BACKGROUND: Cardiovascular disease is the major cause of mortality in patients receiving hemodialysis(HD) for end stage renal disease(ESRD). After renal failure, antioxidant levels increase, possibly in response to increased generation of free radicals. As a result, increased lipid peroxidation may contribute to increased risks of atherosclerosis. The aims of this study was to investigate the distribution of total antioxidant capacity of plasma in Korean adults and ESRD patients, and effects of HD. METHODS: Ninety five patients(41 men and 54 women, mean ages 54.7+/-28.3 years) receiving regular HD for ESRD were recruited. Venous blood samples were taken immediately before HD in 65 patients, and before and after HD in 30 patients. Control subjects were healthy individuals(61 men and 51 women, mean ages 42.7+/-10.8 years). Total antioxidant capacity of plasma and serum uric acid concentration were assessed. RESULTS: Reference range of plasma total antioxidant capacity in Korean population is 1.04 ~ 1.52 mmol/L. Total antioxidant capacities in male(1.32+/-0.11 mmol/L; mean+/-SD) were higher than those of female(1.24+/-0.12 mmol/L, P<0.001). Total antioxidant capacities in ESRD patients(1.72+/-0.26 mmol/L) were higher than controls(1.28+/-0.12 mmol/L, P<0.001). Total antioxidant capacities in pre-HD samples(1.55+/-0.16 mmol/L) were higher than post-HD(1.33+/-0.10 mmol/L). Plasma total antioxidant capacities and serum uric acid concentrations showed positive correlation(r = 0.69, P < 0.0001). DISCUSSION: The increase in total antioxidant capacity in ESRD patients might be due to high serum uric acid. Plasma total antioxidant capacities decreased after HD in ESRD patients due to decrease of uric acid concentration.
Adult ; Atherosclerosis ; Cardiovascular Diseases ; Female ; Free Radicals ; Humans ; Kidney Failure, Chronic* ; Lipid Peroxidation ; Male ; Mortality ; Plasma ; Reference Values ; Renal Dialysis* ; Renal Insufficiency ; Uric Acid

BACKGROUND: We have evaluated the analytical performance of SureStep Flexx (Johnson and Johnson, USA) which can report the plasma equivalent glucose test results and be connected to the hospital information networks, following ISO15197 analytic procedure for glucometer for the first time. METHODS: Adopting the guidelines of ISO15197, we measured the precision of ten glucometers from their repeatability and intermediate precision, and determined the accuracies of the glucometer, comparing to those of GEM Premier 4000 (Instrumentation Laboratory, USA). In addition, the guidelines of CLSI EP9-A2 and EP6-A were applied to correlate between data of glucometer and those of laboratory reference method by TBA-200FR (Toshiba Medical Systems, Japan) and to examine its linearity of glucose concentrations measured by SureStep Flexx. We used the clinical specimens and commercial control materials. RESULTS: Repeatabilities and intermediate precisions of those glucometers were 4.0-7.3%, and 4.3-6.2%, respectively. When glucose levels are under 75 mg/dL, the difference between results of those meters and the reference values were within +/-6 mg/dL. However when glucose levels are over 75 mg/dL, those differences were within +/-12.7%. These results were acceptable for the ISO15197 criteria in all glucose concentrations. The glucose concentrations showed the clinically relevant linearity in the range from 36 mg/dL to 491 mg/dL. Moreover, Error Grid Analysis showed that all glucose results were in "zone A", which means that these values were clinically accurate. CONCLUSIONS: This study showed that SureStep Flexx can provide reliable results for patients and clinicians to manage the diabetes mellitus, satisfying the ISO15197 criteria.
Blood Glucose/*analysis ; Blood Glucose Self-Monitoring/*instrumentation/methods/*standards ; Diabetes Mellitus/blood/diagnosis ; Humans ; Quality Control ; Reference Values ; Reproducibility of Results

We performed two trials on the external quality assessment for therapeutic drug monitoring (TDM) and testing for drugs of abuse (DOA) organized by the Therapeutic Drug Monitoring (TDM) subcommittee of the Korean Association of Quality Assurance for Clinical Laboratories (KAQACL) in 2013. In each trial, two levels of control material for TDM, and positive and negative control material for DOA testing, were requested from candidate institutions. The number of participating laboratories was 106 and 105 for the first and second trials, respectively. The average number of drug items was 5.6 per institution. The most commonly tested substances were valproic acid, followed by digoxin, phenytoin, carbamazepine, and tacrolimus, in descending order. The mean inter-laboratory coefficients of variation for low- and high-level control materials were 9.3% and 6.7%, respectively. The most widely used TDM analysers were Architect i System (Abbott Diagnostics, USA), followed by Cobas Integra (Roche Diagnostics, Switzerland) and Cobas c501 analyser (Roche Diagnostics). The number of participating laboratories for DOA testing increased by 30% compared with that in 2012. We received 100% and 98.2% correct answers from the participating DOA laboratories in each trial, respectively. In the external quality assessment for TDM by the TDM subcommittee of KAQACL in 2013, the overall performance of TDM was similar to previous years and the inter-laboratory precision was improved compared with that in 2012. Continuous quality improvement for TDM testing is needed through participation in a proficiency-testing program.
Carbamazepine ; Digoxin ; Drug Monitoring* ; Korea ; Laboratory Proficiency Testing ; Phenytoin ; Quality Improvement ; Street Drugs* ; Tacrolimus ; Valproic Acid

In this study, we evaluated the performance of a recently developed immunoassay analyser, the VISTA 500 (Siemens, Germany). Precision, linearity, and comparison studies were performed according to the Clinical and Laboratory Standards Institute guidelines. The test items evaluated included IgG, IgA, IgM, C3, C4, ceruloplasmin, prealbumin, transferrin, haptoglobin, rheumatoid factor, anti-streptolysin O, and cystatin C. Commercial control materials (BioRad Laboratories, USA), commercial linearity validation materials (Maine Standards, USA), and patient samples were used for the evaluation. For the correlation study, analysis with a BN-II nephelometer (Siemens) was used as a comparative method. Total coefficients of variation of analytes were found to be between 1.9% and 5.5%. Results of the linearity evaluation were also acceptable for the range tested. Correlations with comparative methods were acceptable. The VISTA 500 analyser showed satisfactory analytical performance with respect to precision, linearity, and comparison. We conclude that the VISTA 500 is likely a good candidate as an immunology analyser.
Allergy and Immunology ; Ceruloplasmin ; Cystatin C ; Evaluation Studies as Topic ; Haptoglobins ; Humans ; Immunoassay ; Immunoglobulin A ; Immunoglobulin G ; Immunoglobulin M ; Prealbumin ; Rheumatoid Factor ; Statistics as Topic ; Transferrin

BACKGROUND: Neutrophil gelatinase-associated lipocalin (NGAL) has recently been introduced as a renal biomarker and an increase in its level suggests tubular injury. Diabetic nephropathy, a leading cause of end-stage renal disease, causes typical changes characterized by glomerulosclerosis and eventual tubular damage in the kidney. In the present study, we attempted to validate the usefulness of plasma NGAL (pNGAL) as a biomarker for tubular damage in diabetic nephropathy. METHODS: The plasma NGAL levels of 260 diabetes mellitus patients and 50 healthy individuals werewas measured by means of fluorescent immunoassay using with the Triage NGAL test (Biosite, USA). The patients were divided into 3 groups on the basis of their urinary albumin excretion (UAE) levels, and the pNGAL differences among each group were analyzed. The degree of albuminuria and cystatin C-based glomerular filtration rate (GFR) were also compared with the pNGAL levels. RESULTS: The mean pNGAL levels of the normal subjects and diabetic patients were 61.9 +/- 4.81 ng/mL and 93.4 +/- 71.78 ng/mL, respectively. pNGAL level was significantly increased in patients with severe albuminuria (P < 0.001). The pNGAL level was found to be positively correlated with the degree of albuminuria (R2 = 0.218, P < 0.001) and inversely correlated with GFR (R2 = 0.269, P < 0.001). Particularly, the pNGAL level of patients with diabetic nephropathy was found to be associated with the renal damage and independent of other factors influencing the renal damage (R2 = 0.218). CONCLUSIONS: pNGAL level independently reflects renal damage in patients with diabetic nephropathy. Measurement of pNGAL level combined with UAE would help enable to detect both glomerular and tubular damage in diabetic nephropathy patients.
Albuminuria ; Diabetes Mellitus ; Diabetic Nephropathies ; Glomerular Filtration Rate ; Humans ; Immunoassay ; Kidney ; Kidney Failure, Chronic ; Lipocalins ; Neutrophils ; Plasma ; Triage

We have evaluated the performance of a recently developed immunoassay analyzer, ADVIA Centaur XPT (Siemens, Germany). Precision, linearity, and comparison studies were performed according to the CLSI guidelines. The test items evaluated were ferritin, folate, human epidermal growth factor receptor 2/neu, homocysteine, vitamin B₁₂, B-type natriuretic peptide, creatine kinase–myocardial band, myoglobin, procalcitonin, troponin I. Bio-Rad control materials, linearity materials, and patients' samples were used for the evaluation. For the correlation study, ADVIA Centaur XP (Siemens) were used as comparative methods. The total coefficients of variations (CVs) of the analytes were between 2.5% and 7.0%. The results of linearity evaluation were also acceptable for the range tested. Correlations with comparative methods were good. The overall analytical performance of ADVIA Centaur XPT is acceptable for the immunology analyzer. Therefore, ADVIA Centaur XPT is expected to be widely used.
Allergy and Immunology ; Creatine ; Ferritins ; Folic Acid ; Homocysteine ; Humans ; Immunoassay ; Myoglobin ; Natriuretic Peptide, Brain ; Receptor, Epidermal Growth Factor ; Statistics as Topic ; Troponin I ; Vitamins

BACKGROUND: Neuron-specific enolase (NSE) is an enzyme specifically found in neurons and neuroendocrine tissue. It is a common marker for small cell lung cancer diagnosis and is also useful as a predictor of brain damage. This study evaluates the performance of Elecsys NSE (Roche Diagnostics, Switzerland), an electrochemiluminescent immunoassay. METHODS: The precision, linearity, limit of detection, and reference interval of the Elecsys NSE, as well as the correlation between Elecsys NSE and ELSA-NSE (Cis-Bio International, France) were evaluated in accordance with the Clinical Laboratory Standards Institute (CLSI) guidelines. PreciControl Tumor Marker (Roche Diagnostics), patient sera, and sera from healthy individuals were used for the analysis. RESULTS: The measured coefficient of variation for the assay was below 3%, and it demonstrated linearity from 0.20 to 234.5 ng/mL. The detection limit was 0.032 ng/mL and the reference interval ranged from 0.05 to 16.3 ng/mL. Compared with the ELSA-NSE assay, the correlation coefficient was 0.9128. CONCLUSIONS: The Elecsys assay showed suitable precision, linearity, limit of detection and reference range for clinical laboratory use; however, the correlation coefficient of Elecsys NSE as compared to ELSA-NSE was below 0.975. This result may be associated with the use of different monoclonal antibodies in the two different NSE assays. Elecsys NSE demonstrated a high sensitivity without the use of radioactive reagents; therefore, Elecsys NSE will be quite useful for NSE analysis in the clinical laboratory setting.
Antibodies, Monoclonal ; Brain ; Diagnosis ; Humans ; Immunoassay ; Indicators and Reagents ; Limit of Detection ; Neurons ; Phosphopyruvate Hydratase* ; Reference Values ; Small Cell Lung Carcinoma

BACKGROUND: Neuron-specific enolase (NSE) is an enzyme specifically found in neurons and neuroendocrine tissue. It is a common marker for small cell lung cancer diagnosis and is also useful as a predictor of brain damage. This study evaluates the performance of Elecsys NSE (Roche Diagnostics, Switzerland), an electrochemiluminescent immunoassay. METHODS: The precision, linearity, limit of detection, and reference interval of the Elecsys NSE, as well as the correlation between Elecsys NSE and ELSA-NSE (Cis-Bio International, France) were evaluated in accordance with the Clinical Laboratory Standards Institute (CLSI) guidelines. PreciControl Tumor Marker (Roche Diagnostics), patient sera, and sera from healthy individuals were used for the analysis. RESULTS: The measured coefficient of variation for the assay was below 3%, and it demonstrated linearity from 0.20 to 234.5 ng/mL. The detection limit was 0.032 ng/mL and the reference interval ranged from 0.05 to 16.3 ng/mL. Compared with the ELSA-NSE assay, the correlation coefficient was 0.9128. CONCLUSIONS: The Elecsys assay showed suitable precision, linearity, limit of detection and reference range for clinical laboratory use; however, the correlation coefficient of Elecsys NSE as compared to ELSA-NSE was below 0.975. This result may be associated with the use of different monoclonal antibodies in the two different NSE assays. Elecsys NSE demonstrated a high sensitivity without the use of radioactive reagents; therefore, Elecsys NSE will be quite useful for NSE analysis in the clinical laboratory setting.
Antibodies, Monoclonal ; Brain ; Diagnosis ; Humans ; Immunoassay ; Indicators and Reagents ; Limit of Detection ; Neurons ; Phosphopyruvate Hydratase* ; Reference Values ; Small Cell Lung Carcinoma

Herein, we report a case in which cholestasis caused discrepancy in high-density lipoprotein (HDL)-cholesterol levels measured using various methods. The discrepancy in HDL-cholesterol level originated from the abnormal increase in the level of an unusual lipoprotein, apo E-rich HDL, in the patient's serum. An abnormal slow alpha-migrating lipoprotein was observed on agarose gel electrophoresis, and an abnormal large-sized HDL was observed in a lipoprotein subfraction study. The level of apolipoprotein E was elevated.
Apolipoproteins ; Cholestasis ; Electrophoresis, Agar Gel ; Lipoproteins

Herein, we report a case in which cholestasis caused discrepancy in high-density lipoprotein (HDL)-cholesterol levels measured using various methods. The discrepancy in HDL-cholesterol level originated from the abnormal increase in the level of an unusual lipoprotein, apo E-rich HDL, in the patient's serum. An abnormal slow alpha-migrating lipoprotein was observed on agarose gel electrophoresis, and an abnormal large-sized HDL was observed in a lipoprotein subfraction study. The level of apolipoprotein E was elevated.
Apolipoproteins ; Cholestasis ; Electrophoresis, Agar Gel ; Lipoproteins