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 Harmonization of Serum Thyroid-Stimulating Hormone Measurements Paves the Way for the Adoption of a More Uniform Reference Interval

2017 ◽  
Vol 63 (7) ◽  
pp. 1248-1260 ◽  
Author(s):  
Linda M Thienpont ◽  
Katleen Van Uytfanghe ◽  
Linde A C De Grande ◽  
Dries Reynders ◽  
Barnali Das ◽  
...  
Keyword(s):  
Total Error ◽  
Method Comparison ◽  
Reference Interval ◽  
Thyroid Stimulating Hormone ◽  
Thyroid Function Tests ◽  
Nonparametric Bootstrap ◽  
Serum Samples ◽  
Global Harmonization ◽  
Method Comparison Study ◽  
Stimulating Hormone

Abstract BACKGROUND The IFCC Committee for Standardization of Thyroid Function Tests developed a global harmonization approach for thyroid-stimulating hormone measurements. It is based on a multiassay method comparison study with clinical serum samples and target setting with a robust factor analysis method. Here we describe the Phase IV method comparison and reference interval (RI) studies conducted with the objective to recalibrate the participating assays and demonstrate the proof-of-concept. METHODS Fourteen manufacturers measured the harmonization and RI panel; 4 of them quantified the harmonization and first follow-up panel in parallel. All recalibrated their assays to the statistically inferred targets. For validation, we used desirable specifications from the biological variation for the bias and total error (TE). The RI measurements were done with the assays' current calibrators, but data were also reported after transformation to the new calibration status. We estimated the pre- and postrecalibration RIs with a nonparametric bootstrap procedure. RESULTS After recalibration, 14 of 15 assays met the bias specification with 95% confidence; 8 assays complied with the TE specification. The CV of the assay means for the harmonization panel was reduced from 9.5% to 4.2%. The RI study showed improved uniformity after recalibration: the ranges (i.e., maximum differences) exhibited by the assay-specific 2.5th, 50th, and 97.5th percentile estimates were reduced from 0.27, 0.89, and 2.13 mIU/L to 0.12, 0.29, and 0.77 mIU/L. CONCLUSIONS We showed that harmonization increased the agreement of results from the participating immunoassays, and may allow them to adopt a more uniform RI in the future.

Evaluation of a new free-thyroxin assay.

1981 ◽  
Vol 27 (12) ◽  
pp. 2022-2024 ◽  
Author(s):  
M L Wellby ◽  
L Guthrie ◽  
C P Reilly
Keyword(s):  
Oral Contraceptives ◽  
Reference Interval ◽  
Free T4 ◽  
Single Tube ◽  
High Affinity ◽  
Assay Precision ◽  
Very High ◽  
Interassay Precision ◽  
Better Than

Abstract The Amerlex Free Thyroxin (T4) Radioimmunoassay Kit (Amersham International Ltd.) is a new direct equilibrium radioimmunoassay for free T4 based on an antiserum with very high affinity for T4, and a unique 125I-labeled T4 analog as tracer. It is a very simple single-tube radioimmunoassay, making use of Amerlex particles to separate antibody-bound from free species. Interassay precision (CV) is 3.7% at 13 pmol/L and 2.3% at 30 pmol/L; within-assay precision is 4.2% at 21 pmol/L. The reference interval is 11-22 pmol/L. The assay did not misclassify any patients tested who had untreated myxedema or untreated thyrotoxicosis. The free T4 assay excelled both the free T4 index and the T4/T4-binding globulin ratio in correcting for increased thyroxin-binding globulin from pregnancy, and it was better than the index but not better than the ratio in correcting for increased thyroxin-binding globulin in users of oral contraceptives.

scholarly journals Digital immunoassay for biomarker concentration quantification using solid-state nanopores

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Liqun He ◽  
Daniel R. Tessier ◽  
Kyle Briggs ◽  
Matthaios Tsangaris ◽  
Martin Charron ◽  
...  
Keyword(s):  
Solid State ◽  
Single Molecule ◽  
Dynamic Range ◽  
Point Of Care ◽  
Magnetic Bead ◽  
Thyroid Stimulating Hormone ◽  
Target Protein ◽  
Diagnostic Tools ◽  
Dna Nanostructures ◽  
Serum Samples

ABSTRACTSingle-molecule counting is the most accurate and precise method for determining the concentration of a biomarker in solution and is leading to the emergence of digital diagnostic platforms enabling precision medicine. In principle, solid-state nanopores—fully electronic sensors with single-molecule sensitivity—are well suited to the task. Here we present a digital immunoassay scheme capable of reliably quantifying the concentration of a target protein in complex biofluids that overcomes specificity, sensitivity, and consistency challenges associated with the use of solid-state nanopores for protein sensing. This is achieved by employing easily-identifiable DNA nanostructures as proxies for the presence (“1”) or absence (“0”) of the target protein captured via a magnetic bead-based sandwich immunoassay. As a proof-of-concept, we demonstrate quantification of the concentration of thyroid-stimulating hormone from human serum samples down to the high femtomolar range. Further optimization to the method will push sensitivity and dynamic range, allowing for development of precision diagnostic tools compatible with point-of-care format.

scholarly journals Validation of Nonradioactive Chemiluminescent Immunoassay Methods for the Analysis of Thyroxine and Cortisol in Blood Samples Obtained from Dogs, Cats, and Horses

1997 ◽  
Vol 9 (3) ◽  
pp. 261-268 ◽  
Author(s):  
A. K. Singh ◽  
Y. Jiang ◽  
T. White ◽  
D. Spassova
Keyword(s):  
Enzyme Immunoassay ◽  
Thyroid Stimulating Hormone ◽  
Good Precision ◽  
Blood Samples ◽  
Human Samples ◽  
Total Thyroxine ◽  
Chemiluminescent Immunoassay ◽  
Radioimmunoassay Method ◽  
Reference Samples ◽  
Chemiluminescent Enzyme Immunoassay

The performances of a radioimmunoassay method, a chemiluminescent immunoassay method, and a chemiluminescent-enzyme immunoassay method were evaluated for the analysis of cortisol and total thyroxine in blood samples obtained from dogs, cats, horses, and humans (reference samples). The analysis of cortisol in human and animal samples exhibited good precision, linearity, and recovery. The 3 methods gave comparable values for the ACTH-induced increase and the dexamethasone-induced decrease in cortisol concentrations in animal samples. The recoveries of total thyroxine from human samples, analyzed by the 3 methods, were comparable. However, the basal total thyroxine concentrations determined by the chemiluminescent immunoassay method were 30–40% lower than those determined by the radioimmunoassay and the chemiluminescent-enzyme immunoassay methods in animal samples. In both human and animal samples, the plot of thyroxine values obtained by the radioimmunoassay method against those obtained by the chemiluminescent immunoassay method or the chemiluminescent-enzyme immunoassay method was linear. However, although the slope of the radioimmunoassay versus chemiluminescent-enzyme immunoassay curve was close to unity, the slope of the radioimmunoassay versus chemiluminescent immunoassay curve was 0.6. This result suggests that, compared with the radioimmunoassay method, the chemiluminescent immunoassay method underestimated thyroxine values in animal samples but not in human samples. Although all 3 methods yielded comparable changes in thyroxine concentrations in response to thyroid stimulating hormone, they did not yield comparable thyroxine concentrations in response to T3 suppression in dogs and cats.

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.

Evaluation of a commercially available, point-of-care Coccidioides antibody lateral flow assay to aid in rapid diagnosis of coccidioidomycosis in dogs

2019 ◽  
Vol 58 (3) ◽  
pp. 328-332 ◽  
Author(s):  
Sallianne Schlacks ◽  
Polina Vishkautsan ◽  
Christine Butkiewicz ◽  
Lisa Shubitz
Keyword(s):  
Point Of Care ◽  
Lateral Flow ◽  
Lateral Flow Assay ◽  
Reference Laboratory ◽  
Serum Samples ◽  
Percent Agreement ◽  
Life Threatening Illness ◽  
Life Threatening ◽  
Paired Serum ◽  
High Level

Abstract Coccidioidomycosis in dogs can range from mild respiratory disease or vague, chronic malaise to acute, severe life-threatening illness. The diagnosis of coccidioidomycosis in dogs is based on clinical presentation and serology. Spherule identification is not typical because of low numbers of organisms in specimens, and the invasive nature of sampling tissues and lungs. Conventional serological assays require samples to be submitted to a reference laboratory and results take several days to one week. The sōna Coccidioides Antibody Lateral Flow Assay (LFA) (IMMY Diagnostics) is a rapid, bench-side test used for detection of Coccidioides antibodies that is available and FDA-cleared for use in humans but has not been evaluated in dogs. The goal of this study was to compare the LFA to conventional agar gel immunodiffusion (AGID). Paired serum samples were collected for screening by the LFA and submitted to a commercial reference laboratory for AGID screen and titer. Of 56 paired serum samples analyzed, 30 were positive and 26 were negative on the sōna Coccidioides antibody LFA. The overall percentage agreement plus 95% confidence interval (CI) was 87.5% (76.20–93.99). Positive percent agreement was 89.7% (73.38–96.65) and negative percent agreement was 85.2% (67.25–94.36). The kappa coefficient to assess agreement was 0.749 (95% CI, 0.576–0.923), which is interpreted as good agreement between the tests (>70%). The sōna Coccidioides antibody LFA provided rapid, point-of-care results with a high level of agreement to standard AGID serology in dogs clinically suspected to have coccidioidomycosis, and may aid in diagnosis of coccidioidomycosis in dogs.

scholarly journals Second-Trimester Reference Intervals for Thyroid Tests: The Role of Ethnicity

2007 ◽  
Vol 53 (9) ◽  
pp. 1658-1664 ◽  
Author(s):  
Sonia L La’ulu ◽  
William L Roberts
Keyword(s):  
Thyroid Function ◽  
Thyroid Function Test ◽  
Reference Interval ◽  
Reference Intervals ◽  
Thyroid Stimulating Hormone ◽  
Adverse Outcomes ◽  
Thyroid Peroxidase ◽  
Serum Samples ◽  
Free Triiodothyronine ◽  
Thyroglobulin Autoantibodies

Abstract Background: Thyroid function changes during pregnancy, complicating the diagnosis of thyroid disorders. Maternal thyroid dysfunction has been associated with a variety of adverse outcomes. We evaluated thyroid function test results by ethnicity and week of gestation during the 2nd trimester of pregnancy. Methods: We collected 3064 blood specimens in serum tubes from Asians (13%), blacks (22%), Hispanics (23%), and whites (42%). We measured thyroid-stimulating hormone (TSH), total and free thyroxine (TT4 and FT4), total and free triiodothyronine (TT3 and FT3), thyroglobulin autoantibodies (TgAb), and thyroid peroxidase autoantibodies (TPOAb) by use of an ARCHITECT i2000SR (Abbott Diagnostics). The TSH reference interval was calculated for samples negative for both TgAb and TPOAb and reference intervals for TT4, FT4, TT3, and FT3 in antibody-negative samples with normal TSH. Results: Serum samples were positive for TgAb in 10.6%, 1.8%, 6.2%, 6.5%, and 5.9% of Asian, black, Hispanic, white, and combined groups, respectively. Samples were positive for TPOAb in 12.4%, 4.1%, 11.8%, 12.3%, and 10.4% of the same groups, respectively. The nonparametric reference intervals for all participants were 0.15–3.11 mIU/L (TSH), 9.3–15.2 pmol/L (0.72–1.18 ng/dL; FT4), 89.0–176.3 nmol/L (6.90–13.67 μg/dL; TT4), 3.82–5.96 pmol/L (2.48–3.87 pg/mL; FT3), and 1.82–3.68 nmol/L (118–239 ng/dL; TT3). Conclusions: Blacks had lower prevalences of TgAb and TPOAb positivity and of increased serum TSH. The prevalence of TgAb and TPOAb positivity was highest in Asians. Whites had the highest prevalence of increased TSH. The lower and upper reference limits of TT3 were significantly lower for Asians. Reference intervals for women in the 2nd trimester were different from those of nonpregnant individuals.

scholarly journals 476Associations between prenatal perfluoroalkyl substance exposure and cord thyroid hormones using BKMR model

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Hong Liang
Keyword(s):  
Thyroid Hormones ◽  
Maternal Plasma ◽  
Thyroid Stimulating Hormone ◽  
Birth Cohort Study ◽  
Free T4 ◽  
Exposure Effect ◽  
Substance Exposure ◽  
Total Triiodothyronine ◽  
Total Thyroxine ◽  
Highly Correlated

Abstract Background Perfluoroalkyl substances (PFASs) are a class of synthetic compounds widely detected in humans. We aimed to examine associations between prenatal PFAS exposure and cord thyroid hormones levels. Methods We studied 300 mother-infant pairs in Shanghai-Minhang Birth Cohort Study. We measured eight PFASs in maternal plasma samples collected at 12-16 gestational weeks, and total thyroxine (T4), free T4 (FT4), total triiodothyronine (T3), free T3 (FT3), and thyroid stimulating hormone (TSH) in cord plasma. Bayesian kernel machine regression (BKMR) model was used addressing high correlations between PFAS mixture. Results Maternal PFAS mixture was positively associated with cord T3/FT3 concentrations, such that the 75th percentile of PFAS mixture was associated with 0.074 (95%CI: 0.037, 0.146) nmol/l increase in T3 and 0.095 (95%CI: -0.005, 0.195) pmol/l increase in FT3, compared with the 25th percentile. Regarding single-exposure effect, PFOA at 75th percentile was associated with increased T3 (0.0396 nmol/l, 95%CI: 0.007, 0.072), FT3 (0.159 pmol/l, 95%CI: 0.055, 0.264) and TSH (1.50 uIU/ml, 95%CI: 0.379, 2.621), while PFNA was associated with decreased FT3 (-0.148 pmol/l, 95%CI -0.271, -0.0253) and TSH (-1.621 uIU/ml, 95%CI: -2.959, -0.2835). PFDA was associated with increased FT3 (0.112 pmol/l, 95%CI: -0.0311, 0.2559). Conclusions Prenatal FPAS exposure was positively associated with T3/FT3 with predominant compounds of PFOA, PFNA, and PFDA. Key messages Using BKMR addressing highly correlated PFASs, prenatal exposure to eight PFASs was associated with increased cord T3/FT3 levels with PFOA, PFNA, and PFDA being predominant compounds.

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.

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