D, ionised calcium, albumin, phosphate, and total alkaline phosphatases (t-ALP).

RESULTS

Both groups of dialysis patients had lower BMD in the femoral neck (BMD(neck)) (P < 0.001) and forearm (BMD(forearm)) (P < 0.001) compared to healthy controls, but comparable BMD in the lumbar spine (BMD(spine)). BMD did not differ between dialysis types, but patients ever-treated with glucocorticoids had significantly lower BMD, while patients with polycystic kidney disease had higher BMD. BMD correlated with body weight, actual age, age at initiation of dialysis, duration of dialysis and levels of PTH and t-ALP. However, t-ALP only remained associated with low BMD(spine) after adjusting for other factors (P = 0.001). In the follow-up study all patients had decreased BMD in all three locations, but only for the lumbar spine there was a significant association between BMD and the bone markers t-ALP (P = 0.009) and PTH (P = 0.013).

CONCLUSIONS

Both HD and PD patients have low BMD, and increased concentrations of t-ALP is associated BMD(spine) after adjustment, while PTH and t-ALP is associated with decrease in BMD(spine) over time. This substantiates the use of these biomarkers in both types of dialysis patients.