What should I pay attention to when testing myocardial enzyme profile clinical diagnostic reagent assay kit

Sample pretreatment is a key step to ensure the accuracy of the test. After the serum sample is collected, centrifugation should be completed within 30 minutes to effectively avoid the interference of cellular metabolites on subsequent test results. For plasma samples, the proportion of anticoagulants must be strictly controlled. For example, the final concentration of EDTA-K2 should be 1.5mg/mL. Any deviation may lead to inhibition of enzyme activity. For hemolytic samples, when the hemoglobin concentration exceeds 2g/L, it is recommended to use a dual wavelength method (such as 450nm and 630nm) to eliminate interference, or correct it by a formula (such as OD correction value = OD measured value-0.001×hemoglobin concentration). When processing lipemia samples, if the triglyceride concentration exceeds 5.65mmol/L, ultracentrifugation (10000×g, 10 minutes) is required to remove chylomicrons. In addition, the storage conditions of the sample are also crucial. It must be frozen at -20℃, and repeated freezing and thawing (no more than 2 times) must be avoided, otherwise the activity of enzymes such as CK-MB may decrease by more than 30%.

The stability of the myocardial enzyme profile clinical diagnostic reagent assay kit is the core guarantee to ensure the reliability of the test. The kit should be stored at 2-8℃ away from light, and restored to room temperature before use, and left to stand for 30 minutes to reduce the effect of temperature gradient on the enzymatic reaction. The concentrated washing solution needs to be diluted with deionized water at a ratio of 1:24, and the color developing agents A and B need to be mixed in equal volumes and stored away from light. The validity period of the mixed solution is only 4 hours. If the batch number of the reagent changes, the linearity must be re-verified. For example, the linear correlation coefficient r of CK-MB in the range of 25-1000U/L should be ≥0.995, and the instrument parameters need to be calibrated. For quality control products containing human components, pathogens such as HBV, HIV, and HCV need to be tested to ensure their safety.

Instrument calibration is a technical prerequisite for ensuring detection consistency. The fully automatic biochemical analyzer needs to be calibrated daily for wavelength (such as 450nm wavelength deviation should be ≤±2nm), temperature calibration (37℃ deviation should be ≤±0.3℃) and sample volume calibration (10μL deviation should be ≤±5%). The spectrophotometer needs to use national first-level standard substances to calibrate the cuvette, and clean the optical system regularly to eliminate dust interference with the test results. During the test, negative quality control (A value ≤ 0.1), positive quality control (A value ≥ 0.6) and critical value quality control (such as CK-MB 25U/L ± 10%) should be set. If the quality control result exceeds the range of 3 standard deviations, the machine should be stopped immediately for cause investigation.

The interpretation of the results should be combined with clinical information and dynamic monitoring for comprehensive analysis. When the CK-MB level is elevated, a comprehensive judgment should be made in combination with troponin I (cTnI) and electrocardiogram (ECG) results: if CK-MB>100U/L and cTnI>0.4ng/mL, the possibility of acute myocardial infarction (AMI) is more than 90%; if CK-MB is slightly elevated (26-50U/L) and cTnI is negative, differential diagnosis of diseases such as myocarditis, skeletal muscle injury or stroke should be considered. For patients receiving thrombolytic therapy, the peak time of CK-MB needs to be dynamically monitored (AMI patients usually reach the peak within 12-24 hours). If the peak is delayed or not reached, it indicates the risk of thrombolytic failure or re-infarction. Through the above rigorous sample processing, reagent management, instrument calibration and result interpretation, the accuracy and reliability of the test can be effectively improved, thus providing a solid foundation for clinical decision-making.