Anne Sophie Bargnoux

Plasma brain natriuretic peptide and troponin levels in severe sepsis and septic shock: relationships with systolic myocardial dysfunction and intensive care unit mortality.

The aim of this study was to evaluate and compare brain natriuretic peptide (BNP) and cardiac troponin I (cTnI) levels as mortality prognosticator and predictor for myocardial dysfunction in severe sepsis and septic shock. Baseline clinical and biological variables were collected from 47 patients with severe sepsis or septic shock. Ventricular systolic function assessed by echocardiography was measured over a 5-day period. Both cTnI and BNP plasmatic levels were determined at intensive care unit (ICU) admission and during the following 15 days. At admission, cTnI and BNP levels were compared to those of 12 control critically ill nonseptic patients. The plasma levels of BNP and cTnI in patients with sepsis were elevated at admission and significantly higher than in the controls. Among patients with sepsis, BNP levels were significantly more elevated in nonsurvivors compared to survivors at admission and 1 day later. The cTnI levels were also significantly more elevated in nonsurvivors compared to survivors, but only at admission. From admission to day 5, patients with sepsis with left ventricular systolic dysfunction had higher BNP plasmatic concentrations than those without; differences were significant at days 3 and 4. In contrast, plasma cTnI levels were similar between the 2 groups. In critically ill patients, sepsis induces significant increase in BNP and cTnI levels. High BNP and cTnI plasma levels during ICU admission appear to be associated with poor outcome of sepsis. Time course of BNP levels seems helpful to discriminate between surviving and nonsurviving patients with sepsis and to detect myocardial dysfunction where troponin levels fail to do so.

Bone biomarkers help grading severity of coronary calcifications in non dialysis chronic kidney disease patients.

Background Osteoprotegerin (OPG) and fibroblast growth factor-23 (FGF23) are recognized as strong risk factors of vascular calcifications in non dialysis chronic kidney disease (ND-CKD) patients. The aim of this study was to investigate the relationships between FGF23, OPG, and coronary artery calcifications (CAC) in this population and to attempt identification of the most powerful biomarker of CAC: FGF23? OPG? Methodology/Principal Findings 195 ND-CKD patients (112 males/83 females, 70.8 [27.4–94.6] years) were enrolled in this cross-sectional study. All underwent chest multidetector computed tomography for CAC scoring. Vascular risk markers including FGF23 and OPG were measured. Logistic regression analyses were used to study the potential relationships between CAC and these markers. The fully adjusted-univariate analysis clearly showed high OPG (≥10.71 pmol/L) as the only variable significantly associated with moderate CAC ([100–400[) (OR = 2.73 [1.03;7.26]; p = 0.04). Such association failed to persist for CAC scoring higher than 400. Indeed, severe CAC was only associated with high phosphate fractional excretion (FEPO4) (≥38.71%) (OR = 5.47 [1.76;17.0]; p = 0.003) and high FGF23 (≥173.30 RU/mL) (OR = 5.40 [1.91;15.3]; p = 0.002). In addition, the risk to present severe CAC when FGF23 level was high was not significantly different when OPG was normal or high. Conversely, the risk to present moderate CAC when OPG level was high was not significantly different when FGF23 was normal or high. Conclusions Our results strongly suggest that OPG is associated to moderate CAC while FGF23 rather represents a biomarker of severe CAC in ND-CKD patients.

Evaluation of two automated capillary electrophoresis systems for human serum protein analysis

OBJECTIVES We compared automated capillary electrophoresis (CE) systems Capillarys 2 from Sebia and V8 from Helena Biosciences Europe (Elitech) with the semi-automated Hydrasys-Hyrys agarose gel electrophoresis (AGE) from Sebia. DESIGN AND METHODS We evaluated analytical performances and compared 129 fresh routine sera (group A) to 164 frozen pathologic samples with suspicion or antecedent of monoclonal component (MC) (group B). Immunofixation was then compared with immunotyping provided by both CE systems. RESULTS Analytical performances from both CE systems have proven suitable results for clinical use, with within-run and between-run coefficients of variation inferior or equal to 5.2% and 7.7%, respectively. A good correlation was found between AGE and CE with r-value ranging from 0.81 to 0.96 for both CE systems. We observed high MC detection sensitivities (>85%) of in electrophoretogram readings for both CE systems. MC identification using CE systems provided suitable concordance with immunofixation, although failing to detect some IgM proteins or free light chains. CONCLUSIONS Both Capillarys 2 and V8 are reliable automated CE systems for patient care.

Evaluation of two sirolimus assays using the ARCHITECT-i1000(®) CMIA or RxL(®) ACMIA methods in comparison with the IMx(®) MEIA method.

Routine monitoring of the immunosuppressive drug sirolimus is necessary to minimize potential toxic effects associated with high trough concentrations, and to ensure effective immunosuppression (1). Early strategies suggested an optimal target range of 4–12 ng/mL in the presence of cyclosporin or 12–20 ng/mL when cyclosporin was absent (1). More recently, it has been proposed that C0 sirolimus concentrations with de novo use should be maintained between 10 and 15 ng/mL during the first 6 months then between 5 and 10 ng/mL, depending on concomitant immunosuppressant therapy (2). In order to facilitate sirolimus monitoring, we evaluated the analytical performance of three immunoassays for sirolimus determination, a microparticle enzyme immunoassay (MEIA) (Abbott IMx sirolimus), a chemiluminescent assay (CMIA) (Abbott ARCHITECT sirolimus) and a magnetic particle immunoassay (ACMIA) (Siemens Dimension sirolimus). Both methods from Abbott (Abbott Laboratories, Abbott Park, IL, USA) require manual pre-treatment steps in order to lyse the red blood cells and extract sirolimus from whole blood. The automated method from Siemens (Siemens Healthcare Diagnostics Inc., Deerfield, IL, USA) does not require a separate, manual pre-treatment step since the analyzer automatically lyses whole blood samples.

Analytical evaluation of point of care cTnT and clinical performances in an unselected population as compared with central laboratory highly sensitive cTnT

OBJECTIVES To report the analytical performances of the Radiometer AQT90 FLEX® cTnT assay (Neuilly-Plaisance, France) and to evaluate the concordance with hs-cTnT results from central laboratory for the diagnosis of acute myocardial infarction (AMI) at baseline and during a short follow-up among unselected patients admitted in emergency room or cardiology department. DESIGN AND METHODS Analytical performances of AQT90 FLEX® cTnT immunoassay included imprecision study with determination of a coefficient of variation at 10% and 20%, linearity, and limit of detection. The concordance study was based on samples obtained from 170 consecutive patients with chest pain suggestive of acute coronary syndrome (ACS) admitted in the emergency room or cardiology department. The kinetic study (within 62 additional samples 3h later) was based on absolute delta criterion and the combination of relative change of 30% with absolute change of 7ng/L. RESULTS The cTnT assay from Radiometer was evaluated as clinically usable, although less sensitive than the Roche hs-cTnT assay as demonstrated by the concordance and the kinetic studies. CONCLUSIONS In non-selected population, the cTnT AQT Flex© assay on AQT90© with kinetic change at 3h, provides similar clinical classification of patients, particularly for AMI group as compared to central laboratory hs-cTnT assay and could be suitable for clinical use.

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

Abstract 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.

Stability of routine biochemical analytes in whole blood and plasma/serum: focus on potassium stability from lithium heparin

Abstract Background: Blood specimens are transported from clinical departments to the biochemistry laboratory by hospital courier service, sometimes over long distances. The aim of this study was to assess the stability of common biochemical analytes in venous blood under our routine transport conditions and to evaluate analyte stability after prompt or delayed centrifugation. Methods: We investigated pre- and postanalytical contributions of 32 biochemical analytes in plasma and serum samples from 10 patients (healthy adults and patients from intensive care units). Differences in analyte concentrations between baseline (T0) and different time intervals (2, 4, 6, 8, 12 and 24 h) following storage after prompt and delayed centrifugation were reported. Evaluation was against the total change limit as described by Oddoze et al. (Oddoze C, Lombard E, Portugal H. Stability study of 81 analytes in human whole blood, in serum and in plasma. Clin Biochem 2012;45:464–9). Results: The majority of analytes were stable with delayed separation up to 12 h, except for potassium, C-peptide, osteocalcin, parathyroid hormone (PTH), bicarbonate and LDH. After prompt centrifugation and storage at 4°C, stability was greatly increased up to 48 h for most analytes. LDH and bicarbonate had the lowest stability after centrifugation; therefore, no reanalysis of these analytes in a centrifuged tube can be allowed. Conclusions: Knowledge of analyte stability is crucial to interpret biological analysis with confidence. However, centrifugation prior to transport is time consuming, and the transfer of plasma or serum from a primary tube to a secondary tube increases the risk of preanalytical errors. For analytes that are stable in whole blood for 24 h or more, it seems that there is no benefit to centrifuge before transport.

Analytical evaluation of Lumipulse® BRAHMS PCT CLEIA assay and clinical performances in an unselected population as compared with central lab PCT assay

OBJECTIVES We report the analytical performances of the Lumipulse®G BRAHMS PCT assay (Fujirebio, Courteboeuf, France) and the concordance with BRAHMS PCT Kryptor CompactPlus© results from central laboratory. DESIGN AND METHODS Lumipulse®G BRAHMS PCT immunoassay on Lumipulse®G600II instrument is a chemiluminescence enzyme immunoassay (CLEIA). Analytical performances included imprecision study, linearity, limit of detection and comparison study on 138 plasma specimen on Lumipulse®G600II vs plasma on Kryptor CompactPlus©. RESULTS The intra and inter assay imprecision of Lumipulse®G BRAHMS PCT was between 2 and 5%. The LoD in our condition was 0.0029ng/mL in accordance with the LoD provided by the manufacturer (0.0048ng/mL). The linear equation of linearity was y=1,001×-0,052 with r2=0.99, with a mean recovery (SD) percentage of 1.8% (8%). Correlation studies showed a good correlation (r=0.99) between plasma on Kryptor and Lumipulse, with a bias of 0.02 in the range from 0.12 to 1ng/mL. CONCLUSION The new adaptation developed from Fujirebio on quantification of PCT with CLEIA technology from monoclonal antibodies from ThermoFisher appears to be acceptable for clinical use.

Analytical Performance and Clinical Use of a Hemoglobin A1c Point-of-Care Analyzer in a Pediatric Unit

The implementation of point-of-care (POC) analyzers in the clinical department is growing. However, Lenters-Westra and Slingerland’s study1 on several POC tests for hemoglobin A1c (HbA1c) highlighted the necessity to evaluate the accuracy of each POC device. The aim of our study is to assess the analytical performance of DCA-Vantage® from Siemens, France, including (1) imprecision, (2) effects of presence of variants on the results of HbA1c, (3) correlation with central laboratory high-performance liquid chromatography (HPLC; MenariniHA8140®), and (4) usefulness of POC analyzer for the department of pediatrics. The POC system for the determination of HbA1c showed good analytical performances, with imprecision values below the reasonable coefficients of variation (CVs) of 3%.2 At HbA1c levels of 4.9%, 5.6%, and 8.7%, the intra-assay CV on 10 replicates of each HbA1c level was 2.7%, 1.6%, and 1.4%, respectively. The interassay CV, assessed twice a day on 10 consecutive workdays ranged from 1.8% to 2.4%. In 124 routine samples with hemoglobin F <1%, covering a range of 4.6% (27 mmol/mol) to 11.7% (104 mmol/mol), excellent correlation was observed between the HbA1c values with the POC analyzer in comparison with the HPLC method (Figure 1). Regrettably, the POC method did not pass the NGSP criteria, with a difference beyond the clinically significant limits of ±7% HbA1c. The analysis of 25 samples with hemoglobin F from 1% to 8.6% brings to light an overestimation (mean difference was 0.44% ± 0.6%) with regard to HPLC method. In addition, in 24 samples with hemoglobin A/S, 7 samples with hemoglobin A/C, and 3 samples with hemoglobin S/C, the correlation with comparative method HPLC did not pass the NGSP criteria, whatever the variant. From a clinical point of view,3 we observed no clinically significant differences attributable to the presence of hemoglobin C trait for any level, while for hemoglobin S trait, negative clinically bias was found at both evaluation limits of 6% (0.42) and 7% (0.49). This observation was not in agreement with previously published data4,5 and Siemens on their own studies. This discrepancy is not only due to the presence of variants but also due to the cumulative effect of the gap between technologies and away from the presence of variants. The Kappa coefficient was higher than 0.75, and the strength of agreement could be considered to be good. However, according to the classification in three categories of American Diabetes Association criteria,2 a total of 14.5% of results disagreed with the category assignment of HPLC, with an underestimation in 11.3% of samples and an overestimation in 3.2% of samples. Figure 1. (A) Linear regression of %HbA1c obtained with the HPLC and the POC instrument with y = 0 . 9 616 x + 0.1846, r = 0.97. (B) Bla nd– Altman difference plot. Dotted lines represent the mean ± 1.96 SD of the observed mean difference. According to the answers given by nurses and biologists to a questionnaire, the following are considered to be the greatest benefits for adopting a POC HbA1c assay: fast results obtained in 6 min in real time, the low 1 µl volume of blood required for testing, and the ability for more rapid decision making. Before adopting a POC methodology, practices are encouraged to review its feasibility in the context of the office routine and also to conduct periodic comparisons of the accuracy of POC test results compared with those from laboratory analysis. Their use should remain marginal and requires taking some precautions, as the standardization is not complete.

Moving from the second to the third generation Roche PTH assays: what are the consequences for clinical practice?

Abstract Background The determination of parathyroid hormone (PTH) is essential for exploring phosphocalcic disorders especially in patients with renal failure. At present, second or third generation PTH assays are available on the market from Roche Diagnostics as well as from others companies but the lack of standardization has complicated the interpretation. Methods We wanted to assess the clinical impact by measuring the PTH levels with the two generations concomitantly on different groups of populations including 46 healthy, 103 pre-dialyzed and 73 hemodialyzed (HD) patients. Results In healthy subjects, the PTH concentrations were not different whatever the generation used, whereas beyond 200 pg/mL, we reported an overestimation of the second generation PTH. In patients with chronic kidney disease (CKD) stage 3–5 the observed differences between the two generations increase with increasing PTH levels and decreasing glomerular filtration rate (GFR). Classification according to the kidney disease: improving global outcomes (KDIGO) revealed a high percentage of discordant results between the two generations (κ coefficient <0.20). These discrepancies are clinically relevant as PTH levels remain the cornerstone for diagnosis and treatment of the CKD-mineral and bone disorder (CKD-MBD). Conclusions The introduction of a new PTH assay generation in clinical practice should be carried out with caution.