A utilização da metodologia semiautomática não interfere significativamente na mensuração da atividade da gama glutamil transferase urinária em cães

Murilo Catelani Ferraz,Tamires Ramborger Antunes,Marcel Capelini Sartoretto,Gustavo Gomes De Oliveira,Alda Izabel De Souza,Mikaelle De Oliveira Castilho

doi:10.21708/avb.2019.13.3.8380

Murilo Catelani Ferraz, Tamires Ramborger Antunes + Show 4 more

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https://doi.org/10.21708/avb.2019.13.3.8380

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Abstract

The urinary gamma-glutamyltransferase (GGTu) is a precocious indicator of renal lesion and the gold standard for the measurement of its activity is the automated method, although semi-automation is often utilized and studies relating this methodology to the occurrence and intensity of analytical errors are still scarce. Therefore, this work aimed to calculate the systematic and random errors in the determination of the GGTu activity in dogs with the use of the semi-automated method and evaluate if that methodology statistically differs from the automated method. 49 dog urine samples were collected through cystocentesis and centrifuged for separation of the supernatant, which was employed for the measurement of the GGTu activity by automated (reference) and semi-automated methods.  Linear regression and Pearson correlation (r) tests were employed for the establishment of the systematic error. The random error was calculated according to Westgard; Hunt (1973). Lin’s concordance correlation coefficient was employed to evaluate the presence of concordance between automated and semi-automated techniques. In the analysis of results, a constant error of + 9.51 UI/L (a = 9.5118), a proportional error of – 9.37% (b=0.9063) and a random error of 9.91% was observed when the semi-automated methodology was employed. The determination (R2) and Lin coefficients were, respectively, 0.9859 with p<0.0001 and 0.9912, suggesting a great similarity and almost perfect concordance between the two methods. Therefore, the data verified that the semi-automation does not interfere significantly in the measurement of the GGTu activity within the minimum and maximum values observed in the study.

Highlights

The gamma-glutamyltransferase is an enzyme that is primarily located in the cells of the loop of Henle and in the proximal convoluted tubules of the nephrons (MELO et al, 2006), possessing antioxidant action and participating in the homeostasis of glutathione and in the transport of amino acids through the cell membranes (YESIL et al, 2014)
This work aimed to calculate the systematic and random errors in the determination of the gama glutamil transferase urinária (GGTu) activity in dogs with the use of the semi-automated method and evaluate if that methodology statistically differs from the automated method. 49 dog urine samples were collected through cystocentesis and centrifuged for separation of the supernatant, which was employed for the measurement of the GGTu activity by automated and semiautomated methods
Since semi-automation is still often employed in several laboratories of clinical analyses, and that studies referring the occurrence and intensity of analytical errors in the measurement of the activity of the GGTu in this type of equipment, this work aimed to calculate the systematic and random errors in the determination of the activity of the GGTu from dogs based on the semiautomated method, as well as to evaluate if the methodology statistically differs from the automated method

Summary

Introduction

The gamma-glutamyltransferase is an enzyme that is primarily located in the cells of the loop of Henle and in the proximal convoluted tubules of the nephrons (MELO et al, 2006), possessing antioxidant action and participating in the homeostasis of glutathione and in the transport of amino acids through the cell membranes (YESIL et al, 2014). This enzyme is a precocious biomarker of renal tubular lesions and precedes alterations in urinary density, serum biochemistry and in the histopathological examination of the patients (CRIVELLENTI et al, 2014; GRAUER et al, 1994). Automated techniques are considered the gold standard test for biochemical analyses, since they provide greater reliability and safety with the minimization of repeatability errors and individual variation between tests, besides the greater quickness to provide test results and the decrease in residue generation (CAMPANA; OPLUSTIL, 2011). Semi-automation, elevates the percentage of errors due to possible failures in the calibration and variation among operators, besides requiring more time and volume for the processing of the samples

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