How does storage condition interfere with the renal function clinical diagnostic reagent assay kit

Renal function clinical diagnostic kits are widely used in clinical biochemical tests, and the test indicators include creatinine, urea, uric acid, cystatin C, etc. The test results directly affect the evaluation of renal function status and are an important basis for judging acute and chronic renal function damage, adjusting drug dosage, and monitoring the prognosis of renal disease. The kit contains a variety of bioactive substances, enzyme preparations, buffers and calibrators, and their storage conditions have a direct impact on their stability and functionality. Improper storage conditions will lead to degradation of reagent components, reduced activity or changes in the reaction system, seriously affecting the accuracy and reliability of the test.

Effect of temperature on reagent stability
Destructive effect of high temperature environment
High temperature will accelerate the denaturation and inactivation of components such as enzymes and bioactive proteins. For example, creatinase and creatinase used for creatinine detection are very likely to lose their activity at temperatures above 37°C. Some sensitive colorimetric substrates may also undergo spontaneous degradation in high temperature environments, resulting in increased blank values ​​and abnormal background signals. Reagents stored in high temperature environments for a long time may have performance degradation even in the unopened state.
Irreversible damage to some components caused by freezing
Most renal function test kits are recommended to be stored at 2–8°C, and freezing is strictly prohibited. Enzyme proteins or immune components may produce protein aggregation or structural damage during the freezing process, resulting in irreversible loss of their activity. Freezing and thawing may also cause phase separation between components, affecting the stability of the buffer system, and thus interfering with the detection curve.
Effect of temperature fluctuations on intra-batch consistency
Frequent temperature changes will aggravate the physical changes of components in the reagents, such as precipitation, turbidity, and bubble formation. In calibrators and quality control products, concentration stability is extremely dependent on a constant refrigerated environment. Repeated temperature fluctuations will cause calibration value drift, resulting in accumulation of system errors, and reducing intra-batch consistency and repeatability.

Interference of humidity on the physical properties of reagents
Some of the renal function diagnostic kits are powdered or freeze-dried reagents, such as some calibrators, antibody powders, coenzymes, etc., which are easy to absorb moisture and deteriorate. Excessive humidity will cause the following problems:
Moisture absorption causes particles to agglomerate, making it difficult to fully dissolve, and incomplete mixing, affecting the test results.
Water intrusion causes freeze-dried components to rehydrate prematurely, causing degradation or contamination.
Multiple openings or uncontrolled environmental humidity during use will shorten the life of the kit and cause significant batch differences.
For liquid reagents, such as enzyme solutions and substrate solutions, increased humidity does not directly affect their performance, but poor packaging sealing will accelerate gas exchange and indirectly affect their pH stability and reaction kinetics.

Effect of light on chemical stability
Some reagents are particularly sensitive to light, especially colorimetric systems containing photosensitive dyes or substrates (such as TMB, NBT, etc.). Exposure to strong light will cause spontaneous oxidation of the substrate, resulting in color changes or the formation of irreversible intermediates, leading to increased background interference signals. In addition, ultraviolet irradiation may destroy the structure of enzymes and immune complexes, reduce reaction efficiency, and ultimately affect sensitivity and detection limits.
To prevent light interference, renal function diagnostic kits should be stored in a light-proof environment and use light-proof packaging such as brown bottles and aluminum foil bags. During operation, the time the reagents are exposed to direct light should also be minimized.

Effects of air exposure and oxidation on the reaction system
Reagents that are frequently opened, poorly sealed, or exposed to air for a long time are prone to oxidation reactions. Enzyme components such as uricase and catalase are highly sensitive to redox states, and the continuous action of oxygen and moisture in the air may lead to loss of activity. In addition, some reagent systems rely on strict pH control, and the absorption of carbon dioxide in the air will change the pH, affect the speed of substrate catalytic reactions, and cause quantitative deviations.
In particular, if liquid reagents are not tightly sealed or the packaging structure is damaged, they are prone to slow oxidation, reducing storage stability. Once the calibrator is oxidized, it will cause the standard curve to shift, thereby affecting the precision and accuracy of the entire system.

Interaction between packaging materials and storage environment
Packaging materials have a protective and barrier effect on the stability of reagents. Poor-quality packaging materials may adsorb active ingredients, release plasticizers, or react with solutions, resulting in potential contamination. For example, some PVC or PE bottles may undergo adsorption reactions with organic substrates, resulting in a decrease in concentration. In addition, defects in packaging sealing (such as loose bottle caps and poor heat sealing) will also lead to water volatilization and component imbalance.
The cleanliness and microbial control level of the storage environment cannot be ignored. High humidity, high temperature and polluted storage environments are prone to the growth of bacteria or mold, especially for test kits after opening, and more attention should be paid to anti-corrosion and anti-pollution management.