Title:
[Establishment and evaluation of an automatic method for seminal plasma gamma-L-glutamyl transpeptidase detection].

Abstract:
To establish an automatic method for seminal plasma gamma-L-glutamyl transpeptidase (GGT) detection and evaluate its accuracy, repeatability and linear range.
We detected the GGT activity in the seminal plasma by rate assay, and established the detection parameters on an automatic biochemical analyzer. Then, we evaluated the reagent blank absorbance, accuracy, repeatability and linear range of the automatic method, and compared the results obtained from the method and the seminal plasma GGT detection kit (Xindi Biological Pharmaceutical Engineering Co., Ltd, Nanjing, China) commonly used in clinical laboratories.
The average absorbance of reagent blank was 0.0476, and the average change rate of blank absorbance (deltaA/min) was 0.000168. The coefficients of variation (CV) for 3 seminal plasma samples with high, middle and low GGT activity detected for 10 times, respectively, were 0.26%, 4.83% and 1.60%. The accuracy of the automatic method was evaluated by a comparison test, and the relative deviation for each concentration point of 40 seminal plasma samples ranged from 13.38% to 11.05%, which met the requirement of < 15%. There was a good linear relationship (r > 0.99) when the seminal plasma GGT activity was between 299 and 1 833 U/L. A significant positive correlation was found between the seminal plasma GGT detection kit (a colorimetric method) as the control and the automatic method as the test reagent in the results of 115 seminal plasma samples (r = 0.981, P < 0.01), with a Kappa value of 0.776 (P < 0.05) and a coincidence rate of 90.43%.
The established automatic method to detect seminal plasma GGT activity has a low reagent blank, good repeatability and accuracy, and fine concordance with the colorimetric method commonly used in clinical laboratories. It is simple, rapid and suitable for screening large numbers of samples, avoids the necessity of diluting the seminal plasma sample, and saves a lot of manpower and reagents.