scholarly journals Test validation, method comparison and reference range for the measurement of β-hydroxybutyrate in peripheral blood samples

2020 ◽  
Vol 30 (1) ◽  
pp. 118-127
Author(s):  
Frank Bernhard Kraus ◽  
Marija Kocijancic ◽  
Alexander Kluttig ◽  
Beatrice Ludwig-Kraus
Keyword(s):  
Peripheral Blood ◽  
Reference Range ◽  
Limit Of Detection ◽  
Method Comparison ◽  
Population Based ◽  
Good Precision ◽  
Serum Samples ◽  
German National Cohort ◽  
Study Results ◽  
National Cohort

Introduction: The measurement of β-hydroxybutyrate (βOHB) concentrations is a corner stone of the diagnosis of diabetic ketoacidosis and other ketonic states. The aim of this study was to perform a validation of a peripheral blood βOHB assay (Randox) on a Roche cobas c502 analyser and to establish a βOHB reference range for the validated assay. Materials and methods: Precision, linearity and limit of detection and blank (LoD, LoB) were determined according to Clinical and Laboratory Standards Institute (CLSI) EP05-A3, EP 06-A and EP17-A2 guidelines, using commercial control material and residual patient sample pools. As method comparison, for 190 semi-quantitative measurements of urine ketones we determined the corresponding βOHB blood concentration. The reference range was based on the CLSI C28-A3 guideline, using 304 randomly selected serum samples from population based German National Cohort (GNC) study. Results: Coefficients of variation for the validated assay ranged from 1.5% for high concentrations (3.1 mmol/L) to 6.5% for low concentrations (0.1 mmol/L). Detection capacity was LoB = 0.011 mmol/L and LoD = 0.037 mmol/L. Linearity of the assay ranged from 0.10 to 3.95 mmol/L. The agreement between the semi-quantitative urine ketone test and the βOHB blood test was moderate (Kappa = 0.66). The obtained 95% serum reference range was estimated as 0.02 to 0.28 mmol/l βOHB. Conclusions: The Ranbut βOHB assay showed good precision and analytical performance. Our results confirm that βOHB measurement in peripheral blood is indeed a preferable alternative to the semi-quantitative measurement of urine ketones.

Rapid 5-fluorouracil plasma quantification by immunoassay: Validation with FOLFOX6 clinical samples.

2011 ◽  
Vol 29 (4_suppl) ◽  
pp. 563-563 ◽  
Author(s):  
S. J. Salamone ◽  
C. N. Benfield ◽  
J. B. Courtney ◽  
R. L. Harney ◽  
D. R. Kozo ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Limit Of Detection ◽  
Plasma Concentrations ◽  
Method Comparison ◽  
Medical Decision ◽  
Clinical Samples ◽  
Fast Time ◽  
Good Precision ◽  
Limit Of Quantitation ◽  
Modified Folfox6

563 Background: 5-fluorouracil (5-FU) is one of the most widely used chemotherapy agents in the treatment of colorectal cancer. Studies over the last 30 years have demonstrated wide pharmacokinetic variability of 5-FU which can lead to undue toxicity and suboptimal treatment. Recent clinical studies have demonstrated that managing plasma 5-FU levels and adjusting doses to target steady state concentrations effectively minimizes toxicity and improves outcome. Methods: An existing immunoassay using a novel antibody to 5-FU was modified to directly quantify 5-FU in patient plasma samples without any sample pretreatment. The assay was adapted to Beckman Coulter AU analyzers and to Roche COBAS c 111 analyzer. Method comparison to LC-MS/MS, limit of detection (LoD), lower limit of quantitation (LLoQ), precision, and linearity of the assay were evaluated. The assay was also validated by testing samples of patients being treated by modified FOLFOX6 from an on-going clinical trial ( NCT00943137 ). Results: The modified immunoassay was confirmed to have a linear reportable range from 85 to 18,000ng/mL and a LoD of 52ng/mL. The immunoassay was established to have good precision (CV<6%) around the medical decision points for FOLFOX and FOLFIRI regimens. Method comparison of the immunoassay obtained by testing 58 clinical samples from patients under 5-FU treatment provides excellent correlation to LC- MS/MS: Deming slope 1 ± 0.05, R > 0.98. Another 82 samples of patients on modified FOLFOX6 regimen from clinical trial (( NCT00943137 ) were tested using the immunoassay and range of these sample were reported to be from 95 to 2,970 ng/mL. Conclusions: The assay provided the performance required to rapidly quantify 5-FU plasma concentrations. It was fast (time to 1st result < 10 minutes), precise, correlated well to a physical method, required only 100uL sample on the analyzer and 7ul for actual testing per assay, and was easily adapted to a variety of clinical analyzers. Clinical and pharmacokinetic laboratories could use this assay to introduce an evidence-based approach to optimize 5-FU dosing that would have higher throughput, simpler methodology, and require less labor, space or expense than the physical methods. [Table: see text]

scholarly journals The method comparison and the verification of precision of Mindray CL-6000i thyroid function tests (TFTs)

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Giray Bozkaya ◽  
Ali Rıza Şişman
Keyword(s):  
Thyroid Function ◽  
Method Comparison ◽  
Endocrine Disorders ◽  
Thyroid Function Tests ◽  
Good Precision ◽  
Serum Samples ◽  
Function Tests ◽  
The Mean ◽  
The Difference ◽  
Mean Differences

AbstractObjectivesThyroid diseases are the most frequent endocrine disorders and thyroid function tests (TFTs) are the most commonly requested endocrine tests. The reliable measurements of these tests are quite important. The aim of our study was to determine the bias and to verify the precision of the newly introduced Mindray CL-6000i immunoassay system in the guidance of CLSI guidelines.MethodsA precision and bias study was performed in Mindray CL-6000i analyzer for FT3, FT4, TSH, Anti-TG, and Anti-TPO tests by using BioRad quality control (QC) materials and serum samples, respectively. Bland–Altman difference plot and Passing-Bablok regression analysis was made for method comparison with Beckman Coulter DXI 800 analyzer.ResultsThe repeatability coefficient of variations (CVs) of FT3, FT4, TSH, Anti-TG, and Anti-TPO tests were ≤2.36, ≤1.66, ≤2.38, ≤3.48, and ≤3.31% while within laboratory CVs were ≤2.85, ≤4.61, ≤2.59, ≤3.78, and ≤3.60%, respectively. The mean differences between the two methods obtained from Bland–Altman analysis for FT3, FT4, TSH, Anti-TG, and Anti-TPO were defined to be −19%, 1.95%, −5.9%, −3.5%, and 7.3%, respectively.ConclusionsMindray CL-6000i had good precision in all tests, but the difference between the two methods in some tests shows that the harmonization and standardization of TFTs initiated globally is required.

scholarly journals Determination of nasal and oropharyngeal microbiomes in a multicenter population-based study – findings from Pretest 1 of the German National Cohort

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Manas K. Akmatov ◽  
Nadine Koch ◽  
Marius Vital ◽  
Wolfgang Ahrens ◽  
Dieter Flesch-Janys ◽  
...  
Keyword(s):  
Population Based ◽  
Population Based Study ◽  
German National Cohort ◽  
National Cohort

Comparison of in-clinic point-of-care and reference laboratory total thyroxine immunoassays for diagnosis and post-treatment monitoring of hyperthyroid cats

2017 ◽  
Vol 20 (4) ◽  
pp. 319-324 ◽  
Author(s):  
Mark E Peterson ◽  
Mark Rishniw ◽  
Graham E Bilbrough ◽  
Kate B Cote
Keyword(s):  
Point Of Care ◽  
Method Comparison ◽  
Reference Interval ◽  
Thyroid Stimulating Hormone ◽  
Reference Laboratory ◽  
Good Precision ◽  
Serum Samples ◽  
Free T4 ◽  
Total Thyroxine ◽  
Assay Precision

Objectives The Catalyst One Chemistry Analyzer (IDEXX Laboratories) is a point-of-care instrument that can measure total thyroxine (TT4) by immunoassay. The aims of this study were to evaluate the analytic performance of the Catalyst TT4 assay in feline sera and to examine agreement of the Catalyst TT4 results with those measured by immunoassay at a veterinary reference laboratory. Methods Assay precision, reproducibility and linearity were evaluated for the Catalyst TT4 assay. For method comparison, TT4 concentrations in serum samples from 157 cats (127 hyperthyroid, 30 radioiodine-treated cats) were analyzed by both in-clinic and reference laboratory methods. Results The Catalyst TT4 demonstrated good precision and reproducibility (coefficients of variation ⩽8.5%) and excellent linearity in the diagnostic range of 6–150 nmol/l. Differences between the two TT4 methods showed no proportional or fixed bias (Bland–Altman plots) but did demonstrate greater spread of values at higher TT4 concentrations. Statistical analysis of percent differences between methods indicated 95% limits of agreement of ± 30%. When serum TT4 concentrations were classified as low, high or within the reference interval (12–50 nmol/l) for each assay, there was strong agreement (96.8%) in classification between methods. Conclusions and relevance The Catalyst TT4 assay provided precise serum TT4 concentrations in the 157 samples analyzed, which agreed well with results provided by a reference laboratory. Cats with Catalyst TT4 concentrations near decision thresholds (eg, normal vs high) should either have TT4 concentration repeated a few weeks later and/or undergo further testing (eg, free T4, serum thyroid-stimulating hormone, thyroid scintigraphy) to determine thyroid status.

scholarly journals Vitamin D testing: Comparison and limitations of currently employed immunoassay with a novel liquid chromatography and tandem mass spectrometry (LCMS/MS) technique.

2021 ◽  
Vol 28 (7) ◽  
pp. 1053-1057
Author(s):  
Sehrish Naz ◽  
◽  
Muhammad Aamir ◽  
Zujaja Hina Haroon ◽  
Sobia Irum ◽  
...  
Keyword(s):  
Vitamin D ◽  
Liquid Chromatography ◽  
Limit Of Detection ◽  
Tertiary Care ◽  
Method Comparison ◽  
Cross Reactivity ◽  
Serum Samples ◽  
Cross Sectional ◽  
Comparison Results ◽  
Limit Of Quantitation

Objective: To compare analytical method for 25 hydroxy vitamin D2 and D3 on LC/MS-MS and with routine vitamin D Immunoassay method. Study Design: Cross Sectional study. Setting: Department of Chemical Pathology and Endocrinology, Pakistan. Period: March 2019 to March 2020. Material & Methods: Samples were extracted and a mass spectrometer coupled to high performance liquid chromatography was adopted for quantitation of 25-hydroxyvitamin D2 and D3 in human samples (serum). After validation it was then applied to 120 serum samples from healthy individuals for method comparison. Results: The method was validated in terms of accuracy, precision, linearity on calibration curve, Limit of Detection and Limit of Quantitation. Our study showed a statistically insignificant difference in results among both the methods (p=0.715). Limit of detection (LOD) was 2.49 ng/ml and limit of quantitation (LOQ) was 3.9 ng/ml for both the metabolites. Percentage RSD was 0.8% and 1.3% for D2 and D3 respectively. This method has an advantage of minimal cross-reactivity with 24,25 hydroxy vit D and 25,26 di- hydroxy vit D metabolite than the routinely used assays. Conclusion: This methodology will be helpful in guiding patient management and assess possibility of malabsorption syndrome in patients on D2 therapy. It can give highly cost effective reliable results of Vitamin D at a tertiary care setting which has an already installed LCMS/MS with huge workload, as compared to costly Immunoassay method.

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