Prognostic importance of serum alkaline phosphatase in CKD stages 3-4 in a clinical population

Morphological changes and their associations with clinical parameters in children with nephropathic cystinosis and chronic kidney disease prior to kidney replacement therapy over 25 years

BACKGROUND

Infantile nephropathic cystinosis (INC) is a rare lysosomal storage disorder, mostly and often firstly affecting the kidneys, together with impaired disharmonious growth and rickets, eventually resulting in progressive chronic kidney disease (CKD). With the introduction of cysteamine therapy, most pediatric patients reach adulthood with no need for kidney replacement therapy. Still, detailed changes in INC patients' clinical and morphological presentation over the past decades have not yet been thoroughly investigated.

METHODS

Two groups with a respective total of 64 children with INC and 302 children with CKD, both treated conservatively and aged 2 to 18 years, were prospectively observed in the time span from 1998 to 2022 with 1186 combined annual clinical and morphological examinations clustered into two measurement periods (1998 to 2015 and ≥ 2016).

RESULTS

In INC patients, thoracic proportion indices remained markedly increased, whereas body fat stores remained decreased over the past 25 years (+ 1 vs. below ± 0 z-score, respectively). Their CKD peers presented with overall improved growth, general harmonization of body proportions, and improved body fat stores, while INC patients only presented with an isolated significant increase in leg length over time (∆0.36 z-score). eGFR adjusted for age did not significantly change over the past 25 years in both groups. Alkaline phosphatase (ALP) showed a significant decrease in CKD patients over time, while remaining above normal levels in INC patients.

CONCLUSIONS

Disproportionate thoracic shape and impaired body fat stores remain the most characteristic morphological traits in INC patients over the past 25 years, while causal mechanisms remain unclear.

Longitudinal study on the change trend of serum alkaline phosphatase and its possible influencing factors in peritoneal dialysis patients

The aim of the study was to analyze the change trend of serum ALP over time and identify factors influencing its levels in peritoneal dialysis patients. Then to investigate the impact of serum ALP changes on calcium and phosphorus metabolism in single peritoneal dialysis center utilizing repeated measurement data. A retrospective cohort study was conducted with a total follow-up duration of 30 months. Serum ALP and other biomarkers, including calcium (Ca), phosphorus (P), 25(OH)D, intact parathyroid hormone (iPTH), albumin(ALB), and hemoglobin(Hb) were measured every 3 months. The generalized estimation equation (GEE) was utilized to analyze the change trend of serum ALP over time, and to assess whether there were differences in changes over time between different genders and different primary disease groups. Additionally, factors influencing serum ALP levels were analyzed, and the impact of serum ALP changes on calcium and phosphorus metabolism was also explored. A total of 34 patients were included in the study. Serum ALP and other indicators were measured repeatedly, with a maximum of 8 times and a minimum of 4 times. The median of serum ALP values at all measurement times for all selected patients was 89 U/L. The GEE analysis revealed that serum ALP gradually increased with time, and patients in diabetes group increased faster than those in non-diabetes group. A positive correlation was observed between serum ALP and dialysis duration, also between serum ALP and hemoglobin. However, variations in serum ALP did not significantly affect serum corrected calcium, phosphorus, or iPTH concentrations. The serum ALP levels of peritoneal dialysis patients increase gradually over time, and the concentrations are influenced by dialysis duration. The changes in serum ALP values do not have a significant impact on serum calcium, phosphorus, and iPTH levels.

Clinical correlates of CT imaging-derived phenotypes among lean and overweight patients with hepatic steatosis

The objective of this study is to define CT imaging derived phenotypes for patients with hepatic steatosis, a common metabolic liver condition, and determine its association with patient data from a medical biobank. There is a need to further characterize hepatic steatosis in lean patients, as its epidemiology may differ from that in overweight patients. A deep learning method determined the spleen-hepatic attenuation difference (SHAD) in Hounsfield Units (HU) on abdominal CT scans as a quantitative measure of hepatic steatosis. The patient cohort was stratified by BMI with a threshold of 25 kg/m2 and hepatic steatosis with threshold SHAD ≥  - 1 HU or liver mean attenuation ≤ 40 HU. Patient characteristics, diagnoses, and laboratory results representing metabolism and liver function were investigated. A phenome-wide association study (PheWAS) was performed for the statistical interaction between SHAD and the binary characteristic LEAN. The cohort contained 8914 patients-lean patients with (N = 278, 3.1%) and without (N = 1867, 20.9%) steatosis, and overweight patients with (N = 1863, 20.9%) and without (N = 4906, 55.0%) steatosis. Among all lean patients, those with steatosis had increased rates of cardiovascular disease (41.7 vs 27.8%), hypertension (86.7 vs 49.8%), and type 2 diabetes mellitus (29.1 vs 15.7%) (all p < 0.0001). Ten phenotypes were significant in the PheWAS, including chronic kidney disease, renal failure, and cardiovascular disease. Hepatic steatosis was found to be associated with cardiovascular, kidney, and metabolic conditions, separate from overweight BMI.

Research-based Analytical Procedures to Evaluate Diabetic Biomarkers and Related Parameters: In Vitro and In Vivo Methods

BACKGROUND

The degenerative tendency of diabetes leads to micro- and macrovascular complications due to abnormal levels of biochemicals, particularly in patients with poor diabetic control. Diabetes is supposed to be treated by reducing blood glucose levels, scavenging free radicals, and maintaining other relevant parameters close to normal ranges. In preclinical studies, numerous in vivo trials on animals as well as in vitro tests are used to assess the antidiabetic and antioxidant effects of the test substances. Since a substance that performs poorly in vitro won't perform better in vivo, the outcomes of in vitro studies can be utilized as a direct indicator of in vivo activities.

OBJECTIVE

The objective of the present study is to provide research scholars with a comprehensive overview of laboratory methods and procedures for a few selected diabetic biomarkers and related parameters.

METHOD

The search was conducted on scientific database portals such as ScienceDirect, PubMed, Google Scholar, BASE, DOAJ, etc. Conclusion: The development of new biomarkers is greatly facilitated by modern technology such as cell culture research, lipidomics study, microRNA biomarkers, machine learning techniques, and improved electron microscopies. These biomarkers do, however, have some usage restrictions. There is a critical need to find more accurate and sensitive biomarkers. With a few modifications, these biomarkers can be used with or even replace conventional markers of diabetes.

Novel Model of Oxalate Diet-Induced Chronic Kidney Disease in Dahl-Salt-Sensitive Rats

Diet-induced models of chronic kidney disease (CKD) offer several advantages, including clinical relevance and animal welfare, compared with surgical models. Oxalate is a plant-based, terminal toxic metabolite that is eliminated by the kidneys through glomerular filtration and tubular secretion. An increased load of dietary oxalate leads to supersaturation, calcium oxalate crystal formation, renal tubular obstruction, and eventually CKD. Dahl-Salt-Sensitive (SS) rats are a common strain used to study hypertensive renal disease; however, the characterization of other diet-induced models on this background would allow for comparative studies of CKD within the same strain. In the present study, we hypothesized that SS rats on a low-salt, oxalate rich diet would have increased renal injury and serve as novel, clinically relevant and reproducible CKD rat models. Ten-week-old male SS rats were fed either 0.2% salt normal chow (SS-NC) or a 0.2% salt diet containing 0.67% sodium oxalate (SS-OX) for five weeks.Real-time PCR demonstrated an increased expression of inflammatory marker interleukin-6 (IL-6) (p < 0.0001) and fibrotic marker Timp-1 metalloproteinase (p < 0.0001) in the renal cortex of SS-OX rat kidneys compared with SS-NC. The immunohistochemistry of kidney tissue demonstrated an increase in CD-68 levels, a marker of macrophage infiltration in SS-OX rats (p < 0.001). In addition, SS-OX rats displayed increased 24 h urinary protein excretion (UPE) (p < 0.01) as well as significant elevations in plasma Cystatin C (p < 0.01). Furthermore, the oxalate diet induced hypertension (p < 0.05). A renin-angiotensin-aldosterone system (RAAS) profiling (via liquid chromatography-mass spectrometry; LC-MS) in the SS-OX plasma showed significant (p < 0.05) increases in multiple RAAS metabolites including angiotensin (1-5), angiotensin (1-7), and aldosterone. The oxalate diet induces significant renal inflammation, fibrosis, and renal dysfunction as well as RAAS activation and hypertension in SS rats compared with a normal chow diet. This study introduces a novel diet-induced model to study hypertension and CKD that is more clinically translatable and reproducible than the currently available models.

Biomarkers Involved in the Mineral-Bone Disorders Secondary to Chronic Hemodialysis

Introduction. Chronic kidney disease (CKD) is one of the most prevalent public health problems of the elderly population. End-Stage Renal Disease (ESRD)’s most common treatment is dialysis. There are some dissimilarities between the sexes that are apparent in the status and the possible outcomes of CKD. This study aims to shed some light on these somewhat overlooked wwwvariations and their implications.

Materials and methods. We conducted an observational study on subjects with CKD, undergoing hemodialysis for at least 2 years. For participation, we selected an equal number of men and women, which were divided into 2 groups according to gender. Plasma levels of the following parameters were monitored: creatinine, urea, bicarbonate, phosphorus, calcium, alkaline phosphatase, vitamin D, FGF-23 and TNF-alpha. The differences of the variables between the two groups were evaluated using TTEST and CORREL test.

Results. A significant correlation was between the plasma levels of FGF-23 and gender (p =0.02). Regarding the plasmatic levels of urea, besides the expected difference in pre- and post- dialysis levels, we obtained a significant correlation between its post-dialysis value and gender (p =0.045). In regard to the plasmatic levels of the alkaline phosphatase, there was a significant correlation between its value and gender (p =0.01).

Conclusions. There is a significant correlation between the plasmatic levels of creatinine, urea, alkaline phosphatase, vitamin D, FGF-23 and gender. Women present lower levels of creatinine and urea, while men present lower plasmatic levels of vitamin D, alkaline phosphatase and FGF-23.

Nonalcoholic Fatty Liver Disease before Kidney Transplantation Correlates with New Onset Diabetes and Poor Metabolic Outcomes

INTRODUCTION

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality after kidney transplantation. Metabolic syndrome is common in renal transplant recipients and is associated with increased CVD risk in those patients. Nonalcoholic fatty liver disease (NAFLD) is considered to be the hepatic manifestation of a multi-system disorder, including CVD and metabolic syndrome. The data about prevalence of NAFLD before kidney transplantation and its consequences following transplantation are scarce.

METHODS

A retrospective study of metabolic parameters and sonographic evidence of NAFLD, and an analysis of its metabolic outcomes, was performed in 341 consecutive kidney transplant recipients.

RESULTS

One-hundred twenty-four (36.4%) kidney recipients had NAFLD before transplantation. The risk of NAFLD before kidney transplantation was independently and significantly related to diabetes (OR = 1.8), male gender (OR = 1.4), older age (every year of age increased the risk by 4%), higher BMI (every increase of 1 kg/m2 increased the risk by 15%), and higher triglycerides level. Mean levels of liver enzymes were similar in patients with and without NAFLD. Recipients with NAFLD before transplantation had a higher prevalence of new onset diabetes, even after adjustment to covariables. In addition, they had a higher increase in liver enzymes, triglycerides, and FIB-4 score, as an indication of liver fibrosis, after transplantation. Furthermore, NAFLD pre-transplantation was independently associated with cardiovascular mortality (HR = 4.4) following kidney transplantation.

CONCLUSIONS

Sonographic evidence of NAFLD before kidney transplantation is associated with significant metabolic outcomes including de novo diabetes and cardiovascular mortality following transplantation and should be included as part of the assessment of kidney transplant candidate.

Low-molecular weight oligosaccharides from gum tragacanth (Astragalus gossypinus) ameliorate nonalcoholic fatty liver disease (NAFLD) in Wistar male rats

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease affecting 25% of the world's population. The effects of oligosaccharides from Gum tragacanth (Astragalus gossypinus) (GT) on oxidative stress, glucose metabolism, and expression of autophagy genes were investigated in induced non-alcoholic fatty liver. Twenty-four male healthy rats were divided into four groups, Control; high-fat diet, high-fat diet + 100 mg GT oligosaccharides/kg body weight, high-fat diet + 200 mg GT oligosaccharides/kg body weight and fed with the trial diets for 70 days. At the end of the experiment, the results indicated that GT oligosaccharides affected the weight gain and liver weight in NAFLD-induced rats. In addition, the results showed that the use of GT oligosaccharides significantly decreased oxidative stress, liver injury, and hyperglycemia (p < .05) and upregulated the expression of autophagy genes in NAFLD-induced rats.

Practical applications

Overall, the results of the current study demonstrated that the use of GT oligosaccharides obtained from Gum tragacanth (Astragalus gossypinus) showed significant antioxidant properties and hypoglycemia in NAFLD induced rats and could be used as a useful nutritional strategy for the prevention and treatment of NAFLD.

Ameliorating Effects of Bioactive Peptides Extracted from Litopenaeus vannamei Wastes on Oxidative Stress, Glucose Regulation, and Autophagy Gene Expression in Nonalcoholic Fatty Liver-Induced Rats

This study aimed to investigate the effect of bioactive peptides from Litopenaeus vannamei on oxidative stress, glucose regulation, and autophagy gene expression in the induced nonalcoholic fatty liver rats. Bioactive peptides used in the current study were extracted in a progressive rise in temperature (40–60°C) (GP). For this purpose, twenty-four healthy male rats (initial weight, 230.1 ± 22 g) were divided in four experimental groups including control (standard diet), HFD (high-fat diet), HFD + GP20, and 300 (high-fat diet + 20, 300 mg peptides/kg body weight). After 70 days, the results indicated that experimental treatments did not affect the body and liver weight (P > 0.05), although the higher liver weight was seen in HFD treatment. Based on these results, the use of GP peptides improved antioxidant enzymes and decreased MDA concentration, and a significant difference was observed between peptide treatments and HFD (P < 0.05). In comparison to the HFD group, significantly lower liver enzymes (ALT and AST) were seen in peptide treatments (P < 0.05). Also, the results indicated that the lowest amylase, alkaline phosphatase, glucose, insulin, HOMA-IR, and inflammation cytokines (TNF-ɑ and IL-6) were seen in peptide groups. The autophagy gene expression was measured in the liver cells, and the results showed that, unlike HFD treatment, the use of GP peptides decreased Beclin 1, Atg7, and P62 expression in male rat's livers. Overall, the results of the current study demonstrated that the use of GP peptides at low concentration shows significant hypoglycemia and antioxidant properties in nonalcoholic fatty liver-induced rats.

CKD-MBD Biomarkers and CKD Progression: an Analysis by the Joint Model

BACKGROUND

Biomarkers of the CKD- Bone Mineral Disorder (CKD-BMD have been implicated in CKD progression in follow up studies focusing on single measurements of individual biomarkers made at baseline only. The simultaneous relationship between the time trend of these biomarkers over the course of CKD and renal outcomes has never been tested.

METHODS

We applied the Joint Model (JM) to investigate the longitudinal relationship between repeated measurements of CKD-MBD biomarkers and a combined renal endpoint (eGFR reduction >30%, dialysis or transplantation) in 729 stage 2-5 CKD patients over a 36 months follow up.

RESULTS

In the survival sub-model of the JM the longitudinal series of PTH values was directly and independently related to the risk of renal events [HR (1ln PTH) = 2.0 (from 1.5 to 2.8), p<0.001)] and this was also true for repeated measurements of serum phosphate [HR(1mg/dl) = 1.3924 (from 1.1459 to 1.6918), p = 0.001], serum calcium [HR(1mg/dl) = 0.7487 (from 0.5843 to 0.9593), p = 0.022], baseline FGF23 [HR(1pg/ml) = 1.001 (from 1.00 to 1.002), p = 0.045] and 1,25 dihydroxy Vitamin D [HR (1pg/ml) = 0.9796 (from 0.9652 to 0.9942), p = 0.006].

CONCLUSION

Repeated measurements of serum PTH, calcium and phosphate as well as baseline FGF23 and 1,25 dihydroxy vitamin D are independently related with the progression to kidney failure in a cohort of stage 2-5 CKD patients. This longitudinal study generates the hypothesis that interventions at multiple levels on BMD biomarkers can mitigate renal function loss in this population.

Clinical utility of bone turnover markers in patients with chronic kidney disease

PURPOSE OF REVIEW

The burden of fractures is very high in patients with chronic kidney disease (CKD). It is increasingly recognized that knowledge of bone turnover is of paramount importance in guiding mineral metabolism and osteoporosis therapy in CKD. Bone histomorphometry is the gold standard to assess bone turnover, but is seldomly performed in clinical practice. Bone turnover markers (BTMs) may be the long awaited noninvasive diagnostic that may help to close the therapeutic gap in patients with advanced CKD presenting with bone fragility.

RECENT FINDINGS

Mounting evidence indicates that BTMs may be useful in skeletal and nonskeletal risk stratification, in guiding mineral metabolism and osteoporosis therapy, and in monitoring the therapeutic response.

SUMMARY

BTMs provide information that is complementary to other clinical tests. It may be envisioned that in the near future, the assessment of nonkidney cleared BTMs may become part of routine clinical evaluation and monitoring of bone health in CKD patients, integrated with clinical risk factors, imaging data and, eventually, bone histomorphometry. Panels of BTMs will likely be more informative than single markers, and the same might hold true for trends as opposed to single time point data.

Prognostic significance of albumin to alkaline phosphatase ratio in critically ill patients with acute kidney injury

OBJECTIVE

No epidemiological evidence has investigated the effect of albumin to alkaline phosphatase ratio (AAPR) on the prognosis among critically ill patients with acute kidney injury (AKI). We aimed to explore the prognostic value of AAPR in these patients.

METHODS

We extracted all clinical data from MIMIC III. ROC curve analysis was used to evaluate the discrimination of AAPR for predicting in-hospital mortality. A generalized additive model was applied to identify a nonlinear association between AAPR and in-hospital mortality. The Cox proportional hazards models were used to determine the association between AAPR and in-hospital and 30-day mortality.

RESULTS

A total of 6894 eligible subjects were enrolled in this study. The relationship between AAPR and in-hospital mortality was nonlinear. Multivariate analysis demonstrated that lower AAPR (AAPR < 0.35) was an independent predictor of in-hospital and 30-day mortality after adjusting for potential confounders (HR 1.74, 95% CI 1.72-2.20, P < 0.001; HR 1.89, 95% CI 1.66-2.14, P < 0.001, respectively).

CONCLUSIONS

AAPR may serve as a potential prognostic biomarker in critically ill patients with AKI and lower AAPR was associated with increased risk of in-hospital and 30-day mortality among these patients.

Acute kidney injury after hip fracture in organ transplant recipients

BACKGROUND

This study aimed to investigate the incidence and risk factors of acute kidney injury (AKI) after hip fracture in organ transplant recipients.

METHODS

In this single-center retrospective cohort study, 795 elderly patients who underwent hip fracture surgery were enrolled. AKI was defined according to Acute Kidney Injury Network criteria. Among the 795 patients, 23 underwent kidney transplantation (KT) and 20 underwent liver transplantation (LT). The incidence of AKI, dialysis requirement, and renal recovery rate were investigated.

RESULTS

AKI occurred in 83 patients (10.5%), of whom 9 (39.1%), 3 (15%), and 71 (9.5%) were in the KT, LT, and non-transplantation groups, respectively. The incidence rates of AKI and severe AKI (17.4% vs. 1.4%) were significantly higher in the KT group than in the non-transplantation group (p = 0.001 for both). The renal recovery rate was significantly lower in the KT group than in the non-transplantation group (p = 0.033). The multivariate analysis revealed that male; body mass index; CKD; alkaline phosphatase; intraoperative hypotension; and history of KT were independent predictors of AKI development.

CONCLUSIONS

AKI and severe AKI after hip fracture occurred more frequently in the KT recipients with lower renal recovery rates. Transplanted kidneys are more vulnerable to AKI after hip fracture. This article is protected by copyright. All rights reserved.

Interaction of Serum Alkaline Phosphatase and Folic Acid Treatment on Chronic Kidney Disease Progression in Treated Hypertensive Adults

The relation of alkaline phosphatase (ALP) with chronic kidney disease (CKD) is still uncertain. We aimed to examine the prospective association between serum ALP and CKD progression, and the modifying effect of serum ALP on folic acid in preventing CKD progression in treated hypertensive patients. This is a post-hoc analysis of 12,734 hypertensive adults with relevant measurements and without liver disease at baseline from the renal sub-study of the China Stroke Primary Prevention Trial, where participants were randomly assigned to daily treatments of 10 mg enalapril and 0.8 mg folic acid, or 10 mg enalapril alone. The primary outcome was CKD progression, defined as a decrease in estimated glomerular filtration rate (eGFR) of ≥30% and to a level of <60 ml/min/1.73 m² if baseline eGFR was ≥60 ml/min/1.73 m²; or a decrease in eGFR of ≥50% if baseline eGFR was <60 ml/min/1.73 m²; or end-stage renal disease. Over a median of 4.4 years, in the enalapril only group, participants with baseline serum ALP≥110IU/L (quartile 4) had a significantly higher risk of CKD progression (3.4% vs 2.3%; adjusted OR,1.61; 95%CI:1.11, 2.32), compared with those with ALP<110IU/L. For those with enalapril and folic acid treatment, compared with the enalapril only treatment, the risk of CKD progression was reduced from 3.4 to 2.1% (adjusted OR, 0.53; 95%CI:0.34, 0.83) among participants with baseline ALP≥110IU/L, whereas there was no significant effect among those with ALP<110IU/L. In hypertensive patients, higher serum ALP was associated with increased risk of CKD progression, and this risk was reduced by 47% with folic acid treatment.

Association between serum alkaline phosphatase and renal outcome in patients with type 2 diabetes mellitus

This retrospective study included 299 patients with type 2 diabetes mellitus and biopsy-confirmed diabetic nephropathy (DN) to investigate the prognostic value of alkaline phosphatase (ALP) for renal outcome. Cox proportional hazards models were used to estimate the hazard ratios (HRs) for the serum ALP level on renal outcome, which was defined as end-stage renal disease (ESRD) or a 50% decline in estimated glomerular filtration rate (eGFR) from baseline. The median baseline ALP was 80 IU/L with an interquartile range of 64–97 IU/L. Serum ALP was negatively associated with eGFR but positively associated with proteinuria and renal interstitial fibrosis. During a median follow-up period of 23 months, ESRD or a 50% declined in the eGFR occurred in 156 (52.2%) patients. The highest quartile of ALP was significantly associated with poor renal outcome, as defined above (HR 2.38, 95% confidence interval [CI] 1.09–5.17), when adjusted for sociodemographics, baseline eGFR, proteinuria, liver function parameters, parathyroid hormone levels, and renal pathological findings. Each standard deviation higher in the natural log-transformed ALP was associated with a 25% increased risk for poor renal outcome. Additionally, there was a graded increase in the risk for poor renal outcome with higher ALP in patients with nephrotic-range proteinuria. However, no significant associations were observed between serum ALP levels and renal outcome in patients with non-nephrotic-range proteinuria. In conclusion, an elevated ALP level was independently associated with poor renal outcome in patients with type 2 diabetes mellitus and nephrotic-range proteinuria after multivariate adjustment.

Baseline liver function tests and full blood count indices and their association with progression of chronic kidney disease and renal outcomes in Aboriginal and Torres Strait Islander people: the eGFR follow- up study

Background

Determination of risks for chronic kidney disease (CKD) progression could improve strategies to reduce progression to ESKD. The eGFR Study recruited a cohort of adult Aboriginal and Torres Strait Islander people (Indigenous Australians) from Northern Queensland, Northern Territory and Western Australia, aiming to address the heavy CKD burden experienced within these communities.

Methods

Using data from the eGFR study, we explored the association of baseline liver function tests (LFTs) (alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT), bilirubin and albumin) and full blood count (FBC) indices (white blood cell and red blood cell counts and haemoglobin) with annual eGFR decline and renal outcomes (first of 30% decline in eGFR with a follow-up eGFR < 60 mL/min/1.73 m², initiation of renal replacement therapy, or renal death). Comparisons of baseline variables across eGFR categories were calculated using analysis of variance and logistic regression as appropriate. Linear and multivariable regression models were used to estimate the annual change in eGFR for changes in FBC indices and LFTs. Cox proportional hazard models were used to estimate the hazard ratio for developing renal outcome for changes in baseline FBC indices and LFTs.

Results

Of 547 participants, 540 had at least one baseline measure of LFTs and FBC indices. The mean age was 46.1 (14.7) years and 63.6% were female. The median follow-up was 3.1 (IQR 2.8–3.6) years. Annual decline in eGFR was associated with low serum albumin (p < 0.001) and haemoglobin (p = 0.007). After adjustment for age, gender, urine albumin/creatinine ratio, diabetes, BMI, CRP, WHR, alcohol consumption, cholesterol and triglycerides, low serum albumin (p < 0.001), haemoglobin (p = 0.012) and bilirubin (p = 0.011) were associated with annual decline in eGFR.

Renal outcomes were inversely associated with serum albumin (p < 0.001), bilirubin (p = 0.012) and haemoglobin (p < 0.001) and directly with GGT (p = 0.007) and ALP (p < 0.001). Other FBC indices and LFTs were not associated with annual decline in eGFR or renal outcomes.

Conclusions

GGT, ALP, bilirubin, albumin and haemoglobin independently associate with renal outcomes. Contrary to findings from other studies, no association was found between renal outcomes and other FBC indices. These findings may help focus strategies to prevent disease progression in this high-risk population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-020-02185-x.

Correlation Between Parathyroid Hormone Levels with Urinary Magnesium Excretion in Patients with Non-Dialysis Dependent Chronic Kidney Disease

Background

Disorders of mineral metabolism occur in most patients with chronic kidney disease (CKD). The aim of this work was to correlate parathyroid hormone (PTH) levels with urinary magnesium excretion in patients with non-dialysis dependent CKD.

Methods

Cross-sectional study. Concentrations of creatinine, magnesium, calcium, phosphate, parathyroid hormone (PTH), 25-hydroxyvitamin D [25(OH)D] and alkaline phosphatase (ALP) were determined in blood samples. The assessment of urinary magnesium levels was performed by means of total daily excretion and by the excretion fraction (FEMg).

Results

The study evaluated 163 patients with a mean age of 60.7 ± 11.7 years and 51.0% were male. In the highest quartile of PTH (>89.5pg/mL), the mean levels of FEMg and ALP were higher (p<0.05). In the unadjusted regression analysis, the following variables were related to serum PTH levels: FEMg (odds ratio (OR) = 1.12; 95% confidence intervals (CI): 1.02–1.23), calcium (OR = 0.45; 95% CI: 0.22–0.90), ALP (OR = 1.02; 95% CI: 1.00–1.03) and eGFR (OR = 0.92; 95% CI: 1.00–1.03). After an adjusted analysis, only one FEMg and ALP will remain correlated with PTH.

Conclusion

In patients with non-dialysis dependent CKD, FEMg and ALP were some variables that remained associated with PTH.

Liver Function Enzymes are Potential Predictive Markers for Kidney Allograft Dysfunction

Introduction

Biopsy of the allograft is the gold standard for assessing kidney allograft dysfunction. The aim of our pilot study was to identify serum biomarkers that could obviate the need for biopsy.

Materials and Methods

We conducted a study to identify the biomarkers in the serum from different groups of chronic kidney disease (CKD) patients and kidney transplanted patients vs. healthy individuals. The four groups (n=25 in each group) were as follows: 1) Patients with unstable kidney allograft transplants requiring biopsy for cause, 2) Patients with stable kidney allograft transplants, 3) Patients with CKD not on immunosuppressive therapy and, 4) healthy subjects. We measured the activity and level of serum alkaline phosphatase (ALP) and other liver enzymes (alanine transaminase (ALT) and aspartate transaminase (AST)) as potential serum biomarkers in acute allograft dysfunction.

Results

We found that ALP correlated with allograft biopsy findings, liver function, and clinical outcomes and possibly graft survival. Additionally, AST and ALT were higher in patients with graft rejection compared to non-rejected and stable kidney transplants. Moreover, the low Pearson correlations (r- values) between ALP level with age (r=0.179), gender, body mass index (r=0.236), creatinine (r=0.044) or estimated glomerular filtration rate (r=0.048) suggest that ALP may be an independent biomarker which is relatively unaffected by other individual-level variables.

Conclusion

ALP may be a putative biomarker to predict kidney allograft function and rejection. Data also indicated that liver function plays an important role for the overall success of kidney transplantation.

Alkaline phosphatase affects renal function in never-treated hypertensive patients: effect modification by age

Several studies in patients with chronic kidney disease or normal renal function have shown that high levels of tissue non-specific alkaline phosphatase (ALP) are associated with an increased risk of all cause and cardiovascular (CV) mortality. Considering the independent prognostic role of renal function, we investigated the possible association between ALP levels and estimated glomerular filtration rate (e-GFR) in a large cohort of hypertensive subjects. We enrolled 2157 never-treated uncomplicated hypertensive patients with ALP levels within normal range. In the whole population, e-GFR was strongly related to ALP (r = −0.43, P < 0.0001) with similar magnitude in females and in males, resulting ALP the second independent predictor of renal function. In a multiple linear regression model, both on crude (P < 0.001) and adjusted (P = 0.01) analyses age significantly modified the effect of a fixed increase in ALP (20 UI/L) on renal function so that the reduction in e-GFR associated to a 20 UI/L increase in ALP was of lower magnitude in younger patients and progressively of higher extent from 20 years of age onwards. In conclusion, present data indicate a significant relationship between ALP levels and e-GFR in uncomplicated hypertensive patients that is modulated by age and that persisted after adjusting for several confounders.

High alkaline phosphatase and low intact parathyroid hormone associate with worse clinical outcome in peritoneal dialysis patients

OBJECTIVE

Alkaline phosphatase (ALP) is used as a biomarker to monitor the chronic kidney disease-mineral bone disorder (CKD-MBD) and high levels of parathyroid hormone (PTH) that were reported to be related to increased mortality in CKD patients. Therefore, we conducted this longitudinal cohort study to evaluate the relations between ALP and intact PTH (iPTH) and the associations with all-cause and cardiovascular mortality in peritoneal dialysis (PD) patients.

METHODS

In 1276 incident PD patients (median age 50 years, 56% males), baseline serum ALP, iPTH, and metabolic biomarkers potentially linked to CKD-MBD were analyzed in relation to mortality during follow-up period of up to 60 months. All-cause and cardiovascular mortality risk of ALP and iPTH were analyzed with competing-risks regression models with transplantation as competing risk adjusting for all covariates.

RESULTS

After adjustments for confounders by logistic regression model, older age, higher change level to levels of iPTH, S-albumin, calcium, alanine transaminase (ALT), and lower level of phosphorus were associated with higher ALP level (>79 U/L), and female gender, non-diabetes mellitus, younger age, lower calcium, higher ALT, total bilirubin, phosphorus, and ALP were associated with higher iPTH level (>300 pg/mL). During 60 months (median 44 months) of follow-up, the all-cause mortality rate was 16%, and 91 (46%) of the 199 deaths were caused by cardiovascular disease. In competing-risks regression analysis, "high ALP + low iPTH" was independently associated with all-cause and cardiovascular mortality after adjustment for age, gender, presence of diabetes, and cardiovascular disease, the calendar year of recruitment and vitamin D therapy in PD patients. The subhazard ratio (sHR) of group "high ALP + low iPTH" was 1.96 times and 3.35 times higher than sHR of group "low ALP + high iPTH" for all-cause mortality and cardiovascular mortality, respectively.

CONCLUSIONS

The combination of high ALP and low iPTH was independently associated with increased all-cause and cardiovascular mortality in PD patients, suggesting that ALP and iPTH have the potential to predict clinical outcomes and might be useful risk assessment tools in PD patients. Further studies exploring the observed association between combination of ALP with iPTH and mortality are warranted.

Digital radiography as an alternative method in the evaluation of bone density in uremic rats

INTRODUCTION

Digital radiography (DRx) may provide a suitable alternative to investigate mineral and bone disorder (MBD) and loss of bone density (BD) in rodent models of chronic kidney disease (CKD). The objective of this study was to use DRx to evaluate BD in CKD rats, and to evaluate the correlation between DRx findings and serum MBD markers and bone histomorphometry.

METHODS

Uremia was induced by feeding Wistar rats an adenine-enriched diet (0.75% for 4 weeks/0.10% for 3 weeks); outcomes were compared to a control group at experimental weeks 3, 4, and 7. The following biochemical markers were measured: creatinine clearance (CrC), phosphate (P), calcium (Ca), fractional excretion of P (FeP), alkaline phosphatase (ALP), fibroblast growth factor-23 (FGF-23), and parathyroid hormone (PTH). DRx imaging was performed and histomorphometry analysis was conducted using the left femur.

RESULTS

As expected, at week 7, uremic rats presented with reduced CrC and higher levels of P, FeP, and ALP compared to controls. DRx confirmed the lower BD in uremic animals (0.57±0.07 vs. 0.68 ± 0.06 a.u.; p = 0.016) compared to controls at the end of week 7, when MBD was more prominent. A severe form of high-turnover bone disease accompanied these biochemical changes. BD measured on DRx correlated to P (r=-0.81; p = 0.002), ALP (r = -0.69, p = 0.01), PTH (r = -0.83, p = 0.01), OS/BS (r = -0.70; p = 0.02), and ObS/BS (r = -0.70; p = 0.02).

CONCLUSION

BD quantified by DRx was associated with the typical complications of MBD in CKD and showed to be viable in the evaluation of bone alterations in CKD.

Serum alkaline phosphatase levels correlate with long-term mortality solely in peritoneal dialysis patients with residual renal function

Introduction: Increased serum alkaline phosphatase (ALP) is predictive of a higher mortality in patients with end-stage renal disease. However, it remains unknown whether residual renal function (RRF) influences the outcome-association of serum ALP among peritoneal dialysis (PD) patients.

Methods: A total of 650 incident PD patients receiving PD catheter implantation in an institute between 1 November 2005 and 28 February 2017 were retrospectively enrolled. These patients were divided into groups with and without RRF (RRF and non-RRF groups) and those with serum ALP levels in tertiles. The Kaplan–Meier method and multivariate Cox proportional hazard models were used to analyze their outcomes based on RRF and serum ALP levels.

Results: These 650 patients had a mean age of 49.4 ± 14.0 years old, their median ALP level was 74 U/L (interquartile range (IQR): 59–98). After 28-month (IQR: 14–41) follow-up, 80 patients in RRF group and 40 patients in non-RRF group died. PD patients with the highest serum ALP tertile had significant lower survival (p = .014), when compared to other patients in the RRF group. However, this relationship was not observed in patients in the non-RRF group. After multivariate adjustment, in the RRF group, patients with the highest ALP tertile had a significantly higher risk of mortality (hazard ratio (HR): 2.26, 95% confidence interval (CI): 1.06–4.82, p = .034). Each 10-U/L increase in ALP level was associated with a 4% (HR: 1.04, 95% CI: 1.00–1.08, p = .045) higher mortality risk.

Conclusions: Higher serum ALP level is associated with increased mortality solely in PD patients with RRF.

Nutritional Status and Mortality Predictability for Time-Varying Serum Alkaline Phosphatase in Hemodialysis Patients: A Longitudinal Study

OBJECTIVE

Higher serum alkaline phosphatase (sALP) levels associate with a poor prognosis in maintenance hemodialysis patients. However, little is known about the meaning of lower sALP in this population. We hypothesized that lower sALP concentrations may express nutritional status and survival accordingly.

METHODS

A retrospective, longitudinal cohort study of a clinical database containing the medical records of 554 patients (367 men and 187 women, mean age 67.6 ± 14.2 years) receiving maintenance hemodialysis from November 2007 to July 2018 in a single center was conducted. sALP, nutritional, bone turnover, and inflammatory marker levels were recorded at 0, 6, 12, 18, 24, 30,and 36 months followed by 58 additional months of clinical observations.

RESULTS

The median sALP level was 90.0 (71.0-125.8) U/L. In a linear mixed effects model adjusted for baseline demographics and clinical parameters, each 1.0 U/L increase above the mean sALP at baseline was associated with 0.7% slower rate of decline in geriatric nutritional risk index per 3 years (P = .02 for sALP × time interaction). sALP remained associated with the rate of change in geriatric nutritional risk index, even after controlling for C-reactive protein and intact parathyroid hormone levels. For each 1.0 U/L increase in sALP over time, the fully adjusted all-cause mortality hazard ratio using Cox models with the time-varying risk effect was 0.996 (95% confidence interval 0.993-1.000, P = .04).

CONCLUSIONS

Increasing longitudinal levels of sALP associate with improved nutritional status and lower mortality rates. sALP can be used as an integrated marker, combining the properties of the nutritional marker, the marker of mineral-bone disease and inflammation, according to its levels.

Bromodomain and Extraterminal Proteins as Novel Epigenetic Targets for Renal Diseases

Epigenetic mechanisms, especially DNA methylation and histone modifications, are dynamic processes that regulate the gene expression transcriptional program in normal and diseased states. The bromodomain and extraterminal (BET) protein family (BRD2, BRD3, BRD4, and BRDT) are epigenetic readers that, via bromodomains, regulate gene transcription by binding to acetylated lysine residues on histones and master transcriptional factors. Experimental data have demonstrated the involvement of some BET proteins in many pathological conditions, including tumor development, infections, autoimmunity, and inflammation. Selective bromodomain inhibitors are epigenetic drugs that block the interaction between BET proteins and acetylated proteins, thus exerting beneficial effects. Recent data have described the beneficial effect of BET inhibition on experimental renal diseases. Emerging evidence underscores the importance of environmental modifications in the origin of pathological features in chronic kidney diseases (CKD). Several cellular processes such as oxidation, metabolic disorders, cytokines, inflammation, or accumulated uremic toxins may induce epigenetic modifications that regulate key processes involved in renal damage and in other pathological conditions observed in CKD patients. Here, we review how targeting bromodomains in BET proteins may regulate essential processes involved in renal diseases and in associated complications found in CKD patients, such as cardiovascular damage, highlighting the potential of epigenetic therapeutic strategies against BET proteins for CKD treatment and associated risks.

Prognostic significance of pre-end-stage renal disease serum alkaline phosphatase for post-end-stage renal disease mortality in late-stage chronic kidney disease patients transitioning to dialysis

Background

Higher serum alkaline phosphatase (ALP) levels have been associated with excess mortality in patients with non-dialysis-dependent chronic kidney disease (NDD-CKD) and end-stage renal disease (ESRD). However, little is known about the impact of late-stage NDD-CKD ALP levels on outcomes after dialysis initiation.

Methods

Among 17 732 US veterans who transitioned to dialysis between October 2007 and September 2011, we examined the association of serum ALP levels averaged over the last 6 months of the pre-ESRD transition period ('prelude period') with all-cause, cardiovascular and infection-related mortality following dialysis initiation, using Cox (for all-cause mortality) and competing risk (for cause-specific mortality) regressions adjusted for demographics, comorbidities, medications, estimated glomerular filtration rate and serum albumin levels over the 6-month prelude period, and vascular access type at dialysis initiation.

Results

During a median follow-up of 2.0 (interquartile range, 1.1-3.2) years following dialysis initiation, a total of 9196 all-cause deaths occurred. Higher ALP levels were incrementally associated with higher all-cause, cardiovascular and infection-related mortality. Compared with patients in the lowest ALP quartile (<66.0 U/L), those in the highest quartile (≥111.1 U/L) had multivariable-adjusted hazard/subhazard ratios (95% confidence interval) of 1.42 (1.34-1.51), 1.43 (1.09-1.88) and 1.39 (1.09-1.78) for all-cause, cardiovascular and infection-related mortality, respectively. The associations remained consistent in various subgroups and after further adjustment for liver enzymes, serum phosphorus and intact parathyroid hormone levels.

Conclusions

Higher pre-ESRD serum ALP levels are independently associated with higher post-ESRD mortality risk. Further studies are warranted to determine if interventions that lower pre-ESRD ALP levels reduce mortality in incident dialysis patients.

Mitsugumin 53 promotes mitochondrial autophagy through regulating Ambra1 expression in C2C12 myoblast cells

In this study, we investigated the function of Mitsugumin 53 (MG53) in regulation of mitochondrial autophagy in skeletal muscle cells and explored its potential application in the prevention and treatment of skeletal muscle atrophy in rats with chronic kidney disease (CKD). The expression of autophagy beclin 1 regulator 1 (Ambra1) and MG53 in skeletal muscles of 5/6 nephrectomized rats was measured, and the effect of MG53 on mitochondrial autophagy of C2C12 myoblasts was investigated by in vitro experiments. Our results show the expression of Ambra1 and MG53 in the skeletal muscle of CKD rats was significantly decreased. In vitro experiments showed that MG53 overexpression could promote the expression of Ambra1 and mitochondrial autophagy in C2C12 cells, suggesting that recovery of autophagy by MG53 intervention may help remove abnormal mitochondria and alleviate muscle atrophy. In conclusion, the damaged or functionally incomplete mitochondria in CKD rats could not be effectively removed, which may be related to the low activity of Ambra1. In vitro experiments showed that MG53 overexpression could promote the expression of Ambra1 in C2C12 cells and restore mitochondrial autophagy. Whether MG53 can help remove abnormal mitochondria and relieve CKD-induced muscle atrophy requires further study.

A meta-analysis of phosphate binders lanthanum carbonate versus sevelamer hydrochloride in patients with end-stage renal disease undergoing hemodialysis

BACKGROUND AND OBJECTIVES

The purpose of this study was to compare the effects of phosphate binders lanthanum carbonate (LC) versus sevelamer hydrochloride (SH) in end-stage renal disease (ESRD) patients undergoing hemodialysis.

METHODS

Studies including randomized controlled trials (RCTs) comparing phosphate binders lanthanum carbonate versus sevelamer hydrochloride, in ESRD patients undergoing hemodialysis, were identified using a pre-defined search strategy. Phosphate, calcium, calcium-phosphorus product, intact parathyroid hormone, alkaline phosphatase, total cholesterol, and triglyceride were extracted and compared by RevMan 5.1 (The Cochrane Collaboration, Oxford, UK).

RESULTS

Six studies were identified. Meta-analysis showed that SH treatment reduced levels of phosphate, intact parathyroid hormone, and total serum alkaline phosphatase (ALP) when compared with LC treatment. Furthermore, patients on SH treatment tended to have reduced calcium levels, calcium-phosphorus product, total cholesterol, and triglyceride when compared to patients treated with LC, but there was no statistical difference.

CONCLUSION

SH treatment of patients with ESRD is more effective compared to LC treatment. However, more well-designed random control trails are required for confirmation.

Relationship between alkaline phosphatase and impaired coronary flow in patients with ST-segment elevated myocardial infarction

Objective Recent studies have shown that alkaline phosphatase (ALP) might play a negative role in clinical outcomes of patients with peripheral and coronary artery disease. This study aimed to investigate the relationship between serum ALP levels and coronary thrombolysis in myocardial infarction (TIMI) frame counts in patients with ST-segment elevated myocardial infarction undergoing primary percutaneous coronary intervention (PCI). Methods A total of 198 patients were enrolled in the current study. Serum ALP levels were measured in lithium-heparin plasma samples via a standardized, colorimetric enzyme assay. Coronary TIMI flow was evaluated by counting the number of cine frames that were required for contrast to reach a standardized distal coronary landmark in the culprit vessel. Results The Spearman correlation coefficient test showed strong positive relationships between coronary TIMI frame counts after primary PCI and serum ALP levels on admittance for the left anterior descending, circumflex, and right coronary arteries (r = 0.774, r = 0.831, and r = 0.730, respectively). Conclusion Elevated serum ALP levels appear to be a predictor of impaired coronary TIMI frame count in patients suffering from ST-segment elevated myocardial infarction.

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.

Apabetalone Mediated Epigenetic Modulation is Associated with Favorable Kidney Function and Alkaline Phosphatase Profile in Patients with Chronic Kidney Disease

BACKGROUND/AIMS

The association between serum alkaline phosphatase (ALP) with adverse cardiovascular outcomes, in Chronic Kidney Disease (CKD) patients has previously been reported and may be a result of increased vascular calcification and inflammation. Here we report, for the first time, the effects of pharmacologic epigenetic modulation on levels of ALP and kidney function via a novel oral small molecule BET inhibitor, apabetalone, in CKD patients.

METHODS

A post-hoc analysis evaluated patients with estimated glomerular filtration rate (eGFR) <60 mL/min/1.73m2, who participated in the apabetalone phase 2 randomized controlled trials (SUSTAIN and ASSURE). 48 CKD subjects with a history of cardiovascular disease (CVD) were treated with 100mg twice-daily of 24 and 26 weeks of apabetalone or placebo. ALP and eGFR were measured prior to randomization and at final visits.

RESULTS

Patients who received apabetalone (n=35) versus placebo (n=13) over 6 months showed significantly (p=0.02) lowered serum ALP -14.0% (p<0.0001 versus baseline) versus -6.3% (p=0.9 versus baseline). The eGFR in the apabetalone group increased by 3.4% (1.7 mL/min/1.73 m2) (p=0.04 versus baseline) and decreased by 5.8% (2.9 mL/min/1.73 m2) (p=0.6 versus baseline) in the placebo group. Apabetalone was well tolerated.

CONCLUSION

A post-hoc analysis of CKD subjects from the SUSTAIN and ASSURE randomized controlled trials demonstrated favorable effects of apabetalone on ALP and eGFR, and generated the hypothesis that epigenetic modulation by BET inhibition may potentially offer a novel therapeutic strategy to treat CVD and progressive kidney function loss in CKD patients. This is being examined in the phase III trial BETonMACE.

NUTRITIONAL OR ACTIVE VITAMIN D FOR THE CORRECTION OF MINERAL METABOLISM ABNORMALITIES IN NON-DIALYSIS CHRONIC KIDNEY DISEASE PATIENTS?

Context

Benefits of vitamin D therapies in chronic kidney disease (CKD) are debated.

Objective

To compare the effects of medium-term native (VitD) and active (VDRA) vitamin D on parameters of mineral metabolism and arterial function in non-dialysis CKD.

Design

Open-label, active comparator, randomized study.

Subjects and Methods

Forty-eight adult patients, vitamin D naïve, CKD stage 3 to 5 with increased parathyroid hormone (iPTH) were randomized to receive either oral cholecalciferol 1000UI/day (n=24) or paricalcitol 1mcg/day (n=24) for 6 months. Median changes at end of study vs. baseline in serum calcidiol, iPTH, total alkaline phosphatase (ALP), and cardio-ankle vascular index (CAVI) were the efficacy parameters.

Results

Higher increase in calcidiol (15.5 [95%CI 13.3; 17.2] vs. 0.4 [95%CI -6.1; 3.7]ng/mL, p<0.001) were found in VitD group. Conversely, the decline of iPTH (-35.2 [95%CI -83; 9] vs. 13.3 [95%CI -8.1; 35]pg/mL, p=0.008) and ALP (-34 [95%CI -58; -11] vs. -10 [95%CI -23; -2]U/L, p=0.02) were greater after paricalcitol. More subjects experienced iPTH decrease in VDRA group (71% vs. 39%, p=0.03). The variation in CAVI and the incidence of hypercalcemia and hyperphosphatemia were similar.

Conclusions

It seems that secondary hyperparathyroidism was more efficiently treated by VDRA, whereas cholecalciferol better corrected the calcidiol deficiency in non-dialysis CKD.

Alkaline phosphatase: a novel treatment target for cardiovascular disease in CKD

Cardiovascular disease is the main cause of early death in the settings of chronic kidney disease (CKD), type 2 diabetes mellitus (T2DM), and ageing. Cardiovascular events can be caused by an imbalance between promoters and inhibitors of mineralization, which leads to vascular calcification. This process is akin to skeletal mineralization, which is carefully regulated and in which isozymes of alkaline phosphatase (ALP) have a crucial role. Four genes encode ALP isozymes in humans. Intestinal, placental and germ cell ALPs are tissue-specific, whereas the tissue-nonspecific isozyme of ALP (TNALP) is present in several tissues, including bone, liver and kidney. TNALP has a pivotal role in bone calcification. Experimental overexpression of TNALP in the vasculature is sufficient to induce vascular calcification, cardiac hypertrophy and premature death, mimicking the cardiovascular phenotype often found in CKD and T2DM. Intestinal ALP contributes to the gut mucosal defence and intestinal and liver ALPs might contribute to the acute inflammatory response to endogenous or pathogenic stimuli. Here we review novel mechanisms that link ALP to vascular calcification, inflammation, and endothelial dysfunction in kidney and cardiovascular diseases. We also discuss new drugs that target ALP, which have the potential to improve cardiovascular outcomes without inhibiting skeletal mineralization.

An association between time-varying serum alkaline phosphatase concentrations and mortality rate in patients undergoing peritoneal dialysis: a five-year cohort study

The relationship between serum alkaline phosphatase (ALP) concentrations and mortality in peritoneal dialysis (PD) patients is rarely reported. We enrolled 667 PD patients in one PD centre in Taiwan to retrospectively examine the association between three ALP concentrations (baseline, time-averaged, time-dependent) and mortality over a 5-year period (2011–2015). Baseline data collection included demographics, clinical, and laboratory parameters. Multivariable-adjusted Cox models were used to analyse the association. Four ALP quartiles were defined at the baseline: ≤62, 63–82, 83–118, and ≥119 U/L. Of 667 patients, 65 patients died, of which 8 patients died due to cardiovascular disease. Females were predominant in the higher ALP quartiles, and 24-h urine volume was significantly proportionately decreased in the higher ALP quartiles. ALP quartiles expressed by the three models were not associated with all-cause or cardiovascular mortalities after adjusting for demographics, liver function, bone metabolism, mortality, hemoglobin, and 24-h urine volume. In conclusion, ALP concentrations were not associated with death risk in PD patients over the 5-year period.

Subclinical cardiovascular disease markers and vitamin D deficiency in non-dialysis chronic kidney disease patients

INTRODUCTION

Since 25-hydroxyvitamin D (25(OH)D) deficiency has been linked to an increased risk for cardiovascular disease (CVD) in the hemodialysis population, we aimed to determine the relationship between serum 25(OH)D level and markers of subclinical CVD in non-dialysis chronic kidney disease (CKD) patients.

MATERIAL AND METHODS

This cross-sectional, single-center study prospectively enrolled 87 clinically stable CKD patients (median age: 61 (57-66) years, 51% male, median estimated glomerular filtration rate (eGFR): 32 (27-37) ml/min). Five markers of subclinical CVD were assessed: intima-media thickness, abdominal aortic calcifications (AAC) using the Kauppila score, cardio-ankle vascular index, ankle-brachial index (ABI) and interventricular septum thickness.

RESULTS

Vascular (37%), glomerular (23%) and interstitial (18%) nephropathies were the main causes of CKD. 25(OH)D had a median value of 14 (12.5-17.1) ng/ml, and its levels decreased with eGFR (rs = 0.19; p = 0.04). Patients with 25(OH)D deficiency (54%) were older, had a higher serum alkaline phosphatase level, lower ABI and higher AAC score. There were no differences between the two groups regarding other traditional or non-traditional risk factors for atherosclerosis. The association between subclinical CVD markers and 25(OH)D was further evaluated in multivariable binomial logistic regression models adjusted for CV risk factors. Lower 25(OH)D level was retained as an independent predictor only for pathological ABI.

CONCLUSIONS

This is the first study to evaluate the relationship between a large set of subclinical CVD markers and 25(OH)D deficiency in non-dialysis CKD patients. We found that hypovitaminosis D is associated with subclinical peripheral arterial disease, independently of other cardiovascular risk factors.

Oxidative Stress as Estimated by Gamma-Glutamyl Transferase Levels Amplifies the Alkaline Phosphatase-Dependent Risk for Mortality in ESKD Patients on Dialysis

Alkaline phosphatase (Alk-Phos) is a powerful predictor of death in patients with end-stage kidney disease (ESKD) and oxidative stress is a strong inducer of Alk-Phos in various tissues. We tested the hypothesis that oxidative stress, as estimated by a robust marker of systemic oxidative stress like γ-Glutamyl-Transpeptidase (GGT) levels, may interact with Alk-Phos in the high risk of death in a cohort of 993 ESKD patients maintained on chronic dialysis. In fully adjusted analyses the HR for mortality associated with Alk-Phos (50 IU/L increase) was progressively higher across GGT quintiles, being minimal in patients in the first quintile (HR: 0.89, 95% CI: 0.77–1.03) and highest in the GGT fifth quintile (HR: 1.13, 95% CI: 1.03–1.2) (P for the effect modification = 0.02). These findings were fully confirmed in sensitivity analyses excluding patients with preexisting liver disease, excessive alcohol intake, or altered liver disease biomarkers. GGT amplifies the risk of death associated with high Alk-Phos levels in ESKD patients. This observation is compatible with the hypothesis that oxidative stress is a strong modifier of the adverse biological effects of high Alk-Phos in this population.

Association between serum alkaline phosphatase and primary resistance to erythropoiesis stimulating agents in chronic kidney disease: a secondary analysis of the HERO trial

BACKGROUND

Erythropoiesis stimulating agent (ESA)-resistant anemia is common in chronic kidney disease (CKD).

OBJECTIVES

To evaluate the determinants of severity of ESA resistance in patients with CKD and primary ESA-resistance.

DESIGN

Secondary analysis of a randomized controlled trial (the Handling Erythropoietin Resistance with Oxpentifylline, HERO).

SETTING AND PATIENTS

53 adult patients with CKD stage 4 or 5 and primary ESA-resistant anemia (hemoglobin ≤120 g/L, ESA resistance index [ERI] ≥1.0 IU/kg/week/gHb for erythropoietin or ≥0.005 μg/kg/week/gHb for darbepoeitin, no cause for ESA-resistance identified).

MEASUREMENTS

Iron studies, parathyroid hormone, albumin, liver enzymes, phosphate or markers of oxidative stress and inflammation.

METHODS

Participants were divided into tertiles of ERI. Multinomial logistic regression was used to analyse the determinants of ERI tertiles.

RESULTS

All patients, except one, were receiving dialysis for end-stage kidney disease. The mean ± SD ERI values in the low (n = 18), medium (n = 18) and high (n = 17) ERI tertiles were 1.4 ± 0.3, 2.3 ± 0.2 and 3.5 ± 0.8 IU/kg/week/gHb, respectively (P < 0.001). There were no significant differences observed in age, gender, ethnicity, cause of kidney disease, diabetes, iron studies, parathyroid hormone, albumin, liver enzymes, phosphate or markers of oxidative stress and inflammation between the ERI tertiles. The median [inter-quartile range] serum alkaline phosphatase concentrations in the low, medium and high ERI tertiles were 89 [64,121], 99 [76,134 and 148 [87,175] U/L, respectively (P = 0.054). There was a weak but statistically significant association between ERI and serum alkaline phosphatase (R(2) = 0.06, P = 0.03). Using multinomial logistic regression, the risk of being in the high ERI tertile relative to the low ERI tertile increased with increasing serum alkaline phosphatase levels (P = 0.02). No other variables were significantly associated with ERI.

LIMITATIONS

Small sample size; bone-specific alkaline phosphatase, other markers of bone turnover and bone biopsies not evaluated.

CONCLUSIONS

Serum alkaline phosphatase was associated with severity of ESA resistance in ESA-resistant patients with CKD. Large prospective studies are required to confirm this association. (

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry 12608000199314).

Association of serum alkaline phosphatase with mortality in non-selected European patients with CKD5D: an observational, three-centre survival analysis

OBJECTIVES

For characterisation of mineral bone disease in chronic kidney disease (CKD), laboratory surrogates have been suggested. This observational should investigate the association of total and skeletal alkaline phosphatase (AP) with mortality of patients undergoing maintenance renal replacement therapy.

SETTING

Three renal outpatient centers in eastern-central Germany (secondary and tertiary care).

PARTICIPANTS

Complete survival and laboratory datasets were available in 407 of 493 patients. Age and gender distribution was equivalent to a general population with end-stage CKD (CKD5D). Patients were included between 2008 and 2010 if at least 2 weeks of maintenance treatment were documented.

PRIMARY OUTCOME MEASURES

Mortality was estimated by setting the end of dialysis date as event date. Events other than death (change to another centre, life-sustaining renal function or transplantation) were censored.

RESULTS

The OR to die within follow-up for patients in the higher of two total AP strata was 2.70 (95% CI 1.76 to 4.15). In univariate Kaplan-Meier analysis, total AP had a strong association with all-cause mortality (LogRank=24.1, p<0.001). Mean total AP and individual lowest skeletal AP, but not mean skeletal AP entered step-wise Cox models for survival from dialysis start (χ(2)=22.4; p<0.001) after adjusting for age, Kt/V, diabetes and vintage. Mean values of skeletal, total AP and parathyroid hormone were 14.8±8.9 µg/L, 91.9±55.3 U/L and 188±164 ng/L, respectively. Skeletal and total AP were highly correlated (R=0.86; p<0.001).

CONCLUSIONS

This unselected CKD5D population exhibited a clinical significant association of total AP with crude mortality and a stronger death risk association of total AP and individual lowest skeletal AP with crude mortality.

Alkaline phosphatase and mortality in patients on peritoneal dialysis

BACKGROUND AND OBJECTIVES

Elevated total serum alkaline phosphatase levels have been associated with higher mortality in the general population, CKD patients, and hemodialysis patients. However, in peritoneal dialysis patients, this association has received little attention. The aim of this study was to evaluate the association between alkaline phosphatase and all-cause and cardiovascular mortality in peritoneal dialysis patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this single center retrospective cohort study, 1021 incident peritoneal dialysis patients from January 1, 2006, to December 31, 2010 with baseline serum alkaline phosphatase values were enrolled. Collected baseline data included demographic characteristics and clinical and laboratory measurements. All patients were followed until December 31, 2012. The associations of total serum alkaline phosphatase levels with all-cause and cardiovascular mortality were assessed using multivariable-adjusted Cox models.

RESULTS

Of 1021 patients, mean age was 47.5 (± 15.5) years, 59.1% of patients were men, and 22.8% of patients were diabetic. The median serum alkaline phosphatase level was 64 U/L (interquartile range=52-82 U/L). During a median 31-month (interquartile range=19-45 months) follow-up period, 203 patients died, of which 109 deaths were caused by cardiovascular disease. After adjusting for demographics, comorbid conditions, liver function, and bone metabolism parameters, the highest alkaline phosphatase quartile was significantly associated with a hazard ratio for all-cause mortality of 1.70 (95% confidence interval, 1.06 to 2.74, P=0.03) and a hazard ratio for cardiovascular mortality of 1.94 (95% confidence interval, 1.02 to 3.72, P=0.04). Each 10 U/L higher baseline alkaline phosphatase level was associated with 4% (95% confidence interval, 1.00 to 1.08, P=0.04) and 7% (95% confidence interval, 1.02 to 1.11, P=0.003) higher risk of all-cause and cardiovascular mortality, respectively.

CONCLUSION

Higher total serum alkaline phosphatase levels at the commencement of peritoneal dialysis were independently associated with all-cause and cardiovascular mortality in peritoneal dialysis patients.