1,721,147 research outputs found
Harmonization protocols for thyroid stimulating hormone (TSH) immunoassays: different approaches based on the consensus mean value
No full textHarmonization protocols for thyroid stimulating hormone (TSH) immunoassays: different approaches based on the consensus mean value.
No full textThe lack of interchangeable laboratory results and consensus in current practices has underpinned greater attention to standardization and harmonization projects. In the area of method standardization and harmonization, there is considerable debate about how best to achieve comparability of measurement for immunoassays, and in particular heterogeneous proteins. The term standardization should be used only when comparable results among measurement procedures are based on calibration traceability to the International System of Units (SI unit) using a reference measurement procedure (RMP). Recently, it has been promoted the harmonization of methods for many immunoassays, and in particular for thyreotropin (TSH), as accepted RMPs are not available. In a recent paper published in this journal, a group of well-recognized authors used a complex statistical approach in order to reduce variability between the results observed with the 14 TSH immunoassay methods tested in their study. Here we provide data demonstrating that data from an external quality assessment (EQA) study allow similar results to those obtained using the reported statistical approach
Serum thyroglobulin measurement: clinical background and main methodological aspects with clinical impact
No full textIt is worldwide recognized that circulating thyroglobulin (Tg) measurement represents a fundamental tool in the follow-up of patients affected by differentiated thyroid cancer (DTC). In the last American and European Consensus Conferences, a surveillance guideline has been extended to the use of thyrotropin (TSH)-stimulated Tg levels for thyroidectomized patients without clinical evidence of residual tumor with Tg below 1 microg/l during TSH suppression. Therefore, sensitivity of the methods is critical to detect small amounts of Tg and/or to observe minimal changes in Tg concentration in the management of DTC patients. It has been proposed that only methods providing the greatest distinction between the lower limit of euthyroid reference range (approximately 3.0 microg/l) and the functional sensitivity limit (at least 1 microg/l) of the assay may offer a suitable clinical sensitivity for detecting small amounts of functioning thyroid tissue in TSH-suppressed state (1 g of normal thyroid tissue results in a serum Tg of approximately 1 microg/l when TSH is normal and about 0.5 microg/l when TSH is suppressed). In the last 30 years sensitivity of Tg measurements has been greatly improved, nowadays methods can achieve very good analytical and functional sensitivity to give reliable results also in the very low concentration range (between 0.1 and 1 microg/l). In addition, with the introduction of fully automated assays, results can be readily available to the clinician while patients are still in the ambulatory area. However, despite the large clinical use of Tg measurement, wide differences (by threefold) still remain between results produced in different laboratories due to poor standardization, heterogeneity of circulating Tg, interference from auto-antibodies, differences in the epitope recognition by antibodies used in the assay
Evaluation of triiodothyronine (T3) kinetics in normal subjects, in hypothyroid, and hyperthyroid patients using specific antiserum for the determination of labeled T3 in plasma
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Clinical relevance of highly sensitive Tg assay in monitoring patients treated for differentiated thyroid cancer.
No full textOBJECTIVE: Serum thyroglobulin (Tg) represents a highly specific biomarker for detecting residual thyroid tissue/recurrence/metastases after treatment for differentiated thyroid cancer (DTC). We evaluated the clinical impact of a highly sensitive Tg assay during routine follow-up of DTC patients. DESIGN: Tg values were measured by a highly sensitive Tg assay during L-T4 suppressive therapy and after recombinant human thyrotropin (rh-TSH) stimulation and were compared with those obtained by using a routinely employed Tg assay. PATIENTS: One hundred and sixty consecutive DTC-treated patients (papillary carcinoma n = 124, follicular carcinoma n = 36) were studied. MEASUREMENTS: Measured variables included neck ultrasonography, (131)I whole body scanning, and Tg assayed by Immulite (Diagnostic Products Corporation, Los Angeles, CA) and by the highly sensitive Access assay (Beckman Coulter, Brea, CA). RESULTS: During L-T4 therapy, measurable Tg was found in only two patients (1% of total) by Immulite and in 23 patients (14% of total) by Access assay. Using the institutional cut-off of 2 microg/l after rh-TSH, a negative response was associated with undetectable Immulite Tg during L-T4 therapy in all patients (negative predictive value, NPV, 100%) and in 137 out of 152 patients with Access assay (NPV 90%). Measurable Tg during L-T4 therapy was found in 17% of positive patients with Immulite and in 100% of patients with Access, respectively. CONCLUSIONS: The use of a highly sensitive Tg assay may represent a useful diagnostic tool for improving the interpretation of Tg results during monitoring of DTC-treated patients for the early detection of recurrence and for optimizing the use of the more expensive rh-TSH test
Free triiodothyronine (T3) index obtained from measurements of T3 resin uptake and total T3 serum concentration
No full textThyroid hormone concentrations and inhibition of thyroid stimulating hormone secretion in euthyroid subjects wit autonomous thyroid nodules
No full textNatriuretic peptides (NPs): Automated electrochemiluminescent immunoassay for N-terminal pro-BNP compared with IRMAs for ANP and BNP in heart failure patients and healthy individuals.
No full textThe clinical impact of a new highly sensitive thyroglobulin assay in low-risk patients treated for differentiated thyroid cancer
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