Economic burden of secondary hyperparathyroidism in Germany: a matched comparison.

PURPOSE: Secondary hyperparathyroidism (SHPT) of renal origin is a progressive complication in chronic kidney disease (CKD) and is associated with serious osseous and non-osseous complications, CKD progression, and economic burden for healthcare systems worldwide. We aimed at assessing characteristics, healthcare resource utilization, and costs of incident SHPT patients in CKD stage 3 (CKD3) and 4 (CKD4), using administrative claims data. METHODS: German claims data were used to identify CKD3 and CKD4 patients, who were stratified by the occurrence of incident SHPT. Patients with SHPT were matched 1:1 to non-SHPT patients with the same CKD stage using propensity scores. Matched groups were compared during a 2-year follow-up period. RESULTS: Overall, 1156 CKD3 and 517 CKD4 incident SHPT patients and their respective matches were identified. Mean number of all-cause hospitalizations were significantly higher among SHPT patients (2.7 vs. 2.0 in CKD3, 2.8 vs. 1.5 in CKD4) during follow-up. Similarly, the mean number of outpatient encounters was significantly higher among the SHPT cohorts (95.0 vs. 64.3 in CKD3, 101.4 vs. 49.8 in CKD4). SHPT patients progressed to CKD5 more often (6.1% vs. 1.2% from CKD3, 26.7% vs. 2.9% from CKD4, both P < 0.01) resulting in a higher proportion of dialysis (6.1% vs. 1.3% in CKD3, 22.1% vs. 3.7% in CKD4, both P < 0.01). Consequently, average all-cause healthcare costs significantly increased per patient (€19,477 vs. €15,115 in CKD3, €25,921 vs. €12,265 in CKD4). CONCLUSIONS: Patients with CKD3&4 and incident SHPT of renal origin presented with significantly higher healthcare resource utilization and costs, as well as increased disease progression compared to non-SHPT patients.

Pyroptosis: A Common Feature of Immune Cells of Haemodialysis Patients.

NLRP-3 inflammasome activation can result in interleukin-1ß (IL-1ß) release and inflammatory cell death (pyroptosis). Caspase-1 is able to trigger both processes. However, other caspases, caspase-4, -5 and -8, are believed to initiate pyroptosis without affecting IL-1 secretion. In this study, we evaluated two cardiovascular risk groups, haemodialysis patients (HD) and patients with intact kidney function but high blood pressure (BP), to analyse the mechanisms driving pyroptosis. Twenty HD were age-, gender- and diabetes-matched to BP. We found a common pyroptotic pattern in both patient groups, at which pyroptosis rates but not IL-1 ß levels were significantly higher in monocytes (HD vs. BP: p < 0.05), granulocytes (p < 0.01) and lymphocytes (p < 0.01) of HD patients. As uremic toxins are drivers of inflammation and regulated cell death, we applied a monocyte- and macrophage-like THP-1 model system to demonstrate that the protein-bound uremic toxin indoxyl sulfate (IS) is an inducer of pyroptotic cell death, particularly engaging caspase-4/caspase-5 and to a lesser extent caspase-8 and caspase-1. These data suggest that the uremic toxin IS can mediate pyroptosis in HD patients and the inflammatory caspase-4 and/or caspase-5 contribute to pyroptosis rates to a higher extent in comparison to caspase-1.

Serum Testosterone Levels Are Not Modified by Vitamin D Supplementation in Dialysis Patients and Healthy Subjects.

INTRODUCTION: Low serum testosterone is related to increased mortality in male dialysis patients. An association of vitamin D status with serum androgen levels with concordant seasonal variation has been described, but it is undecided whether vitamin D supplementation improves testosterone levels. METHODS: In a randomized, placebo-controlled, and double-blind manner, we investigated the effects of an oral vitamin D supplementation in healthy subjects and hemodialysis patients on testosterone levels. One hundred three healthy individuals received cholecalciferol 800 IE/day (n = 52) or placebo (n = 51) for 12 weeks. Thirty-three hemodialysis patients received cholecalciferol adapted to their serum levels following current guidelines (n = 15) or placebo (n = 18) for 12 weeks. RESULTS: In healthy individuals, 25(OH)D3 levels rose significantly in the verum group (38.1 ± 13.7 vs. 72.5 ± 15.4 nmol/L, p < 0.001), whereas in the placebo group, levels dropped (37.7 ± 14.7 vs. 31.9 ± 13.1, p < 0.001). Testosterone levels did not change significantly (verum, males: 20.9 ± 6.6 vs. 20.5 ± 7.9 nmol/L, p = 0.6; verum, females: 0.9 ± 0.5 vs. 0.92 ± 0.5, p = 0.4; placebo, males: 18.5 ± 10.2 vs. 21.8 ± 16.5, p = 0.07, placebo, females: 1.6 ± 4.2 vs. 1.6 ± 4.9, p = 0.6). In dialysis patients, the mean cholecalciferol level was only 32.3 ± 17.8 nmol/L, with only 2% of the values being within the normal range. Cholecalciferol levels normalized in the verum group (29.4 ± 11.2 vs. 87.8 ± 22.3, p < 0.001), whereas levels dropped further in the placebo group (33.6 ± 16.6 vs. 24.6 ± 8.0 nmol/L, p < 0.001). Testosterone levels did not change significantly (verum, males: 8.0 ± 3.7 vs. 7.8 ± 3.8, p = 0.8; verum, females: 1.3 ± 1.0 vs. 1.2 ± 1.0 nmol/L, p = 0.5; placebo, males: 11.9 ± 5.0 vs. 11.6 ± 4.0 nmol/L, p = 0.6; placebo, females: 0.8 ± 0.5 vs. 0.7 ± 0.4 nmol/L, p = 0.8). CONCLUSION: Serum testosterone levels in hemodialysis patients and healthy individuals are independent from vitamin D status and cannot be significantly increased by cholecalciferol supplementation.

NLRP3 Inflammasome Activation in Hemodialysis and Hypertensive Patients with Intact Kidney Function.

Hypertension is not only an integrative characteristic of hemodialysis (HD) patients but is also very common in the general population. There is evidence that the inflammatory cytokine IL-ß, regulated by the NLRP3 inflammasome via caspase-1, contributes to the hypertensive setting. Therefore, we investigated in an observational pilot study whether IL-1ß secretion and inflammatory cell death (pyroptosis) are different in HD and hypertensive patients with intact kidney function. Twenty HD patients were age-, gender-, and diabetes-mellitus-matched to patients with hypertension and intact kidney function. Caspase-1 activity and pyroptosis rates were measured by flow cytometry. IL-1ß was determined by qPCR and the ELISA technique. The inflammatory status (CRP) did not differ between both groups; however, the body mass index, a classical cardiovascular risk factor, was significantly elevated in blood pressure (BP) patients. BP patients had a higher frequency of caspase-1-positive monocytes compared to HD (p < 0.001). IL1-ß protein secretion was significantly enhanced in BP, but ex vivo stimulation of blood cells resulted in higher pyroptosis rates in HD compared to BP patients (p < 0.01). Therefore, HD and BP patients differ in the extent of the NLRP3 inflammasome activation. The consequences of overweight, present in BP patients, may contribute to the significantly higher inflammasomal induction level. Whether low pyroptotic rates are equivalent to a dysfunctional immune response or a high pyroptotic output corresponds to over-activation remains to be clarified.

Influence of SPRINT Study Type Automated Office Blood Pressure Measurements on Hypertension Diagnosis in Kidney Transplant Patients.

BACKGROUND/AIMS: We compare conventional office blood pressure measurements with automated SPRINT-study type readings in kidney transplant recipients in order to determine the impact of the white coat effect in a prospective observational study. METHODS: Adult patients with a functional renal transplant not dependent on dialysis were eligible. Readings were taken in the office in presence of the physician with an oscillometric method. Afterwards, readings were repeated with the patients resting alone in a quiet examination room with an automated blood pressure monitor. After 5 minutes of rest, 3 readings were taken at 1 minute intervals, with an average of these 3 readings calculated by the monitor. RESULTS: 120 patients with an average age of 58.5±12.2 years were included. Mean time since transplantation was 7.95±6.48 years. Mean eGFR (CKD-EPI) was 48.5±18.3 ml/min. SPRINT-study type readings were significantly lower than office readings (139.01±18.45 vs. 149.00±21.02 mmHg systolic, p<0.001; 80.88±11.63 mmHg vs. 84.35±12.41 mmHg diastolic, p <0.001). Correlation analysis for many potentially influencing factors (diabetes mellitus, transplant vintage, proteinuria, age, immunosuppression, donor type) was not significant but obese women were significantly more prone to white coat hypertension. CONCLUSION: Automated office blood pressure measurements should be considered the method of choice in kidney transplant recipients.

Effect of Change in Fluid Status Evaluated by Bioimpedance Techniques on Body Composition in Hemodialysis Patients.

OBJECTIVE: This prospective study uses calf bioimpedance spectroscopy (cBIS) to guide the attainment of dry weight (DWcBIS) in chronic hemodialysis (HD) patients. The primary aim of this study was to evaluate whether body composition is altered when fluid status is reduced to DWcBIS. METHODS: Target post-HD weight was gradually reduced from baseline (BL) until DWcBIS was achieved. DWcBIS was defined as the presence of both flattening of the curve of extracellular resistance and the attainment calf normalized resistivity in the normal range during the dialysis treatment. Extracellular volume (ECV), intracellular volume, and total body water (TBW) were measured using whole body BIS (Hydra 4200). Fluid overload, lean body mass, and fat mass were calculated according to a body composition model. RESULTS: Seventy-three patients enrolled and 60 completed the study (55 ± 13 years, 49% male). Twenty-eight patients (25% diabetes) achieved DWcBIS, whereas 32 patients (47% diabetes) did not. Number of treatment measurements were 16 ± 10 and 12 ± 13 studies per patient in the DWcBIS and non-DWcBIS groups, respectively. Although significant decreases in body weight and ECV were observed, lean body mass and FM did not differ significantly in both groups from BL to the end of study. ECV, ECV/TBW, and fluid overload were higher in the non-DWcBIS than in the DWcBIS group both at BL and at the end of study. Ratios of intradialytic changes in calf normalized resistivity, ECV, and ECV/TBW to ultrafiltration volume were significantly lower in diabetic than in non-diabetic patients. CONCLUSIONS: This study shows that decreasing fluid status by gradual reduction of post-HD weight in both DWcBIS and Non-DWcBIS groups did not affect body composition significantly over a period of about 4 weeks.

Serum klotho levels in acute kidney injury
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AIMS: Klotho is a co-receptor for FGF-23 and key regulator of phosphate excretion. Soluble klotho modulates ion-channel expression and growth factor sensitivity. In chronic kidney disease (CKD), impaired klotho expression has been demonstrated. Likewise, reduced soluble klotho levels in serum and urine have been established in rodents in experimental acute kidney injury (AKI). In contrast, no data on soluble serum klotho levels in human AKI has been presented to date. MATERIAL AND METHODS: A cross-sectional case-control study of klotho serum levels in 30 subjects with AKI and 126 control subjects with kidney functions ranging from normal to end-stage renal disease (ESRD). RESULTS: Klotho levels were higher in AKI patients (567.6 ± 294.4 pg/mL, vs. 403.5 ± 152.5 pg/mL, p < 0.01) and females (463.0 ± 202.6 pg/mL vs. 387.6 ± 132.0 pg/mL, p < 0.01) and lower in ESRD patients than in healthy adults and patients with moderate CKD (368.3 ± 99.0 pg/mL vs. 468.1 ± 205.8, p < 0.01 and 368.3 ± 99.0 pg/mL vs. 498.7 ± 221.9, p < 0.01). There was a correlation with estimated glomerular filtration rate (eGFR) in CKD (p < 0.0001, r = 0.34). CONCLUSIONS: In AKI, serum klotho levels are not associated with kidney function whereas in CKD, impaired klotho levels may be observed and are significantly correlated to eGFR.
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Monocytic angiotensin-converting enzyme 2 relates to atherosclerosis in patients with chronic kidney disease.

Background: Increased levels of monocytic angiotensin-converting enzyme (ACE) found in haemodialysis (HD) patients may directly participate in the pathogenesis of atherosclerosis. We demonstrated recently that uremia triggers the development of highly pro-atherogenic monocytes via an angiotensin II (AngII)­dependent mechanism. Opposing actions of the AngII-degrading ACE2 remain largely unknown. We examined the status of both ACEs and related receptors in circulating leukocytes of HD, not-dialyzed CKD and healthy individuals. Furthermore, we tested the possible impact of monocytic ACEs on atherogenesis and behaviour of the cells under conditions mimicking chronic renal failure. Methods: Expression of ACE, ACE2, AT1R, AT2R and MASR was investigated on circulating leukocytes from 71 HD (62 ± 14 years), 24 CKD stage 3­5 (74 ± 10 years) patients and 37 healthy control subjects (53 ± 6 years) and isolated healthy monocytes treated with normal and uremic serum. Analyses of ACE, ACE2, ICAM-1, VCAM-1, MCSF and endothelial adhesion were tested on ACE-overexpressing THP-1 monocytes treated with captopril or losartan. ACE2-overexpressing monocytes were subjected to transmigration and adhesion assays and investigated for MCP-1, ICAM-1, VCAM-1, MCSF, AT1R and AT2R expression. Results: The ACE mRNA level was significantly increased in HD and CKD stage 3­5 leukocytes. Correspondingly, ACE2 was downregulated and AngII as well as MAS receptor expression was upregulated in these cells. Healthy monocytes preconditioned with uremic serum reflected the same expressional regulation of ACE/ACE2, MAS and AngII receptors as those observed in HD and CKD stage 3­5 leukocytes. Overexpression of monocytic ACE dramatically decreased levels of ACE2 and induced a pro-atherogenic phenotype, partly reversed by AngII-modifying treatments, leading to an increase in ACE2. Overexpression of ACE2 in monocytes led to reduced endothelial adhesion, transmigration and downregulation of adhesion-related molecules. Conclusions: HD and not-dialyzed CKD stage 3­5 patients show enhanced ACE and decreased ACE2 expression on monocytes. This constellation renders the cells endothelial adhesive and likely supports the development of atherosclerosis.

Vitamin D3 supplementation does not modify cardiovascular risk profile of adults with inadequate vitamin D status.

PURPOSE: The Nutrition Societies in Germany, Austria, and Switzerland recommend a daily intake of 20 µg vitamin D3 for adults when endogenous synthesis is absent. The current study aimed to elucidate whether this vitamin D3 dose impacts cardiovascular risk markers of adults during the winter months. METHODS: The study was conducted in Halle (Saale), Germany (51o northern latitude) as a placebo-controlled, double-blinded, randomised trial (from January to April). A total of 105 apparently healthy subjects (male and female, 20-71 years old) were included. Subjects were randomly allocated to two groups. One group received a daily 20-µg vitamin D3 dose (n = 54), and the other group received a placebo (n = 51) for 12 weeks. Outcome measures included blood pressure, heart rate, concentrations of renin, aldosterone, serum lipids and vascular calcification markers, and haematologic variables such as pro-inflammatory monocytes. RESULTS: Blood pressure and systemic cardiovascular risk markers remained unchanged by vitamin D3 supplementation, although serum 25-hydroxyvitamin D3 increased from 38 ± 14 to 73 ± 16 nmol/L at week 12. The placebo and vitamin D groups did not differ in their final cardiovascular risk profile. CONCLUSION: Daily supplementation of 20 µg vitamin D3 during winter is unlikely to change cardiovascular risk profile.

Differential Expression of Lipoprotein-Associated Phospholipase A2 in Monocyte Subsets: Impact of Uremia and Atherosclerosis.

BACKGROUND: Monocytic products, such as lipoprotein-associated phospholipase A2 (Lp-PLA2), may participate in the development of atherosclerosis. Heterogeneity of monocytes is widely acknowledged. Classical, intermediate, and non-classical subsets can be discerned. Recently, an inflammatory, pro-atherogenic monocyte population could be identified in hemodialysis patients. In this study, we investigated the expression of Lp-PLA2 on leucocytes and different monocyte subpopulations and their possible role in uremia, inflammation, and atherosclerosis. METHODS: Chronic kidney disease stage 5-D (CKD5-D; n = 57), healthy control subjects with hs-C-reactive protein (CRP) levels ≤1 mg/L (CO-N, n = 22) and a control group with inflammatory activation (CRP levels >1 mg/L, CO-I, n = 29) were enrolled in this cross-sectional observation. The CKD5-D cohort was dichotomized into patients with (A+) and without subclinical atherosclerosis (A-) by carotid artery ultrasound measurement. Lp-PLA2 activity was determined in plasma samples, Lp-PLA2 mRNA expression analysis in leucocytes, and sorted monocyte subsets. Effects of Lp-PLA2 overexpression were studied in classical vs. intermediate and non-classical subsets. RESULTS: The classical monocytes expressed the highest Lp-PLA2 mRNA levels as compared to other subpopulations. CKD5-D patients revealed significantly higher Lp-PLA2 transcripts, as well as higher Lp-PLA2 plasma activity as compared to healthy and "inflammatory" controls. In vitro data confirmed that uremia significantly contributes to Lp-PLA2 mRNA upregulation. Non-classical monocytes of A+ patients revealed significant higher Lp-PLA2 mRNA compared to A-. CONCLUSION: Uremic environment but not inflammation per se increases plasma Lp-PLA2 activity and upregulates monocytic Lp-PLA2 mRNA expression. The highest Lp-PLA2 levels were found in the classical and not in the inflammatory subsets. Atherosclerosis also contributes to a subset-specific increase in Lp-PLA2 mRNA expression.

Calf Resistivity Values in Chronic Kidney Disease in a Caucasian Population.

BACKGROUND: Continuous intradialytic calf bioimpedance spectroscopy (cBIS) allows assessment of changes in calf extracellular fluid volume (ECV) to determine dry weight (DW) in hemodialysis patients. During dialysis, calf ECV decreases until excessive ECV has been removed and normalized resistivity ρN,5 rises to values comparable to those of a normal population (cBIS-DW). It is not clear whether chronic kidney disease (CKD) itself influences ρN,5 and whether normal values depend on race and ethnicity. METHODS: Therefore, we determined ρN,5 in 2 populations consisting of 35 healthy Caucasians and 37 with CKD in KDIGO stages G2-G4. Calf resistivity was determined using a bioimpedance spectrum analyzer (Xitron Technologies, San Diego, CA, USA) and was normalized for body mass index. RESULTS: ρN,5 was significantly higher in healthy subjects than in CKD patients (males: 18.2 ± 2.2 vs. 15.0 ± 2.8 × 10-2·Ωm3kg-1, p < 0.001; females: 19.7 ± 3.2 vs. 16.4 ± 3.3 × 10-2·Ωm3kg-1, p = 0.009). ρN,5 in Caucasians was significantly lower than in previously examined North American healthy subjects with prevailing African American race or Hispanic ethnicity (males: 18.2 ± 2.2 vs. 20.5 ± 2.0 × 10-2·Ωm3kg-1, p < 0.001; females: 19.7 ± 3.2 vs. 21.7 ± 2.6 × 10-2·Ωm3kg-1, p = 0.026). CONCLUSION: We present the first determination of ρN,5 values in a Caucasian healthy as well as a non-dialysis dependent CKD population. Both groups differ significantly. Due to higher amounts of extracellular water, subclinical fluid overload already occurs in pre-dialysis stages of CKD. ρN,5 in Caucasians differs significantly from previously established normal ranges in other races/ethnicities. Population-based reference ranges should be established and used in the future to determine DW by means of cBIS.

Plasma vitamin C levels in ESRD patients and occurrence of hypochromic erythrocytes.

INTRODUCTION: The achievement of erythropoiesis in hemodialysis (HD) patients is typically managed with erythropoiesis-stimulating-agents (ESA's) and intravenous iron (IV-iron). Using this treatment strategy, HD patients frequently show an elevated fraction of red blood cells (RBC) with hemoglobin (Hb) content per cell that is below the normal range, called hypochromic RBC. The low Hb content per RBC is the result of the clinical challenge of providing sufficient iron content to the bone marrow during erythropoiesis. Vitamin C supplements have been used to increase Hb levels in HD patients with refractory anemia, which supports the hypothesis that vitamin C mobilizes iron needed for Hb synthesis. METHODS: We conducted a cross-sectional survey in 149 prevalent HD patients of the percent hypochromic RBC, defined as RBC with Hb < 300 ng/uL of packed RBC, in relation to plasma vitamin C levels. We also measured high-sensitivity CRP, (hs-CRP), iron, and ferritin levels. and calculated ESA dose. FINDINGS: High plasma levels of vitamin C were negatively associated with hypochromic RBC (P < 0.003), and high ESA doses were positively associated (P < 0.001). There was no significant association of hs-CRP with percent hypochromic RBC. DISCUSSION: This finding supports the hypothesis that vitamin C mobilizes iron stores, improves iron delivery to the bone marrow, and increase the fraction of RBC with normal Hb content. Further research is warranted on development of protocols for safe and effective use of supplemental vitamin C for management of renal anemia.

Clinical Course of Acute Kidney Injury in Elderly Individuals Above 80 Years.

BACKGROUND/AIMS: Aging is associated with renal function decline and elderly patients are more vulnerable to acute kidney injury (AKI). The causes and prognosis of AKI according to new KDIGO definition that broadened the diagnosis and included more patients without dialysis dependence have not yet been compared between younger and elderly patients. METHODS: In a retrospective analysis all patients with AKI admitted to a tertiary care Nephrology department (N=424) were included. Individuals were stratified by age (≤80 years, >80 years). Primary end-point was death or dialysis dependence at hospital discharge, secondary analyses addressed the need for dialysis, creatinine at discharge, mortality, and length of stay. RESULTS: The distribution of AKI causes was different between the age groups. Circulatory AKI was the most important cause in both groups; however, septic or toxic AKI contributed relevantly in younger patients. Nevertheless, the number of patients reaching the primary end-point was similar (younger, 20.4%; older, 18.0%; OR 1.17, 95%CI, 0.703-1.948). While mortality tended to be higher in the older population, none of the secondary analyses indicated worse outcome for the older patients. CONCLUSION: The prognosis of AKI in elderly patients is not necessarily worse than in middle aged individuals. Nevertheless, older patients may be particularly vulnerable to circulatory or ischemic insults of the kidneys.

Association between autonomic nervous dysfunction and cellular inflammation in end-stage renal disease.

BACKGROUND: Alterations in autonomic nervous function are common in hemodialysis (HD) patients. Sympathetic as well as parasympathetic activation may be associated with immune and inflammatory responses. We intended to confirm a role of autonomous dysregulation for inflammation in HD patients. METHODS: 30 HD patients (including 15 diabetics) and 15 healthy controls were studied for heart rate variability (HRV) using 5 min ECG recordings. Heart rate variability was estimated by time-domain parameters (the standard deviation of the RR intervals (SDNN) and the percentage of pairs of adjacent RR intervals differing by >50 ms (pNN50)) and frequency-domain-analysis (high- and low-frequency variation of RR intervals, HF and LF). Inflammation was detected as serum C-reactive Protein (CRP), IL-6 and circulating monocyte subpopulation numbers. Immune cells were characterized by ACh receptor expression. RESULTS: Patients differed from controls in terms of age (68.0 [14.8] yrs vs. 58.0 [13.0] yrs, p < 0.001; Median [IQR]) and sex. However, HRV parameters were different in controls and HD patients (SDNN controls 34.0 [14.0] ms, HD patients 15.5 [14.8] ms, p < 0.01). This finding was not restricted to patients with diabetes mellitus (diab), although diabetes is an important cause of autonomous dysfunction (SDNN, diab 13.0 [14.0] ms, non-diab 18.0 [15.3] ms, p = 0.8). LF and HF were reduced by the same magnitude to 1/3 of those in controls. Patients suffered from chronic inflammation (CRP 9.4 [12.9] mg/l, controls 1.6 [2.4] mg/l, p < 0.001) and expanded proinflammatory monocyte subpopulations (CD14++/CD16+ cells: patients 41 [27]/µl, controls 24 [18]/µl, p < 0.01). ECG parameters did not correlate with inflammation in patients, but monocyte ACh receptor expression was enhanced, indicating potentially elevated responsiveness of this cell type to parasympathetic regulation. CONCLUSIONS: HD patients have strongly impaired HRV. Chronic inflammation is not related to autonomous dysfunction, although monocytes express the ACh receptor at enhanced density making them potentially more sensitive to parasympathetic effects. TRIAL REGISTRATION: This study was listed with ClinicalTrials.gov ( NCT00878033 ).

Vitamin D3 supplementation: Response and predictors of vitamin D3 metabolites - A randomized controlled trial.

BACKGROUND & AIMS: Large parts of the population are insufficiently supplied with vitamin D, in particular when endogenous synthesis is absent. Therefore many health care providers recommend the use of vitamin D supplements. The current study aimed to investigate the efficacy of an once-daily oral dose of 20 µg vitamin D3 to improve the vitamin D status and to evaluate predictors of response. METHODS: The study was conducted as a double-blind, randomized, placebo-controlled parallel trial from January till April 2013. In total, 105 subjects (20-71 years) were allocated to receive either a vitamin D3 supplement (20 µg/d) or a placebo for 12 weeks. Circulating levels of vitamin D3 metabolites such as the 25(OH)D3 and the 24,25(OH)2D3, and biomarkers of calcium and phosphate metabolism were quantified. RESULTS: The 25(OH)D3 serum concentrations in the placebo group decreased from 38 ± 15 nmol/L at baseline to 32 ± 14 nmol/L and 32 ± 13 nmol/L at weeks 8 and 12 of the study, respectively (p < 0.01). In the vitamin D3 group, the serum 25(OH)D3 concentration increased from 38 ± 14 nmol/L at baseline to 70 ± 15 nmol/L and 73 ± 16 nmol/L at weeks 8 and 12 of vitamin D3 supplementation (p < 0.001), respectively. As a result, 94% of the vitamin D3-supplemented participants reached 25(OH)D3 concentrations of ≥50 nmol/L and thereof 46% attained 25(OH)D3 levels of ≥75 nmol/L until the end of the study. The extent of the 25(OH)D3 increase upon vitamin D3 supplementation depended on 25(OH)D3 baseline levels, age, body weight and circulating levels of triglycerides. In contrast to 25(OH)D3, the response of 24,25(OH)2D3 to the vitamin D3 treatment was affected only by baseline levels of 24,25(OH)2D3 and age. CONCLUSIONS: The average improvement of 25(OH)D3 levels in individuals who received 20 µg vitamin D3 per day during the winter months was 41 nmol/L compared to individuals without supplementation. As a result almost all participants with the vitamin D3 supplementation attained 25(OH)D3 concentrations of 50 nmol/L and higher. The suitability of 24,25(OH)2D3 as a marker of vitamin D status needs further investigation. Clinical trial registration number at clinicaltrials.gov: NCT01711905.

Uremic conditions drive human monocytes to pro-atherogenic differentiation via an angiotensin-dependent mechanism.

AIMS: Elevated expression levels of monocytic-ACE have been found in haemodialysis patients. They are not only epidemiologically linked with increased mortality and cardiovascular disease, but may also directly participate in the initial steps of atherosclerosis. To further address this question we tested the role of monocytic-ACE in promotion of atherosclerotic events in vitro under conditions mimicking those of chronic renal failure. METHODS AND RESULTS: Treatment of human primary monocytes or THP-1 cells with uremic serum as well as PMA-induced differentiation led to significantly up-regulated expression of ACE, further increased by additional treatment with LPS. Functionally, these monocytes revealed significantly increased adhesion and transmigration through endothelial monolayers. Overexpression of ACE in transfected monocytes or THP-1 cells led to development of more differentiated, macrophage-like phenotype with up-regulated expression of Arg1, MCSF, MCP-1 and CCR2. Expression of pro-inflammatory cytokines TNFa and IL-6 were also noticeably up-regulated. ACE overexpression resulted in significantly increased adhesion and transmigration properties. Transcriptional screening of ACE-overexpressing monocytes revealed noticeably increased expression of Angiotensin II receptors and adhesion- as well as atherosclerosis-related ICAM-1 and VCAM1. Inhibition of monocyte ACE or AngII-receptor signalling led to decreased adhesion potential of ACE-overexpressing cells. CONCLUSIONS: Taken together, these data demonstrate that uremia induced expression of monocytic-ACE mediates the development of highly pro-atherogenic cells via an AngII-dependent mechanism.

Influence of cholecalciferol supplementation in hemodialysis patients on monocyte subsets: a randomized, double-blind, placebo-controlled clinical trial.

BACKGROUND/AIMS: Although most hemodialysis patients share a significant 25-hydroxyvitamin D [25(OH)D] deficiency, supplementation is controversially discussed. A potential influence on monocyte and T lymphocyte dysfunction advocates blood level-adapted supplementation as recommended by K/DOQI guidelines. This was a prospective double-blind randomized placebo controlled trial examining immune effects of 12 weeks of cholecalciferol supplementation. METHODS: We initiated serum level-adapted de novo cholecalciferol supplementation in 38 hemodialysis patients. Outcome measures were: monocyte subset cell counts (CD14+CD16++ vs. CD14++CD16+ vs. CD14++CD16-), lymphocyte Th1/Th2 differentiation frequencies, serum inflammatory proteins CRP and TNFα, parathyroid hormone (PTH), FGF-23, and α-Klotho. RESULTS: At baseline, the mean 25(OH)D serum level in the study population was 31.7 ± 14.3 nmol/l, and only 3% of patients had levels within the normal range. At 12 weeks, 25(OH)D levels were normalized in the verum group (87.8 ± 22.3 vs. placebo 24.6 ± 8.0 nmol/l, p < 0.0001). In parallel, 1,25(OH)2D levels increased in the verum group. Monocyte subset cell counts as well as Th1 and Th2 lymphocyte frequencies did not change significantly after 12 weeks of cholecalciferol supplementation. There was also no significant difference in PTH, alkaline phosphatase, calcium, phosphate, TNFα, FGF-23, α-Klotho and CRP levels. CONCLUSIONS: Oral cholecalciferol supplementation according to the K/DOQI recommendations normalizes 25(OH)D levels without relevant side effects such as hyperphosphatemia or hypercalcemia. However, beneficial pleiotropic effects on monocyte subset cell counts, T cell differentiation, or cytokine production could not be confirmed at least at the used dosage. PTH and FGF23 levels were not affected during cholecalciferol administration.

Calf bioimpedance spectroscopy for determination of dry weight in hemodialysis patients: effects on hypertension and left ventricular hypertrophy.

BACKGROUND/AIMS: Dry weight estimation in hemodialysis patients is still a substantial problem. Despite meticulous clinical assessment, fluid overload is common, leading to hypertension and left ventricular hypertrophy (LVH). Segmental calf bioimpedance spectroscopy (cBIS) is a novel tool for dry weight assessment. Here we tested the hypothesis, that its clinical routine use reduces arterial hypertension and left ventricular mass. METHODS: Left ventricular mass (determined by magnetic resonance imaging), blood pressure and antihypertensive medication (defined daily doses, ddd) were assessed at baseline (BL). Thereafter post-dialytic target weight was reduced until cBIS-defined dry weight was reached (DW). During a 6-month follow up, DW was re-evaluated monthly by cBIS and end-dialytic weight was adjusted correspondingly. At the end, left ventricular mass, blood pressure and antihypertensive medication were determined a 3rd time (follow-up, FU). RESULTS: Eleven out of 15 patients were available for analysis after 6 months. Left ventricular mass showed a declining trend during the study period (Mean±SD; BL 145±54 g; DW 142±55 g; FU 137±52 g; p=0.61, linear mixed model). Comparable results were obtained for systolic blood pressure (BL 158±18 mmHg; DW 144±19 mmHg; FU 149±21 mmHg; p=0.07), and antihypertensive medication (BL 3.28±2.82ddd; DW 2.86±2.81ddd; FU 3.36±3.05ddd; p=0.37). CONCLUSIONS: We conclude that attainment of dry weight assessed by cBIS tends to reduce left ventricular mass and blood pressure while antihypertensive medication remains unchanged. While the study was underpowered, its results provide an important hypothesis generating data basis for the design of larger studies.

Randomized controlled pilot study of 2 weeks' treatment with high cutoff membrane for hemodialysis patients with elevated C-reactive protein.

Chronic inflammation in hemodialysis (HD) patients is associated with cardiovascular complications and mortality. Circulating immune active proteins in the molecular range 15-45 kD that cannot be efficiently cleared by high-flux (HF) dialysis may be causally involved. We intended to test the feasibility of using a high cutoff (HCO) dialyzer in chronic HD patients and its influence on inflammation and monocyte activation. The Gambro HCO1100 dialyzer was compared to a conventional HF membrane in a randomized double-blind crossover trial in 19 chronic HD patients selected for the presence of elevated serum C-reactive protein levels. Patients were treated for six consecutive dialysis sessions (2 weeks) with each membrane. Safety analysis recorded adverse events and albumin losses through the protein-leaking membranes. Efficacy analysis observed reductions in the number of proinflammatory (CD14+CD16+) monocyte subpopulations in circulating blood. Treatment with the HCO membrane was well tolerated, although the number of adverse events was slightly higher. Despite significant serum albumin loss (from 34.1 ± 2.7 to 29.6 ± 3.0 g/L; P < 0.01), there was no need to supplement albumin, and rising activity of cholinesterase during HCO treatment indicated compensation by enhanced hepatic synthesis. The HCO membrane cleared high amounts of proinflammatory cytokines, but did not reduce predialysis inflammatory monocytes and markers. Although the time of HD session was extended, the study was hampered by a lower Kt/V in the HCO compared to the HF period. Treatment of chronic HD patients with this HCO dialyzer for 2 weeks is tolerable in terms of albumin loss and able to clear proinflammatory cytokines; however, this was not sufficient to decrease monocyte activation. Therefore, a more selective, less albumin-leaking membrane is desirable to allow prolonged high-efficient dialysis with more effective cytokine clearance.

Slope analysis of blood volume and calf bioimpedance monitoring in hemodialysis patients.

BACKGROUND: Continuous intradialytic bioelectrical impedance spectroscopy of the calf (cBIS) monitors changes in calf extracellular fluid volume (cECV), thus allowing estimation of hydration in end-stage renal disease patients. Blood volume monitoring (BVM) during hemodialysis (HD) provides information about relative changes in intravascular volume, which indirectly reflects plasma refilling. We hypothesize that the rate of plasma refilling changes when cBIS-determined dry weight (BIS-DW) is reached. METHODS: Post-HD weight was reduced from baseline (BL) in 15 patients until dry weight was reached according to cBIS criteria (BIS-DW). The slopes of cBIS and BVM curves were analysed during the first 30 and last 20 min in 31 BL treatments, which were compared to the slopes during 31 treatments when BIS-DW was reached. RESULTS: During BL treatments, BVM slopes did not differ between the first 30 and last 20 min (-0.112 ± 0.157%/min versus -0.089 ± 0.036, P = n.s.), while cBIS slopes were generally steeper at the beginning than at the end of HD (-0.184 ± 0.139%/min versus 0.10 ± 0.127, P < 0.01). During BIS-DW treatments, BVM and cBIS slopes were steeper at the beginning than at the end (BVM: -0.131 ± 0.122 versus -0.064 ± 0.051, P < 0.01; cBIS: -0.192 ± 0.129 versus -0.035 ± 0.012, P < 0.001) and the cBIS slopes were steeper than BVM slopes at the beginning of HD. This relationship is inverted at the end of HD, when BIS-DW is reached (beginning: -0.192 ± 0.129 versus -0.131 ± 0.122, P < 0.05, end: -0.035 ± 0.012 versus -0.064 ± 0.051, P = 0.05). CONCLUSIONS: This study demonstrates that cECV changes faster at the beginning than at the end of HD. A reversal steepness of the cBIS slope in relation to BVM slope is observed at the time when BIS-DW is reached. Therefore, combined analysis of cBIS and BVM aiming at clinical end points may be useful to assess the relationship between plasma refilling and tissue hydration during dialysis.