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Common Problem
Q：What is the solution for mixing different lots of reagents?
A：At present, different lots of reagents are often mixed for detection. On the one hand, mixing them is to save the cost and on the other hand, mixing is for convenient detection. However, no matter what brand of reagent is used, since different lots of reagents were made in different time, the activity of enzyme in the reagent varies and the concentration of hydrolysis substrate varies over time. Therefore, if they are mixed but not calibrated, the detection result may be accurate. If some reagents are uncapped for a long time, the dust or bacteria in the air will enter the reagent bottle. Since some reagents contain a great amount of protein and salt, these components are favorable for bacterial growth. Although some reagents are added with preservative, the preservative has a limited effect on preservation; moreover, the reagents made by most manufacturers do not contain preservative.
Solution:
① It is not recommended to mix different lots of reagents; otherwise, they should be preferably re-calibrated;
② Do not use the reagent bottle too long in the instrument and replace it in time.
③ In general, more or less reagent (several milliliters) will be left in the reagent bottle since it cannot be completely aspirated by the reagent needle. If the reagents are the same lot. In case of the same lot, it can be transferred to the uncapped reagent bottle. In case it comes from different lots, after transferred, it is preferably calibrated. The best way is to retain the residual reagent from each lot and then mix together after reaching a certain volume and then re-calibrate the mixture for detection.
Solution:
① It is not recommended to mix different lots of reagents; otherwise, they should be preferably re-calibrated;
② Do not use the reagent bottle too long in the instrument and replace it in time.
③ In general, more or less reagent (several milliliters) will be left in the reagent bottle since it cannot be completely aspirated by the reagent needle. If the reagents are the same lot. In case of the same lot, it can be transferred to the uncapped reagent bottle. In case it comes from different lots, after transferred, it is preferably calibrated. The best way is to retain the residual reagent from each lot and then mix together after reaching a certain volume and then re-calibrate the mixture for detection.
Q：What are the factors that affect the biochemistry results?
A：1. Instrument
The light-source lamp, transparent window and incubator are not clean. An expired light-source lamp, dirt transparent window and bacterial growth that causes floccular suspension in the water of incubator will directly cause light diffusion and affect the result. Whether the assay cup is clean or not directly affect the precision of detection results. Different assay cups vary in light transmittance. The difference in new assay cups is small, and that in used ones is big; the longer the use time, the bigger the influence. The dirt assay cup will affect the light transmittance, and the residue in the cup will react with the reagent added, so as to affect the detection result. Whether there are bubbles in the sample and reagent pipette and whether the seal ring is aged will also affect the detection result. In case of bubbles in the syringe, replace the seal ring in time. Check whether the sample adding probe and reagent needle are clogged and whether the washing nozzle and waste discharge pipe ware clogged. In case of clogging, it will cause inaccurate liquid volume; unsmooth waste discharge will cause incomplete sample adding probe cleaning, which will have a great influence on the detection result.
2. Reagent, calibrator and control
Expired reagents or their improper storage will cause calibration error, leading to system error of detection result. At the same time, pay attention to the stability period of reagent after uncapping. Select the reagent package suitable for the laboratory volume, so as to ensure the accuracy of detection result. Calibrator and control: after the calibrator is uncapped the calibrator should be used on that day. If the volume is big and the calibrator is expensive, it should be frozen in time, but cannot be frozen and thawed repeatedly. After the control is thawed, it should be sub-packed and frozen so as to ensure accurate detection result. Cross contamination of reagent: the assay cups, pipettes and stirrer of most automatic analyzers are not dedicated; according to the reaction principle of reagents, there is interference between reagents, that may cause:
① Reaction between reagents;
② Influence of residual reagent ();
③ Reaction between the residual reagent and the new reagent;
④ Reaction between the residual reagent, sample and reaction reagent. Therefore, the detection item sequence should be adjusted according to the reaction principle of reagent when setting the detection items.
3. Improper parameter setting
The main parameter settings include:
① Test method and reaction type;
② Sample volume fraction;
③ Selection of primary and secondary wavelengths;
④ Reaction time and temperature;
⑤ Calculation factor;
⑥ Upper and lower limits of linear range and absorbance. If the above parameters are not set properly, it will have a great influence on the test results.
The light-source lamp, transparent window and incubator are not clean. An expired light-source lamp, dirt transparent window and bacterial growth that causes floccular suspension in the water of incubator will directly cause light diffusion and affect the result. Whether the assay cup is clean or not directly affect the precision of detection results. Different assay cups vary in light transmittance. The difference in new assay cups is small, and that in used ones is big; the longer the use time, the bigger the influence. The dirt assay cup will affect the light transmittance, and the residue in the cup will react with the reagent added, so as to affect the detection result. Whether there are bubbles in the sample and reagent pipette and whether the seal ring is aged will also affect the detection result. In case of bubbles in the syringe, replace the seal ring in time. Check whether the sample adding probe and reagent needle are clogged and whether the washing nozzle and waste discharge pipe ware clogged. In case of clogging, it will cause inaccurate liquid volume; unsmooth waste discharge will cause incomplete sample adding probe cleaning, which will have a great influence on the detection result.
2. Reagent, calibrator and control
Expired reagents or their improper storage will cause calibration error, leading to system error of detection result. At the same time, pay attention to the stability period of reagent after uncapping. Select the reagent package suitable for the laboratory volume, so as to ensure the accuracy of detection result. Calibrator and control: after the calibrator is uncapped the calibrator should be used on that day. If the volume is big and the calibrator is expensive, it should be frozen in time, but cannot be frozen and thawed repeatedly. After the control is thawed, it should be sub-packed and frozen so as to ensure accurate detection result. Cross contamination of reagent: the assay cups, pipettes and stirrer of most automatic analyzers are not dedicated; according to the reaction principle of reagents, there is interference between reagents, that may cause:
① Reaction between reagents;
② Influence of residual reagent ();
③ Reaction between the residual reagent and the new reagent;
④ Reaction between the residual reagent, sample and reaction reagent. Therefore, the detection item sequence should be adjusted according to the reaction principle of reagent when setting the detection items.
3. Improper parameter setting
The main parameter settings include:
① Test method and reaction type;
② Sample volume fraction;
③ Selection of primary and secondary wavelengths;
④ Reaction time and temperature;
⑤ Calculation factor;
⑥ Upper and lower limits of linear range and absorbance. If the above parameters are not set properly, it will have a great influence on the test results.
Q：The result of blood sugar measurement is high. The instrument model is AU680. What are the reasons?
A：There are three possible reasons:
1. Interference or cross-contamination can be solved by checking the cleaning device and replacing the reagent test channel in sequence;
2. Reagent failure, which can be verified and solved by replacing a new reagent;
3. The optical path problem of the instrument can be determined by observing the repeatability of ALT and ALT test results, and can be solved by replacing light bulbs and other optical path devices.
1. Interference or cross-contamination can be solved by checking the cleaning device and replacing the reagent test channel in sequence;
2. Reagent failure, which can be verified and solved by replacing a new reagent;
3. The optical path problem of the instrument can be determined by observing the repeatability of ALT and ALT test results, and can be solved by replacing light bulbs and other optical path devices.
Q：The detection result of Cys-C in infants exceeds the upper limit of the recommended reference range (0.56~1.15mg/L). Is it judged as abnormal renal function?
A：Studies have shown that the concentration of serum creatinine in children gradually increases with age, and it does not reach stability until adulthood, so it is difficult to evaluate children's renal function by Scr. In recent years, when some scholars measured the blood CYS-C of 258 normal children without kidney disease, and found that the blood CYS-C concentration was very high within 1 ~ 3 days after birth, reaching 1.64 ~ 2.59 mg/L, which decreased rapidly within 4 months after birth, and gradually stabilized at about 1 year old, about 0.7 ~ 1.38 mg/L. In 69 children aged from 1 to 16, when Cr2EDTA was used as the gold standard for GFR evaluation, the correlation between CYS-C and GFR (r=0.83) was significantly better than that between serum creatinine and GFR (r=0.67).
CYS-C was measured in 58 premature infants, 50 full-term infants and 299 children aged 8 days to 16 years after birth, and there was no gender difference. CYS-C fluctuated from 1.34 to 2.57 mg/L in premature infants and 1.36 to 2.23 mg/L in full-term infants, 0.75 ~ 1.87 mg/L for one year old and 0.68 ~ 1.6 mg/L for one to three years old. Clinically, it was found that CYS-C in children over 3 years old tended to be stable at 0.51 ~ 1.31 mg/L. It is suggested that compared with adults, blood CYS-C as a measure of GFR is also suitable for children and has its own uniqueness.
CYS-C was measured in 58 premature infants, 50 full-term infants and 299 children aged 8 days to 16 years after birth, and there was no gender difference. CYS-C fluctuated from 1.34 to 2.57 mg/L in premature infants and 1.36 to 2.23 mg/L in full-term infants, 0.75 ~ 1.87 mg/L for one year old and 0.68 ~ 1.6 mg/L for one to three years old. Clinically, it was found that CYS-C in children over 3 years old tended to be stable at 0.51 ~ 1.31 mg/L. It is suggested that compared with adults, blood CYS-C as a measure of GFR is also suitable for children and has its own uniqueness.
Q：Why is the CKMB result greater than CK?
A：(1) Detection principle: CK includes two subunits, M.B. The detection principle of three isoenzymes, CK-MM, CK-MB and CK-BB. CK-MB: the content of CK-BB in normal human body is extremely low, which can be ignored. Anti-M subunit antibody is added to the reagent to inhibit the activity of M subunit, and the content of CKMB is expressed by detecting B subunit. When some diseases increase CKBB, it will lead to CKMB false positive.
(2) When CKMB is normal and CK is high, what conditions may appear in patients?
Hemolytic specimen, muscle injury, post-surgery, strenuous exercise, alcoholism, muscular dystrophy;
Example: A retired teacher had CK3000U/L through a physical examination, but CK-MB was normal. After investigation, the teacher was a swimming coach and did excessive exercise the day before the physical examination;
(3) What are the possible causes of CKMB > CK?
① Specimen hemolysis
② CK-BB elevation, giant CK cells, malignant tumor, and brain diseases;
③ Cancer patients with type O or type B blood, the reason is that the immune system of some cancer patients is in disorder, and some immunoglobulins act as coenzymes;
(4) Why the CK-MB result of some controls is greater than CK?
Because there are some additives in the controls, animal tissue (bovine brain) may contain CKBB, so the result of CKMB is greater than CK, but it should not be 2 times greater than CK.
(2) When CKMB is normal and CK is high, what conditions may appear in patients?
Hemolytic specimen, muscle injury, post-surgery, strenuous exercise, alcoholism, muscular dystrophy;
Example: A retired teacher had CK3000U/L through a physical examination, but CK-MB was normal. After investigation, the teacher was a swimming coach and did excessive exercise the day before the physical examination;
(3) What are the possible causes of CKMB > CK?
① Specimen hemolysis
② CK-BB elevation, giant CK cells, malignant tumor, and brain diseases;
③ Cancer patients with type O or type B blood, the reason is that the immune system of some cancer patients is in disorder, and some immunoglobulins act as coenzymes;
(4) Why the CK-MB result of some controls is greater than CK?
Because there are some additives in the controls, animal tissue (bovine brain) may contain CKBB, so the result of CKMB is greater than CK, but it should not be 2 times greater than CK.