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Functional Sensitivity (functional + sensitivity)

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Medical Sciences	100%

Selected Abstracts

Basal TSH levels compared with TRH-stimulated TSH levels to diagnose different degrees of TSH suppression: diagnostic and therapeutic impact of assay performance

EUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2002
M. Christ-Crain
Abstract Background The estimated prevalence of endogenous subclinical hyperthyroidism varies from 4% to 6% and a basal thyroid stimulating hormone (TSH) level < 0·5 mU L,1 may be associated with increased mortality in subjects over 60 years of age who are not on thyroid medication. Exogenous TSH suppression is a mainstay in the treatment of thyroid cancer. Because of recent concerns about potential adverse effects, especially of endogenous TSH suppression on bone, the cardiovascular system and cognitive functions, subclinical hyperthyroidism obtained new clinical importance. We therefore re-evaluated the diagnostic value of basal and thyrotrop in TRH-stimulated serum TSH measurements using TSH assays with different sensitivities. Materials and methods A total of 805 oral and nasal TRH stimulation tests were performed on 409 ambulatory subjects with low basal serum TSH concentrations of less than 0·1 mIU L,1. Basal serum TSH was measured either using a second generation assay (functional sensitivity > 0·03 mIU L,1) or two third generation assays (functional sensitivity 0·01 mIU L,1 and 0·007 mU L,1, respectively). Serum TSH concentration was determined before and 3 h after oral administration of 40 mg of TRH and before and 30 min after nasal administration of 2 mg of TRH. Results In the oral testing group, the basal TSH levels measured by the different TSH assays were 0·06 ± 0·03, 0·04 ± 0·02 and 0·03 ± 0·02, respectively, whereas the peak TSH levels were 0·4 ± 0·6, 0·4 ± 0·6 and 0·3 ± 0·5 in the patients with subclinical hyperthyroidism. In overt hyperthyroidism, the basal TSH levels were 0·06 ± 0·02, 0·03 ± 0·02 and 0·03 ± 0·02, whereas the peak TSH levels were 0·19 ± 0·3, 0·16 ± 0·3 and 0·15 ± 0·2, respectively. Basal TSH values could discriminate between different degrees of TSH suppression if measured with a third generation assay (P < 0·001), but not with a second generation assay. There was only a weak correlation between basal TSH and peak TSH when measured by a second generation assay (n = 126; r = 0·3; P < 0·001) in contrast to the strong correlation found using the third generation assays (n = 128; r = 0·7; P < 0·001 and n = 69; r = 0·8; P < 0·001, respectively). Conclusions In view of the recent concerns about potential adverse effects in TSH suppression and based on our data, it is mandatory to select a TSH assay with a functional sensitivity of , 0·01 mIU L,1 for optimal titration of L-T4 suppressive therapy, especially in patients with thyroid cancer. If, however, only a second generation TSH assay is available, additional TRH testing allows a more careful titration of suppressive thyroxine therapy. [source]

Usefulness of high-sensitivity IL-6 measurement for clinical characterization of patients with coronary artery disease

JOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2005
Valter Lubrano
Abstract Interleukin 6 (IL-6) may represent an early marker of inflammatory activation and may be useful to ameliorate risk stratification in patients with ischemic heart disease. The aim of this study was to verify the performance characteristics of an ultrasensitive immunoassay (Biosource International, Camarillo, CA) for high-sensitivity (hs)-IL-6 measurement in comparison with hs-R&D Systems (Abingdon, United Kingdom) and Immulite System (Diagnostic Products Corporation [DPC], Los Angeles, CA) methods in patients with ischemic heart disease. In addition, hs,C-reactive protein (hs-CRP) concentrations were measured, to evaluate the correlation with hs-IL-6 levels. We measured IL-6 and CRP serum levels in 39 patients with ischemic heart disease and in 12 controls. Out of the 39 patients studied, 13 were affected by unstable angina, 13 by post,acute myocardial infarction (AMI) unstable angina, and 13 by stable angina. The imprecision profile and functional sensitivity were performed measuring 9 different serum pools in 10 runs. The Biosource method had the best performance characteristics as compared to the others. Mean IL-6 level was higher in patients with unstable and post-AMI unstable angina with respect to controls. CRP levels were elevated in patients with post-AMI. In the whole population a high significant linear regression was observed between Biosource hs-IL-6 and hs-CRP serum levels. The Biosource method for IL-6 measurement is characterized by a high functional sensitivity that allows a better stratification of patients with ischemic heart disease. J. Clin. Lab. Anal. 19:110,114, 2005. © 2005 Wiley-Liss, Inc. [source]

Preoperative undetectable serum thyroglobulin in differentiated thyroid carcinoma: incidence, causes and management strategy

CLINICAL ENDOCRINOLOGY, Issue 4 2007
Luca Giovanella
Summary Background, In recent years serum thyroglobulin (Tg) measurement during thyroxine (T4) treatment and/or after stimulation by endogenous TSH or recombinant human TSH (rhTSH) has eclipsed other diagnostic procedures in managing patients with differentiated thyroid cancer (DTC). However, preoperative undetectable Tg was reported in up to 12% of patients affected by DTC and recurrences of DTC with no increase in serum Tg have also been described. Clearly, a negative Tg measurement may falsely reassure both the patient and the clinician in these cases. Aim, We retrospectively evaluated the incidence of undetectable or reduced preoperative serum Tg in a group of 436 patients affected by DTC. Additionally, we evaluated the role of Tg retesting by two different immunoassays in patients with low Tg at first measurement. Methods, We retrospectively selected 17 patients with undetectable (i.e. less than functional sensitivity of assay method) or reduced Tg (i.e. between functional sensitivity and minimum normal value) among 436 patients with histologically proved DTC. The remaining 419 patients were used as control cases. Frozen sera from all patients were retested by two different Tg immunoassays. Results, Globally, 17 out of 436 (3·8%) patients showed undetectable (n = 5, 1·1%) or reduced (n = 12, 2·7%) preoperative Tg. The Tg level was above the minimum normal value in 3 and 4 out of 5, and 8 and 9 out of 12 of these patients, respectively, when two different immunoassays were employed. On the other hand, undetectable or reduced Tg levels were found in 3·0%,5·1% of control cases when different immunoassays were used. Conclusions, Regardless of the method employed, 3·0,5·1% of patients with DTC showed undetectable or reduced preoperative Tg. This fact must be recognized, as Tg cannot be used as a benchmark for DTC follow-up in these cases. However, Tg retesting with different immunoassays seems to be useful in ruling out these pitfalls in a large majority of patients, and also indicates the most effective assay to be employed in these cases. [source]