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Glutathione redox potential is low and glutathionylated and cysteinylated hemoglobin levels are elevated in maintenance hemodialysis patients.

ABSTRACT: Glutathione (GSH), the most abundant intracellular low molecular mass thiol, protects cells from oxidative damage and regulates their function. Available information is inconsistent regarding levels of GSH and its disulfide (GSSG) in maintenance hemodialysis patients (HD). In addition, very limited data are available in HD about the relationship of GSH and GSSG with other measures of thiol metabolism and with the clinical profile. We tested the hypothesis that erythrocyte GSH/GSSG redox potential (Eh) is lower in HD than in healthy controls (C), and that Eh correlates with posttranslational thiolation of hemoglobin (Hb) and with standard clinical parameters in HD. In cross-sectional comparison of 33 stable HD and 21 C, we found a net loss of reducing capacity in HD as indicated by low erythrocyte GSH/GSSG Eh (-257 ± 5.5 vs -270 ± 5.6 mV, P = 0.002). Glutathionylated Hb (HbSSG) was 46% higher in HD than C (19.3 ± 4.80 vs 13.2 ± 2.79 pmol/mg Hb; P = 0.001) and cysteinylated Hb (HbSSCy) was >3-fold higher in HD than C [38.3 (29.0-63.3) vs 11.5 (9.6-17.2) pmol/mg Hb; P = 0.001]. In multiple regression analysis of the HD cases, statistically significant associations were found between the GSH/GSSG Eh and the blood urea nitrogen (P = 0.001), creatinine (P = 0.015) and normalized protein catabolic rate (P = 0.05), after adjusting for age, race/ethnicity, and etiology of end-stage renal disease. In conclusion, accurate and precise analysis of GSH, GSSG, and mixed disulfides reveals loss of erythrocyte GSH/GSSG Eh, rise of both HbSSG and HbSSCy, and correlation of these thiols with measures of uremia and dietary protein intake.

SUBMITTER: Khazim K

PROVIDER: S-EPMC3683567 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature

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Glutathione redox potential is low and glutathionylated and cysteinylated hemoglobin levels are elevated in maintenance hemodialysis patients.

Khazim Khaled K Giustarini Daniela D Rossi Ranieri R Verkaik Darlene D Cornell John E JE Cunningham Sue E D SE Mohammad Maryam M Trochta Kara K Lorenzo Carlos C Folli Franco F Bansal Shweta S Fanti Paolo P

Translational research : the journal of laboratory and clinical medicine 20130117 1

Glutathione (GSH), the most abundant intracellular low molecular mass thiol, protects cells from oxidative damage and regulates their function. Available information is inconsistent regarding levels of GSH and its disulfide (GSSG) in maintenance hemodialysis patients (HD). In addition, very limited data are available in HD about the relationship of GSH and GSSG with other measures of thiol metabolism and with the clinical profile. We tested the hypothesis that erythrocyte GSH/GSSG redox potentia ...[more]

PMID: 23333585

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Project description:BackgroundOptimal iron levels in patients on hemodialysis are currently unknown, and a higher level than that for the healthy population is usually set for such patients considering the use of erythropoiesis-stimulating agents or the occurrence of chronic inflammation. However, excessive iron causes oxidative stress and impairment of its utilization by cells. Therefore we investigated the relationship between hemoglobin (Hb) level and iron status in hemodialysis patients to identify the optimal iron levels for patients undergoing hemodialysis.MethodsA total of 208 outpatients on maintenance hemodialysis were followed up between July 2006 and June 2007. Men accounted for 64.9% cases [mean age, 59.3 ± 13.1 years and median dialysis history, 7.7 (3.6-13.2) years], and diabetic nephropathy accounted for 25.0% cases. Hemoglobin level was measured twice a month and serum ferritin, serum iron, and total iron-binding capacity were measured once a month. The doses of recombinant human erythropoietin and low-dose iron supplement were adjusted to maintain a hemoglobin level of 10-11 g/dL, according to the guidelines of the Japanese Society for Dialysis Therapy. Hepcidin was measured at baseline. Using the mean values for 1-year period, the relationships among hemoglobin, serum ferritin levels, and transferrin saturation levels were investigated based on a receiver operating characteristic curve and a logistic regression model. In addition, the correlations among serum ferritin, transferrin saturation, and hepcidin levels were analyzed by Pearson product-moment correlation coefficient and linear regression model.ResultsBy receiver operating characteristic curve, the cutoff point of serum ferritin and transferrin saturation levels with a hemoglobin ?10 g/dL showed <90 ng/mL (sensitivity: 69.1%, specificity: 72.1%, p < 0.001) and ?20% (sensitivity: 77.6%, specificity: 48.8%, p = 0.302). Upon logistic regression model analysis with a hemoglobin ?10 g/dL as the endpoint, the analysis of odds ratios relative to a group with serum ferritin ?90 ng/mL and transferrin saturation <20% revealed that the group with serum ferritin <90 ng/mL and transferrin saturation ?20% had the highest ratio: 46.75 (95% confidence interval: 10.89-200.70, p < 0.001). In Pearson product-moment correlation coefficient, hepcidin showed a strong positive correlation with serum ferritin [r = 0.78 (95% confidence interval: 0.72-0.83, p < 0.001)] and a weak positive correlation with transferrin saturation [r = 0.18 (95% confidence interval: 0.04-0.31, p = 0.010)]. In the multivariable analyses of the linear regression model, a positive relationship was shown between hepcidin and serum ferritin [?-coefficient of 0.30 (95% confidence interval: 0.27-0.34, p < 0.001)]; however, no relationship was shown with transferrin saturation [?-coefficient of 0.09 (95% confidence interval: -0.31-0.49, p = 0.660)].ConclusionsIn this study, the iron status of serum ferritin <90 ng/mL and transferrin saturation ?20% was optimal in hemodialysis patients receiving recombinant human erythropoietin for anemia therapy. This result indicates that the threshold values for the optimal iron status may be lower than those currently recommended in iron-level management guideline.

Project description:BackgroundElevated cardiac troponin I (TnI) levels are associated with all-cause mortality in stable hemodialysis patients. Their relationship to cardiac-specific death has been inconsistent, and the reason for their elevation is not well understood. We hypothesized that elevated TnI levels in chronic stable hemodialysis patients more specifically track with cardiac mortality, and this mechanism is independent of other contributors of cardiac mortality, such as inflammation.MethodsWe conducted a single-centre, cohort study of prevalent hemodialysis patients at a tertiary care hospital. Plasma TnI levels were measured with routine monthly blood tests in clinically stable patients for two consecutive months. Plasma TnI was measured by immunoassay and a value above the laboratory reference range (0.06 ?g/L) was considered elevated. The primary outcome of death was adjudicated separately for this study, and classified as cardiac, non-cardiac, or unknown. Cox proportional hazard models were used to examine the association of TnI with the all-cause and cardiac-specific mortality, adjusting for potential confounders, including C-reactive protein (CRP) as a marker of inflammation.ResultsOf 133 patients followed for a median of 1.7 years, there were 38 deaths (58% non-cardiac, 39% cardiac, 3% unknown). Elevated TnI was associated with adjusted HR for all-cause mortality of 2.57 (95% CI 1.30-5.09) and an adjusted HR for cardiac death of 3.14 (95% CI 1.07-9.2), after accounting for age, time on dialysis, diabetes status, prior coronary artery disease history, and C-reactive protein. Although CRP was also independently associated with all-cause mortality, it did not add prognostic information to TnI for cardiac-specific death.ConclusionElevated TnI levels are independently associated with cardiac and all-cause mortality in asymptomatic hemodialysis patients. The mechanism for this risk is likely independent of inflammation, but may reflect chronic subclinical myocardial injury or unmask those with subclinical atherosclerotic heart disease. Whether those with elevated TnI levels may benefit from additional investigations or more aggressive therapies to treat cardiovascular disease remains to be determined.

Dataset Information

Glutathione redox potential is low and glutathionylated and cysteinylated hemoglobin levels are elevated in maintenance hemodialysis patients.

Publications

Glutathione redox potential is low and glutathionylated and cysteinylated hemoglobin levels are elevated in maintenance hemodialysis patients.

Similar Datasets

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