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Seven Basic Indicators of IVD in Vitro Diagnostic Reagents

1. What is IVD reagent blank?

In vitro diagnostic reagent blank can be understood as the value detected when the content of the substance to be tested is theoretically zero. The general practice is to measure with water as a sample, and theoretically this value should be zero. But the actual situation is not the case. Even if the sample added is water, it will show a certain degree of reactivity. A constant blank reactivity does not affect the performance of the IVD diagnostic reagent. However, if the blank reactivity fluctuates greatly, it may lead to inaccurate clinical results. It is caused by the instability of the reaction system of the reagents, such as the instability of the preservative system, buffer system, enzymatic reaction system, etc., will cause the blank reaction degree to change.

2. In-vitro diagnostic reagents analysis sensitivity

Analytical sensitivity refers to the slope of the calibration curve, which can reflect the sensitivity of IVD in vitro diagnostic reagents to changes in the content of the substance to be tested. Take heart marker test for example. If the sensitivity is higher, corresponding to the change in the content of the substance to be tested, the greater the change in the detected experimental value. In this way, even if the content of the tiny substance to be tested changes, it will be found very easily.

3. In-vitro diagnostic reagents linear range

If within a numerical interval, the content of the substance to be tested and the analytically detected value form a good one-to-one correspondence, then we can call this numerical interval the linear range of the diagnostic reagent. The wider the numerical range covered by the linear range, the wider the coverage of clinical samples. Two IVD reagents for detecting the same substance to be tested. Reagent A has a linear range of 0 to 100, and reagent B has a linear range of 10 to 90. Reagent A will be more popular because it takes care of those 0 to 10 and 90 to 100. You don’t need to find a way to re-test the samples, which saves time and energy.

4. In-vitro diagnostic reagents precision

Simply speaking, precision is the repeatability of test results. Two shooters hit targets, each with 5 rounds. Player A's 5 bullets all hit a fixed point in the 6th ring, Player B's 2 bullets hit 7th ring, 2 bullets hit 5th ring, 1 bullet hit 6th ring, the bullets were scattered on the target; the average scores were all 6 rings. Now let you choose a player to play bird, who would you choose? Don't hesitate to choose player A, because the performance is more stable, and only a slight improvement to the aiming system of player A is very likely to hit the bullseye. Player B, on the other hand, has to rely on uncertain factors such as mood, luck, character, etc., in short, unreliable.

5. IVD reagents accuracy

Accuracy reflects the degree of consistency between the detected value of the substance to be tested and the actual value. Let's use target shooting as an example. Two shooters each shoot 5 bullets. Player A's 5 bullets are all around the 9th ring, and Player B's 5 bullets are all around the 8th ring. Naturally, player A's level is higher because of the result. Both are closer to the 10 bullseye ring.

There is a small logic here. The accuracy is high, and the accuracy must be high; high accuracy does not mean high accuracy, but there are some methods to improve accuracy.

6. IVD reagents analysis specificity

Analytical specificity refers to the ability of the test result of the analyte to not be interfered by other components. In other words, the test results of in vitro diagnostic reagents will be affected by the presence of some substances, leading to deviations from the actual situation. Common interfering factors include hemolysis, blood lipids, bilirubin and VC.

If the test results are not affected at all, unless the human body does not have these substances, they are interferences for IVD in vitro diagnostic tests, but they are the components that maintain the body's functions. In this case, only the diagnostic reagent itself can overcome the difficulties. How to overcome it? Improve your own anti-interference ability. If in an environment where a large number of interfering substances exist, the diagnostic reagent can also control the deviation of the detection result from the actual value within an acceptable range, then the anti-interference ability of the reagent will pass.

7. IVD reagents stability

Stability can be divided into long-term stability and open bottle stability. Let's take canned food as an example. If a canned food manufacturer states that as long as the canned food is unopened, it can be eaten safely within three years, then the three-year period represents long-term stability. If a can is opened, the manufacturer says: In order to ensure the best flavor, please finish eating within one week of opening the can. The one-week period represents the stability of the opening. The manufacturer is not responsible for expired consumption.