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Is measurement of TT3 by immunoassay reliable at low concentrations? A comparison of the Roche Cobas 6000 vs. LC-MSMS.

ABSTRACT: Thyroid dysfunction is a common medical condition affecting an estimated 30 million people in the US alone. Employing gold standard Liquid chromatography-tandem mass spectrometry (LC-MSMS) methods we have examined the extent of inaccuracy of immunoassay (IA) measurement for total T3 (TT3) at low, normal and high concentrations.268 TT3 Roche Cobas 6000 immunoassay TT3 values (covering the low, normal, and high ranges) were compared with LC-MSMS results.At TT3 concentrations between 50 and 113ng/dL (conversion factor for TT3 to SI Units is ng/dL×0.0154=nmol/L), n=122, LC-MSMS values were lower than immunoassay with 72% found to be below the 2.5th percentile by LC-MSMS compared to 27% for immunoassay. Strikingly 45% of the patients classified as normal TT3 by immunoassay were defined as lower than the 2.5th percentile by LC-MSMS. Only 38 of the 122 patients with low T3's were not receiving T4. In this latter group all of whom had TSH's>3.7mIU/L, 74% of results by LC-MSMS were below the 2.5th percentile while only 21% were below the 2.5th percentile by IA. The clinical consequences of these inaccuracies may affect whether dosing with T4 or combination of T4 with T3 is selected for treatment. Finally the correlation of TT3 with TSH was far superior when TT3 was measured by LC-MSMS. A typical case which demonstrates our message is included.T3 being the active hormone needs to be reliably measured and if the patient has low TT3 and hypothyroid symptoms persist; treatment with T3 should be considered. A typical case report is included to illustrate the problems of inaccurate immunoassay results for TT3. Measurement of TT3 by immunoassay at low concentrations is less than optimal and often provides the clinician with a normal result when the LC-MSMS method and the patient's clinical condition suggests that supplementation with T3 (as in combination therapy) may be required to optimize patient care.

SUBMITTER: Masika LS

PROVIDER: S-EPMC4972640 | biostudies-other | 2016 Aug

REPOSITORIES: biostudies-other

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Is measurement of TT3 by immunoassay reliable at low concentrations? A comparison of the Roche Cobas 6000 vs. LC-MSMS.

Masika Likhona Siphe LS Zhao Zhen Z Soldin Steven John SJ

Clinical biochemistry 20160212 12

<h4>Objectives</h4>Thyroid dysfunction is a common medical condition affecting an estimated 30 million people in the US alone. Employing gold standard Liquid chromatography-tandem mass spectrometry (LC-MSMS) methods we have examined the extent of inaccuracy of immunoassay (IA) measurement for total T3 (TT3) at low, normal and high concentrations.<h4>Design and methods</h4>268 TT3 Roche Cobas 6000 immunoassay TT3 values (covering the low, normal, and high ranges) were compared with LC-MSMS result ...[more]

PMID: 26879528

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Project description:BackgroundMethodological comparisons of hormone quantification techniques have repeatedly demonstrated that, in adults, enzyme immunoassay (EIA) inflates steroid hormone concentrations relative to mass spectrometry. However, methodological comparisons in adolescent samples remain rare, and few studies have examined how chemiluminescent immunoassay (CLIA), another popular immunoassay, compares to mass spectrometry. Additionally, no studies have examined how differences in analytical techniques may be affecting relationships between steroid hormone levels and outcomes of interest, such as psychopathology. This pre-registered analysis of an existing dataset measured salivary cortisol and testosterone using both CLIA and liquid chromatography dual mass spectrometry (LC-MS/MS) in a repeated measures (516 samples) sample of 207 9th graders.MethodsIn aim 1, this study sought to expand on past findings by 1) measuring inflation of testosterone and cortisol by CLIA in a relatively large adolescent sample, and 2) showing that CLIA (like EIA) testosterone inflation was especially true in groups with low 'true' testosterone levels. In aim 2, this study sought to examine the impact of hormone quantification method on relationships between hormone levels and psychopathological measures (the Children's Depression Inventory, the Perceived Social Stress Scale, the UCLA Loneliness Scale, and the Anxious Avoidant and Negative Self Evaluation subscales of the Social Anxiety Scale for Adolescents).ResultsWe found that CLIA, like EIA, inflated testosterone and cortisol levels and overestimated female testosterone resulting in suppressed sex differences in testosterone. We did not observe these same patterns when examining testosterone in individuals with differing levels of pubertal development. Results of psychopathology analyses demonstrated no significant method differences in hormone-psychopathology relationships.ConclusionsOur findings show that CLIA introduces proportional bias in cortisol and testosterone in a manner that suppresses sex differences in testosterone. Steroid measurement method did not significantly moderate the relationship between hormones and psychopathology in our sample, though more work is needed to investigate this question in larger, clinical samples.

Project description:Reducing unnecessary tests and treatments is a potentially promising approach for improving the value of health care. However, relatively little is known about whether insurance type or local practice patterns are associated with delivery of low-value care.To compare low-value care in the Medicaid and commercially insured populations, test whether provision of low-value care is associated with insurance type, and assess whether local practice patterns are associated with the provision of low-value care.This cross-sectional study of claims data from the Oregon Division of Medical Assistance Programs and the Oregon All-Payer All-Claims database included Medicaid and commercially insured adults aged 18 to 64 years. The study period was January 1, 2013, through December 31, 2013.Low-value care was assessed using 16 claims-based measures. Logistic regression was used to test the association between Medicaid vs commercial insurance coverage and low-value care and the association between Medicaid and commercial low-value care rates within primary care service areas (PCSAs).This study included 286?769 Medicaid and 1?376?308 commercial enrollees in 2013. Medicaid enrollees were younger (167 847 [58.5%] of Medicaid enrollees were aged 18-34 years vs 505 628 [36.7%] of those with commercial insurance) but generally had worse health status compared with those with commercial insurance. Medicaid enrollees were also more likely to be female (180 363 [62.9%] vs 702 165 [51.0%]) and live in a rural area (120 232 [41.9%] vs 389 964 [28.3%]). A total of 10 304 of 69 338 qualifying Medicaid patients (14.9%; 95% CI, 14.6%-15.1%) received at least 1 low-value service during 2013; the corresponding rate for commercially insured patients was 35 739 of 314 023 (11.4%; 95% CI, 11.3%-11.5%). No consistent association was found between insurance type and low-value care. Compared with commercial patients, Medicaid patients were more likely to receive low-value care for 10 measures and less likely to receive low-value care for 5 others. For 7 of 11 low-value care measures, Medicaid patients were significantly more likely to receive low-value care if they resided in a PCSA with a higher rate of low-value care for commercial patients.Oregon Medicaid and commercially insured patients received moderate amounts of low-value care in 2013. No consistent association was found between insurance type and low-value care. However, Medicaid and commercial rates of low-value care were associated with one another within PCSAs. Low-value care may be more closely related to local practice patterns than to reimbursement generosity or insurance benefit structures.

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Is measurement of TT3 by immunoassay reliable at low concentrations? A comparison of the Roche Cobas 6000 vs. LC-MSMS.

Publications

Is measurement of TT3 by immunoassay reliable at low concentrations? A comparison of the Roche Cobas 6000 vs. LC-MSMS.

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