Elevated Cadmium Levels in Dialysis Patients and Their Links to Inflammation, Oxidative Stress, and Malnutrition

Growing a peritoneal dialysis program: A single‐center experience

Patient survival on dialysis in Korea: a different story?

♦ Oxidative stress plays an important role in the pathogenesis of cardiovascular disease (CVD). Central blood pressure (BP) is thought to be more relevant than peripheral BP for the pathogenesis of CVD. Advanced oxidation protein products (AOPP) are markers of oxidative stress. This study investigated the relationship between AOPP and central BP in peritoneal dialysis (PD) patients. ♦ In a cross-sectional study of 75 PD patients (67% men), we analyzed two oxidative stress markers, AOPP (modified assay, mAOPP, correcting for the impact of triglycerides) and pentosidine, three inflammation markers, interleukin-6 (IL-6), tumor necrosis factor (TNF), and high-sensitivity C-reactive protein (hs-CRP). All patients underwent measurement of central systolic blood pressure (SBP) and diastolic blood pressure (DBP) by applanation tonometry. ♦ Patients with mAOPP levels above the median had a higher central SBP and DBP than those below the median values. In univariate analysis, the levels of mAOPP associated with central SBP and central DBP. Multiple regression analysis, adjusting for age, gender, diabetes, CVD, protein-energy wasting (PEW), hs-CRP and extracellular water by multi-frequency bioimpedance or N-terminal prohormone of brain natriuretic peptide (NT-proBNP), confirmed independent associations between mAOPP and central SBP and central DBP respectively. ♦ The mAOPP level is independently associated with the central SBP and DBP in PD patients. This finding suggests that oxidative stress may be involved in the pathogenesis of hypertension or that hypertension itself or factors associated with hypertension such as fluid overload may have an additional effect on oxidative stress in PD patients.

Increased oxidative stress in dialysis patients is thought to contribute to increased mortality; however, confirmatory data are scarce. We analyzed the serum concentration of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative stress, in relation to mortality in hemodialysis (HD) and peritoneal dialysis (PD) patients. Serum 8-OHdG, interleukin 6 (IL-6), other biochemical markers, Davies comorbidity score, and protein-energy wasting (PEW) were assessed in 303 prevalent patients treated with HD (n = 220; age: 63 ± 14 years) or PD (n = 83; age: 64 ± 14 years). Mortality was assessed after a median follow-up of 31 months. The median (25th - 75th percentile) concentration of 8-OHdG was higher in HD than in PD patients: 1.3 ng/mL (0.9 - 1.8 ng/mL) versus 0.5 ng/mL (0.4 - 0.6 ng/mL), p < 0.001. The HD modality (standard β = 0.57, p < 0.001) and dialysis vintage (standard β = 0.12, p = 0.02) were independent predictors of serum 8-OHdG in a multivariable linear regression model including age, sex, body mass index, dialysis modality (HD or PD), preceding time on dialysis (dialysis vintage), PEW, comorbidity score, IL-6, and use of angiotensin converting-enzyme inhibitors or angiotensin II receptor blockers or statins. During follow-up, 107 patients died. In multivariable Cox regression models including all 303 patients and adjusted for age, sex, body mass index, dialysis modality, dialysis vintage, and comorbidity score, 8-OHdG was significantly associated with all-cause mortality (adjusted hazard ratio: 1.40; 95% confidence limits: 1.05, 1.87 for 1 standard deviation increase of 8-OHdG). In subgroup analyses according to dialysis modality, 8-OHdG was associated with mortality in HD patients but not in PD patients. Oxidative stress as assessed by 8-OHdG is an independent predictor of all-cause mortality in dialysis patients. This association was seen in HD patients, but no such association could be demonstrated for PD patients.

Antibody response and safety of COVID-19 vaccine in peritoneal dialysis patients

Plasma homocysteine (Hcy) is an independent risk factor for cardiovascular disease. High levels of plasma Hcy have been observed in end-stage renal disease patients. Few studies have compared peritoneal dialysis (PD) and hemodialysis (HD) patients and few data are available on erythrocyte folate (ery-F) levels in dialysis patients. To evaluate plasma Hcy concentrations, vitamin B12 (B12), and folate status in dialysis patients; to analyze the possible causes of high Hcy levels; to follow up changes in folate and B12 concentrations after 6 months. A cross-sectional observational study. Nephrology division and laboratory of hematology in a university and clinical research hospital. The study included 82 patients treated with PD for 37 + 37 months and 70 patients treated with HD for 136 + 95 months. LABORATORY METHODS: Plasma Hcy was measured by the immunoenzymatic IMx Hcy FPIA method (Abbott Laboratories, Diagnostic Division, Abbott Park, IL, U.S.A.), serum folate (s-F) and ery-F by the Stratus folate fluorometric enzyme-linked assay, and B12 by the Stratus vitamin B12 fluorometric enzyme-linked assay (DADE-Behring, Newark, DE, U.S.A.). Ninety-six percent of PD and 97% of HD patients had Hcy levels above the cutoff (13.5 micromol/L). Homocysteine level was higher in HD than in PD patients, while the prevalence of hyperhomocysteinemia was similar with the two techniques. Erythrocyte folate was significantly higher in PD (1333 +/- 519 pmol/L) than in HD (1049 +/-511 pmol/L, p < 0.01). Statistically significant correlations were observed between Hcy and B12, s-F, ery-F, and dialysis duration. Multivariate analysis showed a strong correlation between s-F and Hcy. After 6 months there were no differences in Hcy, B12, s-F, and ery-F levels. Plasma Hcy levels were high in more than 95% of our dialysis patients, with no relation to the type of dialysis. Vitamin B12 and folate were normal in the majority of our patients. However, serum folate was the major determinant of Hcy levels. Such a relation between Hcy and folate suggests that levels of folate within the reference interval are inadequate for dialysis patients.

The relationships among serum Apelin, Asymmetric- dimethylarginine (ADMA), N-terminal probrain natriureticpeptide (NT-proBNP) levels, and blood pressures in dialysis patients are not well known. Age and sex matched 30 hemodialysis (HD), 30 peritoneal dialysis (PD) patients, and 20 healthy controls were recruited. Serum apelin-36, ADMA, NT-proBNP levels, and blood pressures of both patients and healthy controls were measured and compared. Serum ADMA and Apelin levels in HD patients were significantly higher than in PD patients. In multiple regression analyses the predictors of higher serum apelin levels were higher BMI, higher ADMA and lower systolic blood pressure. The predictors of serum ADMA levels were being on HD. The predictors of serum NT-proBNP levels were lower serum albumin and higher systolic blood pressure. Being on HD is a predictor of high ADMA levels. HD might be less effective on ADMA removal than PD. It seems that higher serum apelin levels related with lower sytolic blood pressure levels, whereas higher NT-proBNP levels related with higher sytolic blood pressure levels indicating potential roles as independent prognostic factors for systolic hypertension in dialysis patients.

Inflammation and oxidative stress (OS) are cardiovascular risk factors in patients with chronic kidney disease. N-acetylcysteine (NAC) is a thiol-containing antioxidant with anti-inflammatory properties and has been shown to reduce the number of cardiovascular events in hemodialysis patients. The current study aimed to determine the effect of oral NAC (2 x 600 mg/daily) on plasma levels of inflammatory and OS markers in peritoneal dialysis (PD) patients. We performed a placebo-controlled study over 8 weeks in 30 patients (40% males, age 52 +/- 13 years) on regular PD. Before the study was started, the patients were divided into 2 groups of 15 patients matched for age and gender. 22 patients completed the study (12 on NAC, 10 on placebo). Proinflammatory cytokines [high-sensitivity C-reactive protein, interleukin-6 (IL-6), tumor necrosis factor-alpha, and pentraxin 3] and markers of OS (pentosidine, advanced oxidation protein products, homocysteine, glutathione, asymmetric dimethylarginine, and free sulfhydryls) were measured before and after treatment with NAC. Treatment with NAC for 8 weeks increased mean baseline plasma NAC levels from 2.6 to 24.8 mumol/L (p = 0.007). This intervention, which caused no side effects, significantly diminished IL-6 levels, from 9.4 (4.5 - 31) to 7.6 (4.9 - 13.5) pg/mL (p = 0.006), whereas no such changes were observed in the placebo group. NAC treatment did not significantly affect the other inflammatory and OS markers. Short-term oral NAC treatment resulted in reduction of circulating IL-6, suggesting that such treatment could be a useful strategy in blunting the inflammatory response in PD patients.

This month, I review three recent studies from the literature addressing issues important to the care of the peritoneal dialysis (PD) patient. A number of core questions related to modality choice center on whether PD offers specific patient-centered outcomes benefits or whether specific PD prescriptions might result in improved hard (non-surrogate) patient-centered outcomes. When considering whether an intervention results in changes in outcomes, the randomized controlled trial (RCT) has been considered the “holy grail,” as when it is performed rigorously the opportunity for the introduction of bias or confounding is minimized. However, the challenges of conducting RCTs with dialysis modality choice are well documented.1 In this literature watch, I review an RCT that highlights additional limitations that might arise from a well-designed RCT of the small size typical of many RCTs in nephrology. Specifically, I consider what might happen if the baseline risk of individuals randomly assigned to the experimental and control treatments differ significantly. Bias is reduced by randomization if sufficient numbers of patients are included in the study such that by chance alone all important baseline prognostic (known and unknown) factors that might influence the outcome are distributed equally to both groups, and that the groups differ only in the intervention under investigation. In small RCTs the equivalence of prognostic characteristics in each arm of the study cannot be assumed.2, 3 Additionally, when addressing the issue of whether a particular clinical finding might predict poorer outcomes or even result in harm, the RCT is not the ideal study design. To identify a factor as potentially harmful and likely to be causal of an adverse outcome, observational findings evaluated in the context of the Bradford-Hill considerations are preferred. In addition to the ethical constraints on conducting an RCT on a question of causation or harm, well-designed observational/epidemiological studies may be most informative because they are conducted under real-world conditions and may include patients expressing the full spectrum of baseline risk. Here too the size of the study population is likely to matter. In this literature watch I review two recent observational studies that interrogate patient databases to provide evidence about potential harm related to a clinical feature or the lack thereof. The first study evaluates the use of PD for initiation of unplanned dialysis compared with an initiation with hemodialysis (HD). In the second observational study, a study exploiting a very large observational database, the authors investigate whether depressed serum albumin levels are similarly associated with mortality in HD and PD patients. Citation: Takatori Y, Akagi S, Sugiyama H, et al. Icodextrin increases technique survival rates in peritoneal dialysis patients with diabetic nephropathy by improving body fluid management: A randomized controlled trial. Clin J Am Soc Nephrol. 2011;6:1337–1344. Analysis: Takatori and colleagues report the results of an RCT evaluating whether use of icodextrin as the osmotic agent in PD fluid results in preservation of the PD technique in patients with newly diagnosed end-stage renal disease (ESRD) and diabetes. They define technique preservation largely around the ability of the PD to adequately remove fluid.4, 5 As a secondary outcome, they evaluated preservation of renal function and peritoneal membrane function. It has been established in multiple clinical trails that use of icodextrin in place of dextrose solutions (2.5%) results in improved net ultrafiltration and control of volume. The novel finding in this study is that these previously reported findings extend to incident dialysis patients with diabetes. The study was pre-registered in the Japanese clinical trials registry (JPRN registry WMIN00001040) with the control of volume as the primary outcome and with the intended enrollment of 100 patients. The primary finding of this study was that icodextrin resulted in preservation of function defined as the ability to achieve adequate volume removal when compared with standard PD with 2.5% Dianeal. Validity and threats to validity: The optimal study design to assess a question regarding a therapeutic intervention remains the RCT or a systematic review of high-quality RCTs. When well conducted, an RCT can reduce the risk of bias. There are significant limitations to RCTs when performed less than optimally that may distort the findings reported. Some of these are widely recognized and include non-masking of group assignment, non-blinding leading to secondary interventions impacting outcomes, misclassification of outcomes, and so on. Recently, M.W. Walsh and colleagues have attempted to quantify the risk of important imbalances in baseline prognostic characteristics that might occur by chance in RCTs that are too small to ensure that a balance has occurred as a result of random group allocation (personal communication, June 2011). Although this study appears to be a randomized trial with concealment of allocation, a number of the features of the current study may be problematic in the interpretation of the results and their application. First, the study is very small; significantly smaller than the size indicated as necessary in the pre-study plan. No formal power calculations are included in the published report. In such a small study, if prognostic characteristics are not balanced the results might deviate significantly from the “truth.” A recalculation of the effect size using non-parametric statistical tests and changing the outcome of one subject in each group would result in a significant change of the primary finding reported. Importantly, the study is underpowered to evaluate the patient-centered outcomes of peritoneal membrane and renal function survival or any major side effects including mortality and infection. It appears that group assignment may not have been masked after the initial randomization, so that the clinicians could have intervened in other ways (e.g., education, diet) that might have influenced volume control independent of the PD fluid interventions under study. Patients in the control arm were not treated with higher percentage glucose solutions as might be the case in the U.S. for patients who failed to achieve adequate net volume removal. Application of the results and the clinical bottom line: This is a randomized controlled trial that demonstrates improvement in volume management using icodextrin to perform PD as compared with glucose-containing solutions. These findings reiterated multiple other RCT and observational trial findings in renal-failure patient populations. This study does not provide any new evidence about whether icodextrin might result in improvements in peritoneal membrane or renal survival. Before the conversion to icodextrin as the PD fluid of choice can be recommended, additional RCTs of sufficient duration and size need to be conducted. These RCTs need to determine if patient-centered outcomes can be improved upon significantly with the substitution of icodextrin for glucose-based PD solutions. Citation: Koch M, Kohnle M, Trapp R, Haastert B, Rump LC, Aker S. Comparable outcome of acute unplanned peritoneal dialysis and haemodialysis [published online ahead of print May 28, 2011]. Nephrol Dial Transplant. doi:10.1093/ndt/gfr262. Analysis: The issue of whether patients requiring urgent renal replacement therapy (RRT) can be safely managed with PD has here-to-fore not been rigorously investigated. The current study by Koch and colleagues begins to investigate this question. Ideally, an RCT comparing urgent PD to HD would most unambiguously address this question. The ability to conduct such a study despite equipoise has been restricted, however, by a strong clinical bias in the nephrology community that urgent PD cannot be conducted safely in most clinical circumstances. In such an environment, a well-designed observational study can provide evidence supporting the safety (lack of harm) of PD for urgent initiation of dialysis opening up the possibility for the appropriate RCT. Koch and colleages have exploited their unique clinical environment that allows them to provide PD urgently in a closely observed hospital setting to compare their experience with urgent PD versus urgent HD. Validity and threats to validity: As an observational study, it is impossible to exclude bias that might have influenced the results. The most important of these is a selection bias where healthier patients are systematically more likely to receive one versus the other treatments being compared. In the case of the current study, it appears that patients with more severe cardiac disease were more likely to be encouraged to choose PD as treatment. Such an imbalance would be expected to negatively impact the outcomes (mortality, hospitalization rates, etc.) amongst patients undergoing PD. The absence of an observed difference (possibly even a trend favoring PD) can be attributed to the study being underpowered. Alternatively, the absence of a difference in outcomes might be due to an imbalance in prognostic factors, which would be expected in the case of this study to make a superior treatment option such as PD appear less favorable in comparison. Statistical methods to manage the differences in important prognostic factors between the two groups are imperfect. Application of the results and the clinical bottom line: Importantly, this study may provide the necessary evidence of safety with the use of PD in urgent initiation of RRT and, therefore, open up the possibility of an RCT that will test the use of PD for emergency initiation of dialysis. The study results support the conclusion that urgent PD is safe and can be implemented equally effectively as HD for urgent initiation of RRT. If safe, a potential strategy based on PD for urgent RRT warrants further study as a means of reducing HD catheter-related infections—a significant cause of morbidity and mortality among patients new to dialysis. Treating a larger fraction of incident ESRD patients with PD might have other favorable consequences on morbidity, mortality, and quality of life yet to be determined. Citation: Mehrotra R, Duong U, Jiwakanon S, et al. Serum albumin as a predictor of mortality in peritoneal dialysis: Comparisons with hemodialysis [published online ahead of print May 19, 2011]. Am J Kidney Dis. doi:10.1053/j.ajkd.2011.03.018. Analysis: Mehrotra and colleagues exploit a large observational database to investigate whether depressed serum albumin levels are similarly associated with mortality in HD and PD patients. This study is important for two major reasons: First, if the impact of a low albumin is similar in PD and HD patients, PD patients may be placed in higher risk from excessive peritoneal protein losses and therefore, incentives and quality measures designed to prevent hypoalbuminemia might be warranted; and second, if interventions are to be tested or advocated to correct the hypoalbuminemia, the optimal target for serum albumin in PD versus HD patients should be established. This may be seen as an important precursor to studying interventions to alter albumin and to stratify the study populations according to who is most likely to benefit. In the current study, the authors have used the DaVita dataset containing the clinical parameters and outcomes for all patients receiving RRT by DaVita over a five-year period. They demonstrated a significant adjusted risk of mortality and cardiovascular mortality among all patients receiving RRT who were significantly hypoalbuminemic. Importantly, they demonstrated that the increase risk is not seen in PD patients until their serum albumin levels are observed to be below 3.8 g/dL. In contrast, in HD patients the threshold for increased risk with a depressed albumin begins at values below 4.0 g/dL. Validity and threats to validity: Prior to initiation of RCTs to test interventions to normalize serum albumin levels in patients undergoing RRT, it should be firmly established that there is an increased mortality risk associated with the lower serum albumin and whether this risk is modified by treatment modality. This study provides substantial evidence of this association and that the risk might be different for patients treated with PD versus HD. The power of this study rests in that the observations are made using a very large database representing the full spectrum of patients and their comorbidities. The interrogated database represents a long enough period of observation of sufficient duration that it would be reasonable to expect to observe an impact of hypoalbuminemia on mortality. The study cannot, however, prove a causal relationship between a low albumin and mortality. In particular, despite the large size of the population, the robustness of the data allowing for morbidity adjustments, and the precision of the estimates, confounding cannot be excluded. The authors note these limitations. It is, however, fair to note (as the authors do) that despite the limitations of the evidence, agencies that monitor healthcare quality often chose to measure quality using parameters that arise from such observational studies. The rigor of this observational study and the precision of the estimates of the threshold make the findings from this study most compelling. Application of the results and the clinical bottom line: While it is uncertain whether hypoalbuminemia itself is causal for some of the observed increased cardiovascular and all-cause mortality in ESRD patients, the current study by Mehrotra and colleageus adds significantly to our current understandings about serum albumin and nutrition in ESRD patients by more precisely describing the impact of a low albumin on different classes of ESRD patients. This study should provide evidence that will help in the design of clinical trials investigating interventions to correct low serum albumin levels in ESRD patients. Since the decision to switch patients from PD to HD is often influenced by the persistence of a lower serum albumin in PD patients, the results of this study might provide rationale—pending confirmation by an RCT—for a strategy that results in fewer patients switching off of PD and moving to HD. At a minimum, this study should raise the possibility that a slightly higher albumin achieved by switching a PD patient to HD might not translate into a significant survival advantage. This hypothesis requires further testing. The two observational studies reviewed above provide significant insights into safety and harm or risk. As such, these observational studies may be informative for clinical practice. Thus, well-conducted observational studies can provide important insights especially related to risk or harm. In contrast, the first study reviewed above highlights some of the limitations presented by RCTs of small size—sizes typical of the nephrology literature. While the RCT is the optimal study design to investigate a therapy, the RCT reviewed here demonstrates that the results of even a well-designed and well-conducted RCT may, at times, need to be interpreted with caution. The plethora of small RCTs in nephrology and the difficulty of conducting larger trials in ESRD patients should not provide justification for our failure to conduct large, sufficiently powered RCTs on many of our current therapies for the complications of ESRD.

Backgrounds: Oxidative stress (OS) and asymmetric dimethylarginine (ADMA) are accepted as nonclassical cardiovascular risk factors in end-stage renal disease patients. To clarify the role of these factors in the atherosclerotic process, we investigated if OS and ADMA are associated with common carotid artery intima media thickness (CIMT) in peritoneal dialysis (PD) patients. Methods: Thirty PD patients without known atherosclerotic disease and classical cardiovascular risk factors as well as age- and gender-matched 30 healthy individuals were included. We measured serum thiobarbituric acid-reactive substances (TBARS), malondialdehyde (MDA), advanced glycation end product (AGE), pentosidine, advanced oxidation protein products (AOPP), ADMA and CIMT in each subjects. Results: TBARS, MDA, AOPP, AGE, pentosidine and ADMA levels were significantly higher in PD patients than in controls (p < 0.001). CIMT in patients was higher than in the control group (0.83 ± 0.09 vs. 0.77 ± 0.06 mm; p < 0.01). CIMT was independently correlated with TBARS (β = 0.33, p < 0.01), MDA (β = 0.27, p < 0.01), AOPP (β = 0.22, p < 0.02), AGE (β = 0.45, p < 0.01), pentosidine (β = 0.56, p < 0.01) and ADMA (β = 0.54, p < 0.01). Conclusions: OS markers and serum ADMA levels independently predict the CIMT level in PD patients.

Background: Residual renal function (RRF) affects the survival rate and the development of cardiovascular disease in peritoneal dialysis (PD) patients. We evaluated the impact of RRF on oxidative and carbonyl stress in PD patients. Methods: Plasma advanced oxidation protein products (AOPP) and pentosidine were measured in PD patients with a urine volume of ≥300 ml/day (group A, n = 17) and <300 ml/day (group B, n = 14). AOPP and pentosidine were reevaluated after 12 months of follow-up in group A. Results: Plasma levels of AOPP and pentosidine in group A were significantly lower than those in group B. Renal creatinine clearance was inversely correlated with AOPP (p < 0.05) and pentosidine (p < 0.01). After 12 months of follow-up, no significant change was observed in AOPP and pentosidine in groups who maintained a urine volume of ≥300 ml/day, but significantly increased in groups whose urine volume decreased to less than 300 ml/day. There were significant inverse relationships between the changes in renal creatinine clearance and AOPP (p < 0.01) and pentosidine (p < 0.05). Conclusion: Loss of RRF is associated with increased plasma AOPP and pentosidine, indicating that preservation of RRF has a beneficial effect in reducing the oxidative and carbonyl stress in PD patients.

The construct of frailty has been associated with adverse outcomes among elderly individuals, but the prevalence and significance of frailty among patients with end-stage renal disease have not been established. The aim of the current study was to determine the prevalence and predictors of frailty

Objective: To determine and compare the post-earthquake trauma levels of hemodialysis (HD) patients, healthcare professionals working in the HD unit, and peritoneal dialysis (PD) patients in the 11th month of two earthquakes that occurred approximately nine hours apart on February 6, 2023, and affected the east and southeast regions of Turkey. Materials and Methods: The study included a total of 162 individuals, including 87 HD and 35 PD patients who had experienced both earthquakes, and 40 healthcare professionals working in the HD unit. The post-earthquake trauma levels of the participants were assessed using the Scale That Determines the Level of the Trauma After the Earthquake (SDLTAE), consisting of a total of 20 items, developed by Tanhan et al. after the 2011 Van earthquake. The individuals with an SDLTAE score of &gt;52 were considered highly traumatized. Results: The mean age of the participants was 53±16 years, and 79 (49%) were women. The SDLTAE score of the HD patients was found to be higher than that of the PD patients (p=0.006). There were no significant differences between the SDLTAE scores of the healthcare professionals and the HD and PD patients (p=0.419 and p=0.089, respectively). Upon comparing patients with low and high total SDLTAE scores, we observed that the rate of female individuals was higher in all groups (p&lt;0.001 for the HD and PD groups; p=0.017 for healthcare professionals). No correlation was found between the total SDLTAE score and age, dialysis duration, or laboratory parameters among the HD and PD patients (p&gt;0.05). Conclusion: We found that HD patients had a higher level of trauma than PD patients. Our study showed that women were more traumatized than men in sensitive groups, such as those receiving dialysis and healthcare professionals. Regularly conducting psychological assessments for dialysis patients and healthcare professionals may increase the likelihood of early intervention.

Satisfaction with care in peritoneal dialysis patients

This study aimed to determine the relationship between magnesium and PTH levels in peritoneal dialysis (PD) and hemodialysis (HD) patients. This cross-sectional study was performed on HD and PD patients in Kerman, Iran. After recording demographic and clinical data, the pre-dialysis levels of hemoglobin, 25-hydroxy vitamin D, ferritin, creatinine, calcium, phosphorus, albumin, PTH, and magnesium were measured for all patients. The P value of less than 0.05 was considered statistically significant. Magnesium levels in PD patients were significantly higher than in HD patients (P < 0.001). The median PTH level in PD patients was significantly lower than in HD patients (P = 0.046). The correlation between PTH and serum magnesium levels was not significant in PD or HD patients. In the regression model, dialysis modality (PD or HD) was the only significant variable in determining serum magnesium levels (P = 0.005). Magnesium is a neglected ion in peritoneal dialysis and hemodialysis patients. In dialysis centers that use a dialysate with standard magnesium concentration (0.5mmol/L in HD and 0.75mmol/L in PD), special attention is necessary to hypomagnesia and its complications because magnesium levels in PD patients were significantly higher than in HD patients. As the correlation between magnesium and PTH levels in both PD and HD patients were not significant, the association of high magnesium levels with low PTH in PD patients should be considered in terms of increasing the potential for adynamic bone disease. It seems that ordering serum magnesium in the routine tests of dialysis patients is necessary.