Understanding the Korean Dialysis Cohort for Mineral, Vascular Calcification, and Fracture (ORCHESTRA) Study: Design, Method, and Baseline Characteristics.

INTRODUCTION: End-stage renal disease (ESRD) is a growing disease worldwide, including Korea. This is an important condition that affects patient outcome. To provide optimal management for mineral disturbance, vascular calcification, and bone disease in ESRD patients, the Korean dialysis cohort for mineral, vascular calcification, and fracture (ORCHESTRA) study was conducted by enrolling Korean dialysis patients. METHODS: Sixteen university-affiliated hospitals and one Veterans' Health Service Medical Center participated in this study. This prospective cohort study enrolled approximately 900 consecutive patients on dialysis between May 2019 and January 2021. Enrolled subjects were evaluated at baseline for demographic information, laboratory tests, radiologic imaging, and bone mineral densitometry (BMD) scans. After enrollment, regular assessments of the patients were performed, and their biospecimens were collected according to the study protocol. The primary outcomes were the occurrence of major adverse cardiovascular events, invasive treatment for peripheral artery disease, and osteoporotic fractures. The secondary outcomes were hospitalization for cerebrovascular disease or progression of abdominal aortic calcification. Participants will be assessed for up to 3 years to determine whether primary or secondary outcomes occur. RESULTS: Between May 2019 and January 2021, all participating centers recruited 900 consecutive dialysis patients, including 786 undergoing hemodialysis (HD) and 114 undergoing peritoneal dialysis (PD). The mean age of the subjects was 60.4 ± 12.3 years. Males accounted for 57.7% of the total population. The mean dialysis vintage was 6.1 ± 6.0 years. The HD group was significantly older, had a longer dialysis vintage, and more comorbidities. Overall, the severity of vascular calcification was higher and the level of BMD was lower in the HD group than in the PD group. CONCLUSION: This nationwide, multicenter, prospective cohort study focused on chronic kidney disease-mineral and bone disorder and aimed to provide clinical evidence to establish optimal treatment guidelines for Asian dialysis patients.

Renal Mechanisms for Hypercalciuria Induced by Metabolic Acidosis.

BACKGROUND: In metabolic acidosis, a negative calcium balance is induced by decreased renal tubular calcium reabsorption. This occurs independently of the action of parathyroid hormone or vitamin D and was attributed to a direct action of metabolic acidosis on the renal tubular cells. The latter has been verified by recent studies on the molecular levels in the kidney. SUMMARY: Whereas the regulatory role of urinary calcium excretion was traditionally assigned to the transcellular calcium transport in the distal convoluted tubule (DCT) and connecting tubule (CNT), most of the calcium reabsorption from the glomerular filtrate paracellularly occurs through the tight junctions in the proximal tubule (PT) and the thick ascending limb (TAL) of Henle's loop. Interestingly, all these nephron segments participate in producing hypercalciuria caused by metabolic acidosis. Claudin-2 is the major route of paracellular calcium transport in the PT and was downregulated in rats with 5 days' NH4Cl loading. In the TAL, the lumen-positive voltage produced by apical K+ recycling drives paracellular reabsorption of Ca2+ and Mg2+ via the claudin-16/19 complex. Activation of calcium-sensing receptor (CaSR) by extracellular calcium upregulates claudin-14, which in turn interacts with the claudin-16/19 complex and inhibits its cation permeability. This TAL CaSR-claudins axis was activated by chronic NH4Cl loading in rats. Finally, the major transcellular calcium transporters TRPV5 and 28K calcium-binding protein in the DCT-CNT were also downregulated by NH4Cl or acetazolamide administration in mice. KEY MESSAGES: Both paracellular and transcellular calcium transport pathways in the kidney are regulated by metabolic acidosis and lead to renal calcium wasting. In the PT, claudin-2 is downregulated by acidic pH. In the TAL of Henle's loop, CaSR is stimulated by the ionized calcium released from bone and upregulates claudin-14, which in turn inhibits the claudin-16/19 complex and leads to calcium and magnesium wasting. Finally, the transcellular calcium transporters, TRPV5 and calbindin-D28K, are downregulated by metabolic acidosis in the DCT and CNT.

Role of the IL-33/ST2 pathway in renal allograft rejection.

The interleukin-33 (IL-33)/suppression of tumorigenicity 2 (ST2) pathway modulates immune response and inflammation, associated with allograft dysfunction and rejection. We hypothesized that IL-33/ST2 is a marker of renal allograft rejection and IL-33/ST2 expression may differ according to rejection type. IL-33/ST2 expression was measured in sera and kidney tissues from recipients with acute antibody-mediated rejection (AAMR), acute cell-mediated rejection (ACMR), chronic antibody-mediated rejection (CAMR), and healthy controls. The soluble ST2 and IL-33/ST2 expression levels were higher in participants with all three rejection types than in controls. Although the expression levels in recipients with AAMR and ACMR were significantly higher than those with CAMR, there was no significant difference between the expression levels in AAMR and ACMR. Although IL-33, IL-8, and fibronectin expression were significantly increased after the addition of the recipients' serum in primary cultured human renal proximal tubular epithelial cells, the levels decreased after treatment with an anti-ST2 antibody. Furthermore, the anti-ST2 antibody specifically suppressed the upregulation of the mixed lymphocyte reaction. Boyden chamber assays demonstrated that anti-ST2 antibody abrogated chemotaxis induced by recombinant IL-33. Thus, IL-33 and ST2 are potent mediators of rejection. Treatment with an anti-ST2 antibody ameliorates rejection and could be a potential therapeutic strategy for renal allograft rejection.

Psychotropic drugs upregulate aquaporin-2 via vasopressin-2 receptor/cAMP/protein kinase A signaling in inner medullary collecting duct cells.

Psychotropic drugs may be associated with hyponatremia, but an understanding of how they induce water retention in the kidney remains elusive. Previous studies have postulated that they may increase vasopressin production in the hypothalamus without supporting evidence. In this study, we investigated the possibility of drug-induced nephrogenic syndrome of inappropriate antidiuresis using haloperidol, sertraline, and carbamazepine. Haloperidol, sertraline, or carbamazepine were treated in inner medullary collecting duct (IMCD) suspensions and primary cultured IMCD cells prepared from male Sprague-Dawley rats. The responses of intracellular cAMP production, aquaporin-2 (AQP2) protein expression and localization, vasopressin-2 receptor (V2R) and AQP2 mRNA, and cAMP-responsive element-binding protein (CREB) were tested with and without tolvaptan and the protein kinase A (PKA) inhibitors H89 and Rp-cAMPS. In IMCD suspensions, cAMP production was increased by haloperidol, sertraline, or carbamazepine and was relieved by tolvaptan cotreatment. In primary cultured IMCD cells, haloperidol, sertraline, or carbamazepine treatment increased total AQP2 and decreased phosphorylated Ser261-AQP2 protein expression. Notably, these responses were reversed by cotreatment with tolvaptan or a PKA inhibitor. AQP2 membrane trafficking was induced by haloperidol, sertraline, or carbamazepine and was also blocked by cotreatment with tolvaptan or a PKA inhibitor. Furthermore, upregulation of V2R and AQP2 mRNA and phosphorylated CREB was induced by haloperidol, sertraline, or carbamazepine and was blocked by tolvaptan cotreatment. We conclude that, in the rat IMCD, psychotropic drugs upregulate AQP2 via V2R-cAMP-PKA signaling in the absence of vasopressin stimulation. The vasopressin-like action on the kidney appears to accelerate AQP2 transcription and dephosphorylate AQP2 at Ser261.NEW & NOTEWORTHY It is unclear whether antipsychotic drugs can retain water in the kidney in the absence of vasopressin. This study demonstrates that haloperidol, sertraline, and carbamazepine can produce nephrogenic syndrome of inappropriate antidiuresis because they directly upregulate vasopressin-2 receptor and aquaporin-2 (AQP2) via cAMP/PKA signaling. We showed that, in addition to AQP2 trafficking, AQP2 protein abundance was rapidly increased by treatment with antipsychotic drugs in association with dephosphorylation of AQP2 at Ser261 and accelerated AQP2 transcription.

Thick ascending limb claudins are altered to increase calciuria and magnesiuria in metabolic acidosis.

Urinary calcium and magnesium wasting is a characteristic feature of metabolic acidosis, and this study focused on the role of the thick ascending limb of Henle's loop in metabolic acidosis-induced hypercalciuria and hypermagnesiuria because thick ascending limb is an important site of paracellular calcium and magnesium reabsorption. Male Sprague-Dawley rats were used to determine the effects of acid loading (by adding NH4Cl, 7.2 mmol/220 g body wt/day to food slurry for 7 days) on renal expression of claudins and then to evaluate whether the results were reversed by antagonizing calcium-sensing receptor (using NPS-2143). At the end of each animal experiment, the kidneys were harvested for immunoblotting, immunofluorescence microscopy, and quantitative PCR (qPCR) analysis of claudins and the calcium-sensing receptor. As expected, NH4Cl loading lowered urinary pH and increased excretion of urinary calcium and magnesium. In NH4Cl-loaded rats, renal protein and mRNA expression of claudin-16, and claudin-19, were decreased compared with controls. However, claudin-14 protein and mRNA increased in NH4Cl-loaded rats. Consistently, the calcium-sensing receptor protein and mRNA were up-regulated in NH4Cl-loaded rats. All these changes were reversed by NPS-2143 coadministration and were confirmed using immunofluorescence microscopy. Hypercalciuria and hypermagnesiuria in NH4Cl-loaded rats were significantly ameliorated by NPS-2143 coadministration as well. We conclude that in metabolic acidosis, claudin-16 and claudin-19 in the thick ascending limb are down-regulated to produce hypercalciuria and hypermagnesiuria via the calcium-sensing receptor.NEW & NOTEWORTHY This study found that the thick ascending limb of Henle's loop is involved in the mechanisms of hypercalciuria and hypermagnesiuria in metabolic acidosis. Specifically, expression of claudin-16/19 and claudin-14 was altered via up-regulation of calcium-sensing receptor in NH4Cl-induced metabolic acidosis. Our novel findings contribute to understanding the regulatory role of paracellular tight junction proteins in the thick ascending limb.

Diabetes mellitus increases mortality in acute pyelonephritis patients: a population study based on the National Health Insurance Claim Data of South Korea for 2010-2014.

OBJECTIVE: Diabetes mellitus has been suspected to increase mortality in acute pyelonephritis (APN) patients and the goal of this study is to verify this suspicion with a large data set based on almost the entire population of South Korea. METHODS: A nationwide cohort study was conducted using a South Korean Health Insurance Review and Assessment Service claim database. We collected demographic and clinical information including comorbidities of patients with APN as the primary discharge diagnosis during 2010-2014. Then we compared the in-hospital mortality and recurrence of APN across the diabetes and non-diabetes groups. RESULTS: Among 845,656 APN patients, 12.4% had diabetes mellitus. The median age was 65 in the diabetes group, which was much higher than 47 in the non-diabetes group; the female proportion was 91-92% in both groups. The in-hospital mortality rate was higher in the diabetes group (2.6/1000 events in the diabetes group vs. 0.3/1000 in the non-diabetes group, P < 0.001). When covariates (age, sex, and the modified Charlson comorbidity index) were controlled with panel logistic regression, diabetes was still associated with a higher in-hospital mortality in APN patients (OR 2.66, 95% CI 2.19-3.23). The increasing effect of diabetes on in-hospital mortality of APN patients varied greatly with age: the effect was large for age 15-49 (OR 15.06, 95% CI 5.27-43.05), slightly smaller for age 50-64 (OR 12.17, 95% CI 5.71-25.92), and much smaller for age ≥ 65 (OR 2.10, 95% CI 1.72-1.92). CONCLUSIONS: Our data indicate that the mortality of APN is higher in the patients with diabetes and this effect becomes stronger for young patients.

Tight junction protein expression from peritoneal dialysis Effluent.

Background: We hypothesized that tight junction (TJ) proteins may have a role in paracellular transport of solute and water in peritoneal dialysis (PD) patients. Previous studies on TJ proteins in PD patients have used only cultured human peritoneal mesothelial cells (HPMCs). This study was undertaken to test whether TJ proteins are directly identified from PD effluent and whether their expressions are associated with functional parameters of PD.Methods: Dialysis effluents were collected from 40 patients undergoing PD, after the peritoneal equilibration test (PET). Different molecular sizes of Amicon Ultra-15 Centrifugal Filter Units were used to concentrate and purify proteins in PD effluents, and immunoblot analyses for occludin, ZO-1, and claudins were carried out to test for their existence and relationships with peritoneal clearance or results of the PET.Results: Immunoblotting from PD effluents revealed discrete bands of occludin (∼65 kDa), ZO-1 (∼215 kDa), claudin-1 (∼22 kDa), and claudin-15 (∼22 kDa) in all 40 patients. The peritoneal creatinine clearance inversely correlated with the protein expression of claudin-1 (r= -0.369, p= .019), and the dialysate-to-plasma creatinine ratio at 4 h PET correlated with occludin (r = 0.396, p= .011) and inversely correlated with claudin-15 (r= -0.393, p= .012).Conclusion: In PD patients, expression of peritoneal TJ proteins can be estimated from the dialysis effluent and may be used as novel peritoneal biomarkers.

Anti-Inflammatory Action of Sitagliptin and Linagliptin in Doxorubicin Nephropathy.

BACKGROUND/AIMS: Dipeptidyl peptidase-4 (DPP4) inhibitors are known to have a protective effect on diabetic kidney disease, possibly via reduction of oxidative stress and inflammation in the kidney. However, whether these potential mechanisms play a role in non-diabetic proteinuric kidney diseases is not clear. METHODS: Two different animal experiments were carried out using sitagliptin and linagliptin for DPP4 inhibition. In each experiment, male Sprague-Dawley rats were uninephrectomized and randomly divided into vehicle-treated and doxorubicin-treated rats, with or without DPP4 inhibition. Administration of a DPP4 inhibitor was performed daily by oral gavage over six weeks. RESULTS: A single intravenous injection of doxorubicin resulted in hypertension and remarkable proteinuria. Linagliptin, but not sitagliptin, lowered systolic blood pressure in rats with doxorubicin nephropathy. By contrast, sitagliptin ameliorated tubulointerstitial injury, inflammatory cell infiltration, and interstitial fibrosis in rat kidneys with doxorubicin nephropathy. Quantitative polymerase chain reaction analysis revealed that mRNA expression of NLRP3, caspase-1, ASC, and IL-1ß was remarkably increased in rat kidneys with doxorubicin nephropathy, and that this upregulation of the major components of the NLRP3 inflammasome was effectively suppressed by treatment with either sitagliptin or linagliptin. Additionally, upregulation of IL-6 was reversed by linagliptin, but not by sitagliptin. On the other hand, sitagliptin, but not linagliptin, reversed the increase in mRNA expression of gp91phox, p47phox, and p67phox in rat kidneys with doxorubicin nephropathy. CONCLUSION: NLRP3 inflammasome activation was shown in our rat model of doxorubicin nephropathy. DPP4 inhibitors can suppress the activity of NLRP3, with or without relieving NADPH oxidase 2-related oxidative stress.

Safety and Efficacy of Tolvaptan in Korean Patients with Hyponatremia Caused by the Syndrome of Inappropriate Antidiuretic Hormone.

BACKGROUND: The aim of this multicenter study was to evaluate the safety and efficacy of tolvaptan (TLV) in Korean patients with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). METHODS: Of 51 enrolled patients with SIADH, 39 patients (16 female patients, aged 70.8 ± 11.3 years) were included in an intention to treat analysis. All patients received 15 mg/day as the initial dose, and the dose was then increased up to 60 mg/day (as needed) until day 4. RESULTS: Serum sodium increased significantly from baseline during the first 24 hours (126.8 ± 4.3 vs. 133.7 ± 3.8 mmol/L, P < 0.001), rose gradually between days 1 and 4 (133.7 ± 3.8 vs. 135.6 ± 3.6 mmol/L, P < 0.05), and then plateaued until day 11 (136.7 ± 4.5 mmol/L). The correlation between the change in serum sodium for the first 24 hours and initial serum sodium concentration was significant (r = -0.602, P < 0.001). In severe hyponatremia (< 125 mmol/L), the change was significantly higher (11.1 ± 4.8 mmol/L) than in moderate (6.4 ± 2.5 mmol/L, P < 0.05) or mild hyponatremia (4.3 ± 3.3 mmol/L, P < 0.01). In addition, logistic regression analysis showed that body weight (odds ratio [OR], 0.858; 95% confidence interval [CI], 0.775-0.976; P = 0.020) and body mass index (BMI) (OR, 0.692; 95% CI, 0.500-0.956; P = 0.026) were associated with rapid correction. No serious adverse events were reported, but in 13% of patients hyponatremia was overcorrected. CONCLUSION: TLV is effective in correcting hyponatremia and well-tolerated in Korean patients with SIADH. However, those with low body weight, low BMI or severe hyponatremia, could be vulnerable to overcorrection with the initial dose of 15 mg TLV.

Alteration of Tight Junction Protein Expression in Dahl Salt-Sensitive Rat Kidney.

BACKGROUND/AIMS: Altered pressure natriuresis is an important mechanism of hypertension, but it remains elusive at the molecular level. We hypothesized that in the kidney, tight junctions (TJs) may have a role in pressure natriuresis because paracellular NaCl transport affects interstitial hydrostatic pressure. METHODS: To assess the association of salt-sensitive hypertension with altered renal TJ protein expression, Dahl salt-sensitive (SS) and salt-resistant (SR) rats were put on an 8% NaCl-containing rodent diet for 4 weeks. Systolic blood pressure (SBP) and urine NaCl excretion were measured weekly, and kidneys were harvested for immunoblotting and quantitative PCR analysis at the end of the animal experiments. RESULTS: SBP was significantly higher in SS rats than in SR rats during the first to fourth weeks of the animal experiments. During the first and second week, urinary NaCl excretion was significantly lower in SS rats as compared with SR rats. However, the difference between the two groups vanished at the third and fourth weeks. In the kidney, claudin-4 protein and mRNA were significantly increased in SS rats as compared with SR rats. On the other hand, occludin protein and mRNA were significantly decreased in SS rats as compared with SR rats. The expression of claudin-2, claudin-7, and claudin-8 did not vary significantly between the two groups. CONCLUSIONS: In SS rats, SS hypertension was associated with differential changes in renal TJ protein expression. Both upregulation of claudin-4 and downregulation of occludin might increase paracellular NaCl transport in the kidney, resulting in impaired pressure natriuresis in SS rats.

Evaluation of Urinary Indices for Albuminuria and Proteinuria in Patients with Chronic Kidney Disease.

BACKGROUND/AIMS: Either protein-to-creatinine ratio (PCR) or albumin-to-creatinine ratio (ACR) can be adopted for estimation of proteinuria in patients with chronic kidney disease (CKD). Estimated protein excretion rate (ePER) and estimated albumin excretion rate (eAER) may be superior to ACR and PCR. Reports show that urine albumin-to-protein ratio (APR) may be useful in detecting tubular proteinuria, but should be compared with urine protein electrophoresis (PEP). METHODS: Both 24-h urine and spot urine were collected from 77 stable CKD patients for measurement of albumin, protein, and creatinine, and PEP. Based on MDRD and CKD-EPI equations, ePERMDRD, ePERCKD-EPI, eAERMDRD and eAERCKD-EPI were calculated to estimate daily proteinuria and albuminuria. Glomerular CKD was defined by clinical and/or pathological evidence. RESULTS: ACR correlated significantly with PCR. However, microalbuminuria was present in patients without pathologic proteinuria. Twenty-four-hour urine albumin correlated better with eAERMDRD and eAERCKD-EPI than ACR, and 24-h urine protein correlated better with ePERMDRD and ePERCKD-EPI than PCR. APR significantly but not well correlated with the albumin fraction in urine PEP. The albumin fraction obtained from urine PEP was significantly higher in patients with glomerulopathy than those with non-glomerular CKD, whereas there were no differences in APR between groups. In contrast with APR, the albumin fraction in urine PEP was independently associated with glomerular CKD. CONCLUSIONS: Both PCR and ACR are useful in evaluation of proteinuria. In quantifying daily proteinuria and albuminuria, ePER and eAER are superior to PCR and ACR, respectively. Compared with APR, urine PEP is more useful in diagnosing glomerular proteinuria.

A J-Shaped Association Between Serum Uric Acid Level and Allograft Outcomes After Living Donor Kidney Transplantation.

Hyperuricemia following kidney transplantation (KT) may contribute to a decline in allograft renal function, but be affected by KT-related confounding factors. Some studies have even suggested that a reduction in serum uric acid (UA) is associated with poor patient outcomes. Thus, we retrospectively analyzed the impact of serum UA on allograft outcomes in 281 KT recipients. KT recipients were divided into five groups according to serum UA level (mg/dL): Group I (n = 46), ≤ 5; Group II (n = 62), > 5 and ≤ 6; Group III (n = 70), > 6 and ≤ 7; Group IV (n = 53), > 7 and ≤ 8; Group V (n = 50), > 8. Regression analysis showed that serum UA level was significantly associated with future allograft function. In a Kaplan-Meier analysis, the dialysis-free survival of Group II recipients was better than that of the other groups (Group I, 140 ± 5 months; Group II, 208 ± 7 months; Group III, 148 ± 4 months; Group IV, 185 ± 12 months; Group V, 164 ± 11 months; P = 0.0164). In Cox proportional hazard models adjusting for estimated glomerular filtration rate, the relative risk of allograft loss still tended to be elevated in Group I (HR=3.417, 95% CI 1.138-10.258) and Group V (HR=2.793, 95% CI 1.108-7.041), using Group II as the reference. Our results suggest that there is a J-shaped association between serum UA levels and allograft outcomes in living donor KT recipients.

Cyclophosphamide-induced vasopressin-independent activation of aquaporin-2 in the rat kidney.

Because cyclophosphamide-induced hyponatremia was reported to occur without changes in plasma vasopressin in a patient with central diabetes insipidus, we hypothesized that cyclophosphamide or its active metabolite, 4-hydroperoxycyclophosphamide (4-HC), may directly dysregulate the expression of water channels or sodium transporters in the kidney. To investigate whether intrarenal mechanisms for urinary concentration are activated in vivo and in vitro by treatment with cyclophosphamide and 4-HC, respectively, we used water-loaded male Sprague-Dawley rats, primary cultured inner medullary collecting duct (IMCD) cells, and IMCD suspensions prepared from male Sprague-Dawley rats. In cyclophosphamide-treated rats, significant increases in renal expression of aquaporin-2 (AQP2) and Na-K-2Cl cotransporter type 2 (NKCC2) were shown by immunoblot analysis and immunohistochemistry. Apical translocation of AQP2 was also demonstrated by quantitative immunocytochemistry. In both rat kidney and primary cultured IMCD cells, significant increases in AQP2 and vasopressin receptor type 2 (V2R) mRNA expression were demonstrated by real-time quantitative PCR analysis. Confocal laser-scanning microscopy revealed that apical translocation of AQP2 was remarkably increased when primary cultured IMCD cells were treated with 4-HC in the absence of vasopressin stimulation. Moreover, AQP2 upregulation and cAMP accumulation in response to 4-HC were significantly reduced by tolvaptan cotreatment in primary cultured IMCD cells and IMCD suspensions, respectively. We demonstrated that, in the rat kidney, cyclophosphamide may activate V2R and induce upregulation of AQP2 in the absence of vasopressin stimulation, suggesting the possibility of drug-induced nephrogenic syndrome of inappropriate antidiuresis (NSIAD).

The risk of hyponatremia with desmopressin use for nocturnal polyuria.

BACKGROUND: Desmopressin is used for treating nocturnal polyuria, but hyponatremia is an associated concern in the elderly due to impaired urinary dilution. This study was undertaken to characterize hyponatremia occurring in adults using desmopressin for nocturnal polyuria. METHODS: Data from 172 patients who were prescribed desmopressin for nocturnal polyuria at a urology clinic from September 2010 through February 2013 were retrospectively analyzed. Demographic and laboratory parameters were investigated to examine the risk factors for desmopressin-associated hyponatremia. RESULTS: The average follow-up serum sodium measured 21 ± 22 days after using desmopressin was 138 ± 5 mmol/l. Hyponatremia (<135 mmol/l) was found in 24 patients (14%), and it was severe in 7 (<126 mmol/l). In the hyponatremic patients, serum sodium decreased by 11 ± 6 mmol/l. Patients with hyponatremia were older than those with normonatremia (78 ± 7 vs. 68 ± 9 years, p < 0.0001). The presence of either hyponatremia-predisposing comorbidities or concurrent medications was associated with hyponatremia. Patients with hyponatremia had lower basal hemoglobin (11 ± 2 vs. 13 ± 2 g/dl, p < 0.001) and serum sodium (139 ± 2 vs. 140 ± 2 mmol/l, p < 0.05) than those with normonatremia. Multivariate logistic regression after adjustment for basal serum sodium showed that advanced age (OR 1.15; 95% CI 1.03-1.27) and lower hemoglobin level (OR 0.64; 95% CI 0.43-0.94) were independently associated with hyponatremia. CONCLUSION: Hyponatremia is not infrequently associated with desmopressin use. Those with advanced age (≥65 years) and lower hemoglobin are at risk of desmopressin-associated hyponatremia and need to be carefully monitored.

Association between a change in donor kidney function and long-term allograft outcomes in kidney transplant recipients.

Reserve capacity of donated kidney may be an important determinant of allograft survival in kidney transplantation (KT). Here, we investigate change in estimated glomerular filtration rate of donor kidney (ΔeGFR(Donor)) over 30 days after KT as a predictor of the allograft function. A total of 222 recipients were divided into two groups according to ΔeGFR(Donor) as follows: Group I (n = 110), ΔeGFR(Donor) ≥ -25%; Group II (n = 112), ΔeGFR(Donor) < -25%. Three years after KT, Group I had a higher eGFR(Recipient) than Group II (55 ± 21 vs. 47 ± 22 mL/min/1.73 m2, P < 0.05). However, no differences in eGFR(Recipient) were detected between the two groups after 10 years. Linear regression analysis showed that ΔeGFR(Donor) was significantly associated with the eGFR(Recipient) at 3 years post-transplantation, but not at 10 years post-transplantation. In Kaplan-Meier analysis, Group I had a greater dialysis-free survival rate than Group II at the 10-year follow-up (84% vs. 76%, P < 0.05). However, no difference in overall survival rate between groups was detected. In the multivariate-adjusted Cox proportional-hazard model, ΔeGFR(Donor) was independently associated with future allograft loss (hazard ratio 0.973; 95% confidence interval 0.949-0.999). These results suggest that larger recovery of donor kidney function after KT donation is associated with better short/intermediate-term allograft outcomes. Follow-up assessment of donor kidney function may be useful to monitor KT recipients at risk for allograft loss.

Prognostic Significance of 1-Year Serum Albumin Levels Within the Normal Range After Kidney Transplantation.

Hypoalbuminemia is associated with poor outcomes in kidney transplantation (KT). However, what level is optimal in serum albumin is not clear for the long-term prognosis. To determine whether the long-term outcomes are different even between the normal ranges of serum albumin after KT, we analyzed data from 404 renal allograft recipients whose 1-year post-transplant serum albumin levels were within the normal limits (3.5-5.5 g/dL). During a follow-up of 122 ± 56 months, 97 graft losses, 20 patient deaths, and 50 cardiovascular (CV) events occurred. Based on 1-year serum albumin levels, the patients were divided into high normal (≥4.6 g/dL, n = 209) and low normal (<4.6 g/dL, n = 195) groups. Kaplan-Meier analyses revealed that the low normal group had poorer allograft survival (P = 0.01), patient survival (P < 0.001), and CV event-free survival (P < 0.001) than the high normal group. Cox regression analysis confirmed that 1-year serum albumin was inversely associated with the risk of graft loss (hazard ratio [HR] 0.414, 95% confidence interval [CI] 0.200-0.856), patient death (HR 0.097, 95% CI 0.019-0.484), and CV events (HR 0.228, 95% CI 0.074-0.702). In conclusion, a relatively low 1-year post-transplant serum albumin level within the normal limits (<4.6 g/dL) significantly predicts poor long-term outcomes.

Is tolvaptan indicated for refractory oedema in nephrotic syndrome?

Tolvaptan is useful for correcting dilutional hyponatraemia because of its aquaretic effect. On the other hand, there is a distinct lack of data regarding tolvaptan-induced natriuresis, although previous studies have demonstrated improvement of congestive symptoms and signs in heart failure patients following tolvaptan treatment. Here, we report the case of a 47-year-old man diagnosed with minimal change nephrotic syndrome and whose refractory oedema was immediately controlled by tolvaptan before steroid response was induced. With tolvaptan treatment, patient urine output increased dramatically to approximately 5.5 L/day and body weight decreased by 9 kg over 5 days. Interestingly, urine sodium concentration, fractional excretion of sodium and urine osmolality all increased in response to tolvaptan administration. However, serum sodium concentration was maintained within the normal range, and mild azotaemia was corrected. Tolvaptan was discontinued after 11 days when heavy proteinuria and generalized oedema had been resolved. We discuss the potential mechanisms by which V2 receptor antagonists may stimulate natriuresis in the kidney. In conclusion, tolvaptan may be useful as an adjunctive treatment for oedematous disorders.

Effects of dietary salt restriction on renal progression and interstitial fibrosis in adriamycin nephrosis.

BACKGROUND/AIMS: Although high salt intake is thought to accelerate renal progression in proteinuric kidney disease, it is not known whether strict dietary salt restriction could delay renal inflammation and interstitial fibrosis. Here, we sought to answer this question in a rat model of adriamycin-induced nephrotic syndrome. METHODS: Adriamycin was administered via the femoral vein in a single bolus (7.5 mg/kg), and the rats were put on a sodium-deficient rodent diet. Rats with intact kidneys were studied for 5 weeks (experiment 1), and uninephrectomized rats were studied for 6 weeks (experiment 2). RESULTS: In experiment 1, restricting salt intake improved renal tubulointerstitial histopathology in adriamycin-treated rats. Immunohistochemical and immunoblot results additionally showed that restricting dietary salt lowered adriamycin-induced expression of osteopontin, collagen III, and fibronectin. In experiment 2, salt restriction improved adriamycin-induced azotemia, although it did not affect proteinuria or blood pressure. Dietary salt restriction also reduced adriamycin-induced infiltration of ED1-positive cells and the upregulated expression of osteopontin and α-SMA. Masson's trichrome and Sirius red staining revealed that salt restriction slowed Adriamycin-induced progression of renal interstitial fibrosis. Finally, qPCR revealed that adriamycin-induced expression of TNF-α, IκB-α, gp91(phox), p47(phox), and p67(phox) mRNA was blocked by salt restriction. CONCLUSION: Our findings demonstrate that strict dietary salt restriction delays the progress of renal inflammation and fibrosis in proteinuric kidney disease, most likely via relieving the reactive oxygen species-mediated NF-κB activation.

The extended rapid response system: 1-year experience in a university hospital.

The rapid response system (RRS) is an innovative system designed for in-hospital, at-risk patients but underutilization of the RRS generally results in unexpected cardiopulmonary arrests. We implemented an extended RRS (E-RRS) that was triggered by actively screening at-risk patients prior to calls from primary medical attendants. These patients were identified from laboratory data, emergency consults, and step-down units. A four-member rapid response team was assembled that included an ICU staff, and the team visited the patients more than twice per day for evaluation, triage, and treatment of the patients with evidence of acute physiological decline. The goal was to provide this treatment before the team received a call from the patient's primary physician. We sought to describe the effectiveness of the E-RRS at preventing sudden and unexpected arrests and in-hospital mortality. Over the 1-yr intervention period, 2,722 patients were screened by the E-RRS program from 28,661 admissions. There were a total of 1,996 E-RRS activations of simple consultations for invasive procedures. After E-RRS implementation, the mean hospital code rate decreased by 31.1% and the mean in-hospital mortality rate was reduced by 15.3%. In conclusion, the implementation of E-RRS is associated with a reduction in the in-hospital code and mortality rates.