New method to calculate creatinine generation rate using pre- and postdialysis creatinine concentrations

A simple score for malnutrition-inflammation complex syndrome (MICS) is associated with the risk of mortality in Japanese patients undergoing maintenance hemodialysis

INTRODUCTION

Malnutrition-inflammation complex syndrome (MICS) is highly prevalent in patients undergoing hemodialysis. We determined the prognostic value of the Simple MICS score, calculated using a combination of age, body mass index, and serum concentrations of albumin, creatinine, and C-reactive protein.

METHODS

We retrospectively recruited 218 Japanese patients undergoing maintenance hemodialysis. The primary outcome was all-cause mortality, and the main exposure was the Simple MICS score. Cox proportional hazard regression analysis and logistic regression analysis were used to characterize the relationship between the Simple MICS score and mortality.

RESULTS

During a median 4.4-year follow-up period, 56 patients died. Multivariable-adjusted models showed that a higher Simple MICS score was associated with higher risks of mortality. The predictability for all-cause mortality of the Simple MICS score was significantly better than conventional nutrition-related indices.

CONCLUSION

The Simple MICS score can be used to stratify mortality risk in patients undergoing maintenance hemodialysis.

Recent Advances in the Nutritional Screening, Assessment, and Treatment of Japanese Patients on Hemodialysis

Patients on hemodialysis (HD) have a higher rate of protein-energy wasting (PEW) due to lower dietary intake of energy and protein (particularly on dialysis days) and greater loss of many nutrients in the dialysate effluent than other patients. The most well-known method of nutritional screening is the subjective global assessment. Moreover, the Global Leadership Initiative on MalnutIrition has developed the first internationally standardized method for diagnosing malnutrition; however, its use in patients on HD has not been established. In contrast, the nutritional risk index for Japanese patients on HD has recently been developed as a screening tool for malnutrition in patients on HD, based on the modified PEW criteria. These tools are beneficial for screening nutritional disorders, enabling registered dietitians to assess patients' dietary intake on dialysis and non-dialysis days and provide advice on dietary intake, especially immediately after dialysis cessation. Oral supplementation with enteral nutrients containing whey protein may also be administered when needed. In patients that experience adverse effects from oral supplementation, intradialytic parenteral nutrition (IDPN) should be combined with moderate dietary intake because IDPN alone cannot provide sufficient nutrition.

Humoral response after BNT162b2 vaccine in Japanese hemodialysis patients

Background

Hemodialysis patients are more likely to be severely affected if infected by COVID-19. Contributing factors include chronic kidney disease, old age, hypertension, type 2 diabetes, heart disease, and cerebrovascular disease. Therefore, action against COVID-19 for hemodialysis patients is an urgent issue. Vaccines are effective in preventing COVID 19 infection. In hemodialysis patients, however, responses to hepatitis B and influenza vaccines are reportedly weak. The BNT162b2 vaccine has shown an efficacy rate of about 95% in the general population, but as far as we know there are only several reports of efficacy data in hemodialysis patients in Japan.

Methods

We assessed serum anti-SARS-CoV-2 IgG antibody (Abbott SARS-CoV-2 IgG II Quan) in 185 hemodialysis patients and 109 health care workers. The exclusion criterion was positivity for SARS-CoV-2 IgG antibody before vaccination. Adverse reactions to BNT162b2 vaccine were evaluated through interviews.

Results

Following vaccination, 97.6% of the hemodialysis group and 100% of the control group were positive for the anti-spike antibody. The median level of anti-spike antibody was 2,728.7 AU/mL (IQR, 1,024.2-7,688.2 AU/mL) in the hemodialysis group and 10,500 AU/ml (IQR, 9,346.1-2,4500 AU/mL) in the health care workers group. The factors involved in the low response to the BNT152b2 vaccine included old age, low BMI, low Cr index, low nPCR, low GNRI, low lymphocyte count, steroid administration, and complications related to blood disorders.

Conclusions

Humoral responses to BNT162b2 vaccine in hemodialysis patients are weaker than in a healthy control sample. Booster vaccination is necessary for hemodialysis patients, especially those showing a weak or non-response to the two-dose BNT162b2 vaccine.Trial registration UMIN, UMIN000047032. Registered 28 February 2022, https://center6.umin.ac.jp/cgi-bin/ctr/ctr_reg_rec.cgi.

Association between adrenal function and dialysis vintage in hemodialysis patients

INTRODUCTION

Adrenal insufficiency in hemodialysis patients is commonly encountered in clinical practice. However, its association with end-stage renal disease is unclear. We investigated the relationship between adrenal function and relevant clinical parameters, focusing on dialysis vintage.

METHODS

Altogether, 100 maintenance hemodialysis patients were enrolled (age: 69.8 ± 11.8 years, dialysis vintage: 9.4 ± 9.2 years). Basal serum cortisol levels were measured and their associations with relevant clinical parameters were investigated. Subsequently, hormone stimulation tests were performed to assess adrenal function.

RESULTS

Basal serum cortisol significantly decreased with an increase in dialysis vintage (< 10 years, 11.9 ± 3.7 μg/dL; 10-19 years, 10.9 ± 2.9 μg/dL; ≥ 20 years, 9.7 ± 3.8 μg/dL). Basal cortisol was negatively correlated with dry weight, β2-microglobulin, creatinine, and lymphocyte count and positively correlated with brachial-ankle pulse wave velocity. Significant negative correlations were observed between basal cortisol and dialysis vintage after adjusting for confounding variables in the multivariate analysis. Standard adrenocorticotropic hormone (ACTH) and corticotropin-releasing hormone (CRH) stimulation tests were performed in 17 patients. Seven patients were diagnosed with adrenal insufficiency and all of them had a long dialysis vintage (≥ 10 years). According to the rapid ACTH test, cortisol responses were significantly decreased in patients with long dialysis vintage compared to those with short dialysis vintage (< 10 years). Similar findings were observed in ten patients without adrenal insufficiency. The CRH loading test showed similar tendencies, although the differences were not statistically significant.

CONCLUSIONS

Adrenal function decreased with an increase in dialysis vintage. Long-term dialysis patients might be susceptible to adrenal insufficiency.

New polymethylmethacrylate membrane, NF-U, improves nutritional status and reduces patient-reported symptoms in older dialysis patients

Introduction

We previously reported the nutritional advantage of polymethylmethacrylate (PMMA) membranes to prevent the progression of malnutrition in dialysis patients. In this study, we examined whether a new PMMA dialyzer, NF-U, has advantages to improve the nutritional condition, patient-reported symptoms, and other clinical parameters in older dialysis patients.

Methods

We selected ten older chronic dialysis patients who were treated with NF-U for improving their worsening nutritional parameters and retrospectively evaluated nutrition and patient-reported symptoms. Patient-reported symptoms were surveyed by our original questionnaire including 20 items of symptom.

Results

Serum albumin concentration, geriatric nutritional risk index, and percent creatinine generation rate increased from 3.01 ± 0.16 to 3.25 ± 0.17 g/dL, 87.7 ± 5.8 to 91.4 ± 6.2, 100.2 ± 21.6 to 111.9 ± 20.9% at 1 and 4 months after switching to NF-U, respectively. For patient-reported outcomes, fatigue and the total score of patient-reported outcomes were improved after switching to NF-U.

Conclusion

Our results suggest that NF-U is a good choice for older dialysis patients to ameliorate their nutritional status and patient-reported outcomes.

Biocompatibility of Surface-Modified Membranes for Chronic Hemodialysis Therapy

Hemodialysis is a life-sustaining therapy for millions of people worldwide. However, despite considerable technical and scientific improvements, results are still not fully satisfactory in terms of morbidity and mortality. The membrane contained in the hemodialyzer is undoubtedly the main determinant of the success and quality of hemodialysis therapy. Membrane properties influence solute removal and the interactions with blood components that define the membrane’s biocompatibility. Bioincompatibility is considered a potential contributor to several uremic complications. Thus, the development of more biocompatible polymers used as hemodialyzer membrane is of utmost importance for improving results and clinical patient outcomes. Many different surface-modified membranes for hemodialysis have been manufactured over recent years by varying approaches in the attempt to minimize blood incompatibility. Their main characteristics and clinical results in hemodialysis patients were reviewed in the present article.

Total iron binding capacity is a predictor for muscle loss in maintenance hemodialysis patients

BACKGROUND

Protein-energy wasting in hemodialysis (HD) patients is characterized by decreased skeletal muscle mass and plasma protein. Some previous studies reported relationships between skeletal muscle dysfunction and iron deficiency. Dialysis patients with malnutrition may have a functional iron deficiency (FID) because of inflammation. Serum total iron binding capacity (TIBC), correlated with transferrin, is a nutritional status marker in HD patients and a biomarker of iron status. The relationship between muscle loss and iron status is unknown. The aim of the present study was to assess the relationship between iron status and change in skeletal muscle mass.

METHODS

A prospective cohort of 267 HD patients was examined for 12 months. Blood samples were obtained at baseline to measure TIBC, ferritin, transferrin saturation (TSAT), and hepcidin-25. Nutritional status and changes in muscle mass were assessed by subjective global assessment, albumin, creatinine index, and percentage creatinine generation rate.

RESULTS

At baseline, lower tertiles of TIBC were significantly related to lower muscle mass and albumin levels; they were also significantly correlated with high ferritin, hepcidin-25, and TSAT levels, as well as a higher proportion of use of erythropoiesis-stimulating agents. Multiple regression analysis adjusted with confounders showed TIBC was an independent biomarker for decreased muscle mass and albumin. Change in muscle mass remained significantly decreased in the lower tertile of TIBC and in malnourished patients.

CONCLUSIONS

The present study demonstrated relationships between FID and muscle loss. TIBC was an independent biomarker of muscle loss in HD patients, considering iron status, inflammation, oxidative stress, and malnutrition.

Creatinine generation rate can detect sarcopenia in patients with hemodialysis

BACKGROUND

Sarcopenia is strongly associated with long-term mortality in patients undergoing hemodialysis. The diagnostic modalities used to assess muscle mass, such as bioimpedance analysis and dual-energy X-ray absorption measurement, have limitations for application in patients on hemodialysis. Therefore, there is a need to establish a simple index for assessing muscle mass that can be universally performed in patients on hemodialysis.

METHODS

Patients on maintenance hemodialysis were included in this study. Laboratory tests, skeletal muscle mass measured by bioimpedance analysis, and clinical records were obtained retrospectively. The creatinine generation rate (CGR) was calculated from the pre- and postdialysis blood tests using a kinetic model as the index for whole-body muscle mass. Correlations between the CGR and skeletal muscle mass were investigated, and the cut-off value for muscle wasting was determined. Kaplan-Meier survival analysis was performed to investigate the feasibility of the CGR for predicting long-term survival.

RESULTS

Among the 130 patients included, eight were diagnosed with sarcopenia by bioimpedance analysis. The CGR was positively correlated with skeletal muscle mass (r = 0.454, p < 0.001). Multiple linear regression analysis revealed that age and sex independently influenced the CGR. The patients were classified into two groups according to age- and sex-adjusted CGRs. During a median follow-up period of 32 months, the Kaplan-Meier survival analysis showed that patients with low CGR showed significantly poor long-term prognosis (p = 0.002).

CONCLUSION

The CGR is a simple index for muscle mass and can predict long-term mortality in patients on hemodialysis.

Super high-flux membrane dialyzers improve mortality in patients on hemodialysis: a 3-year nationwide cohort study

Introduction

In Japan, dialyzers are classified based on β₂-microglobulin clearance. Type I dialyzers are classified as low-flux dialyzers (<10 mL/min clearance), type II and III as high-flux dialyzers (≥10 to <30 mL/min and ≥30 to <50 mL/min clearance, respectively), and type IV and V as super high-flux dialyzers (≥50 to <70 mL/min and ≥70 mL/min clearance, respectively). Super high-flux dialyzers are commonly used, but their superiority over low-flux dialyzers is controversial.

Methods

In this nationwide prospective cohort study, we analyzed Japanese Society for Dialysis Therapy Renal Data Registry data collected at the end of 2008 and 2011. We enrolled 242,467 patients on maintenance hemodialysis and divided them into five groups by dialyzer type. We assessed the associations of each dialyzer type with 3-year all-cause mortality using Cox proportional hazards models and performed propensity score matching analysis, adjusting for potential confounders.

Results

By the end of 2011, 53,172 (21.9%) prevalent dialysis patients had died. Mortality significantly decreased according to dialyzer type. Hazard ratios (HRs) were significantly higher for type I, II and III compared with type IV (reference) after adjustment for basic factors and further adjustment for dialysis-related factors. HR was significantly higher for type I, but significantly lower for type V, after further adjustment for nutrition- and inflammation-related factors. These significant findings were also evident after propensity score matching.

Conclusions

Hemodialysis using super high-flux dialyzers might reduce mortality. Randomized controlled trials are warranted to clarify whether these type V dialyzers can improve prognosis.

Dialyzer Classification and Mortality in Hemodialysis Patients: A 3-Year Nationwide Cohort Study

Background: Dialyzers are classified as low-flux, high-flux, and protein-leaking membrane dialyzers internationally and as types I, II, III, IV, and V based on β₂-microglobulin clearance rate in Japan. Type I dialyzers correspond to low-flux membrane dialyzers, types II and III to high-flux membrane dialyzers, and types IV and V to protein-leaking membrane dialyzers. Here we aimed to clarify the association of dialyzer type with mortality.

Methods: This nationwide retrospective cohort study analyzed data from the Japanese Society for Dialysis Therapy Renal Data Registry from 2010 to 2013. We enrolled 238,321 patients on hemodialysis who were divided into low-flux, high-flux, and protein-leaking groups in the international classification and into type I to V groups in the Japanese classification. We assessed the associations of each group with 3-year all-cause mortality using Cox proportional hazards models and performed propensity score matching analysis.

Results: By the end of 2013, 55,308 prevalent dialysis patients (23.2%) had died. In the international classification subgroup analysis, the hazard ratio (95% confidence interval) was significantly higher in the low-flux group [1.12 (1.03–1.22), P = 0.009] and significantly lower in the protein-leaking group [0.95 (0.92–0.98), P = 0.006] compared with the high-flux group after adjustment for all confounders. In the Japanese classification subgroup analysis, the hazard ratios were significantly higher for types I [1.10 (1.02–1.19), P = 0.015] and II [1.10 (1.02–1.39), P = 0.014] but significantly lower for type V [0.91 (0.88–0.94), P < 0.0001] compared with type IV after adjustment for all confounders. These significant findings persisted after propensity score matching under both classifications.

Conclusions: Hemodialysis using protein-leaking dialyzers might reduce mortality rates. Furthermore, type V dialyzers are superior to type IV dialyzers in hemodialysis patients.

A case of autosomal dominant polycystic kidney disease with amelioration of refractory cyst infections following prolonged hemodialysis time

Renal cyst infection is a frequent and serious problem in patients with autosomal dominant polycystic kidney disease (ADPKD). Cyst infection is often a refractory complication of treatment that leads to sepsis and death in patients with ADPKD. It was previously reported that a higher dose of dialysis demonstrated clearly better survival than shorten-time dialysis. The relationship between the frequency of cyst infection episodes in hemodialysis (HD) patients with ADPKD and the dialysis dose has not yet been fully elucidated. In this report, we describe a case of an HD patient with ADPKD that was provided elongation of HD time from 4-h twice weekly HD to 8-h thrice weekly nocturnal HD. As a result, the frequency of cyst infection episodes decreased from 10.0 to 1.5 days a month. Our findings suggest that prolonged HD time might contribute to amelioration of refractory cyst infections in patients with ADPKD.

High-performance dialyzers and mortality in maintenance hemodialysis patients

Few data are available regarding the association of dialyzer type with prognosis. In Japan, dialyzers are classified as types I, II, III, IV, and V based on β₂-microglobulin clearance rates of < 10, < 30, < 50, < 70, and ≥ 70 mL/min, respectively. We investigated the relationship of the 5 dialyzer types with 1-year mortality. This nationwide cohort study used data collected at the end of 2008 and 2009 by the Japanese Society for Dialysis Therapy Renal Data Registry. We enrolled 203,008 patients on maintenance hemodialysis who underwent hemodialysis for at least 1 year and were managed with any of the 5 dialyzer types. To evaluate the association of dialyzer type with 1-year all-cause mortality, Cox proportional hazards models and propensity score-matched analyses were performed. After adjustment of the data with clinicodemographic factors, the type I, II, and III groups showed significantly higher hazard ratios (HRs) than the type IV dialyzers (reference). After adjustment for Kt/V and β₂-microglobulin levels, the HRs were significantly higher in the type I and II groups. After further adjustment for nutrition- and inflammation-related factors, the HRs were not significantly different between the type IV and type I and II groups. However, type V dialyzers consistently showed a significantly lower HR. With propensity score matching, the HR for the type V dialyzer group was significantly lower than that for the type IV dialyzer group. Additional long-term trials are required to determine whether type V dialyzers, which are high-performance dialyzers, can improve prognosis.

Muscle mass evaluation using psoas muscle mass index by computed tomography imaging in hemodialysis patients

BACKGROUND AND AIMS

The use of the psoas muscle mass index (PMI) using computed tomography (CT) has become a marker of interest to evaluate whole body muscle mass. However, in hemodialysis (HD) patients, reports about the clinical significance of psoas muscle evaluation are limited. We aimed to clarify the association between PMI and skeletal muscle mass index (SMI) using bioelectrical impedance analysis (BIA), and to investigate factors affecting PMI in HD patients.

METHODS

In this prospective observational study, to evaluate muscle mass, SMI was measured using BIA after HD, and PMI was measured by the manual trace method on routinely available CT scans. PMI measurement was assessed twice by two physicians to compute intra-rater and inter-rater reliability. The correlations between PMI and the clinical factors were evaluated using Pearson's correlation coefficient and a linear regression analysis. Variables with a p-value < 0.05 in the simple linear regression analysis were included in the multivariable linear regression analysis to identify the factors that affected PMI of the HD patients.

RESULTS

Fifty HD patients were recruited (31 males and 19 females; HD duration, 9.0 ± 8.8 years). The SMI was 6.10 ± 1.20 kg/m², and the PMI was 4.79 ± 1.61 cm²/m². Regarding the reliability of PMI measurements, intra-rater reliability [intra-class correlation (ICC) = 0.999] and inter-rater reliability (ICC = 0.998) were high in this study. The mean PMI of male patients was 5.40 ± 1.62 cm²/m², while that of female patients was significantly lower (3.78 ± 0.98 cm²/m²; p < 0.001). The PMI was significantly and positively correlated with SMI (r = 0.630, p < 0.001), in addition to HD duration, body mass index (BMI), serum phosphate and serum creatinine (Cr). In the multivariate linear regression analysis by two models using SMI or BMI, they were respectively extracted as an independent factor associating with PMI, in addition to serum Cr and the difference of sex.

CONCLUSIONS

PMI assessed with CT positively correlated with SMI measured using BIA. PMI might be one of the methods for evaluating the muscle mass in HD patients, when CT scans are taken as part of routine care.

One-year intradialytic leg exercises with resistance bands and fat mass increase in elderly hemodialysis patients: a retrospective study

Background

Intradialytic exercises are recommended to be available as a treatment for enhancing physical functioning. However, there have been few reports which evaluated the results of long-term mild intradialytic exercises in elderly patients. The purpose of this study is to investigate the changes in body weight, body composition, and laboratory data in elderly hemodialysis patients after 1-year intradialytic leg exercises with resistance bands.

Methods

A retrospective study. Twenty-one outpatients, aged 65 or older (mean ± SD, 75.2 ± 5.1 years), received intradialytic leg exercises with resistance bands for a year were analyzed. The values of dry weight, body composition, and laboratory data were collected from the year-ago period, at baseline and 1 year after baseline. Fat and muscle mass were evaluated by using a multi-frequency bioimpedance device.

Results

Physical performance changed and body weight increased after 1-year resistance band exercises. However, the participants gained fat mass, not muscle mass. Although the changes in biochemical data related to protein intake were equivocal, triglyceride levels increased significantly after 1-year exercises. An elevation in serum creatinine levels was observed, even if solute clearance increased significantly.

Conclusions

One-year intradialytic leg exercises with resistance bands may have a potential clinical benefit for body mass index even in elderly hemodialysis patients. However, optimal dietary modification is needed to achieve a balanced increase of muscle and fat mass. An increase of serum creatinine levels does not always mean muscle mass hypertrophy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41100-021-00341-z.

Calcium-based phosphate binder use is associated with lower risk of osteoporosis in hemodialysis patients

Loss of bone mineral density (BMD) is a substantial risk of mortality in addition to fracture in hemodialysis patients. However, the factors affecting BMD are not fully determined. We conducted a single-center, cross-sectional study on 321 maintenance hemodialysis patients who underwent evaluation of femoral neck BMD using dual-energy X-ray absorptiometry from August 1, 2018, to July 31, 2019. We examined factors associated with osteoporosis defined by T-score of ≤  - 2.5, using logistic regression models. Median age of patients was 66 years, and 131 patients (41%) were diagnosed with osteoporosis. Older age, female, lower body mass index, diabetes mellitus, and higher Kt/V ratios were associated with higher osteoporosis risk. The only medication associated with lower osteoporosis risk was calcium-based phosphate binders (CBPBs) [odds ratio (OR), 0.41; 95% confidence interval (CI), 0.21-0.81]. In particular, CBPB reduced the osteoporosis risk within subgroups with dialysis vintage of ≥ 10 years, albumin level of < 3.5 mg/dL, active vitamin D analog use, and no proton pump inhibitor (PPI) use. In conclusion, CBPB use was associated with lower osteoporosis risk in hemodialysis patients. This effect might be partially attributable to calcium supplementation, given its higher impact in users of active vitamin D analogs or non-users of PPI, which modulate calcium absorption.

Influence of albumin leakage on glycated albumin in patients with type 2 diabetes undergoing hemodialysis

Glycated albumin (GA) is recommended as a better glycemic indicator than HbA1c in patients undergoing hemodialysis, because the red blood cell lifespan is generally faster than that in normal subjects. However, GA can be also affected by protein loss in urine and hemodialysis fluid. Therefore, in this study, we investigated the effect of albumin leakage induced by hemodialysis on GA. Nine patients undergoing hemodialysis with a large or small amount of albumin leakage were observed for 9 months in a crossover manner. As a result, it was shown that albumin leakage could affect GA, but the effect was practically small considering the prescription of diabetic drugs. The correlations between HbA1c and blood glucose levels and between GA and blood glucose levels were similar in our study. In conclusion, GA was a reliable indicator, even with the change of hemodialysis modality. The influence of albumin leakage induced by hemodialysis on GA was negligible practically. We should recognize that the preferable glycemic indicator in patients undergoing hemodialysis depends on the hemoglobin and albumin metabolism of each patient.

Creatinine generation from kinetic modeling with or without postdialysis serum creatinine measurement: results from the HEMO study

Background

A convenient method to estimate the creatinine generation rate and measures of creatinine clearance in hemodialysis patients using formal kinetic modeling and standard pre- and postdialysis blood samples has not been described.

Methods

We used data from 366 dialysis sessions characterized during follow-up month 4 of the HEMO study, during which cross-dialyzer clearances for both urea and creatinine were available. Blood samples taken at 1 h into dialysis and 30 min and 60 min after dialysis were used to determine how well a two-pool kinetic model could predict creatinine concentrations and other kinetic parameters, including the creatinine generation rate. An extrarenal creatinine clearance of 0.038 l/kg/24 h was included in the model.

Results

Diffusive cross-dialyzer clearances of urea [230 (SD 37 mL/min] correlated well (R2 = 0.78) with creatinine clearances [164 (SD 30) mL/min]. When the effective diffusion volume flow rate was set at 0.791 times the blood flow rate for the cross-dialyzer clearance measurements at 1 h into dialysis, the mean calculated volume of creatinine distribution averaged 29.6 (SD 7.2) L], compared with 31.6 (SD 7.0) L for urea (P < 0.01). The modeled creatinine generation rate [1183 (SD 463) mg/day] averaged 100.1 % (SD 29; median 99.3) of that predicted in nondialysis patients by an anthropometric equation. A simplified method for modeling the creatinine generation rate using the urea distribution volume and urea dialyzer clearance without use of the postdialysis serum creatinine measurement gave results for creatinine generation rate [1187 (SD 475) mg/day; that closely matched the value calculated using the formally modeled value, R2 = 0.971].

Conclusions

Our analysis confirms previous findings of similar distribution volumes for creatinine and urea. After taking extra-renal clearance into consideration, the creatinine generation rate in dialysis patients is similar to that in nondialysis patients. A simplified method based on urea clearance and urea distribution volume not requiring a postdialysis serum creatinine measurement can be used to yield creatinine generation rates that closely match those determined from standard modeling.

Quantitative analysis of elevation of serum creatinine via renal transporter inhibition by trimethoprim in healthy subjects using physiologically-based pharmacokinetic model

Serum creatinine (SCr) levels rise during trimethoprim therapy for infectious diseases. This study aimed to investigate whether the elevation of SCr can be quantitatively explained using a physiologically-based pharmacokinetic (PBPK) model incorporating inhibition by trimethoprim on tubular secretion of creatinine via renal transporters such as organic cation transporter 2 (OCT2), OCT3, multidrug and toxin extrusion protein 1 (MATE1), and MATE2-K. Firstly, pharmacokinetic parameters in the PBPK model of trimethoprim were determined to reproduce the blood concentration profile after a single intravenous and oral administration of trimethoprim in healthy subjects. The model was verified with datasets of both cumulative urinary excretions after a single administration and the blood concentration profile after repeated oral administration. The pharmacokinetic model of creatinine consisted of the creatinine synthesis rate, distribution volume, and creatinine clearance (CL_cre), including tubular secretion via each transporter. When combining the models for trimethoprim and creatinine, the predicted increments in SCr from baseline were 29.0%, 39.5%, and 25.8% at trimethoprim dosages of 5 mg/kg (b.i.d.), 5 mg/kg (q.i.d.), and 200 mg (b.i.d.), respectively, which were comparable with the observed values. The present model analysis enabled us to quantitatively explain increments in SCr during trimethoprim treatment by its inhibition of renal transporters.

Effect of dialyzer membrane materials on survival in chronic hemodialysis patients: Results from the annual survey of the Japanese Nationwide Dialysis Registry

BACKGROUND

Little information is available regarding which type of dialyzer membrane results in good prognosis in patients on chronic hemodialysis. Therefore, we conducted a cohort study from a nationwide registry of hemodialysis patients in Japan to establish the association between different dialyzer membranes and mortality rates.

METHODS

We followed 142,412 patients on maintenance hemodialysis (female, 39.1%; mean age, 64.8 ± 12.3 years; median dialysis duration, 7 [4-12] years) for a year from 2008 to 2009. We included patients treated with seven types of high-flux dialyzer membranes at baseline, including cellulose triacetate (CTA), ethylene vinyl alcohol (EVAL), polyacrylonitrile (PAN), polyester polymer alloy (PEPA), polyethersulfone (PES), polymethylmethacrylate (PMMA), and polysulfone (PS). Cox regression was used to estimate the association between baseline dialyzers and all-cause mortality as hazard ratios (HRs) and 95% confidence intervals for 1-year mortality adjusting for potential confounders, and propensity score matching analysis was performed.

RESULTS

The distribution of patients treated with each membrane was as follows: PS (56.0%), CTA (17.3%), PES (12.0%), PEPA (7.5%), PMMA (4.9%), PAN (1.2%), and EVAL (1.1%). When data were adjusted using basic factors, with PS as a reference group, the mortality rate was significantly higher in all groups except for the PES group. When data were further adjusted for dialysis-related factors, HRs were significantly higher for the CTA, EVAL, and PEPA groups. When the data were further adjusted for nutrition-and inflammation-related factors, HRs were significantly lower for the PMMA and PES groups compared with the PS group. After propensity score matching, HRs were significantly lower for the PMMA group than for the PS group.

CONCLUSION

The results suggest that the use of different membrane types may affect mortality in hemodialysis patients. However, further long-term prospective studies are needed to clarify these findings, including whether the use of the PMMA membrane can improve prognosis.

High-Performance Membrane Dialyzers and Mortality in Hemodialysis Patients: A 2-Year Cohort Study from the Annual Survey of the Japanese Renal Data Registry

BACKGROUND

Little information is available regarding the type of dialyzer which results in good prognosis. This study is aimed at investigating the association between 7 types of dialyzers and 2-year mortality.

METHODS

We conducted a cohort study using data from a nationwide registry of the Japanese Society for Dialysis Therapy. Subjects were 136,676 patients on maintenance hemodialysis (HD) between 2009 and 2011 who underwent maintenance HD for at least 2 years and were treated with one of the following 7 types of high-performance membrane dialyzers: cellulose triacetate (CTA), ethylene vinyl alcohol (EVAL), polyacrylonitrile (PAN), polyester polymer alloy (PEPA), polyethersulfone (PES), polymethylmethacrylate (PMMA), and polysulfone (PS). Cox regression was used to estimate the association between baseline dialyzers and all-cause 2-year mortality, adjusting for potential confounders.

RESULTS

Data were adjusted using basic factors, with PS as a reference group, and the hazard ratio (HR) was significantly higher in CTA, PMMA, PAN, and EVAL groups. Further data adjustment for Kt/V yielded the same results as were obtained from data adjusted for basic factors. After further adjustment for nutrition- and inflammation-related factors, HR was significantly lowered for the PES and PMMA groups compared with the PS group (HR 0.88; 95% CI 0.82-0.94 and HR 0.84 95% CI 0.76-0.93, respectively). After propensity score matching, HR for the PES and PMMA groups was significantly lowered compared with the PS group.

CONCLUSIONS

The use of different membrane types may affect mortality. Further long-term prospective studies are needed to clarify whether the PES and PMMA membranes can improve prognosis.

Implications of Albumin Leakage for Survival in Maintenance Hemodialysis Patients: A 7-year Observational Study

Albumin leakage during hemodialysis (HD) presents a clinical dilemma. However, protein-binding uremic toxins are suggested to be responsible for increased mortality. No one has investigated the relationship between albumin leakage and mortality. Therefore, the purpose of this observational study was to analyze the association of albumin leakage with mortality in 690 HD patients who survived one year after enrollment. They were divided to three groups who received HD with large (3 g or more per HD session), middle (1 to 3 g) or small (less than 1 g) amount of albumin leakage, respectively. A propensity score analysis minimizing indication bias was performed. Consequently, in a 7-year observation period, 212 patients died. Albumin leakage 3 g or more per HD session provided better prognosis than albumin leakage less than 3 g per HD session. In conclusion, clinically acceptable large albumin leakage provides beneficial effects on mortality in maintenance HD patients.

Metabolism and antioxidant defense in the larval chironomid Tanytarsus minutipalpus: adjustments to diel variations in the extreme conditions of Lake Magadi

Insect larvae are reported to be a major component of the simple but highly productive trophic web found in Lake Magadi (Kenya, Africa), which is considered to be one of the most extreme aquatic environments on Earth. Previous studies show that fish must display biochemical and physiological adjustments to thrive under the extreme conditions of the lake. However, information for invertebrates is lacking. In the present study, the occurrence of the larval chironomid Tanytarsus minutipalpus is reported in Lake Magadi for the first time. Additionally, changes in larval metabolism and antioxidant defense correlated with diel variations in the extremely hostile environmental conditions of the lake are described. Wide variations in water temperature (20.2-29.3°C) and dissolved oxygen content (3.2-18.6 mg O₂ l⁻¹) were observed at different times of day, without significant change in water pH (10.0±0.03). Temperature and dissolved oxygen were higher at 13:00 h (29.3±0.4°C and 18.6±1.0 mg O₂ l⁻¹) and 19:00 h (29.3±0.8°C and 16.2±1.6 mg O₂ l⁻¹) and lower at 01:00 h (21.1±0.1°C and 10.7±0.03 mg O₂ l⁻¹) and 07:00 h (20.2±0.4°C and 3.2±0.7 mg O₂ l⁻¹). Significant and parallel increases in parameters related to metabolism (cholinesterase, glucose, cholesterol, urea, creatinine and hemoglobin) and the antioxidant system (SOD, GPx, GR, GSH and GSSG) were observed in larvae collected at 13:00 h. In contrast, no significant changes were observed in pro-oxidants (ROS and NO), TOSC and oxidative damage parameters (LPO and DNA damage). Therefore, the observed increases in temperature and dissolved O₂ content in Lake Magadi were associated with changes in the antioxidant system of T. minutipalpus larvae. Adjustments performed by the chironomid larvae were efficient in maintaining body homeostasis, as well as protecting biomolecules against oxidative damage, so that oxidative stress did not occur. GSH-GSSG and GPx-GR systems appeared to play an essential role in the adjustments displayed by the chironomid larvae during the diel changes in the extreme conditions of Lake Magadi.

Summary: Insect larvae display adjustments in metabolism and oxidative status to overcome the diel variations in the extreme and harsh physicochemical conditions of Lake Magadi, a saline and alkaline lake in Kenya.

N-Terminal Pro-B-Type Natriuretic Peptide as a Biomarker for Loss of Muscle Mass in Prevalent Hemodialysis Patients

Protein-energy wasting (PEW) is common in hemodialysis (HD) patients. A recent study demonstrated that a high level of N-terminal pro-B-type natriuretic peptide (NT-proBNP) may be associated with PEW in those patients. This prospective study aimed to assess the association of NT-proBNP with body composition and muscle loss. A cohort of prevalent HD patients (n = 238) was examined. Blood samples were obtained at baseline to measure high-sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6), adiponectin and NT-proBNP. Nutritional status and changes in muscle mass were assessed by subjective global assessment, percentage creatinine generation rate (%CGR), creatinine index (CI) and lean body mass (LBM) estimated by dual-energy X-ray absorptiometry (DXA). The %CGR and CI were calculated five times for one year, and DXA was performed at baseline and one year later. Cardiac function was estimated by ultrasonography at baseline. NT-proBNP was significantly higher in HD patients with PEW. High NT-proBNP was associated with cardiac dysfunction, increased levels of hsCRP and IL-6, and serially decreased levels of the indexes for muscle mass. Multiple regression analysis adjusted with confounders showed that NT-proBNP was an independent predictor for decrease in LBM and serial lower levels of %CGR and CI. In conclusion, the present study demonstrated a novel association between NT-proBNP and muscle loss. NT-proBNP may be an independent biomarker for malnutrition in HD patients, especially in patients with muscles loss, regardless of chronic inflammation, cardiac dysfunction, or overhydration.

The effect of albumin leakage in hemodialysis patients on redox status of serum albumin

Human mercaptoalbumin (HMA) is a reduced form of albumin that is associated with cardiovascular disease in dialysis patients. Albumin-leaky hemodialysis (HD) is increasingly recognized as a gold standard therapy because it is correlated with better prognosis compared to conventional HD. However, albumin-leaky HD induces low serum albumin concentration because of albumin leakage, which is a classical risk factor for mortality. The aim of this study was to explain the preferable prognosis in patients undergoing albumin-leaky HD with low serum albumin concentration. Ten HD patients were enrolled. They were preconditioned with albumin-non-leaky HD (mean albumin leakage: 1.0 g) for 2 months. Subsequently, albumin-leaky HD (9.1 g) was performed for 6 months, followed by relatively non-leaky HD (within 3.0 g). The ratio and level of HMA were evaluated. The amount of albumin leakage was related to the ratio of HMA, and inversely correlated with serum albumin concentration. The level of HMA was maintained regardless of albumin leakage. Regarding HMA level, a moderate amount of albumin leakage was acceptable. A stably maintained HMA level in albumin-leaky HD patients can contribute to preferable prognosis even if they have low serum albumin concentration.

Serum Creatinine Modifies Associations between Body Mass Index and Mortality and Morbidity in Prevalent Hemodialysis Patients

Background

High body mass index (BMI) is paradoxically associated with better outcomes in hemodialysis (HD) patients. This study aimed to examine whether serum creatinine (Cr), a marker of muscle mass, could modify the association between BMI, and mortality and morbidity in prevalent HD patients.

Methods

A retrospective study was conducted using a nationwide database from the registry of the Japanese Society for Dialysis Therapy. A total of 119,099 patients were selected (age: 65±12 years; median time on HD: 5.6 years; male: 62%), and we examined the association of basal BMI with mortality and morbidity after a 1-year period. Patients were stratified either by BMI into 4 groups or by serum Cr levels into 3 tertiles. Odds ratio (OR) [95% confidence interval] was calculated by multivariate logistic regression analysis.

Results

Higher BMI did not predict a higher 1-year total mortality. However, when we stratified the patients by serum Cr levels, the risk of cardiac death became significantly higher in obese patients with the lowest Cr levels, in both males (OR 2.82 [1.51–5.27], p<0.01) and females (OR 2.00 [1.03–3.90], p<0.05). The risk of new cerebral infarction was also higher in obese male patients within the lowest Cr tertile. In contrast, there was a significantly lower risk of cardiac, cerebrovascular, and infection-related death in non-obese patients with higher levels of Cr. Higher serum Cr was also related to a lower risk of cardiovascular events and hip fracture in non-obese HD patients.

Conclusions

The obesity paradox was found to be present in HD patients only when obesity was defined by BMI. Decreased serum Cr levels were found to be positively associated with clinical poor outcomes in all BMI groups. Thus, irrespective of BMI, the evaluation of serum Cr levels is important to predict mortality and morbidity in patients receiving regular HD.

Low Serum Neutrophil Gelatinase-associated Lipocalin Level as a Marker of Malnutrition in Maintenance Hemodialysis Patients

Background

Neutrophil gelatinase-associated lipocalin (NGAL or LCN2) is an iron-transporting factor which possesses various activities such as amelioration of kidney injury and host defense against pathogens. Its circulating concentrations are elevated in acute and chronic kidney diseases and show a positive correlation with poor renal outcome and mortality, but its clinical significance in maintenance hemodialysis (HD) patients remains elusive.

Methods

Serum NGAL levels were determined by enzyme-linked immunosorbent assay in out-patient, Japanese HD subjects. Their correlation to laboratory findings and morbidity (as development of severe infection or serum albumin reduction) was investigated using linear regression analysis and χ² test.

Results

Pre-dialysis serum NGAL levels in HD patients were elevated by 13-fold compared to healthy subjects (n=8, P<0.001). In a cross-sectional study of 139 cases, serum NGAL concentrations were determined independently by % creatinine generation rate (an indicator of muscle mass, standardized coefficient β=0.40, P<0.001), peripheral blood neutrophil count (β=0.38, P<0.001) and anion gap (which likely reflects dietary protein intake, β=0.16, P<0.05). Iron administration to anemic HD patients caused marked elevation of peripheral blood hemoglobin, serum ferritin and iron-regulatory hormone hepcidin-25 levels, but NGAL levels were not affected. In a prospective study of 87 cases, increase in serum albumin levels a year later was positively associated to baseline NGAL levels by univariate analysis (r=0.36, P<0.01). Furthermore, within a year, patients with the lowest NGAL tertile showed significantly increased risk for marked decline in serum albumin levels (≥0.4 g/dl; odds ratio 5.5, 95% confidence interval 1.5–20.3, P<0.05) and tendency of increased occurrence of severe infection requiring admission (odds ratio 3.1, not significant) compared to the middle and highest tertiles.

Conclusion

Low serum NGAL levels appear to be associated with current malnutrition and also its progressive worsening in maintenance HD patients.

Plasma levels of fibroblast growth factor-23 are associated with muscle mass in haemodialysis patients

AIM

Malnutrition is highly prevalent in haemodialysis (HD) patients, and it contributes to morbidity and mortality. Fibroblast growth factor-23 (FGF-23) and Klotho contribute to chronic kidney disease-mineral and bone disorder (CKD-MBD) in HD patients, but the role that these molecules play in determining nutritional status is currently unknown.

METHODS

A cross-sectional study examining 77 HD patients was performed. The plasma concentrations of FGF-23 and soluble Klotho (s-Klotho) were studied to evaluate their association with muscle mass, which was investigated by abdominal muscle areas measured using computed tomography and by creatinine (Cr) production estimated using the Cr kinetic model.

RESULTS

Plasma FGF-23 concentrations were significantly and positively correlated with abdominal muscle areas and Cr production (rho = 0.301, P < 0.01 and rho = 0.345, P < 0.01, respectively). In contrast, s-Klotho was not significantly correlated with these muscle mass indices and plasma FGF-23 concentrations. Multiple regression analyses showed that FGF-23 was a significant independent predictor of both muscle mass indices (P < 0.01 and P < 0.05, respectively).

CONCLUSION

Plasma FGF-23 concentrations were associated with muscle mass indices in HD patients. Our findings suggest that FGF-23 and nutritional status are linked and this link is most likely independent of s-Klotho.

Circulating 20S proteasome is independently associated with abdominal muscle mass in hemodialysis patients

Protein-energy wasting is highly prevalent in hemodialysis patients, and it contributes to patient morbidity and mortality. The ubiquitin-proteasome system is the major pathway for intracellular protein degradation and it is involved in the regulation of basic cellular processes. However, the role of this system in the determination of nutritional status is largely unknown. To examine a relationship between protein-energy wasting and the ubiquitin-proteasome system, a cross-sectional study of 76 hemodialysis patients was performed. Plasma concentrations of 20S proteasome were studied to evaluate its association with muscle and fat mass, which were investigated by abdominal muscle and fat areas measured using computed tomography and by creatinine production estimated using the creatinine kinetic model. Plasma 20S proteasome concentrations significantly and negatively correlated with abdominal muscle areas and creatinine production (rho = -0.263, P < 0.05 and rho = -0.241, P < 0.05, respectively), but not abdominal subcutaneous and visceral fat areas. Multiple regression analyses showed that 20S proteasome was a significant independent predictor of abdominal muscle area (P < 0.05). In conclusion, plasma 20S proteasome concentrations were independently associated with abdominal muscle mass in hemodialysis patients. Our findings indicate a relationship between circulating 20S proteasomes and muscle metabolism in these patients.

Skeletal muscle loss is negatively associated with single-pool Kt/V and dialysis duration in hemodialysis patients

We evaluated the skeletal muscle loss in hemodialysis (HD) patients by bioelectrical impedance analysis (BIA) and handgrip strength test. Thirty-four HD patients and 16 healthy subjects (control group) were measured for skeletal muscle mass normalized as the skeletal muscle mass index (SMI), calculated as skeletal muscle mass (kg)/height (m)(2) using a tetrapolar bioelectrical impedance plethysmograph. Handgrip strength test was also performed using a hand dynamometer in both groups. In HD patients, the associations of SMI and handgrip strength with age, sex, HD conditions, and HD parameters such as body mass index (BMI), single-pool Kt/V (spKt/V), normalized protein catabolic rate (nPCR), creatinine generation rate (CGR) and serum albumin level (Alb) were investigated. SMI of HD patients (4.58 ± 0.95 kg/m(2) ) was significantly lower than that of the control group (5.55 ± 0.80 kg/m(2) , P<0.01). The handgrip strength of HD patients (19.9 ± 7.74 kg) was also significantly lower than that of the control group (33.0 ± 8.94 kg, P<0.01). In HD patients, HD duration was associated with both SMI and handgrip strength. Among HD parameters, spKt/V was negatively associated with both SMI and handgrip strength, BMI and Alb were positively associated with SMI, while nPCR and CGR were associated with neither SMI nor handgrip strength. HD duration independently contributed to skeletal muscle loss and the value of spKt/V may be affected by skeletal muscle loss in HD patients.

Association of serum total testosterone concentration with skeletal muscle mass in men under hemodialysis

PURPOSE

Although skeletal muscle wasting can occur in chronic kidney diseases, its relationship with the serum testosterone concentration remains uncertain. This study investigates the relationship between serum testosterone and skeletal muscle mass in men under hemodialysis (HD).

METHODS

Sixty men aged between 41 and 89 years undergoing HD for 15.0 ± 8.1 years were enrolled for this study. The muscle areas of the thigh (TMA) and abdomen (AMA) were measured by computed tomography (CT), and the association between these muscle areas and serum total testosterone was examined with adjustment of age and other nutritional variables.

RESULTS

The mean serum total testosterone in our HD patients (6.33 ± 2.90 ng/mL) was not lower than that of the Japanese general population, but showed a positive correlation with TMA (r = 0.39, p < 0.05), AMA (r = 0.52, p < 0.001), serum creatinine (r = 0.33, p < 0.05), and the creatinine generation rate (r = 0.26, p < 0.05). Serum total testosterone was inversely correlated with age (r = -0.32, p < 0.05), CRP (r = -0.31, p < 0.05), and IL-6 (r = -0.24, p < 0.05). A multiple-regression analysis showed both serum total testosterone and age to be an independent determinant of the muscle mass in these patients.

CONCLUSIONS

This study identified testosterone as a determinant of muscle mass in HD men.

Oral activated charcoal suppresses hyperphosphataemia in haemodialysis patients

AIM

Hyperphosphataemia is almost inevitable in end stage renal disease (ESRD) patients and is associated with increased morbidity and mortality. In this study we examined whether oral activated charcoal (oAC) reduces serum phosphate level in haemodialysis patients.

METHODS

This was an open-label, prospective, uncontrolled study. One hundred and thirty-five haemodialysis patients were included in this study, with cessation of treatment with any phosphate binders during a 2 week washout period. Patients with serum phosphate levels greater than 5.5 mg/dL during the washout period were included for treatment with oAC. oAC was started at a dose of 600 mg three times per day with meals and was administered for 24 weeks. oAC dose was titrated up during the 24 week period to achieve phosphate control (3.5-5.5 mg/dL). A second 2 week washout period followed the end of oAC treatment.

RESULTS

In the 114 patients who successfully completed the trial, the mean dose of activated charcoal was 3190 ± 806 mg/day. oAC reduced mean phosphate levels to below 5.5 mg/dL, with mean decreases of 2.60 ± 0.11 mg/dL (P < 0.01) and 103 (90.4%) of the patients reached the phosphate target. After the second washout period the phosphate levels increased to 7.50 ± 1.03 mg/dL (P < 0.01). Serum intact parathyroid hormone (iPTH) levels declined from 338.75 ± 147.77 pg/mL to 276.51 ± 127.82 pg/mL (P < 0.05) during the study. oAC had no influence on serum prealbumin, total cholesterol, triglycerides, serum ferritin, haemoglobin or platelet levels and the levels of 1,25-dihydroxyvitamin D were stable during the study.

CONCLUSION

In this open-label uncontrolled study, oAC effectively controls hyperphosphataemia and hyperparathyroidism in haemodialysis patients. The safety and efficacy of oAC needs to be assessed in a randomized controlled trial.

Interdialytic creatinine change versus predialysis creatinine as indicators of nutritional status in maintenance hemodialysis

BACKGROUND

Protein-energy wasting is common in patients on maintenance hemodialysis and is strongly associated with poor quality of life and mortality. However, clinical assessment of protein-energy wasting remains difficult. Predialysis creatinine levels are associated with mortality risk but may be influenced by both muscle mass and dialysis dose. This might be overcome by examining the rate of rise in creatinine between dialysis sessions.

METHODS

We conducted an observational cohort study among 81 patients on maintenance hemodialysis at our Veterans Affairs unit. Predialysis serum creatinine and change in serum creatinine between midweek dialysis sessions served as the predictor variables of interest and clinically available proxies of nutritional status and time to mortality served as the outcome variables. Linear regression and Cox proportional hazards models evaluated relationships, respectively.

RESULTS

The mean age of the study participants was 63 ± 10 years, 77 (95%) were male, mean body mass index was 27 ± 6 kg/m(2) and 69% had diabetes. Median follow-up time was 13 months, during which 12 patients (15%) died. Interdialytic change in serum creatinine showed a strong direct correlation with predialysis serum creatinine (R = 0.96). Higher levels of both markers were associated with younger age, less residual urine volume and higher serum albumin, serum phosphorus and normalized protein catabolic rate (P < 0.05 for all). Both markers were approximately equally strongly associated with mortality. For example, compared to the highest predialysis creatinine tertile, participants in the lowest tertile (<6 mg/dL) had 5.5-fold [95% confidence interval (CI) 1.1, 26.6] higher risk of death. Similarly, participants in the lowest tertile of interdialytic change in creatinine (change <3.7 mg/dL/48 h), had 5.0-fold (95% CI 1.0, 24.4) higher death risk.

CONCLUSIONS

Predialysis creatinine and interdialytic change in creatinine are both strongly associated with proxies of nutritional status and mortality in hemodialysis patients and are highly correlated. Interdialytic change in creatinine provided little additional information about nutritional status or mortality risk above and beyond predialysis creatinine levels alone.

Prediction of fluoroquinolone-induced elevation in serum creatinine levels: a case of drug-endogenous substance interaction involving the inhibition of renal secretion

The aim of this study was to examine the mechanism underlying the elevation in serum creatinine levels caused by a novel des-fluoro(6)-quinolone antibacterial agent, DX-619, in healthy subjects. hOCT2 showed a prominent uptake of creatinine (K(m) = 56.4 mmol/l) among renal organic ion transporters. DX-619 is a potent inhibitor of hOCT2 (K(i) = 0.94 micromol/l), hMATE1 (0.82 µmol/l), and hMATE2-K (0.10 micromol/l). The pharmacokinetic model involving the inhibition of hOCT2 (model 1), hOCT2, and MATE1 or MATE2-K (model 2) could predict the elevation in serum creatinine levels in individual subjects receiving DX-619. This assumes that a significant contribution of tubular secretion (59, 38, and 31%) and reabsorption ranged from 3-50, 4-30, and 5-21% in model 1, -2a (hOCT2/hMATE1), and -2b (hOCT2/hMATE2-K), respectively, for creatinine. In conclusion, DX-619, at its therapeutic dose, is able to inhibit hOCT2, hMATE1, and hMATE2-K, leading to a significant inhibition of tubular secretion of creatinine and consequently to elevation of serum creatinine levels.

The Impact of Pre-Dialytic Endurance Training on Nutritional Status and Quality of Life in Stable Hemodialysis Patients (Sawada Study)

BACKGROUND

Protein-energy malnutrition and decreased quality of life (QOL) are common in hemodialysis (HD) patients. Although several studies have proved that regular exercise has beneficial effects, few control studies have shown the effects of exercise training on the nutritional status and QOL in HD patients.

METHODS

Fifty-five HD patients were recruited, and 22 of them were trained to exercise on an ergometer prior to dialysis three times a week for one year. Serum albumin levels, creatinine generation rate (CGR), and the Short Form 36 were assessed as outcome measures.

RESULTS

The serum albumin levels and CGR increased in the training group compared with baseline. The QOL scores also increased in half of the physical health and mental health dimensions in the training group.

CONCLUSION

These observations suggest that low-dose, long-term pre-dialytic endurance training might reverse the poor clinical outcome by improving the nutritional status and QOL in HD patients.

Long-term use of vitamin E-coated polysulfone membrane reduces oxidative stress markers in haemodialysis patients

BACKGROUND

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase and an independent predictor of overall mortality and cardiovascular outcome in haemodialysis (HD) patients. In the present study, we compared the effects of a vitamin E-coated polysulfone membrane (PSE) and a non-vitamin E-coated polysulfone membrane (PS) on oxidative stress markers such as ADMA.

METHODS

Thirty-one HD patients were enrolled to this investigation. They were allocated into two groups: in the PSE group (n = 16), PSE was used for 6 months, followed by PS for an additional 12 months; in the PS group (n = 15), PS was used for the entire observation period. Plasma ADMA, oxidized low density lipoprotein (Ox-LDL) and malondialdehyde LDL (MDA-LDL) levels were measured at baseline, 3, 6, 12 and 18 months. Plasma ADMA in peritoneal dialysis (PD) patients and in healthy individuals was also measured.

RESULTS

Predialysis concentrations of ADMA (0.72+/- 0.13 nmol/ml) were significantly higher in the HD group than in both PD patients (0.63+/-0.10 nmol/ml, P<0.01) and healthy individuals (0.44+/-0.01 nmol/ml, P<0.0001). Treatment with PSE for 6 months significantly reduced predialysis levels of ADMA (0.54+/-0.09 nmol/ml) compared with baseline (0.74+/-0.12 nmol/ml; P<0.01). Predialysis levels of Ox-LDL and MDA-LDL after 6 months therapy with PSE were also significantly lower than baseline values. Treatment with PS subsequent to treatment with PSE again increased ADMA, Ox-LDL and MDA-LDL back to baseline levels. In the PS group, ADMA, Ox-LDL and MDA-LDL levels remained unchanged during the entire treatment period of 18 months.

CONCLUSIONS

We confirmed that use of PSE reduced ADMA that had accumulated in HD patients. This finding indicates that PSE exerts anti-oxidant activity. A randomized controlled study will be required to determine whether PSE prevents cardiovascular diseases and other dialysis-related complications by reducing oxidative stress.

Nicotinamide suppresses hyperphosphatemia in hemodialysis patients

BACKGROUND

The use of calcium- or aluminum-based phosphate binders against hyperphosphatemia is limited by the adverse effects of hypercalcemia or aluminum toxicity in long-term hemodialysis. Because nicotinamide is an inhibitor of sodium-dependent phosphate cotransport in rat renal tubule and small intestine, we examined whether nicotinamide reduces serum levels of phosphorus and intact parathyroid hormone (iPTH) in patients undergoing hemodialysis.

METHODS

Sixty-five hemodialysis patients with a serum phosphorus level of more than 6.0 mg/dL after a 2-week washout of calcium carbonate were enrolled in this study. Nicotinamide was administered for 12 weeks. The starting dose was 500 mg/day, and the dose was increased by 250 mg/day every 2 weeks until serum phosphorus levels were well controlled at less than 6.0 mg/dL. A 2-week posttreatment washout period followed the cessation of nicotinamide. Blood samples were collected every week for measurement of serum calcium, phosphorus, lipids, iPTH, and blood nicotinamide adenine dinucleotide (NAD).

RESULTS

The mean dose of nicotinamide was 1080 mg/day. The mean blood NAD concentration increased from 9.3 +/- 1.9 nmol/105 erythrocytes before treatment to 13.2 +/- 5.3 nmol/105 erythrocytes after treatment (P < 0.01). The serum phosphorus concentration increased from 5.4 +/- 1.5 mg/dL to 6.9 +/- 1.5 mg/dL with the pretreatment washout, then decreased to 5.4 +/- 1.3 mg/dL after the 12-week nicotinamide treatment (P < 0.0001), and rose again to 6.7 +/- 1.6 mg/dL after the posttreatment washout. Serum calcium levels decreased during the pretreatment washout from 9.1 +/- 0.8 mg/dL to 8.7 +/- 0.7 mg/dL with the cessation of calcium carbonate. No significant changes in serum calcium levels were observed during nicotinamide treatment. Median serum iPTH levels increased with pretreatment washout from 130.0 (32.8 to 394.0) pg/mL to 200.0 (92.5 to 535.0) pg/mL and then decreased from the maximum 230.0 (90.8 to 582.0) pg/mL to 150.0 (57.6 to 518.0) pg/mL after the 12-week nicotinamide treatment (P < 0.05). With nicotinamide, serum high-density lipoprotein (HDL) cholesterol concentrations increased from 47.4 +/- 14.9 mg/dL to 67.2 +/- 22.3 mg/dL (P < 0.0001) and serum low-density lipoprotein (LDL) cholesterol concentrations decreased from 78.9 +/- 18.8 mg/dL to 70.1 +/- 25.3 mg/dL (P < 0.01); serum triglyceride levels did not change significantly.

CONCLUSION

Nicotinamide may provide an alternative for controlling hyperphosphatemia and hyperparathyroidism without inducing hypercalcemia in hemodialysis patients.

Creatinine index and lean body mass are excellent predictors of long-term survival in haemodiafiltration patients

BACKGROUND

No single measurement adequately defines protein-energy malnutrition. In the dialysis population, somatic protein mass, a useful marker of protein malnutrition, is estimated using the creatinine index (CI), lean body mass (LBM) or both, but the clinical usefulness of these indices remains uncertain. Moreover, calculating these indices requires formal creatinine kinetics or urine and dialysate collection. A simpler method to estimate the creatinine generation rate (G(Cr)) probably might widen its use.

METHODS

We evaluated the usefulness of creatinine-based indices for predicting mortality in a cohort of 226 French haemodiafiltration patients using the Cox proportional hazards method. We also proposed simple yet precise formulas to calculate post-dialysis creatinine (Cr(post)) concentrations and derive creatinine generation rates (G(Cr)) from readily available measures. These formulas were developed using a large database containing more than 10 000 measured Cr(post) and G(Cr) values based on formal creatinine modelling. A single set of monthly values was used to evaluate the validity of the formulas.

RESULTS

When adjusted for comorbidities, sex and Kt/V, CI and LBM/body weight (LBM/BW) were better predictors of 5 year all-cause mortality than urea-based indices [survival relative risk (RR) = 0.24, P<0.01 for CI<22 mg/kg/day; RR = 0.33, P<0.02 for LBM/BW<0.75]. When the cohort was divided according to gender, similar results were found in males, but not in females. The different formulas allowed adequate prediction of Cr(post) and G(Cr) and classification of patients with good accuracy (CI<22: sensitivity = 94%, specificity = 82%; LBW/BW<0.75: sensitivity = 89%, specificity = 90%).

CONCLUSIONS

In a haemodiafiltration population, CI and LBM are excellent predictors of long-term survival. In anuric Caucasian haemodialysis patients, CI and LBM can be estimated from biochemical and anthropometric measurements without relying on formal modelling.