Comparison of Barricor™ vs. lithium heparin tubes for selected routine biochemical analytes and evaluation of post centrifugation stability.

INTRODUCTION: Obtaining suitable results unaffected by pre- or postanalytical phases is pivotal for clinical chemistry service. We aimed comparison and stability of nine biochemical analytes after centrifugation using Barricor™ plasma tubes with mechanical separator vs standard Vacutainer® lithium heparin tubes. MATERIALS AND METHODS: We collected samples on six healthy volunteers and nine patients from intensive care units into 6 mL plastic Vacutainer® lithium heparin tubes and 5.5 mL plastic Barricor™ plasma tubes. All tubes were centrifuged within 30 minutes after venipuncture. First, we compared results of nine biochemical analytes from lithium heparin tubes with Barricor™ tubes for each analyte using Passing-Bablok and Bland-Altman analyses. Second, we calculated the difference of analyte concentrations between baseline and time intervals in tubes stored at + 4 °C. Based on the total change limit we calculated the maximum allowable concentrations percentage change from baseline. RESULTS: The majority of correlation coefficients were close to 0.99 indicating good correlation in the working range. Bland-Altman analyses showed an acceptable concordance for all analytes. In consequence, the Barricor™ tube might be an alternative to regular lithium heparin tube. Stability with this new generation tube is improved for eight analytes (except for aspartate aminotransferase) in comparison with regular lithium heparin tubes. CONCLUSIONS: By using Barricor™ tubes and prompt centrifugation, supplemental analysis or re-analysis for eight analytes including alanine aminotransferase, alkaline phosphatase, C-reactive protein, high sensitivity troponin T, lactate dehydrogenase, NT-pro BNP, potassium and sodium could be performed within 72 h of specimen collection.

Enzymatic but not compensated Jaffe methods reach the desirable specifications of NKDEP at normal levels of creatinine. Results of the French multicentric evaluation.

The French Society of Clinical Biochemistry conducted this study to compare the accuracy and performances of the best creatinine enzymatic assays and the compensated Jaffe methods from the same manufacturers. Creatinine was measured in 3 serum pools with creatinine levels of 35.9±0.9 µmol/L, 74.4±1.4 µmol/L, and 97.9±1.7 µmol/L (IDMS determination). The performances of the assays (total error that includes the contribution of bias and imprecision) were evaluated using Monte-Carlo simulations and compared against desirable NKDEP criteria. The enzymatic assays always fell within the desirable total Error of 7.6%. By contrast, this requirement was never obtained for the compensated Jaffe methods at the critical level of 74.4±1.4 µmol/L. Only the compensated Jaffe creatinine on Olympus analyzer reached this specification at 35.9±0.9 and 97.9±1.7 µmol/L levels. This study demonstrates that, despite substantial improvement regarding traceability to the IDMS reference method and precision, compensated Jaffe creatinine methods, by contrast to enzymatic ones, do not reach the desirable specifications of NKDEP at normal levels of creatinine.

Antioxidant and oligonutrient status, distribution of amino acids, muscle damage, inflammation, and evaluation of renal function in elite rugby players.

BACKGROUND: Our study investigated the biochemical and anthropometric characteristics in elite athletes of rugby union based in the south of France during the different periods of the competition to identify metabolic and biochemical adaptations to particular lifestyle conditions. METHODS: Participants included 35 players in 2008 and 43 players in 2009. Biochemical variables [creatinine, uric acid, creatine kinase (CK), alanine aminotransferase, aspartate aminotransferase, C-reactive protein] were evaluated. Specific protein levels (albumin, acid α-glycoprotein, prealbumin), vitamins (A, E, C), antioxidant enzymes [glutathione peroxidase (GPx), superoxide dismutase (SOD)], oligoelements (Zn, Se, Cu, erythrocyte magnesium), homocysteine (Hcy), carnitine and the distribution of amino acids were specifically determined for our study during a pre-competition period (September 2008 and 2009). RESULTS: Globally, no deficit was observed for vitamins, oligonutrients and amino acids levels. The high SOD and GPx activities in rugby players suggest a presence of oxidative stress of exercise. The evaluation of renal function should be used with caution because of the interaction between creatinine and lean body mass. In addition, a profound effect of intense exercise on the CK values was reported to establish specific reference values for athletes. The analysis of the biological variation allows optimization of the interpretation of the changes from an increased or decreased baseline value from a season to the other one. CONCLUSIONS: The conclusions of present study were: 1) the necessity of rugby-specific reference intervals for CK and creatinine parameters; 2) the use of enzymatic creatinine for Modification of Diet in Renal Disease (MDRD) and CKD-EPI, or cystatin C to improve glomerular filtration rate estimation; 3) to take into account the oxidative stress testifying of a bad recovery; and 4) better to take care the nutritional status of the players by adapting needs and amino acids supplementations but also to consider a follow-up of oxidative stress and antioxidants according our results.

NADPH oxidase activity is associated with cardiac osteopontin and pro-collagen type I expression in uremia.

Abstract Cardiovascular disease is a frequent complication inducing mortality in chronic kidney disease (CKD) patients, which can be determined by both traditional risk factors and non-traditional risk factors such as malnutrition and oxidative stress. This study aimed to investigate the role of oxidative stress in uremia-induced cardiopathy in an experimental CKD model. CKD was induced in Sprague-Dawley rats by a 4-week diet supplemented in adenine, calcium and phosphorous and depleted in proteins. CKD was associated with a 3-fold increase in superoxide anion production from the NADPH oxidase in the left ventricle, but the maximal activity of mitochondrial respiratory chain complexes was not different. Although manganese mitochondrial SOD activity decreased, total SOD activity was not affected and catalase or GPx activities were increased, strengthening the major role of NADPH oxidase in superoxide anion output. Superoxide anion output was associated with enhanced expression of osteopontin (×7.7) and accumulation of pro-collagen type I (×3.7). To conclude, the increased activity of NADPH oxidase during CKD is associated with protein modifications which could activate a pathway leading to cardiac remodelling.