Evaluation of Performance Characteristics of an In-house Glucose Reagent Compared to Analyzer Specific Commercial Glucose Reagent

Abstract

Blood glucose level is the most frequently analyzed parameter in a routine clinical laboratory in order to assess diabetes mellitus. Currently, commercial reagent kits with high costs are used for this test. However, the same reagent can be prepared in the laboratory at a lower cost. The aim of this study was to examine the performance of an in house reagent method under standard laboratory conditions with the analyzer specific commercial glucose reagent. An evaluation study was carried out at the Clinical Pathology Laboratory, Teaching Hospital, Karapitiya using 200 randomly selected retained blood samples. Glucose values were determined by in-house glucose reagent and commercial glucose reagent. Correlation and the agreement between the two methods were determined. Accuracy, sensitivity, specificity, precision, and stability was checked for the in-house method. Daily IQC and monthly EQA samples were run to assure precision and accuracy. The results were significantly correlated (r=0.9993; p=0.001), and the two methods indicated a good agreement with a positive bias of 0.835±0.488 mg/dL in Bland Altman analysis. There was a good agreement between 0-300 mg/dL. At concentrations above 300 mg/dL, a tendency towards increasing scatter was observed, which could be due to the low number of sample size in this range. Accuracy, sensitivity, and specificity were 96.5%, 96.15% and 97.14% respectively. The in-house method was linear up to 1000mg/dL. An intra-assay precision (CV) of 6.88 and 2.38% and an inter -assay precision of 2.21 and 3.34% were obtained for normal and high levels of glucose respectively. The reagent was stable for a period of three months at 2-8˚C.The in-house glucose reagent is more cost-effective and possesses similar performance characteristics and good stability, compared to the analyzer specific glucose reagent. Thus, it can be adopted for analysis of plasma glucose in routine laboratory checkups.