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1.  Correction of Anemia with Continuous Erythropoietin Receptor Activator in Korean Patients on Long-Term Hemodialysis 
Continuous erythropoietin receptor activator (CERA) is an erythropoietin with a long-half life. This study investigated the efficacy of CERA for correcting anemia in Korean patients on dialysis. Patients (≥18 yr) who were not receiving any ESAs for more than 8 weeks were randomly assigned to either intravenous CERA once every 2 weeks (n=39) or epoetin beta thrice-weekly (n=41) during a 24-week correction phase. Hemoglobin (Hb) response was defined as increase of Hb by at least 1 g/dL and Hb≥11 g/dL without red blood cell (RBC) transfusion. Median dialysis duration was 1.7 (0.3-20.8) and 1.6 (0.4-13.8) yr in CERA and epoetin beta group, respectively. Hemoglobin response rate of CERA was 79.5% (95% confidence interval [CI], 63.5-90.7). As the lower limit of 95% CI was higher than pre-specified 60% response rate, it can be concluded that CERA corrected anemia (P<0.05). Hb response rate of epoetin beta was 87.8% (95% CI, 73.8-95.9) (P=0.37). Median time to response was 12 weeks in CERA and 10.3 weeks in epoetin beta (P=0.03). It is suggested that once every 2 weeks administration of CERA is effective for correcting anemia in Korean patients on long-term hemodialysis with longer time-to-response than thrice weekly epoetin beta. ( registry No. NCT00546481)
PMCID: PMC3890480  PMID: 24431909
Anemia Correction; Continuous Erythropoietin Receptor Activator; Kidney Failure, Chronic; Renal Dialysis
2.  Renal adverse effects of sunitinib and its clinical significance: a single-center experience in Korea 
Sunitinib is an oral multitargeted tyrosine kinase inhibitor used mainly for the treatment of metastatic renal cell carcinoma. The renal adverse effects (RAEs) of sunitinib have not been investigated. The aim of this study was to determine the incidence and risk factors of RAEs (proteinuria [PU] and renal insufficiency [RI]) and to investigate the relationship between PU and antitumor efficacy.
We performed a retrospective review of medical records of patients who had received sunitinib for more than 3 months.
One hundred and fifty-five patients (mean age, 58.7 ± 12.6 years) were enrolled, and the mean baseline creatinine level was 1.24 mg/dL. PU developed in 15 of 111 patients, and preexisting PU was aggravated in six of 111 patients. Only one patient developed typical nephrotic syndrome. Following discontinuation of sunitinib, PU was improved in 12 of 17 patients but persisted in five of 17 patients. RI occurred in 12 of 155 patients, and the maximum creatinine level was 3.31 mg/dL. RI improved in two of 12 patients but persisted in 10 of 12 patients. Risk factors for PU were hypertension, dyslipidemia, and chronic kidney disease. Older age was a risk factor for RI. The median progression-free survival was significantly better for patients who showed PU.
The incidence of RAEs associated with sunitinib was lower than those of previous reports. The severity of RAEs was mild to moderate, and partially reversible after cessation of sunitinib. We suggest that blood pressure, urinalysis, and renal function in patients receiving sunitinib should be monitored closely.
PMCID: PMC3932394  PMID: 24574832
Acute kidney injury; Proteinuria; Sunitinib
3.  High Dose Vitamin D3 Attenuates the Hypocalciuric Effect of Thiazide in Hypercalciuric Rats 
Journal of Korean Medical Science  2010;25(9):1305-1312.
Thiazide is known to decrease urinary calcium excretion. We hypothesized that thiazide shows different hypocalciuric effects depending on the stimuli causing hypercalciuria. The hypocalciuric effect of hydrochlorothiazide (HCTZ) and the expression of transient receptor potential vanilloid 5 (TRPV5), calbindin-D28K, and several sodium transporters were assessed in hypercalciuric rats induced by high calcium diet and vitamin D3. Urine calcium excretion and the expression of transporters were measured from 4 groups of Sprague-Dawley rats; control, HCTZ, high calcium-vitamin D, and high calcium-vitamin D with HCTZ groups. HCTZ decreased urinary calcium excretion by 51.4% in the HCTZ group and only 15% in the high calcium-vitamin D with HCTZ group. TRPV5 protein abundance was not changed by HCTZ in the high calcium-vitamin D with HCTZ group compared to the high calcium-vitamin D group. Protein abundance of NHE3, SGLT1, and NKCC2 decreased in the hypercalciuric rats, and only SGLT1 protein abundance was increased by HCTZ in the hypercalciuric rats. The hypocalciuric effect of HCTZ is attenuated in high calcium and vitamin D-induced hypercalciuric rats. This attenuation seems to have resulted from the lack of HCTZ's effect on protein abundance of TRPV5 in severe hypercalciuric condition induced by high calcium and vitamin D.
PMCID: PMC2923802  PMID: 20808673
Hypercalciuria; TRPV5; Sodium Transporters; Cholecalciferol; Thiazides
4.  Altered Regulation of Renal Sodium Transporters in Salt-Sensitive Hypertensive Rats Induced by Uninephrectomy 
Uninephrectomy (uNx) in young rats causes salt-sensitive hypertension (SSH). Alterations of sodium handling in residual nephrons may play a role in the pathogenesis. Therefore, we evaluated the adaptive alterations of renal sodium transporters according to salt intake in uNx-SSH rats. uNx or sham operations were performed in male Sprague-Dawley rats, and normal-salt diet was fed for 4 weeks. Four experimental groups were used: sham-operated rats raised on a high-salt diet for 2 weeks (CHH) or on a low-salt diet for 1 week after 1 week's high-salt diet (CHL) and uNx rats fed on the same diet (NHH, NHL) as the sham-operated rats were fed. Expression of major renal sodium transporters were determined by semiquantitative immunoblotting. Systolic blood pressure was increased in NHH and NHL groups, compared with CHH and CHL, respectively. Protein abundances of Na+/K+/2Cl- cotransporter (NKCC2) and Na+/Cl- cotransporter (NCC) in the CHH group were lower than the CHL group. Expression of epithelial sodium channel (ENaC)-γ increased in the CHH group. In contrast, expressions of NKCC2 and NCC in the NHH group didn't show any significant alterations, compared to the NHL group. Expressions of ENaC-α and ENaC-β in the NHH group were higher than the CHH group. Adaptive alterations of NKCC2 and NCC to changes of salt intake were different in the uNx group, and changes in ENaC-α and ENaC-β were also different. These altered regulations of sodium transporters may be involved in the pathogenesis of SSH in the uNx rat model.
PMCID: PMC3041484  PMID: 21468187
salt-sensitive hypertension; nephrectomy; sodium-potassium-chloride symporters; sodium chloride symporters; epithelial sodium channel
5.  Hyponatremia in Patients with Neurologic Disorders 
The kidney and the brain play a major role in maintaining normal homeostasis of the extracellular fluid by neuroendocrine regulation of sodium and water balance. Therefore, disturbances of sodium balance are common in patients with central nervous system (CNS) disorders and clinicians should focus not only on the CNS lesion, but also on the potentially deleterious complications. Hyponatremia is the most common and important electrolyte disorder affecting patients with critical neurologic diseases. In these patients, the maladaptation to hyponatremia by impaired osmoregulation in pathologic lesions of brain may cause more aggressive cerebral edema and increased intracranial pressure due to hypoosmolality induced by hyponatremia. Furthermore, hyponatremia accompanied by CNS disorders has shown to increase delayed cerebral ischemia and mortality rates. Two main pathophysiologies of hyponatremia, excluding iatrogenic causes, are inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW) syndrome. Differential diagnosis between these two entities can be difficult due to considerable overlap in the laboratory findings and clinical situations. SIADH is in a volume expanded status due to inappropriately secreted arginine vasopressin (AVP) and requires water restriction. However, CSW syndrome is characterized by renal sodium wasting mainly due to increased natriuretic peptides resulting in volume depletion and follows appropriate secretion of AVP. Therefore, maintenance of volume status and sodium replacement is the mainstay of treatment in CSW syndrome. In this review, we aimed to describe the regulation of sodium and water balance, and pathophysiology, diagnosis and treatment of hyponatremia in neurologic patients, especially focusing on SIADH and CSW syndrome.
PMCID: PMC3041486  PMID: 21468186
hyponatremia; inappropriate ADH syndrome; cerebral salt wasting syndrome; nervous system diseases
6.  Electrolyte and Acid-Base Disturbances Associated with Non-Steroidal Anti-Inflammatory Drugs 
Inhibition of renal prostaglandin synthesis by non-steroidal anti-inflammatory drugs (NSAIDs) causes various electrolyte and acid-base disturbances including sodium retention (edema, hypertension), hyponatremia, hyperkalemia, and decreased renal function. Decreased sodium excretion can result in weight gain, peripheral edema, attenuation of the effects of antihypertensive agents, and rarely aggravation of congestive heart failure. Although rare, NSAIDs can cause hyponatremia by reducing renal free water clearance. Hyperkalemia could occur to a degree sufficient to cause cardiac arrhythmias. Renal function can decline sufficiently enough to cause acute renal failure. NSAIDs associated electrolyte and acid-base disturbances are not uncommon in some clinical situations. Adverse renal effects of NSAIDs are generally associated with prostaglandin dependent states such as volume-contracted states, low cardiac output, or other conditions that tend to compromise renal perfusion. All NSAIDs seem to share these adverse effects. In view of many NSAIDs users' susceptibility to renal adverse effects due to their underlying disease or condition, physicians should be cautious in prescribing NSAIDs to susceptible patients.
PMCID: PMC3894511  PMID: 24459510
Edema; Hyponatremia; Renal tubular acidosis; Non-steroidal anti-inflammatory agents; Acute renal failure
7.  Control of fluid balance guided by body composition monitoring in patients on peritoneal dialysis (COMPASS): study protocol for a randomized controlled trial 
Trials  2014;15(1):432.
The clinical benefits of bioimpedance spectroscopy (BIS)-guided fluid management in patients on hemodialysis have been widely demonstrated. However, no previous reports have evaluated the effect of regular and serial BIS-guided fluid management on the residual renal function (RRF) in patients on peritoneal dialysis (PD). Therefore, we will evaluate the clinical efficacy of BIS-guided fluid management for preserving RRF and protecting cardiovascular events in patients on PD.
This is a multicenter, prospective, randomized controlled trial. A total of 138 participants on PD will be enrolled and randomly assigned to receive either BIS-guided fluid management or fluid management based only on the clinical information for 1 year. The primary outcome is the change in the glomerular filtration rate (GFR) between months 0 and 12 after starting treatment. The secondary outcomes will include GFR at month 12, time to the anuric state (urine volume <100 ml/day), and fatal and nonfatal cardiovascular events during treatment.
This is the first clinical trial to investigate the effect of BIS-guided fluid management on RRF and for protecting against cardiovascular events in patients on PD.
Trial registration
Clinical number NCT01887262, June 24, 2013.
PMCID: PMC4233087  PMID: 25376940
Fluid balance; Bioimpedance spectroscopy; Peritoneal dialysis
8.  Non-linear association of serum 25-hydroxyvitamin D with urinary albumin excretion rate in normoalbuminuric subjects 
BMC Nephrology  2014;15:97.
Vitamin D deficiencies and increases in urinary albumin excretion (UAE) are both important and potentially related health problems; however, the nature of their relationship has not been established in normoalbuminuric subjects.
We obtained data from 14,594 normoalbuminuric Korean adults who underwent voluntary health screenings. We used a generalized additive model to examine the threshold level for relationship between serum 25-hydroxyvitamin D [25(OH)D] and urinary-albumin creatinine ratio (UACR) levels. We conducted multivariate logistic regression for high-normal UAE (UACR, 10–29 mg/g), according to various categories of vitamin D status.
The generalized additive model confirmed a non-linear relationship between serum 25(OH)D and UACR levels, and the threshold concentration of 25(OH)D was 8.0 ng/mL after multivariate adjustment. Comparing subjects who fell into the lowest category of serum 25(OH)D levels with subjects who were in the reference range (the highest category), we observed that the multivariate adjusted odds ratio (OR) for high-normal UAE was significantly increased, regardless of the criteria used to categorize vitamin D levels: OR of the 1st quartile over the 4th quartile, 1.20 (95% CI, 1.04-1.39); OR of the 1.0-4.9th percentile over the 50-100th percentile, 1.56 (95% CI, 1.25-1.93); and OR of vitamin D deficiency group over vitamin D sufficiency group, 1.28 (95% CI, 1.08-1.52).
We demonstrated that there was an inverse relationship between serum 25(OH)D less than 8.0 ng/mL and UACR in normoalbuminuric subjects, suggesting that severe vitamin D deficiency could cause an increase in UAE in subjects with normoalbuminuria.
PMCID: PMC4079922  PMID: 24957097
Epidemiology; Low-grade albuminuria; Threshold; Vitamin D deficiency
9.  Long-term prognosis of clinically early IgA nephropathy is not always favorable 
BMC Nephrology  2014;15:94.
The long-term prognosis of clinically early IgA nephropathy (IgAN) patients remains to be clarified. We investigated the long-term outcomes of IgAN patients with an apparently benign presentation and evaluated prognostic factors for renal survival.
We included patients with biopsy-proven IgAN who had estimated glomerular filtration rates (eGFR) ≥60 mL/min/1.73 m2, normal blood pressure, and proteinuria <0.5 g/day at the time of biopsy. The primary outcome was progression to end-stage renal disease (ESRD). The secondary outcome was a 50% increase in serum creatinine level or an increase in proteinuria to >1 g/day.
The analysis included 153 patients who met the inclusion criteria. At diagnosis, their median systolic blood pressure was 120 (110–130) mmHg, eGFR was 85.9 (74.9–100.1) mL/min/1.73 m2, and proteinuria was 0.25 (0.13–0.38) g/day. Of these, 4 patients died and 6 reached ESRD. The 30-year renal survival rate was 85.5%. Three patients had increased serum creatinine levels and 11 developed proteinuria. Remission was observed in 35 (22.9%) patients. A moderate or severe degree of interstitial fibrosis (adjusted odd ratio [OR] 5.93, 95% confidence interval [CI] 1.44–24.45, P = 0.014) and hypoalbuminemia (adjusted OR 6.18, 95% CI 1.20–31.79, P = 0.029) were independent predictors of the secondary outcome.
This study showed that the prognosis of early IgAN was not always favorable, even resulting in progression to ESRD in some cases. Hypoalbuminemia and interstitial fibrosis should also be considered important prognostic factors in clinically early IgAN patients.
PMCID: PMC4070337  PMID: 24946688
IgA nephropathy; Interstitial fibrosis; Progression of renal failure
10.  Dose selection method for pharmacokinetic study in hemodialysis patients using a subpharmacological dose: oseltamivir as a model drug 
BMC Nephrology  2014;15:46.
Dose selection is an important step in pharmacokinetic (PK) studies of hemodialysis patients. We propose a simulation-based dose-selection method for PK studies of hemodialysis patients using a subpharmacological dose of oseltamivir as a model drug.
The concentrations of oseltamivir and its active metabolite, oseltamivir carboxylate (OC), were measured by liquid chromatography-tandem mass spectrometry. To determine a low oseltamivir dose exhibiting PK linearity, a pilot low dose determination investigation (n = 4) was performed using a single administration dose-escalation study. After the dose was determined, a low dose study (n = 10) was performed, and the optimal dose required to reach the hypothetical target OC exposure (area under the concentration-time curve [AUC] of 60,000 ng · hr/mL) was simulated using a nonparametric superposition method. Finally, observed PKs at the optimal dose were compared to the simulated PKs to verify PK predictability.
In the pilot low dose determination study, 2.5 mg of oseltamivir was determined to be the low dose. Subsequently, we performed a single-dose PK study with the low oseltamivir dose in an additional group of 10 hemodialysis patients. The predicted AUClast of OC following continuous oseltamivir doses was simulated, and 35 mg of oseltamivir corresponded to the hypothetical target AUClast of OC. The observed PK profiles of OC at a 35-mg oseltamivir dose and the simulated data based on the low dose study were in close alignment.
The results indicate that the proposed method provides a rational approach to determine the proper PK dose in hemodialysis patients.
PMCID: PMC3995549  PMID: 24636040
Hemodialysis; Pharmacokinetics; Drug; Dosage
11.  Non-Linear Relationship between Serum 25-Hydroxyvitamin D and Hemoglobin in Korean Females: The Korean National Health and Nutrition Examination Survey 2010–2011 
PLoS ONE  2013;8(8):e72605.
Anemia and vitamin D deficiency are both important health issues; however, the nature of the association between vitamin D and either hemoglobin or anemia remains unresolved in the general population.
Data on 11,206 adults were obtained from the fifth Korean National Health and Nutritional Examination Survey. A generalized additive model was used to examine the threshold level for relationship between serum 25-hydroxyvitamin D [25(OH)D] and hemoglobin levels. A multivariate logistic regression for anemia was conducted according to 25(OH)D quintiles. All analyses were stratified according to sex and menstrual status.
The generalized additive model confirmed a threshold 25(OH)D level of 26.4 ng/mL (male, 27.4 ng/mL; premenopausal females, 11.8 ng/mL; postmenopausal females, 13.4 ng/mL). The threshold level affected the pattern of association between 25(OH)D and anemia risk: the odds ratio of the 1st quintile but not the 2nd, 3rd, and 4th quintiles were significantly different from the 5th quintile in both premenopausal and postmenopausal females, however there was no obvious trend in males.
This population-based study demonstrated a non-linear relationship with a threshold effect between serum 25(OH)D and hemoglobin levels in females. Further interventional studies are warranted to determine whether the appropriate level of hemoglobin can be achieved by the correction of vitamin D deficiency.
PMCID: PMC3755993  PMID: 24015265
12.  Dipeptidyl peptidase IV inhibitor attenuates kidney injury in rat remnant kidney 
BMC Nephrology  2013;14:98.
The inhibition of dipeptidyl peptidase (DPP) IV shows protective effects on tissue injury of the heart, lung, and kidney. Forkhead box O (FoxO) transcriptional factors regulate cellular differentiation, growth, survival, the cell cycle, metabolism, and oxidative stress. The aims of this study were to investigate whether the DPP IV inhibitor sitagliptin could attenuate kidney injury and to evaluate the status of FoxO3a signaling in the rat remnant kidney model.
Rats were received two-step surgery of 5/6 renal mass reduction and fed on an oral dose of 200 mg/kg/day sitagliptin for 8 weeks. Before and after the administration of sitagliptin, physiologic parameters were measured. After 8 weeks of treatment, the kidneys were harvested.
The sitagliptin treatment attenuated renal dysfunction. A histological evaluation revealed that glomerulosclerosis and tubulointerstitial injury were significantly decreased by sitagliptin. Sitagliptin decreased DPP IV activity and increased the renal expression of glucagon-like peptide-1 receptor (GLP-1R). The subtotal nephrectomy led to the activation of phosphatidylinositol 3-kinase (PI3K)-Akt and FoxO3a phosphorylation, whereas sitagliptin treatment reversed these changes, resulting in PI3K-Akt pathway inactivation and FoxO3a dephosphorylation. The renal expression of catalase was increased and the phosphorylation of c-Jun N-terminal kinase (JNK) was decreased by sitagliptin. Sitagliptin treatment reduced apoptosis by decreasing cleaved caspase-3 and −9 and Bax levels and decreased macrophage infiltration.
In rat remnant kidneys, DPP IV inhibitor attenuated renal dysfunction and structural damage. A reduction of apoptosis, inflammation and an increase of antioxidant could be suggested as a renoprotective mechanism together with the activation of FoxO3a signaling. Therefore, DPP IV inhibitors might provide a promising approach for treating CKD, but their application in clinical practice remains to be investigated.
PMCID: PMC3648384  PMID: 23621921
Dipeptidyl peptidase IV; Glucagon-like peptide-1 receptor; FoxO3a; Sitagliptin; Kidney injury
13.  Mortality of IgA Nephropathy Patients: A Single Center Experience over 30 Years 
PLoS ONE  2012;7(12):e51225.
Research on the prognosis of IgA nephropathy (IgAN) has focused on renal survival, with little information being available on patient survival. Hence, this investigation aimed to explore long-term patient outcome in IgAN patients. Clinical and pathological characteristics at the time of renal biopsy were reviewed in 1,364 IgAN patients from 1979 to 2008. The outcomes were patient death and end stage renal disease (ESRD) progression. Overall, 71 deaths (5.3%) and 277 cases of ESRD (20.6%) occurred during 13,916 person-years. Ten-, 20-, and 30-year patient survival rates were 96.3%, 91.8%, and 82.7%, respectively. More than 50% patient deaths occurred without ESRD progression. Overall mortality was elevated by 43% from an age/sex-matched general population (GP) (standardized mortality ratio [SMR], 1.43; 95% confidence interval [CI], 1.04–1.92). Men had comparable mortality to GP (SMR, 1.22; 95% CI, 0.82–1.75), but, in women, the mortality rate was double (SMR, 2.17; 95% CI, 1.21–3.57). Patients with renal risk factors such as initial renal dysfunction (estimated glomerular filgration rate <60 ml/min per 1.73m2; SMR, 1.70; 95% CI, 1.13–2.46), systolic blood pressure ≥140 mmHg (SMR, 1.88; 95% CI, 1.19–2.82) or proteinuria ≥1 g/day (SMR, 1.66; 95% CI, 1.16–2.29) had an elevated mortality rate. Patients with preserved renal function, normotension, and proteinuria <1 g/day, however, had a similar mortality rate to GP. When risk stratification was performed by counting the number of major risk factors present at diagnosis, low-risk IgAN patients had a mortality rate equal to that of GP, whereas high-risk patients had a mortality rate higher than that of GP. This investigation demonstrated that overall mortality in IgAN patients was higher than that of GP. Women and patients with renal risk factors had a higher mortality than that of GP, Therefore, strategies optimized to alleviate major renal risk factors are warranted to reduce patient mortality.
PMCID: PMC3514188  PMID: 23226568
14.  The association of moderate renal dysfunction with impaired preference-based health-related quality of life: 3rd Korean national health and nutritional examination survey 
BMC Nephrology  2012;13:19.
Only a few large-scale studies have investigated the association between health-related quality of life (HRQOL) and renal function. Moreover, the HRQOL of patients with moderate renal dysfunction is frequently underestimated by healthcare providers. This study assessed the impact of renal function on preference-based HRQOL in Korean adult population.
We analyzed data for 5,555 adults from the 3rd Korean National Health and Nutritional Examination Survey 2005. The EuroQol-5D (EQ-5D) utility score was used to evaluate HRQOL. The study subjects were stratified into three groups based on their estimated glomerular filtration rates (eGFRs): ≥ 90.0, 60.0-89.9 and 30.0-59.9 mL/min/1.73 m2. Individuals with advanced renal dysfunction were excluded from the analysis.
The proportions of participants who reported problems in each of the five EQ-5D dimensions increased significantly with decreasing eGFR. However, a significant decrease in the EQ-5D utility score was observed among participants with an eGFR of 30.0-59.9 mL/min/1.73 m2. Participants with an eGFR of 30.0-59.9 mL/min/1.73 m2 had an almost 1.5-fold higher risk of impaired health utility (the lowest quartile of EQ-5D utility score) compared with those participants with eGFRs ≥ 90.0 mL/min/1.73 m2, after adjustment for age, gender, health-related behaviors, socioeconomic and psychological variables, and other comorbidities. Among the five dimensions of the EQ-5D, an eGFR of 30.0-59.9 mL/min/1.73 m2 was an independent determinant of self-reported problems in the mobility and pain/discomfort dimensions.
Although age affects the association between renal dysfunction and the EQ-5D, moderate renal dysfunction seems to be an important determinant of impaired health utility in a general population and may affect the mobility and pain/discomfort dimensions of health utility.
PMCID: PMC3404912  PMID: 22530944
Chronic kidney disease; EuroQol-5D; Preference-based health utility
15.  Outcome of Early Initiation of Peritoneal Dialysis in Patients with End-Stage Renal Failure 
Journal of Korean Medical Science  2012;27(2):170-176.
Recent studies reported that early initiation of hemodialysis may increase mortality. However, studies that assessed the influence of early initiation of peritoneal dialysis (PD) yielded controversial results. In the present study, we evaluated the prognosis of early initiation of PD on the various outcomes of end stage renal failure patients by using propensity-score matching methods. Incident PD patients (n = 491) who started PD at SNU Hospital were enrolled. The patients were divided into 'early starters (n = 244)' and 'late starters (n = 247)' on the basis of the estimated glomerular filtration rate (eGFR) at the start of dialysis. The calculated propensity-score was used for one-to-one matching. After propensity-score-based matching (n = 136, for each group), no significant differences were observed in terms of all-cause mortality (P = 0.17), technique failure (P = 0.62), cardiovascular event (P = 0.96) and composite event (P = 0.86) between the early and late starters. Stratification analysis in the propensity-score quartiles (n = 491) exhibited no trend toward better or poorer survival in terms of all-cause mortality. In conclusion, early commencement of PD does not reduce the mortality risk and other outcomes. Although the recent guidelines suggest that initiation of dialysis at higher eGFR, physicians should not determine the time to initiate PD therapy simply rely on the eGFR alone.
PMCID: PMC3271290  PMID: 22323864
Peritoneal Dialysis; End Stage Renal Failure; Dialysis Initiation; Propensity Score Match; Outcome; Survival
16.  Lower Residual Renal Function is a Risk Factor for Depression and Impaired Health-Related Quality of Life in Korean Peritoneal Dialysis Patients 
We retrospectively evaluated demographic and biochemical parameters associated with depression and health-related quality of life (HRQOL) in maintenance peritoneal dialysis (PD) patients. This study included 105 patients maintaining PD at Seoul National University Hospital. Data were collected from electronic medical record. Korean Beck's Depression Inventory and Korean version of Kidney Disease Quality of Life short form, version 1.3 were used to evaluate depression and HRQOL, respectively. Moderate to severe depression was found in 24.8% of patients. Patients with lower normalized protein equivalent of nitrogen appearance (nPNA) (< 1.2 g/kg/day), lower weekly renal Kt/Vurea (< 0.2), and lower serum albumin level (≤ 4.0 g/dL) were associated with depression (P < 0.05). Among them, lower weekly renal Kt/Vurea was the only independent risk factor associated with depression (OR = 3.1, P = 0.007). Depressed patients showed significantly lower scores in every dimension of HRQOL (P < 0.001). Lower weekly renal Kt/Vurea (β = 0.24, P = 0.005) and lower nPNA (β = 0.15, P = 0.03) were the independent risk factors associated with lower kidney dialysis component summary, whereas lower plasma hemoglobin level was the consistent risk factor for lower physical component summary (β = 0.22, P = 0.03) and mental component summary (β = 0.22, P = 0.01). Depression is a prevalent psychological problem in PD population. Residual renal function is the most important factor associated with depression and impaired HRQOL in PD patients.
PMCID: PMC3247777  PMID: 22219616
Peritoneal Dialysis; Depression; Health-Related Quality of Life; Residual Renal Function; Beck's Depression Inventory; KDQOL-SF
17.  Anti-Proteinuric Effect of Sulodexide in Immunoglobulin A Nephropathy 
Yonsei Medical Journal  2011;52(4):588-594.
We conducted a multi-center randomized double-blind study to determine the effects of 6-month therapy with sulodexide on urinary protein excretion in patients with idiopathic Immunoglobulin A (IgA) nephropathy.
Materials and Methods
A total of seventy-seven patients participated in the study. They were randomly allocated to one of three groups: sulodexide 75 mg or 150 mg daily or the placebo for 6 months. The primary end point was the achievement, at 6 months, of at least 50% reduction in urine protein/creatinine ratio (UPCR) from the baseline value.
At 6 months, the primary end point was achieved by 12.5% of the patients assigned to the placebo, 4.0% of the patients assigned to sulodexide 75 mg daily and 21.4% of those assigned to 150 mg (p=0.308). Treatment with sulodexide 150 mg daily for 6 months significantly reduced log UPCR from 6.38±0.77 at baseline to 5.98±0.94 at 6 months (p=0.045), while treatment with sulodexide 75 mg daily and placebo did not.
A 6-month treatment with sulodexide did not achieve 50% reduction of urinary protein excretion in IgA nephropathy patients, but showed a tendency to increase the time-dependent anti-proteinuric effect. Therefore, long-term clinical trials on a larger scale are warranted to elucidate the hypothesis that sulodexide affords renal protection in IgA nephropathy patients.
PMCID: PMC3104455  PMID: 21623600
IgA nephropathy; sulodexide; proteinuria
18.  Improvement in Erythropoieis-stimulating Agent-induced Pure Red-cell Aplasia by Introduction of Darbepoetin-α When the Anti-erythropoietin Antibody Titer Declines Spontaneously 
Journal of Korean Medical Science  2010;25(11):1676-1679.
Anti-erythropoietin antibodies usually cross-react with all kinds of recombinant erythropoietins; therefore, erythropoiesis-stimulating agent (ESA)-induced pure red-cell aplasia (PRCA) is not rescued by different ESAs. Here, we present a case of ESA-induced PRCA in a 36-yr-old woman with chronic kidney disease, whose anemic condition improved following reintroduction of darbepoetin-α. The patient developed progressive, severe anemia after the use of erythropoietin-α. As the anemia did not improve after the administration of either other erythropoietin-α products or erythropoietin-β, all ESAs were discontinued. Oxymetholone therapy failed to improve the transfusion-dependent anemia and a rechallenge with ESAs continuously failed to obtain a sustained response. However, her anemia improved following reintroduction of darbepoetin-α at 3 yr after the initial diagnosis. Interestingly, anti-erythropoietin antibodies were still detectable, although their concentration was too low for titration. In conclusion, darbepoetin-α can improve ESA-induced PRCA when the anti-erythropoietin antibody titer declines and its neutralizing capacity is lost.
PMCID: PMC2967010  PMID: 21060762
Red-Cell Aplasia, Pure; Kidney Failure, Chronic; Erythropoietin, Recombinant; Darbepoetin-alfa
19.  Clinicopathologic Characteristics of IgA Nephropathy with Steroid-responsive Nephrotic Syndrome 
Journal of Korean Medical Science  2009;24(Suppl 1):S44-S49.
Nephrotic syndrome is an unusual manifestation of IgA Nephropathy (IgAN). Some cases respond to steroid treatment. Here we describe a case-series of IgAN patients with steroid-responsive nephrotic syndrome. Twelve patients with IgAN with steroid-responsive nephrotic syndrome were evaluated and followed up. All patients presented with generalized edema. Renal insufficiency was found in two patients. The renal biopsy of eight patients revealed wide foot process effacement in addition to the typical features of IgAN. They showed complete remission after steroid therapy. Seven relapses were reported in five patients; six of the relapsed cases responded to steroid therapy. Compared with steroid-non-responsive patients, the patients with steroid-responsive nephrotic syndrome had shorter symptom duration, more weight gain, more proteinuria, and lower histologic grade than did those that had steroid-non-responsive nephrotic syndrome at presentation. None of the responders progressed to end stage renal disease, whereas five (38%) non-responders required dialysis or renal transplantation. Patients with IgAN who have steroid-responsive nephrotic syndrome likely have both minimal change disease and IgAN. The clinical features of sudden onset of generalized edema, initial heavy proteinuria and initial severe hypoalbuminemia might help identify the subset of patients, especially in low grade IgAN.
PMCID: PMC2633194  PMID: 19194561
Glomerulonephritis, IGA; Nephrosis, Lipoid; Nephrotic Syndrome; Steroids
20.  Effects of Thiazide on the Expression of TRPV5, Calbindin-D28K, and Sodium Transporters in Hypercalciuric Rats 
Journal of Korean Medical Science  2009;24(Suppl 1):S161-S169.
TRPV5 is believed to play an important role in the regulation of urinary calcium excretion. We assessed the effects of hydrochlorothiazide (HCTZ) on the expression of TRPV5, calbindin-D28K, and several sodium transporters in hypercalciuric rats. Sprague-Dawley rats were divided into 4 groups; control, HCTZ, high salt, and high salt with HCTZ group in experiment 1; control, HCTZ, high calcium (Ca), and high Ca with HCTZ group in experiment 2. To quantitate the expression of TRPV5, calbindin-D28K, and sodium transporters, western blotting was performed. In both experiments, HCTZ significantly decreased urinary calcium excretion. TRPV5 protein abundance decreased in all hypercalciuric rats, and restored by HCTZ in both high salt with HCTZ and high Ca with HCTZ group. Calbindin-D28K protein abundance increased in the high salt and high salt with HCTZ groups, but did not differ among groups in experiment 2. Protein abundance of NHE3 and NKCC2 decreased in all hypercalciuric rats, and were restored by HCTZ in only high Ca-induced hypercalciuric rats. In summary, protein abundance of TRPV5, NHE3, and NKCC2 decreased in all hypercalciuric rats. The hypocalciuric effect of HCTZ is associated with increased protein abundance of TRPV5 in high salt or calcium diet-induced hypercalciuric rats.
PMCID: PMC2633179  PMID: 19194547
Hypercalciuria; Thiazides; Transporters
21.  The Mildly Elevated Serum Bilirubin Level is Negatively Associated with the Incidence of End Stage Renal Disease in Patients with IgA Nephropathy 
Journal of Korean Medical Science  2009;24(Suppl 1):S22-S29.
Oxidative stress plays various roles in the development and progression of IgA nephropathy, while bilirubin is known as a potent antioxidant. We therefore hypothesized that serum bilirubin would be associated with renal prognosis in IgA nephropathy. The study subjects comprised 1,458 adult patients with primary IgA nephropathy in Korea. We grouped patients according to the following quartile levels of bilirubin: <0.4 mg/dL (Q1), 0.4-0.5 mg/dL (Q2), 0.6-0.7 mg/dL (Q3), and >0.8 mg/dL (Q4). The outcome data were obtained from the Korean Registry of end-stage renal disease (ESRD). Eighty patients (5.5%) contracted ESRD during a mean follow-up period of 44.9 months. The ESRD incidences were 10.7% in Q1, 8.2% in Q2, 2.8% in Q3, and 2.8% in Q4 (p<0.001). The relative risk of ESRD compared to that in Q1 was 0.307 (95% confidence interval [CI], 0.126-0.751) in Q3 and 0.315 (95% CI, 0.130-0.765) in Q4. The differences of ESRD incidence were greater in subgroups of males and of patients aged 35 yr or more, with serum albumin 4.0 g/dL or more, with normotension, with eGFR 60 mL/min/1.73 m2 or more, and with proteinuria less then 3+ by dipstick test. In conclusion, higher bilirubin level was negatively associated with ESRD incidence in IgA nephropathy.
PMCID: PMC2633177  PMID: 19194557
Bilirubin; Glomerulonephritis, IGA; Kidney Failure, Chronic
22.  Altered Renal Sodium Transporter Expression in an Animal Model of Type 2 Diabetes Mellitus 
Journal of Korean Medical Science  2007;22(6):1034-1041.
Hemodynamic factors play an important role in the development and/or progression of diabetic nephropathy. We hypothesized that renal sodium transporter dysregulation might contribute to the hemodynamic alterations in diabetic nephropathy. Otsuka Long Evans Tokushima Fatty (OLETF) rats were used as an animal model for type 2 diabetes. Long Evans Tokushima (LETO) rats were used as controls. Renal sodium transporter regulation was investigated by semiquantitative immunoblotting and immunohistochemistry of the kidneys of 40-week-old animals. The mean serum glucose level in OLETF rats was increased to 235±25 mg/dL at 25 weeks, and the hyperglycemia continued up to the end of 40 weeks. Urine protein/creatinine ratios were 10 times higher in OLETF rats than in LETO rats. At 40th week, the abundance of the epithelial sodium channel (ENaC) β-subunit was increased in OLETF rats, but the abundance of the ENaC γ-subunit was decreased. No significant differences were observed in the ENaC α-subunit or other major sodium transporters. Immunohistochemistry for the ENaC β-subunit showed increased immunoreactivity in OLETF rats, whereas the ENaC γ-subunit showed reduced immunoreactivity in these rats. In OLETF rats, ENaC β-subunit upregulation and ENaC γ-subunit downregulation after the development of diabetic nephropathy may reflect an abnormal sodium balance.
PMCID: PMC2694262  PMID: 18162719
Diabetic Nephropathies; Rats, Inbred OLETF; Sodium-Hydrogen Exchanger 3; Bumetanide Sensitive NaK2Cl Cotransporter; Thiazide Sensitive Nacl Cotransporter; Epithelial Sodium Channel
23.  MCP-1 and RANTES Polymorphisms in Korean Diabetic End-Stage Renal Disease 
Journal of Korean Medical Science  2007;22(4):611-615.
Macrophage infiltration has been observed in the renal biopsy specimens of diabetic nephropathy (DN), and hyperglycemic state stimulates the renal expression of RANTES (regulated upon activation, normal T-cell expressed and secreted) and MCP-1 (monocyte chemoattractant protein-1). Upregulation of RANTES and MCP-1 with infiltrating macrophages may play a crucial role in the development and progression of DN. Genetic polymorphisms of RANTES and its receptors were reported to be independent risk factors for DN. We genotyped single nucleotide polymorphism (SNPs) in the MCP-1 G-2518A, CCR2 G46295A, RANTES C-28G and G-403A in 177 diabetic end-stage renal disease (ESRD) patients and 184 patients without renal involvement (controls) in order to investigate the effects of these SNPs on DN in Korean patients with type 2 DM. There were no differences in the frequencies of SNPs and the distribution of haplotypes of RANTES promoter SNPs between two groups. In conclusion, there were no associations of MCP-1, CCR2 and RANTES promoter SNPs with diabetic ESRD in Korean population. Prospective studies with clearly-defined, homogenous cohorts are needed to confirm the effect of these genetic polymorphisms on DN.
PMCID: PMC2693807  PMID: 17728497
Diabetic Nephropathies; Kidney Failure, Chronic; Monocyte Chemoattractant Proteins; RANTES; Polymorphism, Single Nucleotide Polymorphisms; Diabetes Mellitus, Type 2

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