Association of serum copeptin and urinary uromodulin with kidney function, blood pressure and albuminuria at 6 weeks post-partum in pre-eclampsia.

Background: Preeclampsia (PE) is associated with subsequent higher risk of cardiovascular and kidney disease. Serum copeptin, as a proxy for vasopressin, and urinary uromodulin, were associated with PE physiopathology and kidney functional mass respectively. We describe concentrations of these proteins in the post-partum period and characterize their association with persistent hypertension (HTN) or albuminuria. Methods: Patients with PE and healthy controls with uncomplicated pregnancy were prospectively included at two teaching hospitals in Switzerland. Clinical parameters along with serum copeptin and urinary uromodulin were measured at 6 weeks post-partum. PE patients were further characterized based on presence of HTN (defined as either systolic BP (SBP) ≥140 mmHg or diastolic (BP) ≥90 mmHg) or albuminuria [defined as urinary albumin to creatinine ratio (ACR) ≥3 mg/mmol]. Results: We included 226 patients with 35 controls, 120 (62.8%) PE with persistent HTN/albuminuria and 71 (37.1%) PE without persistent HTN/albuminuria. Median serum copeptin concentration was 4.27 (2.9-6.2) pmol/L without differences between study groups (p > 0.05). Higher copeptin levels were associated with higher SBP in controls (p = 0.039), but not in PE (p > 0.05). Median urinary uromodulin concentration was 17.5 (7.8-28.7) mg/g with lower levels in PE patients as compared to healthy controls (p < 0.001), but comparable levels between PE patients with or without HTN/albuminuria (p > 0.05). Higher uromodulin levels were associated with lower albuminuria in PE as well as control patients (p = 0.040). Conclusion: Serum copeptin levels at 6 weeks post-partum are similar between PE patients and healthy controls and cannot distinguish between PE with or without residual kidney damage. This would argue against a significant pathophysiological role of the vasopressin pathway in mediating organ damage in the post-partum period. On the opposite, post-partum urinary uromodulin levels are markedly lower in PE patients as compared to healthy controls, potentially reflecting an increased susceptibility to vascular and kidney damage that could associate with adverse long-term cardiovascular and kidney outcomes.

Predicting solute transfer rate in patients initiating peritoneal dialysis.

BACKGROUND: While assessment of membrane characteristics is fundamental to peritoneal dialysis (PD) prescription in patients initiating therapy, peritoneal equilibration test has theoretical and practical drawbacks. We wished to determine whether an equation using simple clinical variables could predict fast (above population mean) peritoneal solute transfer rate without dialysate sampling. METHODS: We measured peritoneal solute transfer rate, as determined by peritoneal equilibration test using the 4-h dialysate to plasma creatinine ratio, in consecutive PD outpatients attending a single tertiary hospital for their first clinical follow-up within 3 months of dialysis initiation. An equation estimating peritoneal solute transfer rate based on readily available clinical variables was generated in a randomly selected modeling group and tested in a distinct validation group. RESULTS: We included 712 patients, with 562 in the modeling group and 150 in the validation group. Mean age was 58.4 ± 15.9 with 431 (60.5%) men. Mean peritoneal solute transfer rate value was 0.73 ± 0.13. An equation based on gender, race, serum sodium and albumin yielded a receiving operator characteristics (ROC) area under the curve (AUC) to detect fast peritoneal solute transfer rate (> 0.73) of 0.74 (0.67-0.82). Estimated peritoneal solute transfer rate values based on percentiles 15th (> 0.66), 20th (> 0.68), 25th (> 0.69) and 30th (> 0.70) could rule out fast peritoneal solute transfer rate with negative predictive values of 100%, 93.5%, 84.2% and 80.0%, respectively. CONCLUSIONS: An equation based on simple clinical variables allows ruling out fast transport in a significant proportion of patients initiating PD with a high degree of confidence without requiring dialysate sampling. This could prove useful in guiding dialysis prescription of PD patients in daily clinical practice, particularly in low-resource settings.

Dietary Sodium and Human Health.

Sodium, contained in dietary salt, is essential to human life [...].

[Plasma exchange in nephrology]. / Place des échanges plasmatiques en néphrologie.

Plasma exchange is often prescribed in nephrology and represents a technical as well as logistic challenge. It is thus important to master its most frequent indications. In this narrative review, we discuss main diseases requiring therapeutic plasma exchange in nephrology: anti-glomerular basement membrane disease, thrombotic microangiopathy as well as various clinical scenarios in kidney transplant. We also review plasma exchange in ANCA associated vasculitis, where indications have recently been restricted owing to recent scientific evidences.

Dans sa pratique clinique, le néphrologue est souvent confronté à la prescription d'échanges plasmatiques, qui représentent toujours un défi technique et logistique. Il est donc nécessaire d'avoir une bonne connaissance des indications fréquentes. Dans cet article narratif, nous rappelons les principales pathologies bénéficiant de ce type de prise en charge en néphrologie : maladie anti-membrane basale glomérulaire, microangiopathies thrombotiques, ainsi que divers scénarios en transplantation rénale. Finalement, nous revenons sur le cas des vasculites à ANCA, domaine dans lequel les indications aux échanges plasmatiques ont récemment été limitées suite à de nouvelles données scientifiques.

Variability of 24-Hour Sodium Urinary Excretion in Young Healthy Males Based on Consecutive Urine Collections: Impact on Categorization of Salt Intake.

OBJECTIVE: Several nonconsecutive 24-h urinary collections are considered the gold standard for estimating dietary salt intake. As those samples are logistically demanding, we aimed to describe the variability of 24-h sodium urinary excretion over consecutive days and report its adequacy with sodium intake. METHODS: We enrolled 16 healthy male volunteers in a prospective controlled study. All participants randomly received a low salt diet (LSD) (3 g/day of NaCl), a normal salt diet (NSD) (6 g/day of NaCl), and a high salt diet (HSD) (15 g/day of NaCl) for 7 days in a crossover design without wash-out period. RESULTS: On day 6, median sodium urinary excretion was 258 (216-338), 10 (8-18), and 87 (69-121) mmol/day for HSD, LSD, and NSD, respectively (P < .001). When considering days 4-6, sodium urinary excretion was in steady state as models with and without interaction term "diet type X sample day" were not significantly different (P = .163). On day 6, area under the curve (AUC) of receiver operating characteristic for urinary sodium excretion to detect HSD was 1.0 (1.0-1.0) and a cut-point of 175 mmol/day was 100% sensitive and specific to detect HSD. On day 6, receiver operating characteristic AUC to detect LSD was 0.993 (0.978-1.0) and a cut-point of 53 mmol/day was 96.4% sensitive and 100% specific to detect LSD. CONCLUSION: A steady state of sodium balance, where sodium intake is proportional to its excretion, is reached within a few days under a constant diet in the real-life setting. Categorization of salt consumption into low (3 g/day), normal (6 g/day), or high (15 g/day) based on a single 24-h urine collection is nearly perfect. Based on these results, repeated nonconsecutive urine collection might prove unnecessary to estimate sodium intake in daily clinical practice provided that diet is rather constant over time.

Aging and hypertension in kidney function decline: A 10 year population-based study.

Background: Aging is associated with a physiological decline in kidney function (KFD). In this study, we aimed to describe the impact of age on the rate of KFD and its interplay with risk factors for chronic kidney disease (CKD), considering mainly hypertension (HT), in the general population. Materials and methods: Participants of European descent, aged 35-75, were recruited from a populational cohort in Lausanne, Switzerland. Participants with a 10 year follow-up were selected. KFD was defined as the difference in estimated glomerular filtration rate (eGFR) between baseline and follow-up, divided by the observation period. Multivariate linear regressions were used with KFD as the outcome and age as the main predictor. HT was tested as a modifying factor. Results: We included 4,163 participants with mean age 52.2 ± 10.4, 44.7% men, 31.9% HT, and 5.0% diabetics. Mean baseline eGFR was 85.9 ± 14.6 ml/min/1.73 m2. Mean KFD was -0.49 ± 1.08 ml/min/1.73 m2 per year with 70% of participants decreasing their eGFR during follow-up. The relationship between age and KFD was non-linear and age was divided in tertiles. Old participants had faster rates of KFD as compared to young and middle-age participants (p < 0.001). A significant interaction was found between age and HT on KFD prediction (p < 0.001). In HT participants, KFD was significantly different across tertiles of age (p < 0.001). On contrary, KFD was not different across tertiles of age in non-HT participants. Conclusion: A physiological KFD is present over time in the general population. Age contributes non-linearly to the rate of this decline with older subjects declining the fastest. The presence of HT is a major contributing factor in this setting as KFD worsened with age only in hypertensive participants. Thus, HT represents an important pathological factor aggravating the age-related physiological decline in eGFR in the general population.

Comparative efficacy of patiromer and sodium polystyrene sulfonate on potassium levels in chronic haemodialysis patients: a randomized crossover trial.

Background: Hyperkalaemia is frequent in haemodialysis (HD) patients and associated with increased cardiovascular mortality. Despite routine clinical use, evidence regarding the efficacy of potassium (K+) binders in HD is scant. We wished to compare the efficacy of patiromer (PAT) and sodium polystyrene sulfonate (SPS) on K+ levels in this setting. Methods: We screened patients in three HD centres with pre-HD K+ value between 5.0 and 6.4 mmol/L, after an initial 2-week washout period for those previously on K+ binders. We included patients in an unblinded two-arm crossover trial comparing SPS 15 g before each meal on non-dialysis days with PAT 16.8 g once daily on non-dialysis days with randomized attribution order and a 2-week intermediate washout period. The primary outcome was the mean weekly K+ value. Results: We included 51 patients and analysed 48 with mean age of 66.4 ± 19.4 years, 72.9% men and 43.4% diabetics. Mean weekly K+ values were 5.00 ± 0.54 mmol/L, 4.55 ± 0.75 mmol/L and 5.17 ± 0.64 mmol/L under PAT (P = .003), SPS (P < .001) and washout, respectively. In direct comparison, K+ values and prevalence of hyperkalaemia were lower under SPS as compared with PAT (P < .001). While the incidence of gastrointestinal side effects was similar between treatments, SPS showed lower subjective tolerability score (6.0 ± 2.4 and 6.9 ± 1.9) and compliance (10.8 ± 20.4% and 2.4 ± 7.3% missed doses) as compared with PAT (P < .001 for both). Conclusion: Both PAT and SPS are effective in decreasing K+ levels in chronic HD patients. However, at the tested doses, SPS was significantly more effective in doing so as compared with PAT, despite lower tolerability and compliance. Larger randomized controlled trials should be conducted in order to confirm our findings and determine whether they would impact clinical outcomes.

Association between bone mineral density at different anatomical sites and both mortality and fracture risk in patients receiving renal replacement therapy: a longitudinal study.

Background: The clinical utility of bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DXA) is debated in end-stage kidney disease (ESKD). We assessed the ability of BMD measured at different anatomical sites to predict mortality and fracture risk in patients requiring renal replacement therapy (RRT). Methods: We reviewed all-cause mortality as well as incident hip and overall fracture risk in RRT patients who had BMD measured at the femoral neck, lumbar spine, arm, head, pelvis and total body as part of their routine follow-up between January 2004 and June 2012 at a single university centre. Results: A total of 588 patients were included. The median follow-up was 6.5 years, the mean age was 59.6 years and 57.9% were males. Femoral neck BMD (FNBMD) (normal/high versus low) was negatively associated with mortality in univariate and multivariate analyses (P < .001 and P = .048, respectively). Other sites of BMD measurements were not associated with mortality. In multivariate analysis, FNBMD was negatively associated with hip and any fracture risk (P = .004 and P = .013, respectively). No significant interaction was found between FNBMD and gender or parathyroid hormone (PTH) (P = .112 and P = .794, respectively). Conclusions: BMD measured at the femoral neck is predictive of mortality in patients requiring RRT, regardless of modality. Low BMD might be a marker of global patient frailty rather than a direct causal factor in this setting. FNBMD is also a strong predictor of hip and any fracture risk in this population, regardless of bone turnover as assessed by PTH levels. FNBMD is thus an overall prognostic marker in patients requiring RRT.

Outcomes of incident patients treated with incremental haemodialysis as compared with standard haemodialysis and peritoneal dialysis.

BACKGROUND: Residual kidney function is considered better preserved with incremental haemodialysis (I-HD) or peritoneal dialysis (PD) as compared with conventional thrice-weekly HD (TW-HD) and is associated with improved survival. We aimed to describe outcomes of patients initiating dialysis with I-HD, TW-HD or PD. METHODS: We conducted a retrospective analysis of a prospectively assembled cohort in a single university centre including all adults initiating dialysis from January 2013 to December 2020. Primary and secondary endpoints were overall survival and hospitalization days at 1 year, respectively. RESULTS: We included 313 patients with 234 starting on HD (166 TW-HD and 68 I-HD) and 79 on PD. At the end of the study, 10 were still on I-HD while 45 transitioned to TW-HD after a mean duration of 9.8 ± 9.1 months. Patients who stayed on I-HD were less frequently diabetics (P = .007). Mean follow-up was 33.1 ± 30.8 months during which 124 (39.6%) patients died. Compared with patients on TW-HD, those on I-HD had improved survival (hazard ratio 0.49, 95% confidence interval 0.26-0.93, P = .029), while those on PD had similar survival. Initial kidney replacement therapy modality was not significantly associated with hospitalization days at 1 year. CONCLUSIONS: I-HD is suitable for selected patients starting dialysis and can be maintained for a significant amount of time before transition to TW-HD, with diabetes being a risk factor. Although hospitalization days at 1 year are similar, initiation with I-HD is associated with improved survival as compared with TW-HD or PD. Results of randomized controlled trials are awaited prior to large-scale implementation of I-HD programmes.

Relationship between renal function and blood pressure dipping status in renal transplant recipients: a longitudinal study.

BACKGROUND: Hypertension (HT) is associated with adverse outcomes in kidney transplant (KTX) recipients. Blunting of physiological decrease in nighttime compared to daytime blood pressure (non-dipping status) is frequent in this setting. However, weather non-dipping is independently associated with renal function decline in KTX patients is unknown. METHODS: We retrospectively screened KTX outpatients attending for a routine ambulatory blood pressure monitoring (ABPM) (T1) at a single tertiary hospital. Patients had two successive follow-up visits, 1 (T2) and 2 (T3) years later respectively. Routine clinical and laboratory data were collected at each visit. Mixed linear regression models were used with estimated glomerular filtration rate (eGFR) as the dependent variable. RESULTS: A total of 123 patients were included with a mean follow-up of 2.12 ± 0.45 years after ABPM. Mean age and eGFR at T1 were 56.0 ± 15.1 and 54.9 ± 20.0 mL/min/1.73m2 respectively. 61 patients (50.4%) had sustained HT and 81 (65.8%) were non-dippers. In multivariate analysis, systolic dipping status was positively associated with eGFR (p = 0.009) and compared to non-dippers, dippers had a 10.4 mL/min/1.73m2 higher eGFR. HT was negatively associated with eGFR (p = 0.003). CONCLUSIONS: We confirm a high prevalence of non-dippers in KTX recipients. We suggest that preserved systolic dipping is associated with improved renal function in this setting independently of potential confounders, including HT and proteinuria. Whether modification of dipping status by chronotherapy would preserve renal function remains to be tested in clinical trials.

Sodium Intake as a Cardiovascular Risk Factor: A Narrative Review.

While sodium is essential for human homeostasis, current salt consumption far exceeds physiological needs. Strong evidence suggests a direct causal relationship between sodium intake and blood pressure (BP) and a modest reduction in salt consumption is associated with a meaningful reduction in BP in hypertensive as well as normotensive individuals. Moreover, while long-term randomized controlled trials are still lacking, it is reasonable to assume a direct relationship between sodium intake and cardiovascular outcomes. However, a consensus has yet to be reached on the effectiveness, safety and feasibility of sodium intake reduction on an individual level. Beyond indirect BP-mediated effects, detrimental consequences of high sodium intake are manifold and pathways involving vascular damage, oxidative stress, hormonal alterations, the immune system and the gut microbiome have been described. Globally, while individual response to salt intake is variable, sodium should be perceived as a cardiovascular risk factor when consumed in excess. Reduction of sodium intake on a population level thus presents a potential strategy to reduce the burden of cardiovascular disease worldwide. In this review, we provide an update on the consequences of salt intake on human health, focusing on BP and cardiovascular outcomes as well as underlying pathophysiological hypotheses.

Serum sodium variation is a major determinant of peridialytic blood pressure trends in haemodialysis outpatients.

Intradialytic hypotension (IDH) and peridialytic blood pressure (BP) trends are associated with morbidity and mortality in haemodialysis (HD) patients. We aimed to characterise the respective influence of volume status and small solutes variation on peridialytic systolic BP (SBP) trends during HD. We retrospectively analysed the relative peridialytic SBP decrease in 647 prevalent outpatients attending for their mid-week session with corresponding pre- and post-HD bioelectrical impedance analysis. Mean SBP decreased by 10.5 ± 23.6 mmHg. Factors positively associated with the relative decrease in SBP were: serum sodium (Na) decrease, body mass index, serum albumin, dialysis vintage, ultrafiltration rate and urea Kt/V (p < 0.05 for all). Antihypertensive medications and higher dialysate calcium were negatively associated with the relative decrease in SBP (p < 0.05 for both). Age had a quadratic relationship with SBP trends (p < 0.05). Pre-HD volume status measured by extracellular to total body water ratio was not associated with SBP variation (p = 0.216). Peridialytic SBP trends represent a continuum with serum Na variation being a major determinant while volume status has negligible influence. Middle-aged and overweight patients are particularly prone to SBP decline. Tailoring Na and calcium dialysate concentrations could influence haemodynamic stability during HD and improve patient experience and outcomes.

Characterization of sodium removal to ultrafiltration volume in a peritoneal dialysis outpatient cohort.

BACKGROUND: Failure to control volume is the second most common cause of peritoneal dialysis (PD) technique failure. Sodium is primarily removed by convection, but according to the three-pore model, water and sodium movements are not necessarily concordant. We wished to determine factors increasing sodium to water clearance in clinical practice. METHODS: We reviewed 24-h peritoneal dialytic sodium removal (DSR) and ultrafiltration (UF) volume in consecutive PD patients attending for routine assessment of peritoneal membrane function and adequacy testing. We used a regression model with the DSR/UF ratio as the dependent variable. A second model with DSR as the dependent variable and interaction testing for UF was used as sensitivity analysis. RESULTS: We included 718 adult PD patients. Mean values were 51.8 ± 64.6 mmol/day and 512 ± 517 mL/day for DSR and UF, respectively. In multivariable analysis, DSR/UF ratio was positively associated with transport type (fast versus slow, P < 0.001), serum sodium (P < 0.001) and diabetes (P = 0.026), and negatively associated with PD mode [automated PD versus continuous ambulatory PD (CAPD), P < 0.001] and the use of 2.27% glucose dialysate (P < 0.001). Sensitivity analysis showed positive interaction with UF for transport type (P < 0.001) and serum sodium (P = 0.032) and negative interaction for PD mode (P < 0.001) and cycles number (P < 0.001). CONCLUSIONS: CAPD, fast transport and high serum sodium allow relatively more sodium to be removed compared with water. Icodextrin has no effect on sodium removal once confounders have been accounted for. Although widely used in the assessment of PD patients, UF should not be considered as a surrogate for DSR in clinical practice.

Serum ß2-microglobulin as a predictor of residual kidney function in peritoneal dialysis patients.

BACKGROUND: While clinical guidelines recommend that residual kidney function (RKF) is measured in peritoneal dialysis (PD) patients, 24-h urine collection is cumbersome and prone to errors. We wished to determine whether an equation using serum ß2-microglobulin (ß2M) could prove of clinical benefit in estimating RKF and identifying patients who could start PD with incremental prescriptions. METHODS: We measured serum ß2M in consecutive PD outpatients recently starting dialysis with continuous ambulatory PD (CAPD) or automated PD (APD), attending a single tertiary hospital for their routine clinical visit. RKF was defined as the mean of 24-h urine clearances of creatinine and urea. An equation estimating RKF (eRKF) was generated based on serum ß2M levels on a randomly selected modelling group. RESULTS: We included 511 patients, of whom 351 in the modelling group and 150 in the validation group. Mean age was 58.7 ± 15.8, 307 (60.0%) were men and median RKF value was 4.5 (2.4-6.5) mL/min/1.73 m2. In the validation group, an equation based on ß2M, creatinine, urea, age and gender showed minimal bias of - 0.1 mL/min/1.73 m2 to estimate RKF. Area under the receiving operator characteristic curve was 0.915 to detect RKF ≥ 2 mL/min/1.73 m2. CONCLUSION: An equation based on serum ß2M concentration would not be able to replace 24-h urine collection as the standard of care when an exact measurement of RKF is required. However, it could prove useful in identifying patients suitable for an incremental PD prescription and for monitoring RKF in individuals unable to reliably collect urine.

High-flow arteriovenous fistula is not associated with increased extracellular volume or right ventricular dysfunction in haemodialysis patients.

BACKGROUND: High-output congestive heart failure secondary to high-flow arteriovenous fistula (AVF) has been reported in haemodialysis (HD) patients. As high-flow AVF (HFA) would be expected to result in fluid retention, we conducted an observational study to characterize the relationship between AVF flow (Qa) and extracellular water (ECW) in HD patients. METHODS: We measured Qa by ultrasound dilution in prevalent HD outpatients with an AVF in two dialysis centres. The ECW:total body water (TBW) ratio was measured both pre- and post-dialysis by multifrequency bioimpedance analysis. Transthoracic echocardiograms (TTEs) were performed as part of routine clinical management. RESULTS: We included 140 patients, mean age 62.7 ± 15.7 years, 60.7% male, 47.9% diabetic and 22.9% with coronary revascularization. Mean Qa was 1339 ± 761 mL/min and 22 (15.7%) patients had HFA defined as Qa >2.0 L/min. Qa was positively associated with an upper arm AVF (P = 0.005), body mass index (P = 0.012) and N-terminal pro-brain natriuretic peptide (NT-proBNP) (P = 0.047) and negatively associated with diabetes (P < 0.001) and coronary revascularization (P = 0.005). The ECW:TBW ratio was positively associated with age (P < 0.001), Davies comorbidity index (P = 0.034), peripheral vascular disease (P = 0.030) and NT-proBNP (P = 0.002) and negatively associated with serum albumin (P < 0.001). Qa was not associated with the ECW:TBW ratio (P = 0.744). TTE parameters were not associated with Qa. CONCLUSIONS: In our outpatient HD cohort, high AVF flow was not associated with ECW expansion, either pre- or post-dialysis when accounting for potential confounders. By controlling ECW, high access flow should not necessarily be perceived as a threat to cardiovascular physiology.

Exploring blood alterations in chronic kidney disease and haemodialysis using metabolomics.

Chronic kidney disease (CKD) is characterized by retention of uremic solutes. Compared to patients with non-dialysis dependent CKD, those requiring haemodialysis (HD) have increased morbidity and mortality. We wished to characterise metabolic patterns in CKD compared to HD patients using metabolomics. Prevalent non-HD CKD KDIGO stage 3b-4 and stage 5 HD outpatients were screened at a single tertiary hospital. Various liquid chromatography approaches hyphenated with mass spectrometry were used to identify 278 metabolites. Unsupervised and supervised data analyses were conducted to characterize metabolic patterns. 69 patients were included in the CKD group and 35 in the HD group. Unsupervised data analysis showed clear clustering of CKD, pre-dialysis (preHD) and post-dialysis (postHD) patients. Supervised data analysis revealed qualitative as well as quantitative differences in individual metabolites profiles between CKD, preHD and postHD states. An original metabolomics framework could discriminate between CKD stages and highlight HD effect based on 278 identified metabolites. Significant differences in metabolic patterns between CKD and HD patients were found overall as well as for specific metabolites. Those findings could explain clinical discrepancies between patients requiring HD and those with earlier stage of CKD.

Sodium Intake Is Associated With Renal Resistive Index in an Adult Population-Based Study.

Renal resistive index (RRI) has been associated with adverse renal and cardiovascular outcomes. Although traditionally considered a marker of intrinsic renal damage, RRI could also reflect systemic vascular dysfunction. As sodium intake was linked to alterations in vascular properties, we wished to characterize the association of salt consumption with RRI in the general adult population. Participants were recruited in a population-based study in Switzerland. RRI was measured by ultrasound in 3 segmental arteries. Sodium intake (UNa; mmol/24 h) was estimated on 24-hour urine samples. Carotido-femoral pulse wave velocity was obtained by applanation tonometry. Mixed multivariate regression models were used with RRI or pulse wave velocity as independent variables and UNa as dependent variable, adjusting for possible confounders. We included 1002 patients in the analyses with 528 (52.7%) women and mean age of 47.2±17.4. Mean values of UNa and RRI were 141.8±61.1 mmol/24 h and 63.8±5.5%, respectively. In multivariate analysis, UNa was positively associated with RRI (P=0.002) but not with pulse wave velocity (P=0.344). Plasma renin activity and aldosterone did not modify the relationship between UNa and RRI (P=0.087 for interaction). UNa/urinary potassium ratio was positively associated with pulse wave velocity ≥12 m/s (P=0.033). Our results suggest that dietary salt consumption has a direct impact on renal hemodynamic in the adult general population. Alterations in vascular properties likely explain those findings, but inadequate renal vaso-motor response is also possible. Sodium intake could thus potentially be linked to underlying structural systemic damages affecting this population.

Determinants of volume status in peritoneal dialysis: A longitudinal study.

AIM: In peritoneal dialysis (PD), fluid overload is frequent and associated with cardiac dysfunction and mortality. As it is considered a modifiable risk factor, we wished to describe clinical determinants of fluid overload in a longitudinal cohort of PD outpatients. METHODS: We consecutively included PD outpatients treated with continuous ambulatory PD (CAPD) or automated PD (APD) attending for their routine clinical visit at a single tertiary hospital. Extracellular water (ECW) to total body water (TBW) ratio was measured by multifrequency bioelectrical impedance. Peritoneal transport characteristics were measured with a standard peritoneal equilibration test. Patients had a second follow-up visit with the same measurements. Univariable and multivariable mixed linear regression models were conducted with ECW/TBW as the dependent variable. RESULTS: A total of 155 patients were enrolled with a median follow-up time of 12 months. Median dialysis vintage was 13.5 ± 3.4 months. Overall mean value of ECW/TBW was 39.3% ± 1.1. In multivariable analysis, factors positively associated with ECW/TBW were: Age (P < .001), diabetes (P = .002), and SBP (P = .028). Factors negatively associated with ECW/TBW were: nPNA (P = .001), serum albumin (P < .001) and PTH (P = .014). None of the considered variable showed a significant interaction with time. CONCLUSION: We confirm a high prevalence of fluid overload in PD patients and show that it is strongly associated with older age, diabetes, hypoalbuminemia and protein energy wasting. In contrast, when PD prescription is tailored to patient's individual characteristics, residual renal function, PD modality and peritoneal characteristics are not decisive in controlling volume status.

Renal Resistive Index Is Associated With Inactive Matrix Gla (γ-Carboxyglutamate) Protein in an Adult Population-Based Study.

Background Increased renal resistive index (RRI) has been associated with target organ damage as well as renal and cardiovascular outcomes. Matrix Gla (γ-carboxyglutamate) protein (MGP) is a strong inhibitor of soft tissue calcification. Its inactive form (dephospho-uncarboxylated MGP [dp-ucMGP]) has been associated with vascular stiffness, cardiovascular outcomes, and mortality. In this study, we hypothesized that high levels of dp-ucMGP were associated with increased RRI. Methods and Results We recruited participants via a multicenter family-based cross-sectional study in Switzerland. Levels of dp-ucMGP were measured in plasma by sandwich ELISA. RRI was measured by Doppler ultrasound in 3 segmental arteries in both kidneys. We used mixed regression models to assess the relationship between dp-ucMGP and RRI. We adjusted for common determinants of RRI as well as renal function and cardiovascular risk factors. We included 1006 participants in our analyses: 526 women and 480 men. Mean values were 0.44±0.20 nmol/L for dp-ucMGP and 64±5% for RRI. After multivariable adjustment, dp-ucMGP was positively associated with RRI (P=0.001). In subgroup analysis by age tertiles, this association was not significant in the youngest age group (<38 years; P=0.62), whereas it was significant in older age groups (38-55 and >55 years; P=0.016 and P<0.001, respectively). Conclusions Levels of dp-ucMGP are positively and independently associated with RRI after adjustment for common determinants of RRI, cardiovascular risk factors, and renal function. The stronger association among older adults is probably due, in part, to age-related arterial stiffness. RRI thus seems to reflect the global atherosclerotic burden in a general adult population.