Validation study of canine urine cortisol measurement with the Immulite 2000 Xpi cortisol immunoassay

2021 ◽  
pp. 104063872110311
Author(s):  
Jeremie Korchia ◽  
Kathleen P. Freeman
Keyword(s):  
Validation Study ◽  
Interlaboratory Comparison ◽  
Total Error ◽  
Urine Creatinine ◽  
Target Values ◽  
Allowable Error ◽  
Urine Cortisol ◽  
Result Interpretation ◽  
Creatinine Measurement

We report here validation of the Immulite 2000 Xpi cortisol immunoassay (Siemens; with kit lot numbers <550) for measurement of urine cortisol in dogs, with characterization of the precision (CV), accuracy (spiking-recovery [SR] bias), and observed total error (TEo = bias + 2CV) across the reportable range. Linearity assessed by simple linear regression was excellent. Imprecision, SR bias, and TEo increased markedly with decreasing urine cortisol concentration. Interlaboratory comparison studies determined range-based (RB) bias and average bias (AB). The 3 biases (SR, RB, and AB) and resulting TEo differed markedly. At 38.6 and 552 nmol/L (1.4 and 20 μg/dL), between-run CVs were 10% and 4.5%, respectively, and TEoRB were ~30% and 20%, respectively, similar to observations in serum in another validation study. These analytical performance parameters should be considered for urine cortisol:creatinine ratio (UCCR) result interpretation, given that, for any hypothetical errorless urine creatinine measurement, the error % on UCCR mirrors the error % on urine cortisol. Importantly, there is no commonly used interpretation threshold for UCCR, given that UCCR varies greatly depending on measurement methods and threshold computation. To date, there is no manufacturer-provided quality control material (QCM) with target values for urine cortisol with an Immulite; for Liquicheck QCM (Bio-Rad), between-run imprecision was ~5% for both QCM levels. Acceptable QC rules are heavily dependent on the desired total allowable error (TEa) for the QCM system, itself limited by the desired clinical TEa.

scholarly journals Proteinuria in COVID-19: prevalence, characterization and prognostic role

2021 ◽  
Author(s):  
Justine Huart ◽  
Antoine Bouquegneau ◽  
Laurence Lutteri ◽  
Pauline Erpicum ◽  
Stéphanie Grosch ◽  
...  
Keyword(s):  
Urinary Catheter ◽  
Single Center ◽  
Tubular Injury ◽  
Tubular Proteinuria ◽  
Prognostic Role ◽  
Urine Creatinine ◽  
Single Center Study ◽  
Center Study

Abstract Background Proteinuria has been commonly reported in patients with COVID-19. However, only dipstick tests have been frequently used thus far. Here, the quantification and characterization of proteinuria were investigated and their association with mortality was assessed. Methods This retrospective, observational, single center study included 153 patients, hospitalized with COVID-19 between March 28th and April 30th, 2020, in whom total proteinuria and urinary α1-microglobulin (a marker of tubular injury) were measured. Association with mortality was evaluated, with a follow-up until May 7th, 2020. Results According to the Kidney Disease Improving Global Outcomes staging, 14% (n = 21) of the patients had category 1 proteinuria (< 150 mg/g of urine creatinine), 42% (n = 64) had category 2 (between 150 and 500 mg/g) and 44% (n = 68) had category 3 proteinuria (over 500 mg/g). Urine α1-microglobulin concentration was higher than 15 mg/g in 89% of patients. After a median follow-up of 27 [14;30] days, the mortality rate reached 18%. Total proteinuria and urinary α1-microglobulin were associated with mortality in unadjusted and adjusted models. This association was stronger in subgroups of patients with normal renal function and without a urinary catheter. Conclusions Proteinuria is frequent in patients with COVID-19. Its characterization suggests a tubular origin, with increased urinary α1-microglobulin. Tubular proteinuria was associated with mortality in COVID-19 in our restropective, observational study.

Using electrical anisotropy for structural characterization of sediments: an experimental validation study

2016 ◽  
Vol 14 (4) ◽  
pp. 357-369 ◽  
Author(s):  
Sadam Al-Hazaimay ◽  
Johan A. Huisman ◽  
Egon Zimmermann ◽  
Harry Vereecken
Keyword(s):  
Structural Characterization ◽  
Validation Study ◽  
Experimental Validation ◽  
Electrical Anisotropy

Development and Characterization of a Multimycotoxin Reference Material

2019 ◽  
Vol 102 (6) ◽  
pp. 1642-1650 ◽  
Author(s):  
Melissa M. Phillips ◽  
Tomás M. López Seal ◽  
Jennifer M. Ness ◽  
Kai Zhang
Keyword(s):  
Interlaboratory Comparison ◽  
Accurate Determination ◽  
Data Sets ◽  
Mass Fractions ◽  
Adequate Quality ◽  
Multiple Sample ◽  
Lc Tandem Ms ◽  
The U.S

Background: Matrix-matched reference materials (RMs) are critical for adequate quality assurance of extraction, digestion, separation, and/or detection processes for analytes of interest in foods and dietary supplements. The accurate determination of mycotoxins in foods is an international concern. While RMs for mycotoxins are available from a variety of RM producers, these mainly address a single mycotoxin or group of mycotoxins and therefore require the use of multiple RMs for multitarget methods. Objective: To address the increasing needs of laboratories moving toward LC-MS-based multimycotoxin analysis, the U.S. National Institute of Standards and Technology (NIST) collaborated with the U.S. Food and Drug Administration (FDA) to produce a naturally incurred RM for multiple mycotoxins in corn. Methods: Homogeneity of the RM has been assessed using a stratified random sampling of the final product based on mycotoxin mass fractions measured by the FDA and NIST. Multiple sample sizes were evaluated to maximize homogeneity in the obtained results. The mycotoxin levels in the final materials have been evaluated via interlaboratory comparison and isotope dilution LC–tandem MS measurements made at the FDA and NIST. The final value assignment combined results from these data sets. Conclusions: The study successfully developed a certified RM, SRM 1565 Mycotoxins in Corn, and a workflow for the future development of multimycotoxin RMs in different matrices.

Advances in low-field nuclear magnetic resonance (NMR) technologies applied for characterization of pore space inside rocks: a critical review

2020 ◽  
Vol 17 (5) ◽  
pp. 1281-1297 ◽  
Author(s):  
Jian-Chun Guo ◽  
Hang-Yu Zhou ◽  
Jie Zeng ◽  
Kun-Jie Wang ◽  
Jie Lai ◽  
...  
Keyword(s):  
Pore Space ◽  
Structure Characterization ◽  
Fluid Identification ◽  
Low Field ◽  
Signal Collection ◽  
History Of ◽  
Nmr Techniques ◽  
Future Work ◽  
Result Interpretation

Abstract NMR serves as an important technique for probing rock pore space, such as pore structure characterization, fluid identification, and petrophysical property testing, due to the reusability of cores, convenience in sample processing, and time efficiency in laboratory tests. In practice, NMR signal collection is normally achieved through polarized nuclei relaxation which releases crucial relaxation messages for result interpretation. The impetus of this work is to help engineers and researchers with petroleum background obtain new insights into NMR principals and extend existing methodologies for characterization of unconventional formations. This article first gives a brief description of the development history of relaxation theories and models for porous media. Then, the widely used NMR techniques for characterizing petrophysical properties and pore structures are presented. Meanwhile, limitations and deficiencies of them are summarized. Finally, future work on improving these insufficiencies and approaches of enhancement applicability for NMR technologies are discussed.

scholarly journals Clinically Relevant Characterization of Lung Adenocarcinoma Subtypes Based on Cellular Pathways: An International Validation Study

PLoS ONE ◽  
2010 ◽  
Vol 5 (7) ◽  
pp. e11712 ◽  
Author(s):  
Christopher M. Bryant ◽  
Daniel L. Albertus ◽  
Sinae Kim ◽  
Guoan Chen ◽  
Christian Brambilla ◽  
...  
Keyword(s):  
Lung Adenocarcinoma ◽  
Validation Study ◽  
Cellular Pathways

Eight compact analysis systems evaluated for measuring total cholesterol

1994 ◽  
Vol 40 (4) ◽  
pp. 579-585 ◽  
Author(s):  
L C Gregory ◽  
S H Duh ◽  
R H Christenson
Keyword(s):  
Total Cholesterol ◽  
Total Error ◽  
Comparison Method ◽  
The Other ◽  
Sample Type ◽  
Average Bias ◽  
Error Limit ◽  
Absolute Bias ◽  
Allowable Error ◽  
The Mean

Abstract We examined the analytical performance of eight compact systems for measuring total cholesterol: AccuMeter, Cobas Ready, Discovery f2, DT60, L-D-X, Reflotron, QCA, and Vision. We determined average bias at two decision levels, the mean absolute bias, and the percentage of results differing from the comparison method results by &gt; 8.9% allowable total error limit for multiple reagent lots. Average bias was &lt; 3% for all lots tested for AccuMeter, Discovery f2, and DT60, but &gt; 3% for one or more lots or sample types tested with the other systems. Of results from each reagent lot, &gt; 95% were within the 8.9% total error specifications with Discovery f2, DT60, and QCA, whereas the performance of L-D-X, Vision, and Reflotron depended on reagent lot and (or) sample type. Of all results from each lot tested with AccuMeter and Cobas Ready, &gt; 5% exceeded the total allowable error limit. We determined imprecision for five systems: Cobas Ready, Discovery f2, and QCA had CVs &lt; 3%, whereas CVs for AccuMeter and L-D-X were &gt; 3% but &lt; 5%.

Radiochemical characterization of mineral waters for a European interlaboratory comparison

2013 ◽  
Vol 110 ◽  
pp. 675-680 ◽  
Author(s):  
Viktor Jobbágy ◽  
Abdullah Dirican ◽  
Uwe Wätjen
Keyword(s):  
Interlaboratory Comparison ◽  
Mineral Waters

SERS quantitative urine creatinine measurement of human subject

2005 ◽  
Author(s):  
Tsuei Lian Wang ◽  
Hui-hua K. Chiang ◽  
Hui-hsin Lu ◽  
Yung-da Hung
Keyword(s):  
Human Subject ◽  
Urine Creatinine ◽  
Creatinine Measurement

Performance of electrolyte measurements assessed by a trueness verification program

2016 ◽  
Vol 54 (8) ◽  
Author(s):  
Menglei Ge ◽  
Haijian Zhao ◽  
Ying Yan ◽  
Tianjiao Zhang ◽  
Jie Zeng ◽  
...  
Keyword(s):  
External Quality Assessment ◽  
Total Error ◽  
Homogeneous System ◽  
Serum Electrolyte ◽  
Sodium Potassium ◽  
Homogeneous Systems ◽  
Target Values ◽  
Fresh Frozen ◽  
Calcium And Magnesium ◽  
Sodium And Potassium

AbstractIn this study, we analyzed frozen sera with known commutabilities for standardization of serum electrolyte measurements in China.Fresh frozen sera were sent to 187 clinical laboratories in China for measurement of four electrolytes (sodium, potassium, calcium, and magnesium). Target values were assigned by two reference laboratories. Precision (CV), trueness (bias), and accuracy [total error (TEAbout half of the laboratories used a homogeneous system (same manufacturer for instrument, reagent and calibrator) for calcium and magnesium measurement, and more than 80% of laboratories used a homogeneous system for sodium and potassium measurement. More laboratories met the tolerance limit of imprecision (coefficient of variation [CVThe use of commutable proficiency testing/external quality assessment (PT/EQA) samples with values assigned by reference methods can monitor performance and provide reliable data for improving the performance of laboratory electrolyte measurement. The homogeneous systems were superior to the non homogeneous systems, whereas accuracy of assigned values of calibrators and assay stability remained challenges.

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