Abstract: S5-11 ASSESSMENT OF UNCERTAINTY IN MEASUREMENT OF CHOLESTEROL; A MODEL OF CALCULATION

What is it about?

Cholesterol assay are used for screening for atherosclerotic risk in the diagnosis and treatment of disorder involving elevated cholesterol levels as well as lipid and lipoprotein metabolic disorders. The objective of this work was that the laboratory must to identify all the components of uncertainty in measurement Cholesterol, to make a reasonable estimation of results, to ensure the form of reporting and determining total allowable errors in the acceptable method Material and Method For identification of sources contributing of the uncertainty in measurement of total Cholesterol in laboratory were necessary the Reference Standard Cholesterol, daily Internal Quality Control with Precinorm L Universal, Lipid Universal Calibrator C.f.a.s. for the Analyzer Hitachi 912, Reference Interval of own laboratory and External Quality Control.

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Why is it important?

Optimization ester cleavage (> 99.5%), allows the standardization using primary and second In own study was excluded potential errors from pre-analytical phase, removing excessive foaming of reagent, overtaking of storage and stability for samples (2-8* C), specimen collection and preparation (suitable primary tubes of plastic) normal Index serum, centrifuge samples before performing assay, analyzing specific instruction assay from prospect Cholesterol Roche Manufacturer, traceability of samples by Analyzer Hitachi 912 by re-calibrating as blank calibrator after reagent bottle charged, 2-point calibrator after reagent lot changed or 2-point calibration as required following quality control procedures with Calibrator for automated system (C.f.a.s.) and verification with Control Pecinorm L for limits of normal intervals. Limits of method because of Interference, +_10% of initial values was excluded by Index Serum. Was follows the Interval of Reference of European Atherosclerosis Society 105-220 mg/dl. Table 1 The Precision of Repeatability was obtained using a normal Reference Material with the interval of values 100.5-82.1, mg/dl, and target value (Xm), 91mg/dl, In processing of work have had in view the Precision (SD) of the Analyzer Hitachi 912, from Internal Protocol SD=(0.8), Precision for Repeatability to serum samples (SD=2.13) and for the Reference Material as ST SD=(2.66), the Bias for ST (7.05%), Linearity of Analyzer(3-800 mg/dl). A comparison of the cholesterol determination with average of own group of laboratories from External Quality Control shown the Zeta Score, SDI, (own average CHOL-own group score CHOL)/ SD= 0. (Normally being +_2) Inter-laboratory studies according to ISO 5725 typically provide Reproducibility Standard Deviation (SD=1) of uncertainty of measurement of any reagent on Analyzer Hitachi 912 type and may provide an estimate of trueness, measured as Bias with respect to a known Reference Value.

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