Key Points in the Clinical Application and Performance Evaluation of Biochemical Reagent Kits

Methodological Basis of Clinical Chemistry Reagent Kits

Clinical chemistry reagent kits are typically designed around principles such as enzymatic methods, colorimetric methods, and immunoturbidimetric methods, and are used to detect glucose, blood lipids, liver function, renal function, and other indicators in serum or plasma. Different methodologies differ in their sensitivity to factors such as sample anticoagulants, hemolysis, and lipemia. Before introducing a new lot, laboratories should conduct a brief evaluation in combination with the instructions and their own systems. The performance evaluation of clinical chemistry reagent kits generally focuses on items such as blank absorbance, linear range, precision, accuracy, and interference resistance. These indicators need to be confirmed under routine conditions rather than relying solely on the factory parameters provided by the manufacturer.

Main Performance Indicators and Verification Approaches

Precision evaluation is usually divided into within-run and between-run replicate measurements. A common practice is to select quality control materials at normal and abnormal levels for continuous measurement and calculate the coefficient of variation. Linear range verification can be performed by gradient dilution of high-value samples followed by testing, observing the deviation between measured values and theoretical values. Common methods for accuracy evaluation include recovery tests, comparison with established methods, or the use of certified reference materials. The blank absorbance of clinical chemistry reagent kits should remain within the range recommended in the instructions to avoid excessively high reagent background affecting the interpretation of low-value samples. It should be noted that due to differences in instruments, calibrators, and parameter settings among different testing systems, results may show a certain bias. Therefore, reference intervals from other laboratories should not be directly adopted.

Coordination Between Calibration and Internal Quality Control

After opening, clinical chemistry reagent kits should be used according to the storage temperature and in-use shelf life required in the instructions, avoiding repeated freeze-thaw cycles or prolonged exposure to light. Calibration frequency should be determined in combination with instrument stability, reagent lot changes, and internal quality control trends. When quality control results show drift or exceed commonly used rules, the first step should be to investigate whether the reagent kit has expired, whether it has been open for too long, whether the calibrator has lost efficacy, and whether there are abnormalities in the sampling system. Internal quality control should use at least two concentration levels, covering the normal and pathological ranges, which helps identify problems at the end of reagent linearity or cross-contamination.

Common Points for Attention in Clinical Application

In clinical testing, the performance of clinical chemistry reagent kits is not only related to the reagent itself but is also closely associated with sample collection, centrifugation conditions, instrument maintenance, and operator habits. For hemolyzed, lipemic, and icteric samples, laboratories should evaluate their impact on specific test items and record the handling methods. When switching the same test item between different brands or different lots, parallel comparison is recommended to confirm that the bias is within an acceptable range before use for clinical reporting. Only by incorporating clinical chemistry reagent kits into a complete quality management system can the stability and reliability of test results be continuously ensured.