Cancer Antigen 72-4 (CA72-4)

Sugar chain antigen 72-4, also known as carbohydrate antigen 72-4, cancer antigen 72-4, which is a high molecular glycoprotein carcinoembryonic antigen, sugar chain antigen 72-4 is a gastrointestinal tumor and ovarian cancer Markers are more specific for the diagnosis of gastric cancer than sugar chain antigen 19-9 and carcinoembryonic antigen. Basic Information Specialist classification: Oncology examination classification: immune examination Applicable gender: whether men and women apply fasting: fasting Tips: Before eating, the diet is light, alcohol is forbidden, and good sleep is guaranteed. Check for an empty stomach in the morning. Normal value <6ug/L. Clinical significance Elevated in malignant tumors, the positive rate was 69.7% for gastric cancer, 67% for ovarian cancer, 50% for colon cancer, 47% for rectal cancer, 42% for pancreatic cancer, and 41% for breast cancer. High results may be diseases: lung cancer, stomach cancer, ovarian cancer, colon cancer, rectal cancer, pancreatic cancer First, the precautions before blood draw 1, do not eat too greasy, high-protein food the day before the blood, to avoid heavy drinking. The alcohol content in the blood directly affects the test results. 2. After 8 pm on the day before the medical examination, you should start fasting for 12 hours to avoid affecting the test results. 3, should relax when taking blood, to avoid the contraction of blood vessels caused by fear, increase the difficulty of blood collection. Second, should pay attention after blood draw 1. After blood is drawn, local compression is required at the pinhole for 3-5 minutes to stop bleeding. Note: Do not rub, so as not to cause subcutaneous hematoma. 2, the pressing time should be sufficient. There is a difference in clotting time for each person, and some people need a little longer to clotting. Therefore, when the surface of the skin appears to be bleeding, the compression is stopped immediately, and the blood may be infiltrated into the skin due to incomplete hemostasis. Therefore, the compression time is longer to completely stop bleeding. If there is a tendency to bleed, the compression time should be extended. 3, after the blood draw symptoms of fainting such as: dizziness, vertigo, fatigue, etc. should immediately lie down, drink a small amount of syrup, and then undergo a physical examination after the symptoms are relieved. 4. If there is localized congestion, use a warm towel after 24 hours to promote absorption. 3. Please inform the doctor about the recent medication and special physiological changes before the test. Inspection process Immediately after the blood samples are collected, they are sent for examination and tumor immunoassay. The detection procedure is divided into three steps, namely antigen-antibody reaction, B and F separation, and radioactivity determination. 1. Antigen and antibody reaction: The specimen (non-labeled antigen), labeled antigen and antiserum are sequentially dosed into a small test tube, and allowed to stand at room temperature (15-30 ° C) for 24 hours to fully compete for binding. 2, B, F separation: a variety of separation techniques, commonly used precipitation method. 1 second antibody precipitation method: also known as diabody method, after the test antigen specifically reacts with the first antibody, the corresponding second antibody is added, so that the formed antigen-first antibody-second antibody complex is co-precipitated. The labeled antigen B is separated from the free antigen F by centrifugation. This method is a specific precipitation, complete separation, low non-specific binding. However, the amount of the second antibody is large and the cost is high. In addition, the serum concentration and the presence or absence of anticoagulants can affect the results to some extent. 2 Polyethylene glycol (PEG) precipitation method: the protein is in an isoelectric point state, and the hydration layer is destroyed to cause protein precipitation. The advantage of this method is that PEG is convenient to prepare, inexpensive, and rapid to separate. The disadvantage is that there are many non-specific precipitates and the separation is incomplete. 3Second antibody-polyethylene glycol precipitation method: This method not only has the advantage of rapid precipitation of PEG method, but also maintains the effect of specific precipitation of second antibody, reduces the amount of second antibody, and reduces the concentration of PEG, so that non-specific precipitation Reduced material. 4 Activated carbon adsorption method: the free part of small molecules is adsorbed by the surface activity of activated carbon. For example, a layer of dextran is coated on the surface of the activated carbon to make a mesh having a certain pore diameter on the surface, thereby allowing small molecules of free antigen or hapten to escape and being adsorbed, while the macromolecular complex is excluded. After the antigen and the antibody are reacted, the dextran-activated carbon is added and allowed to stand for 5 to 10 minutes, so that the free antigen is adsorbed on the activated carbon particles, and the particles are precipitated by centrifugation, and the supernatant contains the labeled antigen. 3. Determination of radioactivity: After separation of B and F, the radioactivity can be determined. There are two types of measuring instruments: a liquid scintillation counter (measuring beta rays) and a crystal scintillation counter (measuring gamma rays). The unit of counting is the number of electrical pulses output by the detector in units of cpm (number of pulses/min). A standard curve is required for each measurement, and the different concentrations of the standard antigen are plotted on the abscissa, and the corresponding radioactivity measured is plotted on the ordinate. The radioactivity may be optionally B or F, and the calculated values ​​B/B+F, B/F or B/B0 may also be used. Specimens should be determined in duplicate, the average value is taken, and the corresponding antigen concentration is detected on the standard curve. Not suitable for the crowd Those without examination indications should not be tested. Adverse reactions and risks 1. Infection: Pay attention to aseptic operation when collecting blood, avoid contamination of water and other parts at the blood collection site to avoid local infection. 2, bleeding: after the blood is given a full compression time, especially coagulopathy, bleeding tendency, to avoid local subcutaneous oozing, bruising and swelling.

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